KR20140082571A - Silicon nanosheet and preparing method of the same - Google Patents

Abstract

The present invention relates to a silicon nanosheet having a layered structure substantially similar to clay, a manufacturing method thereof, an anode for a lithium ion battery including the silicon nanosheet, and a lithium ion battery including the anode for a lithium ion battery. According to the present invention, the manufacturing method of the silicon nanosheet includes a step of reducing silica, contained in clay, to the silicon nanosheet by treating a mixture containing the clay and alkaline earth metal with heat.

Description

TECHNICAL FIELD [0001] The present invention relates to a silicon nano-

The present invention relates to a silicon nano-sheet including a layered structure substantially similar to that of clay, a method for producing the silicon nano-sheet, an electrode for a battery including the silicon nano-sheet, and a battery including the electrode.

Lithium ion batteries are widely used in energy storage devices for driving electronic devices. BACKGROUND ART [0002] In a lithium ion secondary battery, a material containing graphite is widely used as an anode active material. The average potential when the material containing graphite releases lithium is about 0.2 V (based on Li / Li +), and the potential at the time of discharging changes relatively smoothly. This has the advantage that the voltage of the battery is high and constant. However, since the electrical capacity per unit mass of the graphite material is as small as 372 mAh / g, the capacity of the graphite material at present is improved close to the theoretical capacity, so that the additional capacity increase is difficult.

In order to further increase the capacity of a lithium ion battery, various anode active materials have been studied. As a high capacity negative electrode active material, a material which forms an intermetallic compound with lithium, for example, silicon or tin, is expected as a promising negative electrode active material. Particularly, silicon is an alloy type anode material having a theoretical capacity (4,200 mAh / g) of about 10 times or more higher than that of graphite, and is now regarded as a cathode material of a lithium ion battery. Silicon also has the second greatest occupancy (28% by mass) in the crust, so it can be mass-produced at relatively low cost. For example, Korean Laid-Open Patent Application No. 2012-0061941 discloses an anode material for silicon oxide and a lithium ion secondary battery.

However, the actual capacity tends to decrease sharply because silicon has a large volume change (~ 300%) during charging and discharging, and the physical contact between the materials is broken and the ionic conductivity and electric conductivity are rapidly decreased. Accordingly, it is required to apply a silicon having a high theoretical capacity to a lithium ion battery, and at the same time to develop a technique for minimizing volume change during charging and discharging.

According to the present invention, it is possible to provide a silicon nano-sheet including a layered structure substantially similar to clay, a method for producing the silicon nano-sheet, an electrode for a battery including the silicon nano-sheet, and a battery including the electrode.

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.

According to a first aspect of the present invention, there is provided a method for producing a silicon nanosheet, comprising the step of reducing the silica contained in the clay to a silicon nanosheet by heat treating a mixture comprising clay and an alkaline earth metal Can be provided.

According to the second aspect of the present invention, it is possible to provide a silicon nanosheet including a layered structure substantially similar to clay.

According to a third aspect of the present invention, there is provided an electrode for a battery comprising the silicon nanosheet according to the second aspect of the present invention.

According to a fourth aspect of the present invention, there is provided a lithium ion battery including an anode including a battery electrode according to the third aspect of the present invention, a cathode, and an electrolyte.

According to the manufacturing method of the present invention, a silicon nano-sheet including a layered structure substantially similar to that of clay can be produced. Since the silicon nano-sheet can be manufactured from easily obtainable clay, it is economical and easy to manufacture Do. In addition, since the silicon nanosheets include a structure having a two-dimensional crystal structure, they are resistant to volume change during charging and discharging, so that when used as a negative electrode active material of a battery, the volume change during charging and discharging is minimized and excellent electrical conductivity can be maintained . In addition, since silicon has a high electric capacity, the silicon nanosheets also have a high electrical capacity due to the inherent nature of the silicon.

FIG. 1 is a graph showing a result of powder X-ray diffraction pattern analysis of a silicon nanosheet prepared according to one embodiment of the present invention.
2 is a scanning electron microscope (SEM) image of a silicon nanosheet prepared according to one embodiment of the present application.
FIG. 3 is a graph showing the results of powder X-ray diffraction pattern analysis of the silicon nanosheet prepared according to one embodiment of the present invention.
4 is a scanning electron microscope (SEM) image of a silicon nanosheet prepared according to one embodiment of the invention.
5 is a graph showing the results of powder X-ray diffraction pattern analysis of the silicon nanosheets prepared according to one embodiment of the present invention.
FIG. 6 is a graph showing the results of powder X-ray diffraction pattern analysis of the silicon nanosheet prepared according to one embodiment of the present invention.
FIG. 7 is a graph showing a result of powder X-ray diffraction pattern analysis of a silicon nanosheet prepared according to an embodiment of the present invention.
8 is a high-resolution transmission electron microscope (HR-TEM) image of a silicon nanosheet prepared according to one embodiment of the present invention.
9 is a graph and table showing the BET surface area of silicon nanosheets made from talc according to one embodiment of the present application.
10 is a graph of pore diameter distribution of silicon nanosheets made from talc according to one embodiment of the present application.
Figure 11 is an image of exfoliated laponite made according to one embodiment of the present invention.
Figure 12 is an image of exfoliated bentonite made according to one embodiment of the present invention.
Figure 13 shows a TEM image (a) and a SAED pattern (b) of the laponated laponite prepared according to one embodiment of the present application.
Figure 14 shows a TEM image (a) and a SAED pattern (b) of exfoliated bentonite prepared according to one embodiment of the present application.
15 is a graph comparing the results of powder X-ray diffraction pattern analysis of peeled laponite with unlabeled laponite (a) and peeled bentonite and unpeeled bentonite (b) prepared according to one embodiment of the present invention Fig.
16 is a graph showing the results of powder X-ray diffraction pattern analysis of the peeled laponite silicon nanocrystalline sheet (a) and the peeled bentonite silicon nanocrystal sheet (b) produced according to one embodiment of the present application.
17 is a graph showing a result of a constant current test of a silicon nanosheet manufactured according to an embodiment of the present invention.
18 is a graph showing a result of a constant current test of a silicon nanosheet fabricated according to an embodiment of the present invention.
19 is a graph showing a result of a constant current test of a silicon nanosheet manufactured according to an embodiment of the present invention.
20A to 20C are graphs showing X-ray diffraction analysis results of silicon nanomaterials prepared according to one embodiment of the present invention.
21A to 21C are graphs showing X-ray diffraction analysis results of the silicon nanomaterials prepared according to one embodiment of the present invention.
22A to 22C are graphs showing electrochemical characteristics of silicon nanomaterials prepared according to one embodiment of the present invention.
23A to 23C are graphs showing electrochemical characteristics of silicon nanomaterials prepared according to one embodiment of the present invention.
24A and 24B are graphs showing electrochemical characteristics of silicon nanomaterials prepared according to one embodiment of the present invention.
FIG. 25A is a graph showing the results of X-ray diffraction analysis of silicon nanomaterials prepared according to an embodiment of the present invention, and FIG. 25B is a graph showing the capacity conservation analysis of silicon nanomaterials prepared according to an embodiment of the present invention.
26 is a photograph of a colloidal and pulverized silica-containing material comprising a silica-containing material prepared according to one embodiment of the present application.
27A to 27C are graphs showing X-ray diffraction analysis results of the silicon nanomaterials prepared according to one embodiment of the present invention.
28A to 28C are graphs showing X-ray diffraction analysis results of silicon nanomaterials prepared according to one embodiment of the present invention.
29A-29C show a transmission electron microscope image (Fig. 29A), a high-resolution transmission electron microscope image (Fig. 29B), and a limited field electron diffraction pattern (Fig. 29C) of silicon nanomaterials prepared according to one embodiment of the present application will be.
30A through 30C show a transmission electron microscope image (FIG. 30A), a high resolution transmission electron microscope image (FIG. 30B), and a limited field electron diffraction pattern (FIG. 30C) of silicon nanomaterials prepared according to one embodiment of the present application will be.
31A-C illustrate transmission electron microscopy images (FIG. 31A), high resolution transmission electron microscopy images (FIG. 31B), and limited field electron diffraction patterns (FIG. 31C) of silicon nanomaterials prepared according to one embodiment of the present application will be.
32A to 32C are N ₂ adsorption / desorption isotherms of the silicon nanomaterials prepared according to one embodiment of the present invention.
33A to 33C are graphs showing electrochemical characteristics of silicon nanomaterials prepared according to one embodiment of the present invention.
34A to 34C are graphs showing electrochemical characteristics of silicon nanomaterials prepared according to one embodiment of the present invention.
35A to 35C are graphs showing electrochemical characteristics of silicon nanomaterials prepared according to one embodiment of the present invention.
36A to 36C are graphs showing X-ray diffraction analysis results of silicon nanomaterials prepared according to one embodiment of the present invention.
37A to 37C are graphs showing X-ray diffraction analysis results of the silicon nanomaterials prepared according to one embodiment of the present invention.
38A to 38C show a transmission electron microscope image (Fig. 38A), a high-resolution transmission electron microscope image (Fig. 38B), and a limited field electron diffraction pattern (Fig. 38C) of silicon nanomaterials prepared according to one embodiment of the present application will be.
39A-39C illustrate transmission electron microscopy images (FIG. 39A), high resolution transmission electron microscopy images (FIG. 39B), and limited field electron diffraction patterns (FIG. 39C) of silicon nanomaterials prepared according to one embodiment of the present application will be.
40A to 40C illustrate transmission electron microscopy images (FIG. 40A), high resolution transmission electron microscopy images (FIG. 40B), and limited field electron diffraction patterns (FIG. 40C) of silicon nanomaterials prepared according to one embodiment of the present application will be.
41A to 41C are N ₂ adsorption / desorption isotherms of silicon nanomaterials prepared according to one embodiment of the present invention.
42A to 42C are graphs showing electrochemical characteristics of silicon nanomaterials prepared according to one embodiment of the present invention.
43A to 43C are graphs showing electrochemical characteristics of silicon nanomaterials prepared according to one embodiment of the present invention.
44A to 44C are graphs illustrating electrochemical characteristics of silicon nanomaterials prepared according to one embodiment of the present invention.
45A to 45C are graphs showing X-ray diffraction analysis results of silicon nanomaterials prepared according to one embodiment of the present invention.
46A to 46C are graphs showing X-ray diffraction analysis results of the silicon nanomaterials prepared according to one embodiment of the present invention.
47A through 47C show a transmission electron microscope image (FIG. 47A), a high-resolution transmission electron microscope image (FIG. 47B), and a limited field electron diffraction pattern (FIG. 47C) of silicon nanomaterials prepared according to one embodiment of the present application will be.
48A through 48C show a transmission electron microscope image (FIG. 48A), a high resolution transmission electron microscope image (FIG. 48B), and a limited field electron diffraction pattern (FIG. 48C) of silicon nanomaterials prepared according to one embodiment of the present application will be.
49A through 49C show a transmission electron microscope image (FIG. 49A), a high resolution transmission electron microscope image (FIG. 49B), and a limited field electron diffraction pattern (FIG. 49C) of silicon nanomaterials prepared according to one embodiment of the present application will be.
50A to 50C are N ₂ adsorption / desorption isotherms of silicon nanomaterials prepared according to one embodiment of the present invention.
51A and 51B are graphs showing electrochemical characteristics of silicon nanomaterials prepared according to one embodiment of the present invention.
FIGS. 52A to 52C are graphs showing electrochemical characteristics of silicon nanomaterials prepared according to one embodiment of the present invention.
53A to 53C are graphs showing electrochemical characteristics of silicon nanomaterials prepared according to one embodiment of the present invention.
54A to 54C are graphs showing X-ray diffraction analysis results of the silicon nanomaterials prepared according to one embodiment of the present invention.
55A to 55C are graphs illustrating electrochemical characteristics of silicon nanomaterials prepared according to one embodiment of the present invention.
56A to 56C are graphs illustrating electrochemical characteristics of silicon nanomaterials prepared according to one embodiment of the present invention.

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 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 herein are intended to be taken as a reference to either the numerical value or to the numerical value when the manufacturing and material tolerance inherent in the stated meaning is presented, Accurate or absolute numbers are used to prevent unauthorized exploitation by unauthorized intruders of the mentioned disclosure. Also, throughout the present specification, the phrase " step "or" step "does not mean" step for.

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 the present specification, the term " combination thereof " included in the expression of the machine form means one or more combinations or combinations selected from the group consisting of the constituents described in the expression of the machine form, Quot; and " the "

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

A first aspect of the present invention is a method for producing a silicon nanosheet, comprising reducing the silica contained in the clay to a silicon nanosheet by heat treating a mixture comprising clay and an alkaline earth metal .

As used herein, the term "silicon nano-sheet" specifically refers to a planar structure or a substantially planar structure in which silicon atoms having a two-dimensional crystal form or a tetrahedral crystal form are two- , And the silicon nanosheets may be understood to include one layer of such a planar structure, or the silicon nanosheets include two or more planar structures that are laminated to form a layered structure.

For example, the silicon nanosheets produced by the method of manufacturing a silicon nanosheet according to the present invention may be one in which one or two or more silicon nanosheets are laminated to form a layered structure, but the present invention is not limited thereto .

According to one embodiment of the invention, the clay may comprise a layered structure, for example, may comprise a layered clay, and thus the silica contained in the clay may be reduced, The sheet may also be, but not limited to, having a shape and / or structure corresponding to, or substantially corresponding to, the crystal form and / or structure of the clay.

The two-dimensional plate-like structure of the silicon nanosheets has a large specific surface area and a short lithium ion transfer path and has stability due to structural characteristics. Therefore, the silicon nanosheets having the two-dimensional plate-like structure are maximized in their properties as an electrode material and can be used, for example, as a negative active material for a battery, particularly a lithium ion battery. When the silicon nano-sheet is used as an anode active material of a lithium ion battery, impact due to volume change of deionization of lithium ions due to the structure of the silicon nano-sheet itself can be minimized. In addition, the silicon nano-sheet is an ideal material having high electric capacity due to its inherent nature of silicon. In addition, according to the method for producing a silicon nanosheet, for example, a silicon material having a plate-like structure can be easily synthesized from easily obtainable clay, but the present invention is not limited thereto.

The clay having the layered structure may include a structure in which a sheet including silica and a sheet including a metallic element are alternately stacked in layers. When the clay is reduced, the silica (SiO ₂ ) is reduced to silicon (Si) to form a silicon nanosheet. Impurities other than silicon, such as a metal compound or a metal ion, So that only the silicon nano-sheet can be separated and obtained. For example, the silicon nanosheets may have a structure in which they are layered, but the present invention is not limited thereto.

For example, when the clay is a silicate mineral, silicon tetrahedrons combine in a unique way to form a unique crystal structure, and the silicon nanosheets obtained from the clay can be used as a unique crystal of the used clay Structure, but it is not so limited. For example, when the layered clay is a layered silicate mineral, the silicon nanosheets obtained from the layered silicate mineral having a unique layered bonding method may have a laminated structure derived from the crystal structure of the layered silicate mineral, But may not be limited thereto.

According to one embodiment of the present invention, the reduction of the silica contained in the clay may be by a magnesiothermic reaction, but may not be limited thereto. The magnesiumothermic reaction includes a reaction of reducing an alkali earth metal such as magnesium and a substance to be reduced by heat treatment in a reducing gas atmosphere.

According to an embodiment of the present invention, the heat-treated mixture may further include, but not limited to, obtaining the silicon nanosheet by etching using an acidic solution.

By reducing the silica contained in the clay by heat-treating the mixture comprising the clay and the alkaline earth metal, the silica can be reduced while the alkaline earth metal can be oxidized. The oxidized alkaline earth metal forms an alkaline earth metal oxide, and when the heat-treated mixture is etched using an acidic solution, the alkaline earth metal oxide may be dissolved in the acidic solution and washed out. . For example, when the heat-treated mixture is etched using an acidic solution, the alkaline earth metal oxide and other impurities are washed out, leaving only the reduced layered silica, but not limited thereto.

According to one embodiment of the present invention, the clay may include, but is not limited to, a layered clay.

According to one embodiment of the invention, the layered clay may comprise, but is not limited to, a layered silicate mineral. For example, the layered silicate may comprise a natural layered silicate or a synthetic layered silicate, wherein the layered silicate is selected from the group consisting of three-layer silicates, muscovite, paragonite, Di-to tri-octahedral three-layer silicates of the mica group such as phlogopite and biotite, four-layer silicates of the chlorite group, and kaolinite ), Clay minerals such as montmorillonite, illite, and the like.

According to one embodiment of the present invention, the layer silicate mineral may include, but is not limited to, a phyllosilicate.

According to one embodiment of the present invention, the phyllosilicate may be represented by the following general formula (1), but is not limited thereto.

[Formula 1]

[M _{n / valency} ] ^inter [M ^I _m M ^II _o ] ^oct [M ^III ₄ ] ^tet X ₁₀ Y ₂

Wherein,

M is a metal cation having an oxidation state of 1 to 3,

M ^I is a metal cation whose oxidation state is 2 or 3,

M ^II is a metal cation whose oxidation state is 1 or 2,

M ^III is an element having an oxidation state of 3 or 4,

X is a divalent anion,

Y is a monovalent anion,

M is about 2.0 when the oxidation state of the metal element M ^I is 3, m is about 3.0 when the oxidation state of the metal element M ^I is 2,

o ≤ 1.0,

The layer charge n is about 0.2 to about 0.8.

In the general formula 1, "valence" means the number of covalent bonds that the element can have, "inter" means that the elements are present between the layers of the phyllosilicate, "oct (octahedral) Quot; tetrahedral "may mean that the elements may have an octahedral structure, and" tet (tetrahedral) " may mean that the elements have a tetrahedral structure.

According to one embodiment of the present disclosure, the phyllosilicate is selected from the group consisting of talc, mica, smectite-family minerals, magadiite, kenyaite, stevensite, but are not limited to, those selected from the group consisting of halloysite, aluminate oxide, hydrotalcite, and combinations thereof.

According to one embodiment of the present invention, the smectite-based mineral is selected from the group consisting of montmorillonite, nontronite, beidellite, bentonite, hectorite, but are not limited to, those selected from the group consisting of laponite, saponite, sauconite, vermiculite, and combinations thereof.

According to one embodiment of the present invention, the alkaline earth metal may include, but is not limited to, a metal selected from the group consisting of Be, Mg, Ca, Sr, Ba, and combinations thereof. The preferred alkaline earth metal herein is magnesium.

According to one embodiment of the present invention, the alkaline earth metal may be in powder form, but it is not limited thereto. For example, when the alkaline earth metal is in the form of a powder, it may be easily mixed with the clay at the time of preparation of the mixture, but may not be limited thereto.

According to one embodiment of the disclosure, the heat treatment may be performed at a temperature of about 300 ° C to about 1,000 ° C, but is not limited thereto. For example, the heat treatment may be performed at a temperature of from about 300 캜 to about 1,000 캜, from about 400 캜 to about 1,000 캜, from about 500 캜 to about 1,000 캜, from about 600 캜 to about 1,000 캜, About 300 deg. C to about 700 deg. C, about 300 deg. C to about 600 deg. C, about 300 deg. C to about 1,000 deg. C, about 900 deg. 500 ° C, or from about 300 ° C to about 400 ° C.

According to one embodiment of the present application, the heat treatment may be performed at a temperature of about 400 ° C to about 800 ° C, but may not be limited thereto.

According to one embodiment of the present application, the heat treatment may be performed at a temperature of about 550 ° C to about 750 ° C, but may not be limited thereto. For example, the heat treatment may be performed at a temperature of from about 600 ° C to about 650 ° C, from about 600 ° C to about 700 ° C, from about 600 ° C to about 750 ° C, from about 550 ° C to about 700 ° C, Lt; 0 > C to about 600 < 0 > C, although the present invention is not limited thereto.

According to one embodiment of the invention, the acidic solution may be about pH 6 or less, but it is not limited thereto. For example, the acid solution may be about pH 6 or lower, about pH 5 or lower, about pH 4 or lower, about pH 3 or below, about pH 2 or below, or about pH 1 or below.

According to one embodiment of the present invention, the acidic solution may be, but not limited to, about pH 3 or less.

According to one embodiment of the present invention, the acidic solution may include, but is not limited to, an inorganic acid.

According to one embodiment of the invention, the inorganic acid is selected from the group consisting of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, perchloric acid, chloric acid, chlorous acid, hypochlorous acid, iodic acid, , But may not be limited thereto.

According to one embodiment of the present invention, the molar ratio of silicon contained in the clay and the alkaline earth metal in the mixture may be from about 1: 0.1 to about 1: 10, but is not limited thereto. For example, in the mixture, the molar ratio of silicon contained in the clay and the alkaline earth metal is from about 1: 0.1 to about 1:10, from about 1: 0.1 to about 1: 9, from about 1: 0.1 to about 1: From about 1: 0.1 to about 1: 4, from about 1: 0.1 to about 1: 6, from about 1: 0.1 to about 1: 5, from about 1: From about 1: 0.1 to about 1: 1, from about 1: 0.1 to about 1: 0.5, from about 1: 0.5 to about 1: 10, from about 1: From about 1: 2 to about 1:10, from about 1: 3 to about 1:10, from about 1: 4 to about 1:10, from about 1: 5 to about 1:10, from about 1: 6 to about 1: , About 1: 7 to about 1:10, about 1: 8 to about 1:10, or about 1: 9 to about 1: 10.

According to one embodiment of the invention, the molar ratio of silicon and alkaline earth metal contained in the clay in the mixture may be from about 1: 0.5 to about 1: 5, but is not limited thereto.

According to one embodiment of the invention, the molar ratio of silicon and alkaline earth metal contained in the clay to the clay may be from about 1: 0.5 to about 1: 3, but the present invention is not limited thereto.

For example, the clay may be a layered structure oxide including aluminum and silicon, but may not be limited thereto. Since the clay is inexpensive and easy to obtain and contains layered silica (SiO ₂ ), it is possible to produce the silicon nanosheet easily and economically by reducing the silica.

The Talc is represented by the formula Mg ₃ Si ₃ O ₁₀ (OH) ₂ . The crystal structure of the talc includes a form in which a sheet (Mg ₁₂ O ₁₂ H ₄ ) containing magnesium is sandwiched between _two sheets of silica (SiO ₂ ). The three sheets are combined to form one layer, the one layer being electrically neutral and each layer being bonded by a weak van der Waals force.

The laponite also has a very similar structure to the talc. The laponite includes a shape in which a sheet containing magnesium is sandwiched between two silica sheets. However, unlike the talc, the laponite is negatively charged because each part of the magnesium sheet is replaced by lithium. Therefore, in order to maintain the electrical neutrality as a whole, sodium (Na) cations are contained between the layers and each layer is combined with each other by electrical interaction.

According to one embodiment of the present invention, the reduction may be performed in a reducing atmosphere, but the present invention is not limited thereto.

According to one embodiment of the present invention, the reduction may be performed in an atmosphere containing an inert gas, but may not be limited thereto. For example, the reduction may be performed in an atmosphere containing hydrogen gas and an inert gas, but the present invention is not limited thereto.

For example, the inert gas may include, but is not limited to, a gas selected from the group consisting of nitrogen gas, argon gas, neon gas, helium gas, and combinations thereof.

According to one embodiment of the present invention, the reduction may further include, but is not limited to, stirring and / or washing the heat-treated mixture.

According to one embodiment of the present invention, the stirring and / or washing may be performed using a polar solvent, but the present invention is not limited thereto.

According to one embodiment of the present invention, the polar solvent may include, but is not limited to, water, an alcohol, an organic polar solvent, or a mixture thereof. For example, the water may include, but is not limited to, primary distilled water, secondary distilled water, or tertiary distilled water.

According to one embodiment of the invention, the clay may include, but is not limited to, delaminated.

According to one embodiment of the present application, before the heat treatment of the mixture comprising the clay and the alkaline earth metal, a cation of an alkaline earth metal is added to the clay to restack the clay, or the clay is frozen Drying, and the like, but the present invention is not limited thereto. At least one metal cation selected from the group consisting of beryllium, magnesium, calcium, strontium, barium, and combinations thereof may be included in the cations of the alkaline earth metal for the purposes herein. Preferred cations of the alkaline earth metal herein are magnesium cations.

For example, the specific surface area of the silicon nanosheets may be increased due to the reclaimed layer or freeze-drying, but the present invention is not limited thereto. When the specific surface area of the silicon nanosheets is increased, the area where the interaction with the electrolyte is widened may increase the performance of the battery including the lithium ion battery. However, the present invention is not limited thereto.

According to one embodiment of the present application, the mixture comprising the clay and the alkaline earth metal may include, but is not limited to, addition of graphene oxide. In a preferred embodiment of the invention, the oxidized graphene has a nanosheet form.

According to one embodiment of the present application, the silica and the oxide grains contained in the clay are heat treated with a silicon nano-sheet and a graphene, respectively, by heat-treating the mixture containing the clay and the alkaline earth metal, And forming a complex containing silicon and graphene by reducing the metal complex. In a preferred embodiment of the present invention, the silica contained in the layered clay and the oxidized graphene nanosheet are reduced so that a composite containing the silicon nanosheet and the graphene nanosheet can be obtained.

For example, the silicon and the graphene may be hybridized to each other in the process of reducing the silica contained in the clay and the graphene oxide with the silicon nanosheets and graphene, but the present invention is not limited thereto. For example, due to the hybridization of silicon and graphene, the formed silicon nanosheets may contain silicon and graphene, but the present invention is not limited thereto.

The second aspect of the present application can provide a silicon nanosheet comprising a layered structure substantially similar to clay.

For example, the clay may include a layered clay, and may have a plate-like crystal form and / or a layered structure, and thus the silicon nanosheets produced by reducing the silica contained in the clay may also be used as the clay But may not be limited to, those having a shape and / or structure corresponding to, or substantially corresponding to, a crystalline form and / or structure. For example, the silicon nanosheets may include a plate-like two-dimensional crystal form or a structure having a tetrahedral or tetrahedral crystal form.

According to one embodiment of the present invention, the silicon nanosheets may be produced by the method of the first aspect of the present invention, but are not limited thereto.

According to one embodiment of the present disclosure, the silicon nanosheets may have a BET surface area of from about 20 m ² / g to about 300 m ² / g, but are not limited thereto. For example, the silicon nanosheets may have a BET surface area of from about 20 m ² / g to about 300 m ² / g, from about 40 m ² / g to about 300 m ² / g, from about 60 m ² / g to about 300 m ² / g, about 80 m ² / g to about 300 m ² / g, about 100 m ² / g to about 300 m ² / g, about 150 m ² / g to about 300 m ² / g, about 200 m ² / g to about 300 m ² / g, about 250 m ² / g to about 300 m ² / g, about 20 m ² / g to about 250 m ² / g, about 20 m ² / g to about 200 m ² / g, about 20 m ² / g to about 150 m ² / g, about 20 m ² / g to about 100 m ² / g, about 20 m ² / g to about 80 m ² / g, about 20 m ² / g to about 60 m ² / g, or from about 20 m ² / g to about 40 m, but may be a ² / g, it may not be limited thereto.

According to one embodiment of the present invention, the silicon nanosheets may have a size of about 10 nm to about 300 nm and have an aspect ratio of about 1: 1 to about 1:10, but are not limited thereto. For example, the silicon nanosheets may have a thickness of from about 10 nm to about 300 nm, from about 10 nm to about 250 nm, from about 10 nm to about 200 nm, from about 10 nm to about 150 nm, from about 10 nm to about 100 nm, From about 10 nm to about 30 nm, from about 10 nm to about 20 nm, from about 20 nm to about 300 nm, from about 30 nm to about 300 nm, from about 50 nm to about 300 nm, from about 100 nm To about 300 nm, from about 150 nm to about 300 nm, from about 200 nm to about 300 nm, or from about 250 nm to about 300 nm. For example, the silicon nanosheets can be used at a ratio of about 1: 1 to about 1:10, from about 1: 2 to about 1:10, from about 1: 3 to about 1:10, from about 1: 4 to about 1:10, 1: 5 to about 1:10, about 1: 6 to about 1:10, about 1: 7 to about 1:10, about 1: 8 to about 1:10, about 1: 9 to about 1:10, 1: 1 to about 1: 6, about 1: 1 to about 1: 5, about 1: 1 to about 1: But may not be limited to, having an aspect ratio of from about 1: 1 to about 1: 4, from about 1: 1 to about 1: 3, or from about 1: 1 to about 1: 2.

According to one embodiment of the present invention, the average particle size of the silicon nanosheets may be from about 10 nm to about 400 nm, but is not limited thereto. For example, the average particle size of the silicon nanosheets may range from about 10 nm to about 400 nm, from about 30 nm to about 400 nm, from about 50 nm to about 400 nm, from about 80 nm to about 400 nm, from about 100 nm to about 400 nm About 400 nm to about 400 nm, about 200 nm to about 400 nm, about 250 nm to about 400 nm, about 300 nm to about 400 nm, about 350 nm to about 400 nm, about 10 nm to about 350 nm , From about 10 nm to about 300 nm, from about 10 nm to about 250 nm, from about 10 nm to about 200 nm, from about 10 nm to about 150 nm, from about 10 nm to about 100 nm, from about 10 nm to about 80 nm, From about 10 nm to about 50 nm, from about 10 nm to about 30 nm, from about 100 nm to about 300 nm, from about 100 nm to about 200 nm, or from about 100 nm to about 150 nm.

According to an embodiment of the present invention, the silicon nanosheets may be hybridized with at least one conductive carbon compound. For example, the conductive carbon compound may be selected from the group consisting of carbon black, acetylene black, active carbon, carbon nanotubes (CNT), graphite, graphene, But it is not limited thereto. In certain embodiments of the invention, the silicon nanosheets may exhibit better electrode performance by being hybridized with graphene.

The third aspect of the present invention can provide an electrode for a battery comprising the silicon nanosheet according to the second aspect of the present invention. For example, the electrode can be a battery, particularly a lithium battery such as a lithium ion battery, a lithium air battery, and a lithium sulfur battery, or a sodium battery such as a sodium ion battery and a sodium sulfur battery But may not be limited thereto. For example, the silicon nanosheets may be included as an anode active material of a lithium ion battery, but the present invention is not limited thereto.

A fourth aspect of the present invention may provide a battery comprising an anode, a cathode, and an electrolyte comprising an electrode according to the third aspect of the present application. In certain embodiments of the present application, a lithium ion battery comprising an anode, a cathode, and an electrolyte comprising an electrode according to the third aspect of the present invention can be provided.

According to one embodiment of the present application, the cathode may comprise a material selected from the group consisting of a lithium-containing oxide, a lithium-containing sulfide, a lithium-containing selenide, a lithium-containing halide, and combinations thereof. .

According to one embodiment of the invention, the lithium-containing oxide is _{LixCoO 2 (0.5 <x <1.3} ), Li x NiO 2 (0.5 <x <1.3), Li x MnO 2 (0.5 <x <1.3), Li x Mn _{2 O 4 (0.5 <x <} 1.3), Li x (Ni a Co b Mn c) O 2 (0.5 <x <1.3, 0 <a <1, 0 <b <1, 0 <c <1, a + b + c = 1), Li x Ni 1 - y Co y O 2 (0.5 <x <1.3, 0 <y <1), Li x Co 1 - y Mn y O 2 (0.5 <x <1.3, 0≤ _{y <1), Li x Ni} 1 - y Mn y O 2 (0.5 <x <1.3, O≤y <1), Li x (Ni a Co b Mn c) O 4 (0.5 <x <1.3, 0 < 2, 0 < c < 2, a + b + c = 2), Li _x Mn _{2 - z} Ni _z O _{4 x} Mn _{2 - z} Co _z O ₄ (0.5 <x <1.3, 0 <z <2), Li _x CoPO ₄ (0.5 <x <1.3), Li _x FePO ₄ (0.5 <x <1.3), and combinations thereof But is not limited thereto.

According to another embodiment of the invention, the cathode may comprise at least one sodium-containing compound such as a sodium-metal mixed oxide, particularly at least one cathode active material capable of inserting and de-inserting sodium have. Examples of the cathode active material of the present application _{is, NaFeO 2, NaCoO 2, NaCrO} 2, NaMnO 2, NaNiO 2, NaNi 1/2 Ti 1/2 O 2, NaNi 1/2 Mn 1/2 O 2, Na 2/3 _{Fe 1/3 Mn 2/3 O 2, NaNi} 1/3 Co 1/3 Mn 1/3 O 2, NaMn 2 O 4, NaNi 1/2 Mn 3/2 O 2, NaFePO 4, NaMnPO 4, NaCoPO 4 , Na ₂ FePO ₄ F, Na ₂ MnPO ₄ F, Na ₂ CoPO ₄ F, and any combination thereof.

According to one embodiment of the present invention, the electrolyte is not particularly limited and may include, but is not limited to, a conventional lithium salt and a solvent. For example, the lithium ion battery may include, but is not limited to, an electrolyte containing a silane-based compound represented by the following formula as an additive:

Si- (R) _y (OR ') _4-y

In the above formula, R is an alkyl group or a vinyl group, R 'is an alkyl group or an alkyl group substituted with an alkoxy group, and y is an integer selected from 1 to 3.

In the above formulas, the alkyl group is a C ₁ -C ₃₀ alkyl group, the vinyl group is a C ₂ -C ₂₀ vinyl group, and the alkoxy group may be a C ₁ -C ₃₀ alkoxy group, but the present invention is not limited thereto. The silane compound may be exemplified by Si- (R) ₁ (OR ') _3, and may be exemplified by trimethoxy (methyl) silane (SiCH ₃ (OCH ₃ ) ₃ ), or tris (2-methoxyethoxy) Silane (CH ₂ = CHSi (OCH ₂ CH ₂ OCH ₂ ) ₃ ).

The electrolyte containing the silane-based compound may include about 2 wt% to about 10 wt% of the silane-based compound. In this case, it is possible to efficiently form the protective layer on the surface of the silicon oxide while maintaining the inherent performance of the electrolyte. And may be more advantageous, but may not be limited thereto.

For example, the lithium salt of the electrolyte is selected from the group consisting of LiTFSi, LiPF _6, and the lithium salt is selected from the group consisting of the combination of LiFSi and a non-water-soluble carbonate-based solvent or LiTFSi, LiPF _6, and combinations of LiFSi and But are not limited to, electrolytes containing a room temperature ionic liquid solvent which is one selected from imidazolium series, pyrrolidinium series and piperidinium series. In certain embodiments of the invention, the electrolyte may optionally comprise LiPO ₂ F ₂ in combination with one or more of the lithium salts described above.

According to one embodiment of the present application, the electrolyte may comprise at least one additive, in particular a fluorinated organic compound, such as fluorine-substituted ethylene carbonate, polyfluoro-substituted dimethyl carbonate, But are not limited to, fluorinated carbonic esters selected from the group consisting of fluorine-substituted ethylmethyl carbonate, and fluorine-substituted diethyl carbonate. Preferred fluorine-substituted carbonates are monofluoroethylene carbonate (F1EC), 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate (4,5 fluoro-4-methyl ethylene carbonate, 4,5-difluoro-4-methylethylenecarbonate, 4,5-difluoro-4- methyl ethylene carbonate, 4-fluoro-5-methyl ethylene carbonate, 4,4-difluoro-5-methyl ethylene carbonate, 4- (fluoromethyl) -ethylene carbonate, 4- (difluoromethyl) -ethylenecarbonate, 4- ( Trifluoromethyl) -ethylene carbonate [4- (trifluoromethyl) -ethylene carbonate], 4- (fluoromethyl) -4-fluoroethylenecarbonate Fluoromethyl-5-fluoro-ethylene carbonate], 4- (fluoromethyl) -5-fluoro-ethylene carbonate, 4-fluoro-4,5-dimethyl ethylene carbonate], 4,5-difluoro-4,5-dimethyl ethylene carbonate], 4,5- And 4,4-difluoro-5,5-dimethyl ethylene carbonate; Fluoromethyl methyl carbonate, difluoromethyl methyl carbonate, trifluoromethyl methyl carbonate, bis (difluoro) methyl carbonate [bis (difluoro) methyl carbonate , And bis (trifluoro) methyl carbonate [bis (trifluoromethyl) carbonate]; 2-fluoroethyl methyl carbonate, ethyl fluoromethyl carbonate, 2,2-difluoroethyl methyl carbonate, 2-fluoroethyl methyl carbonate, 2-fluoroethyl fluoromethyl carbonate, ethyl difluoromethyl carbonate, 2,2,2-trifluoroethyl methyl carbonate, 2 (trifluoromethyl) methyl carbonate, , 2-difluoroethyl fluoromethyl carbonate, 2-fluoroethyl difluoromethyl carbonate, and ethyl trifluoromethyl carbonate Ethyl methyl carbonate; Ethyl (2-fluoroethyl) carbonate, ethyl (2,2-difluoroethyl) carbonate, bis (2-fluoroethyl) carbonate, Ethyl (2, 2-trifluoroethyl) carbonate], ethyl (2,2,2-trifluoroethyl) carbonate, 2,2-difluoroethyl 2 Bis (2,2-difluoroethyl) carbonate, 2,2,2-difluoroethyl carbonate, 2,2-difluoroethyl carbonate, Fluoroethyl carbonate [2,2,2-trifluoroethyl 2'-fluoroethyl carbonate], 2,2,2-trifluoroethyl 2 ', 2'-difluoroethyl carbonate [2,2,2- , 2-trifluoroethyl 2 ', 2'-difluoroethyl carbonate], and bis (2,2,2-trifluoroethyl) carbonate [ 4-fluoro-4-vinylethylene carbonate, 4-fluoro-5-vinylethylene carbonate 4-fluoro-5-vinylethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate, 4,5-difluoro-4- 4-fluoro-4-vinylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4,5-difluoro- 4,5-difluoro-4,5-divinylethylene carbonate, 4-fluoro-4-phenylethylene carbonate, 4-fluoro-5-phenyl 4-fluoro-5-phenylethylene carbonate, 4,4-difluoro-5-phenylethylene carbonate, 4,5-difluoro-4-phenyl 4,5-difluoro-4-phenylethylene carbonate and 4,5-difluoro-4,5-diphenylethylene carbonate, fluoromethylphenyl carbonate, Fluoromethyl phenyl carbonate, 2-fluoro 2-fluoroethyl phenyl carbonate, 2,2-difluoroethyl phenyl carbonate, and 2,2,2-trifluoroethyl phenyl carbonate (2,2,2- trifluoromethyl vinyl carbonate, trifluoroethyl phenyl carbonate, fluoromethyl vinyl carbonate, 2-fluoroethyl vinyl carbonate, 2,2-difluoroethyl vinyl carbonate, And 2,2,2-trifluoroethyl vinyl carbonate, fluoromethyl allyl carbonate, 2-fluoroethyl allyl carbonate, Diethyl carbonate containing 2,2-difluoroethyl allyl carbonate and 2,2,2-trifluoroethyl allyl carbonate, Lt; / RTI &gt;

The electrolyte may be used for room temperature ionic liquids which do not contain LiPF ₆ lithium salt, but may not be limited thereto. The ionic liquid at room temperature, which does not contain a lithium salt such as LiPF ₆ , is a mixture of silicon oxide and LiPF ₆ In addition to the absence of the interfacial reaction between the derivatives, the ionic solvent at room temperature forms a solid electrolyte interphase (SEI) layer on the surface of the silicon oxide thin film during the initial charge / discharge process to suppress the interfacial reaction with the electrolyte, It can be.

The solvent is not particularly limited and may include a non-water-soluble carbonate solvent in addition to a room temperature ionic solvent. When the water-insoluble carbonate solvent is contained, the content thereof is about 5 parts by weight to about 100 parts by weight 70 parts by weight. In this case, the ionic liquid solvent may be advantageous because it can provide flame retardancy maintenance or ignition inhibition effect, but the present invention is not limited thereto.

The water-insoluble carbonate-based solvent may include, but is not limited to, dimethyl carbonate (DMC), diethyl carbonate (DEC), or ethyl methyl carbonate (EMC).

The lithium ion battery includes silicon nanosheets produced by the method of manufacturing the silicon nanosheets of the present invention in a negative electrode material. The silicon nanosheets have substantially no volume change during charging and discharging, and have high ion conductivity, electrical conductivity, Capacity. &Lt; / RTI &gt;

Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited thereto.

[ Example ]

Example  1: Preparation of Silicon Nanosheet Using Talc, Magnesium, and 1 M Hydrochloric Acid Solution

In this embodiment, a mixture obtained by mixing magnesium powder (SAMCHUN) and talc (Talc, Alderich) in various ratios (Si: Mg ratios of 1: 1.56, 1: 2.34, 1: 3.12 and 1: the inserts in the form of a tube of an electrically produced in the laboratory (furnace) was heat-treated in _{H 2 (5%) / Ar} (95%) atmosphere and a temperature of 650 ℃ for 3 hours. The powder X-ray diffraction pattern of the heat-treated mixture was then observed using a powder X-ray diffractometer (Rigaku) (Fig. 1). 1, peaks of MgO, Si, and Mg ₂ Si can be observed. As a result of the heat treatment, the silica contained in the talc is reduced and the magnesium is oxidized to form MgO, Si, and Mg ₂ Si As shown in Fig. When the ratio of Si: Mg = 1: 1.56 was mixed, a peak of talc appeared, so that it was necessary to mix magnesium at a higher ratio in order to completely reduce the silica.

Figure 2 is a scanning electron microscope (SEM) image of the heat-treated mixture. FIG. 2 (a) is a scanning electron microscope image when the ratio of Si: Mg is 1: 3.12, and FIG. 2 (b) is 1: 2.34.

Subsequently, a 1 M hydrochloric acid solution was prepared by mixing 35 wt% to 37 wt% hydrochloric acid (SAMCHUN) with distilled water, and the 1 M hydrochloric acid solution was mixed at a ratio of 500 mL per 1 g of the heat-treated mixture. And washed with stirring. The mixture was then centrifuged at 3500 rpm for 30 minutes using a centrifuge (Hanil, Combi 514R) and the mixture was washed with distilled water. After the pH of the mixture reached neutral by the washing, the mixture was dried in a vacuum oven at a temperature of 100 ° C. Then, the X-ray diffraction pattern of the mixture in which the magnesium oxide was dissolved and removed by the washing process was observed (FIG. 3). As shown in FIG. 3, only the peak of silicon was observed as a result of washing with the 1 M HCl solution. As a result, it was confirmed that most of the materials other than silicon in the mixture were washed away.

FIG. 4 is a scanning electron microscope image after washing the heat-treated mixture with the HCl solution. FIG. FIG. 4 (a) is a scanning electron microscope image when the ratio of Si: Mg is 1: 3.12, and FIG. 4 (b) is 1: 2.34. According to Fig. 4 (b), it was observed that the plate-shaped silicon nanosheets overlap.

Example  2 : Laponite , Magnesium, and 1 M hydrochloric acid solution

In this embodiment, magnesium powder (SAMCHUN) and laponite (ROCKWOOD, RDS grade) were mixed so that the ratio of magnesium and silicon was about 3.9: 1. The mixture was then mixed with H ₂ (5%) / Ar %) Atmosphere and a powder X-ray diffraction pattern (after etching) after heat treatment at a temperature of 650 ° C for 3 hours and a powder X-ray diffraction pattern (after etching) after the heat-treated mixture was washed with HCl (Fig. 5). As shown in FIG. 5, it was confirmed that silica was reduced as in the case of talc, and silicon was formed even when laponite was used. In addition, it can be confirmed by comparing peaks before and after etching that the materials other than silicon such as magnesium oxide are removed by washing with HCl solution after the heat treatment (after etching).

Example  3: Preparation of Silicon Nanosheet Using Talc, Magnesium, and 0.5 M Hydrochloric Acid Solution

In this embodiment, magnesium powder (SAMCHUN) and talc (Alderich) were mixed in various ratios (Si: Mg ratios of 1: 1, 1: 2, and 1: 2.3) It was inserted into the electric furnace (furnace) of the heat-treated in _{H 2 (5%) / Ar} (95%) atmosphere and a temperature of 650 ℃ for 3 hours. Thereafter, the powder X-ray diffraction pattern of the heat-treated mixture was observed using a powder X-ray diffractometer (Rigaku) (FIG. 6). As shown in FIG. 6, peaks of residual talc in addition to the peaks of Si and MgO could be observed in the case of the result after heat treatment of the mixture in which Si: Mg was mixed at a molar ratio of 1: 1 and 1: 2. In the mixture with Si: Mg molar ratio of 1: 2.3, the peaks of talc disappeared but the peaks of Mg ₂ Si and Mg ₂ SiO ₄ were observed.

Next, the heat-treated mixture was washed with a 0.5 M hydrochloric acid solution for one day unlike Example 1, and the 0.5 M hydrochloric acid solution was replaced with a fresh one. After washing for another day, the powder was subjected to a powder X-ray diffraction pattern (Fig. 7). 7, peaks of silicon and talc were observed for mixtures with Si: Mg molar ratios of 1: 1 and 1: 2, and peaks of silicon and unidentified materials for mixtures of 1: The small peaks of.

According to the above observations, talc remained when magnesium was used less than the amount of magnesium required for the production of silicon nanosheets, and when pure magnesium was used, more magnesium was needed.

FIG. 8 is a high-resolution transmission electron microscope (HR-TEM, Jeol JEM-2100F) image obtained after heat-treating the mixture having a Si: Mg molar ratio of 1: 2.3 and washing with a 0.5 M hydrochloric acid solution. The average aspect ratio of the silicon nanosheets measured from the image shown in FIG. 8 was about 1: 1 to about 1: 3.

Example  4: B.E.T. of the prepared silicon nanosheets. Surface area measurement

The surface area of the silicon nanosheets prepared from the talc was measured by the N ₂ adsorption-desorption isotherm measurement using a Micromeritics ASAP 2020 instrument according to the same method as in Example 3 above. In addition, the pore size was calculated by applying the BJH (Barrett, Johner and Halenda) equation to the above results. The pore may be a de-insertion path of lithium. If the pore size is large enough to enable the lithium intercalation and the amount of the pore is large, the surface area involved in the reaction becomes large, Performance.

9 is a graph showing the BET surface area of silicon nanosheets with various Si: Mg molar ratios using talc and the BET surface area of the silicon nanosheets derived therefrom. 10 is a graph showing the pore diameter distribution of silicon nanosheets according to various Si: Mg molar ratios using talc. According to this, when the talc was mixed with magnesium and reduced by heat treatment and then washed with a hydrochloric acid solution, the BET surface area and pore size were significantly increased as compared with the pristine talc.

Example  5: Layered Peeled  Manufacture of Silicon Nanosheet Using Clay

In this embodiment, laponite and bentonite (Aldrich) were delaminated, and then silicon nanosheets were prepared and their characteristics were analyzed. First, 0.2% by weight of laponite and bentonite aqueous dispersion were prepared, respectively. The dispersion was stirred vigorously for 24 hours and then sonicated for 1 hour. Thereafter, the ultrasonic treated dispersion was lyophilized to obtain separated laponite and exfoliated bentonite, respectively. Silicon nanosheets were prepared by the same procedure as in Example 3, except that the exfoliated laponite and exfoliated bentonite were used instead of talc, respectively.

11 (a) is a field emission scanning electron microscope (FE-SEM) image of lyophilized laponite after ultrasonic treatment, and Fig. 11 (b) is a photograph showing a tin effect of ultrasonicated laponite , And Fig. 11 (c) is a photograph of lyophilized, peeled laponite.

Fig. 12 (a) is an FE-SEM image of freeze-dried bentonite after ultrasonic treatment, Fig. 12 (b) is a photograph showing a tin effect of ultrasonic treated bentonite, to be.

Fig. 13a shows a TEM image of the peeled laponite, and Fig. 13b shows a pattern of a limited field electron diffraction (SAED, acceleration voltage 200 kV, FEI-TecnaiG2 F20 microscope, FEI company) . In general, the diameter of laponite is known to be about 25 nm. According to FIG. 13a, laponite particles having a size of about 20 nm, about 40 nm, and the like are observed.

Fig. 14 (a) is a TEM image of exfoliated bentonite, and Fig. 14 (b) is a SAED pattern of exfoliated bentonite. According to Fig. 14a, bentonite particles having a size of about 40 nm or more were observed.

15 (a) is a graph comparing XRD patterns of exfoliated and lyophilized laponite and non-exfoliated laponite, and FIG. 15 (b) shows the XRD patterns of exfoliated and lyophilized bentonite and exfoliated bentonite Fig. As shown in Figs. 15 (a) and 15 (b), the peaks generally decreased in size after peeling and freeze-drying. However, when the XRD peak appeared at the same position, it was analyzed that restacking occurred in the lyophilization process.

16A shows an XRD pattern of a silicon nanosheet prepared according to the same method as that of Example 3 except that laponite removed instead of talc was used, and FIG. 16B shows that the removed bentonite was used instead of talc The XRD patterns of the silicon nanosheets prepared in the same manner as in Example 3 are shown. 16A and 16B, it was confirmed that silicon was generated after the reduction. In the case of bentonite, peaks of materials other than silicon were also observed by various metal elements of the clay.

Example  6: Constant current test using fabricated silicon nanosheets ( galvanostatic test )

In this embodiment, a mixture of magnesium powder and talc having a molar ratio of Si: Mg of 1: 2 was subjected to heat treatment and washing in a 0.5 M hydrochloric acid solution according to the method described in the above example, SERIES 4000) was used for the constant current test.

Silicon nanosheets prepared from talc were used as the active material, and the silicon nanosheets: Super P: PAA (polyacrylic acid) as a conductivity improver were mixed in ethanol at a weight ratio of 50: 35: 15, and then coated on copper foil . Subsequently, the applied mixed material was dried at 100 DEG C for 4 hours and then assembled into 2016 cells. A lithium metal foil was used as a counter electrode of the test cell, and Celgard 2500 (Celgard) was used as a separator. As the electrolyte, 1 M LiPF ₆ (EC / DEC = 1/1 (v / v), Solbrain) was used.

First, charge and discharge experiments under different current densities were carried out in order to confirm to what extent the battery capacity was maintained in accordance with the change of the current density. The battery was discharged at a current density of 255 mA / g (0.061 C) and 68 mA / g (0.016 C) until it reached 0.01 V, charged at 255 mA / g to 1.0 V, Was repeated 20 times (Figs. 17 and 18).

17 and 18, a graph showing the capacity of the battery is obtained as follows. Charge-discharge after the first discharge cycle (first cycle, curve indicated by 1) and after the second discharge cycle (second cycle, The capacity remained nearly similar. In particular, as shown in FIG. 17, the capacity was maintained at about 800 mAh / g even after the second cycle. Thus, it was confirmed that the capacity of the silicon nanosheet of the present invention was maintained even if the cycle was repeated. Also, it was confirmed that the lithium intercalation occurs at a low voltage of 0.5 V or less in the lithiation and delithiation steps.

In FIGS. 17 and 18, the potential curve is similar to that in the subsequent cycles because the charge curve of the first cycle and the second cycle in which various irreversible reactions proceed is similar. Generally, as the current density increases, the electrical capacity of the material decreases, and thus the capacity varies as the current density varies. 17 and 18 show that even when charging / discharging at a large current density, the capacity is not significantly different from that in the case of charging / discharging at a small current density, since the charging / discharging at a small current density has a relatively large charging / discharging capacity , It can be confirmed that the silicon nanosheet of the present invention is a material capable of rapidly charging and discharging at a high capacity.

As shown in FIG. 19, even when charging / discharging was repeated up to 20 times, the capacity change of the cell was extremely small. These results show that a cell containing the present silicon nano-sheet as a negative electrode active material stably maintains its capacity even after repeated charging and discharging.

Example  7: Laponite  Used silicon Nanomaterial  Produce - Reclamation

500 mL of a laponite suspension dispersed in distilled water at a concentration of 2 g / L was stirred for 12 hours to peel the laponite. It was then enrolled layer (restacking) the exfoliated Laponite by the addition of Mg ^{2 +} a colloid comprising a peeling the Laponite. Specifically, the Laponite Since the interlayer comprises a Na ⁺ ion, in terms of the total Mg ^{2 +} quantity with the amount of the electric charges on the degree to replace the Na ⁺ ions contained in the Laponite and calculate its value, the double enough, that is, it was added an excess amount of MgCl ₂ to the colloid. In this Example, 20 mL of a 3.5 M MgCl ₂ aqueous solution was added to a 100 mL colloid containing 0.2 g of laponite, and the colloid was pulverized by agitation for 12 hours with stirring.

To obtain a powder, and the register roll layer, SiO _2: establish the Mg ratio, and mixed with the powder layer and the register roll Mg powder. Specifically, the number of moles of silicon was calculated, and the Mg powder was mixed at a ratio of 1: 2 (SiO ₂ : Mg) to the number of moles of silicon, and then pulverized and mixed using a mortar for 30 minutes. Subsequently, the mixture was placed in a self-made tube furnace, heated at a heating rate of 3.3 ° C / min, and subjected to a magnesiothermic reaction in a 5% H ₂ /95% The silica was reduced. The heating temperature for reduction varied from about 500 ° C to about 650 ° C. After completion of the reduction, the mixture was taken out, and the mixture was stirred with 500 mL of a 0.5 M hydrochloric acid solution per g of the mixture for 24 hours. The etching solution used was removed by centrifugation, and 500 mL of a fresh 0.5 M hydrochloric acid solution For 24 hours, and the used etching solution was removed by centrifugation and washed with distilled water. Then, it was dried in a vacuum of 200 캜 for 12 hours. Since the silicon nanomaterials prepared according to the present embodiment contain graphene, they are darker than the silicon nanomaterials prepared without adding the graphene oxide.

Example  8 : Laponite  Used silicon Nanomaterial  Manufacturing - Freeze-dried

100 ml of a laponite suspension having a concentration of 5 g / L was stirred for 24 hours and dispersed using an ultrasonic disperser (5510, Branson) for 1 hour, and the laponite was peeled off twice. Then, the colloid containing the peeled laponite was lyophilized for 5 days to be pulverized. Specifically, the colloid was rapidly cooled using liquid nitrogen, and then freeze-dried in an environment of -75 ° C and 5 mTorr in a freeze dryer (Ilsin Boibase Freeze Dryer FD8508).

The lyophilized powder was obtained and the lyophilized powder and the Mg powder were mixed at the above-mentioned ratio at a SiO ₂ : Mg molar ratio of 1: 2. The mixture was then placed in a self-made tube furnace and heated at a rate of 3.3 ° C / min to reduce the silica contained in the mixture by a magnesiothermic reaction. The heating temperature for the reduction varied from about 550 ° C to about 650 ° C. After completion of the reduction, the mixture was taken out, and the mixture was stirred with 500 mL of a 0.5 M hydrochloric acid solution per g of the mixture for 24 hours. The etching solution used was removed by centrifugation, and 500 mL of a fresh 0.5 M hydrochloric acid solution After stirring for 24 hours, the etching solution used was removed by centrifugation and then washed with distilled water. Then, it was dried in a vacuum of 200 캜 for 12 hours.

Example  9: Laponite  Silicon produced by using Nanomaterial  Character analysis

In this example, characteristics of silicon nanomaterials prepared using X-ray diffraction analysis (D / max 2000vk, Rigaku powder X-ray diffractometer) were analyzed. Although the silicon nanomaterials were obtained by the methods of Examples 7 and 8, since the silicon nanomaterials may contain some impurities or have different crystallizabilities depending on the heat treatment conditions and the molar ratio of Si: Mg, - ray diffraction analysis. FIGS. 20A to 20C are cross-sectional diagrams showing the results of X-ray diffraction analysis of the silicon nanomaterials obtained by pulverizing the colloid containing the silica-containing material obtained from laponite by a re-layering method and reducing and etching it by a magnesio- Fig. The molar ratio of SiO ₂ : Mg was 1: 2. Fig. 20 (a) was annealed at 550 캜 for 6 hours, Fig. 20 (b) was annealed at 600 캜 for 1 hour, It is the diffraction pattern of the material. In FIGS. 20A and 20B, a broad and gentle peak between 20 ° and 30 °, which is seen as amorphous silicon oxide, with distinct silicon peaks was observed. In FIG. 20C, distinct silicon peaks and small peaks, which are assumed to be impurities, were observed.

FIGS. 21A to 21C are diagrams showing a state in which a colloid containing a silica-containing material obtained from laponite is pulverized by a re-lamination method, reduced through a magnesioamic reaction, and then subjected to X- Ray diffraction analysis. The molar ratio of Si: Mg was 1: 2. Fig. 21a shows the results of the heat treatment at 550 DEG C for 6 hours, Fig. 21B shows the heat treatment at 600 DEG C for 1 hour, Diffraction pattern. 21A to 21C, it was observed that the material having re-deposited laponite changed into a material containing silicon nano material, MgO, Mg ₂ Si and some impurities through magnesioamic reaction.

From the above experimental results, it was confirmed that most of the impurities in the reduced silicon material were removed by performing the etching process, so that only the silicon nanomaterials were mainly left.

The electrochemical properties were analyzed by using a Maccor 2000 series charge / discharge device under the conditions of potential range of 0.01 V to 1 V and 210 mA / g (0.05 C). At this time, 3 vol% of F1EC, which is an additive for increasing the stability of a battery anode, was added to 1 M LiPF ₆ (in EC / DEC 1: 1 volume ratio) as an electrolyte.

FIGS. 22A to 22C are diagrams showing a state in which a colloid containing a silica-containing material obtained from laponite is pulverized by a re-laminating method, followed by reduction and etching at 550 DEG C for 6 hours by a magnesium- And the electrochemical characteristics of the polymer electrolyte membrane were measured. FIG. 22A is a graph showing measured capacity retention, FIG. 22B is a rate capability, and FIG. 22C is a charge-discharge profile. As analyzed in the graphs, a capacity loss of about 6% was observed after 18 cycles.

FIGS. 23A to 23C are diagrams showing a case in which a colloid containing a silica-containing material obtained from laponite is pulverized by a re-layering method, followed by reduction at 600.degree. C. for 1 hour by a magnesium- And the electrochemical characteristics of the polymer electrolyte membrane were measured. FIG. 23A is a graph showing measured capacity retention, FIG. 23B is a rate capability, and FIG. 23C is a charge-discharge profile. As analyzed in the graphs, a capacity loss of about 4% after 17 cycles was observed.

24A to 24B are graphs showing the relationship between the amount of the silica nanomaterials obtained by laminating the colloid containing the silica-containing material obtained from the laponite by the re-layering method, reducing it at 650 DEG C for 3 hours by the magnesio- And the electrochemical characteristics of the polymer electrolyte membrane were measured. FIG. 24A is a graph showing the capacity retention, and FIG. 24B is a graph showing a measured charge-discharge profile. As analyzed in the graphs, a capacity loss of about 70% was observed after 50 cycles.

25A is a graph showing the results of X-ray diffraction analysis of silicon nanomaterials obtained by pulverizing silica-containing colloids obtained from laponite by a freeze-drying method, reducing and etching the particles by temperature and time by a magnesioamic reaction Fig. The upper graph is the diffraction pattern of the silicon material obtained by annealing at 550 ° C for 3 hours, the interruption graph at 525 ° C for 6 hours, and the lower graph at annealing at 525 ° C for 3 hours. The diffraction pattern of the silicon material reacted at 525 ° C for 3 hours and at 525 ° C for 6 hours showed a broad and gentle peak between 20 ° and 30 °, which appears to be amorphous silicon oxide, with distinct silicon peaks . In the diffraction pattern of the silicon material reacted at 550 ° C for 3 hours, distinct silicon peaks were observed.

25B is a graph showing the capacity preservation analysis of the silicon nanomaterial obtained by powdering the silica-containing colloid obtained from laponite by a freeze-drying method and reducing and etching at 525 DEG C for 6 hours by a magnesioamic reaction. Si: Mg ratio was 1: 2, and F1EC was not used. The silicon nanomaterials obtained by the freeze-drying method showed lower capacity than the silicon nanomaterials obtained by the re-layering method, but showed high stability instead.

Example  10: Laponite  And Oxidized graphene  Used silicon Nanomaterial  Produce ( Reclamation )

500 mL of a laponite suspension having a concentration of 2 g / L was stirred for 18 hours to peel off the laponite. A suspension containing 0.05 wt% of the graphene oxide prepared by the modified Hummer's method was then added to the colloid containing the exfoliated laponite. The amount of graphene oxide added to the colloid containing laponite was determined relative to the weight of silicon contained in the laponite. The laponite contains 59.5 wt% SiO ₂ , and the SiO ₂ contains 46.7 wt% of silicon, so that the laponite contains 27.8 wt% of silicon. In view of this, the weight ratio of graphene to silicon contained in the final product (composite of graphene and silicon) was calculated to be 10%, 7.5%, and 5%, respectively. In this example, suspensions containing 0.05% by weight of graphene oxide are added to a 500 mL suspension containing 1 g of laponite in amounts of 62 mL, 45 mL and 29 mL, respectively, and 500 mL of 3.6 mM MgCl ₂ solution is added And then agitated for 12 hours. Then, the laponite and the oxidized graphene were re-layered together, washed with distilled water using a centrifuge, and then dried in an oven at 50 ° C for pulverization.

The re-laminated powder was obtained, and the re-deposited powder and Mg powder were mixed with SiO ₂ : Mg molar ratio of 1: 2. The mixture was then placed in a self-made tube furnace and heated at a rate of 3.3 ° C / min to reduce the silica contained in the mixture by a magnesiothermic reaction. The heating temperature for reduction varied from about 500 ° C to about 650 ° C. After completion of the reduction, the mixture was taken out, and the mixture was stirred with 500 mL of a 0.5 M hydrochloric acid solution per g of the mixture for 24 hours. The etching solution used was removed by centrifugation, and 500 mL of a fresh 0.5 M hydrochloric acid solution After stirring for 24 hours, the etching solution used was removed by centrifugation and then washed with distilled water. Then, it was dried in a vacuum of 200 캜 for 24 hours. Since the silicon nanomaterials prepared according to the present embodiment contain graphene, they are darker than the silicon nanomaterials prepared without adding the graphene oxide.

26 is a silica-containing colloid prepared according to this embodiment, and the right photograph of FIG. 26 is a powdered silica-containing material produced according to this embodiment.

Example  11: Laponite  And Oxidized graphene  Silicon produced by using Nanomaterial Analysis of characteristics - Reclamation

In this example, characteristics of silicon nanomaterials prepared using X-ray diffraction analysis were analyzed.

(1) Silicon Nanomaterial  Contained within Grapin  5% by weight

In this example, the characteristics of silicon nanomaterials prepared so that the mass ratio of graphene in the final product was 5 wt% by using laponite and oxidized graphene solution were analyzed.

FIGS. 27A to 27C are graphs showing the relationship between the X-ray diffraction intensity of the silicon nanomaterial obtained by pulverizing colloid containing silica-containing material obtained from laponite and oxidized graphene by re-lamination method and reducing and etching by magnesio- - ray diffraction analysis. The molar ratio of Si: Mg was 1: 2. 27A is an analysis result of silicon nanomaterials obtained by heat treatment at 550 DEG C for 6 hours, FIG. 27B at 600 DEG C for 1 hour and FIG. 27C at 650 DEG C for 3 hours, respectively, and then etching. 27A to 27C, a diffuse pattern of silicon and a broad and gentle peak between 20 DEG and 30 DEG appearing as amorphous silicon oxide were observed.

FIGS. 28A to 28C are diagrams showing the results obtained by pulverizing a colloid containing a silica-containing material obtained from laponite and oxidized graphene by a re-lamination method, reducing it through a magnesioamic reaction, X-ray diffraction analysis of nanomaterials. The molar ratio of Si: Mg was 1: 2. Fig. 28A is a diffraction pattern of the silicon material obtained by heat treatment at 550 DEG C for 6 hours, Fig. 28B is at 600 DEG C for 1 hour, and Fig. 28C is at 650 DEG C for 3 hours. According to that observed in Figure 28a and Figure 28b, it was confirmed that the resulting material comprises silicon nano material, MgO, Mg ₂ Si and some impurities, and reportedly observed in Figure 28c, including the silicon nano-material, MgO It was confirmed that the material was produced.

From the above experimental results, it was confirmed that most of the impurities in the reduced silicon material were removed by performing the etching process, so that only the silicon nanomaterials were mainly left.

29A to 29C show that a colloid containing a silica-containing material obtained from laponite and oxidized graphene is pulverized by a re-laminating method and then reduced and etched at 550 DEG C for 6 hours through a magnesio- (FIG. 29A), a high-resolution transmission electron microscope (HR-TEM) image (FIG. 29B), and a limited field electron diffraction (SAED) pattern (FIG. 29C) of a silicon nanomaterial. 29A, it is confirmed that silicon particles of about 50 nm or less are gathered on the silicon particles of about 300 nm. In Fig. 29B, a lattice of a silicon (111) plane with an interplanar distance of 0.30 nm was confirmed. In Fig. 29C, a pattern generated by crystal of silicon was confirmed.

30A to 30C show that colloids containing a silica-containing material obtained from laponite and oxidized graphene are pulverized by a re-layering method and then reduced and etched at 600 DEG C for 1 hour through a magnesio- (FIG. 30A), a high-resolution transmission electron microscope (HR-TEM) image (FIG. 30B), and a limited field electron diffraction (SAED) pattern (FIG. 30C) of a silicon nanomaterial. 30A, it is confirmed that silicon particles of about 100 nm or less and about 50 nm or less are gathered on a large silicon particle of about 500 nm. In Fig. 30 (b), a lattice of a silicon (111) plane with an interplanar distance of 0.31 nm was confirmed. In Fig. 30C, a pattern formed by the crystal of silicon was confirmed.

31A to 31C show that a colloid containing a silica-containing material obtained from laponite and oxidized graphene is pulverized by a re-laminating method, followed by reduction and etching at 650 DEG C for 3 hours through a magnesio- (FIG. 31A), a high-resolution transmission electron microscope (HR-TEM) image (FIG. 31B), and a limited field electron diffraction (SAED) pattern (FIG. 31C) of a silicon nanomaterial. In Fig. 31 (a), about 400 nm of silicon particles without small particles were identified. In Fig. 31B, a lattice of a silicon (111) face having an interplanar distance of 0.30 nm was confirmed. In Fig. 31C, a pattern formed by the crystal structure of silicon was confirmed.

FIGS. 32A to 32C are graphs showing the relationship between the number of N atoms of the silicon nanomaterial obtained by pulverizing the colloid containing the silica-containing material obtained from laponite and the oxidized graphene by reallocation method, reducing and etching through the magnesioamic reaction, ₂ adsorption / desorption isotherm analysis results. 32A is the analysis of the silicon nanomaterials obtained by reducing them at 550 DEG C for 6 hours, FIG. 32B for 600 DEG C for 1 hour, and FIG. 32C for 650 DEG C for 3 hours. The pore sizes of the silicon nanomaterials derived therefrom were analyzed to be less than about 10.8 nm in FIG. 32A, less than about 10.1 nm in FIG. 32B, and less than about 10.7 nm in FIG. 32C.

33A to 33C show that a colloid containing a silica-containing material obtained from laponite and oxidized graphene is pulverized by a re-layering method and then reduced and etched at 550 DEG C for 6 hours through a magnesio- And the electrochemical characteristics of a silicon nanomaterial are measured. FIG. 33A shows capacity retention, FIG. 33B shows a rate capability, and FIG. 33C shows a charge-discharge profile. As analyzed in the graphs, a capacity loss of about 23% was observed after 50 cycles.

34A to 34C show that colloid containing silica-containing material obtained from laponite and oxidized graphene is pulverized by re-layering method and then reduced and etched at 600 DEG C for 1 hour through a magnesio- And the electrochemical characteristics of a silicon nanomaterial are measured. FIG. 34A shows capacity retention, FIG. 34B shows a rate capability, and FIG. 34C shows a graph of measured charge-discharge profile. As analyzed in the graphs, a capacity loss of about 17% was observed after 48 cycles.

35A to 35C show that colloids containing a silica-containing material obtained from laponite and oxidized graphene are pulverized by a re-layering method and then reduced and etched at 650 DEG C for 3 hours through a magnesio- And the electrochemical characteristics of a silicon nanomaterial are measured. FIG. 35A is a graph showing measured capacity retention, FIG. 35B is a rate capability, and FIG. 35C is a charge-discharge profile. As analyzed in the graphs, a capacity loss of about 35% was observed after 40 cycles.

(2) Silicon Nanomaterial  Contained within Grapin  7.5% by weight

In this example, the characteristics of silicon nanomaterials prepared so that the mass ratio of graphene in the final product was 7.5 wt% by using laponite and oxidized graphene solution were analyzed.

FIGS. 36A to 36C are diagrams showing a state in which a colloid containing a silica-containing material obtained from laponite and oxidized graphene is pulverized by a re-layering method and then subjected to reduction by a magnetosimic reaction and X - ray diffraction analysis. The molar ratio of Si: Mg was 1: 2. 36A is an analysis result of silicon nanomaterials obtained by heat treatment at 550 DEG C for 6 hours, FIG. 36B at 600 DEG C for 1 hour, FIG. 36C at 650 DEG C for 3 hours, and then etching. 36A to 36C, a diffuse pattern of silicon and a broad and gentle peak between 20 [deg.] And 30 [deg.], Which is indicated by amorphous silicon oxide, were observed.

37A to 37C are cross-sectional views illustrating a method for producing a silicon nanomaterial according to the present invention, in which a colloid containing a silica-containing material obtained from laponite and oxidized graphene is pulverized by a re-laminating method and then reduced through a magnesiothermic reaction, X-ray diffraction analysis. The molar ratio of Si: Mg was 1: 2. FIG. 37A shows the result of analyzing the material obtained by heat treatment at 550 ° C. for 6 hours and FIG. 37B at 600 ° C. for 1 hour. According to the analysis, the silicon nano material, MgO, Mg ₂ Si, It was confirmed that a substance containing impurities was generated. FIG. 37C shows the results of analysis of the silicon material obtained by heat treatment at 650 ° C for 3 hours. As a result, it was confirmed that silicon nano materials and MgO-containing materials were produced through the magnesioamic reaction.

From the above experimental results, it was confirmed that most of the impurities in the reduced silicon material were removed by performing the etching process, so that only the silicon nanomaterials were mainly left.

38A to 38C show that a colloid containing a silica-containing material obtained from laponite and oxidized graphene is pulverized by a re-laminating method and then reduced and etched at 550 DEG C for 6 hours through a magnesio- (FIG. 38A), a high-resolution transmission electron microscope (HR-TEM) image (FIG. 38B) and a limited field electron diffraction (SAED) pattern (FIG. 38C) of a silicon nanomaterial. In Fig. 38A, about 400 nm of silicon particles not containing small particles were identified. In Fig. 38 (b), a lattice of a silicon (111) plane with an interplanar distance of 0.31 nm was confirmed. In Fig. 38C, a pattern caused by the crystal structure of silicon was observed.

39A to 39C show that a colloid containing a silica-containing material obtained from laponite and oxidized graphene is pulverized by a re-laminating method, followed by reduction and etching at 600 DEG C for 1 hour through a magnesium- (FIG. 39A), a high-resolution transmission electron microscope (HR-TEM) image (FIG. 39B) and a limited field electron diffraction (SAED) pattern (FIG. 39C) of a silicon nanomaterial. In Fig. 39 (a), about 400 nm of silicon particles were observed which hardly contained small particles. In Fig. 39 (b), a lattice of a silicon (111) face having an interplanar distance of 0.30 nm was confirmed. In Fig. 39C, a pattern caused by the crystal structure of silicon was observed.

40A to 40C show that colloids containing a silica-containing material obtained from laponite and oxidized graphene are pulverized by a re-laminating method, followed by reduction and etching at 650 DEG C for 3 hours through a magnesio- (FIG. 40A), a high-resolution transmission electron microscope (HR-TEM) image (FIG. 40B) and a limited field electron diffraction (SAED) pattern (FIG. 40C) of a silicon nanomaterial. In FIG. 40a, it was confirmed that the synthesized material includes small silicon particles of various sizes ranging from small silicon particles of about 10 nm or less to silicon particles of about 100 nm or less. In Fig. 40B, a lattice of a silicon (111) plane with an interplanar distance of 0.31 nm was observed. In Fig. 40C, a pattern caused by the crystal structure of silicon was observed.

Figs. 41A to 41C are diagrams showing the relationship between the number of N atoms of the silicon nanomaterial obtained by pulverizing a colloid containing a silica-containing material obtained from laponite and oxidized graphene by a re-layering method, reducing and etching through a magnesioamic reaction, ₂ adsorption / desorption isotherm analysis results. FIG. 41A is a graph showing the results of analysis of silicon nanomaterials obtained by reducing at 550.degree. C. for 6 hours, FIG. 41B at 600.degree. C. for 1 hour, and FIG. 41C at 650.degree. C. for 3 hours. The pore sizes of the silicon nanomaterials derived therefrom were analyzed to be about 8.3 nm or less in FIG. 41A, about 8.7 nm or less in FIG. 41B, and about 12.0 nm or less in FIG. 41C.

42A to 42C show that the colloid containing the silica-containing material obtained from laponite and the oxidized graphene is pulverized by the re-laminating method and then subjected to reduction and etching at 550 DEG C for 6 hours through a magnesium- And the electrochemical characteristics of a silicon nanomaterial are measured. FIG. 42A is a graph showing the capacity retention, FIG. 42B is a rate capability, and FIG. 42C is a charge-discharge profile. As analyzed in the graphs, a capacity loss of about 23% was observed after 50 cycles.

43A to 43C show that a colloid containing a silica-containing material obtained from laponite and oxidized graphene is pulverized by a re-layering method and then reduced and etched at 600 ° C for 1 hour through a magnesium- And the electrochemical characteristics of a silicon nanomaterial are measured. FIG. 43A is a graph showing measured capacity retention, FIG. 43B is a rate capability, and FIG. 43C is a charge-discharge profile. As analyzed in the graphs, a capacity loss of about 18% was observed after 50 cycles.

44A to 44C show that a colloid containing a silica-containing material obtained from laponite and oxidized graphene is pulverized by a reclamation method and then reduced and etched at 650 DEG C for 3 hours through a magnesioamic reaction And the electrochemical characteristics of a silicon nanomaterial are measured. FIG. 44A shows capacity retention, FIG. 44B shows a rate capability, and FIG. 44C shows a graph of measured charge-discharge profile. As analyzed in the graphs, a capacity loss of about 39% was observed after 30 cycles

(3) Silicon Nanomaterial  Contained within Grapin  10% by weight

In this example, the characteristics of silicon nanomaterials prepared so that the mass ratio of graphene in the final product was 10 wt% using laponite and oxidized graphene solution were analyzed.

FIGS. 45A to 45C are diagrams showing a state in which a colloid containing a silica-containing material obtained from laponite and oxidized graphene is pulverized by a re-lamination method and then subjected to reduction by a magnetosimic reaction and X - ray diffraction analysis. The molar ratio of Si: Mg was 1: 2. 45A is the analysis result of the silicon nanomaterials obtained by heat treatment at 550 DEG C for 6 hours, FIG. 45B for 600 DEG C for 1 hour and FIG. 45C for 650 DEG C for 3 hours. 45A to 45C, a broad and gentle peak between 20 DEG and 30 DEG, which is seen as an amorphous silicon oxide, was observed in the diffraction pattern of silicon.

46A to 46C are diagrams showing a state in which a colloid containing a silica-containing material obtained from laponite and oxidized graphene is pulverized by a re-laminating method and then reduced through a magnesiothermic reaction, and then the silicon nanomaterial X-ray diffraction analysis. The molar ratio of Si: Mg was 1: 2. FIG. 46A shows the results of analysis by heat treatment at 550 ° C. for 6 hours and FIG. 46B at 600 ° C. for 1 hour. As a result of the analysis, the material including silicon nano material, MgO, Mg ₂ Si and some impurities Was generated. Figure 46 (c) shows that silicon nano materials and MgO-containing materials were produced as a result of the heat treatment at 650 ° C for 3 hours.

From the above experimental results, it was confirmed that most of the impurities in the reduced silicon material were removed by performing the etching process, so that only the silicon nanomaterials were mainly left.

47A to 47C show that a colloid containing a silica-containing material obtained from laponite and oxidized graphene is pulverized by a re-layering method and then reduced and etched at 550 DEG C for 6 hours through a magnesioamic reaction (FIG. 47A), a high-resolution transmission electron microscope (HR-TEM) image (FIG. 47B) and a limited field electron diffraction (SAED) pattern (FIG. 47C) of a silicon nanomaterial. 47A shows graphene and small silicon particles of 20 nm or less. In Fig. 47B, a lattice of a silicon (111) face having an interplanar distance of 0.31 nm was confirmed. In Fig. 47C, a pattern caused by the crystal structure of silicon was confirmed.

48A to 48C show that colloid containing silica-containing material obtained from laponite and oxidized graphene is pulverized by re-layering method and then reduced and etched at 600 DEG C for 1 hour through a magnesio- (FIG. 48A), a high-resolution transmission electron microscope (HR-TEM) image (FIG. 48B), and a limited field electron diffraction (SAED) pattern (FIG. 48C) of a silicon nanomaterial. 48A, small silicon particles of about 20 nm or less were identified. In Fig. 48B, a lattice of a silicon (111) plane with an interplanar distance of 0.31 nm was confirmed. In Fig. 48C, a pattern caused by the crystal structure of silicon was confirmed.

49A to 49C show that colloids containing a silica-containing material obtained from laponite and oxidized graphene are pulverized by a re-layering method, followed by reduction and etching at 650 DEG C for 3 hours through a magnesio- (FIG. 49A), a high-resolution transmission electron microscope (HR-TEM) image (FIG. 49B) and a limited field electron diffraction (SAED) pattern (FIG. 49C) of a silicon nanomaterial. 49A, about 400 nm silicon particles and silicon particles as small as about 20 nm are identified. In Fig. 49 (b), a lattice of a silicon (111) plane with an interplanar distance of 0.31 nm was confirmed. In Fig. 49C, a pattern caused by the crystal structure of silicon was confirmed.

FIGS. 50A to 50C are graphs showing the relationship between the number of N atoms of a silicon nanomaterial obtained by pulverizing a colloid containing a silica-containing material obtained from laponite and oxidized graphene by a re-layering method, reducing and etching through a magnesioamic reaction, ₂ adsorption / desorption isotherm analysis results. FIG. 50A is the analysis of the obtained silicon nanomaterials by reducing them at 550 DEG C for 6 hours, FIG. 50B for 600 DEG C for 1 hour, and FIG. 50C for 650 DEG C for 3 hours. The pore sizes of the silicon nanomaterials derived therefrom were analyzed to be about 10.2 nm or less in FIG. 50A, about 11.2 nm or less in FIG. 50B, and about 9.7 nm or less in FIG. 50C.

Figures 51A and 51B show a method in which a colloid containing a silica-containing material obtained from laponite and oxidized graphene is pulverized by a re-layering method, followed by reduction and etching at 550 ° C for 6 hours through a magnesium- And the electrochemical characteristics of a silicon nanomaterial are measured. FIG. 51A is a graph showing a rate capability and FIG. 51B is a graph showing a charge-discharge profile measured. As can be seen from the above graphs, the rate characteristics are not significantly different from those of the heat-treated materials at other temperatures, but they are confirmed to have a relatively low capacity.

FIGS. 52A to 52C show that a colloid containing a silica-containing material obtained from laponite and oxidized graphene is pulverized by a re-layering method and then reduced and etched at 600 DEG C for 1 hour through a magnesium- And the electrochemical characteristics of a silicon nanomaterial are measured. FIG. 52A shows a capacity retention, FIG. 52B shows a rate capability, and FIG. 52C shows a charge-discharge profile. As analyzed in the graphs, a capacity loss of about 32% was observed after 40 cycles.

53A to 53C show that colloid containing silica-containing material obtained from laponite and oxidized graphene is pulverized by re-layering method and then reduced and etched at 650 DEG C for 3 hours through a magnesio- And the electrochemical characteristics of a silicon nanomaterial are measured. FIG. 53A is a graph showing measured capacity retention, FIG. 53B is a rate capability, and FIG. 53C is a charge-discharge profile. As analyzed in the graphs, a capacity loss of about 11% was observed after 50 cycles.

Example  12: Laponite  And Oxidized graphene  Used silicon Nanomaterial  Manufacturing - Freeze-dried

In this Example, a colloid containing a silica-containing material obtained from laponite and oxidized graphene was pulverized by a lyophilization method and then reduced to prepare a silicon nanomaterial.

500 mL of a laponite suspension having a concentration of 5 g / L was stirred for 48 hours to peel off the laponite. A suspension containing 0.05 wt% of the graphene oxide prepared by the modified Hummer's method was then added to the colloid containing the exfoliated laponite. The amount of graphene oxide was determined in comparison with the weight of silicon contained in the laponite. The laponite contains 59.5% by weight of SiO ₂ , and the SiO ₂ contains 46.7% by weight of Si, so that the laponite contains 27.8% by weight of silicon. In consideration of this, the weight ratio of graphene to silicon contained in the final product, silicon nanomaterial (a complex of graphene and silicon) was calculated to be 6.5%, 10%, and 12.5%, respectively. In this embodiment, 170 mL of laponite dispersed in 30 mL of colloid containing 0.05 wt% of oxidized graphene is added, or 155 mL of laponite dispersed in 45 mL of colloid containing 0.05 wt% of graphene oxide is added, 146 mL of laponite dispersed in 54 mL of a colloid containing 0.05 wt% of graphene oxide was added and stirred for 1 hour. Then, the mixed colloid was lyophilized and pulverized for 5 days. Specifically, the colloid was rapidly cooled using liquid nitrogen, and then freeze-dried in an environment of -75 ° C and 5 mTorr in a freeze dryer (Ilsin Boibase Freeze Dryer FD8508).

Thereafter, the powder was mixed with the Mg powder by varying the SiO ₂ : Mg molar ratio. Specifically, SiO ₂ : Mg molar ratios were 1: 2, 1: 2.5, 1: 3, and 1: 4. The mixture was then placed in a self-made tube furnace and heated at a rate of 3.3 ° C / min to reduce the silica contained in the mixture by a magnesiothermic reaction. The heating temperature for the reduction varied from about 520 ° C to about 550 ° C. The reducing atmosphere was 5% H ₂ /95% Ar gas atmosphere and the temperature was maintained for 3 hours after the heating. After completion of the reduction, the mixture was taken out, and the mixture was stirred with 500 mL of a 0.5 M hydrochloric acid solution per g of the mixture for 24 hours. The etching solution used was removed by centrifugation, and 500 mL of a fresh 0.5 M hydrochloric acid solution After stirring for 24 hours, the used etching solution was removed by centrifugation and washed with distilled water. Then, it was dried in a vacuum of 180 캜 for 24 hours.

Example  13: Laponite  And Oxidized graphene  Silicon produced by using Nanomaterial  Character analysis

In this example, the concentration of the oxidized graphene solution used in the preparation of the silicon nanomaterial and the characteristics of the silicon nanomaterials prepared by varying the reducing conditions were analyzed.

54A to 54C are graphs showing the X-ray diffraction analysis results of the silicon nanomaterials obtained by pulverizing and colloidizing the colloid containing the silica-containing material obtained from laponite and oxidized graphene by the lyophilization method to be. FIG. 54A is a result of analysis of a silicon nanomaterial including 6.5 wt% graphene, FIG. 54B is a silicon nanomaterial including 10 wt% graphene, and FIG. 54C is an analysis result of silicon nanomaterial including 12.5 wt% graphene.

The upper graph of FIG. 54A shows the results of X-ray diffraction analysis of the obtained silicon nanomaterials at 520 DEG C for 3 hours, wherein the molar ratio of Si: Mg was 1: 2.5, and the lower graph of FIG. Ray diffraction analysis of the silicon nanomaterial obtained by reduction for 30 minutes, wherein the molar ratio of Si: Mg was 1: 2.

The upper graph of FIG. 54B shows the results of X-ray diffraction analysis of the obtained silicon nanomaterials at 550 ° C. for 3 hours, wherein the molar ratio of Si: Mg was 1: 4, and the lower graph of FIG. X-ray diffraction analysis of the silicon nanomaterial obtained by reduction over time showed that the molar ratio of Si: Mg was 1: 3.

FIG. 54C shows X-ray diffraction analysis results of the silicon nanomaterial obtained by reduction at 550 ° C. for 3 hours, wherein the molar ratio of Si: Mg was 1: 2.

55A to 55C show that colloids containing a silica-containing material obtained from laponite and oxidized graphene are pulverized by a lyophilization method and then reduced at 550 DEG C for 3 hours through a magnesiothermic reaction to obtain a silicone And the electrochemical characteristics of the nanomaterial are measured. The graphene contained in the silicon nanomaterial was prepared to be about 10% by weight, and the molar ratio of Si: Mg was 1: 4. FIG. 55A is a graph showing measured capacity retention, FIG. 55B is a rate capability, and FIG. 55C is a charge-discharge profile. According to the analysis of the graphs, the capacity of the silicon nanomaterial including 10 wt% graphene varies according to the content of F1EC according to FIG. 55A. However, the results were not completely different depending on the F1EC content. A capacity loss of about 12% was observed after 50 cycles when the electrolyte contained 10% F1EC. 55B and 55C show the stable capacity and the stable potential vs. the high current density. Capacity graph is shown.

56a to 56c are graphs showing the electrochemical characteristics of silicon nanomaterials obtained by pulverizing colloids containing silica-containing material obtained from laponite and oxidized graphene by a lyophilization method and reducing them through a magnesioamic reaction As shown in FIG. FIG. 56A shows the capacity retention characteristics of silicon nanomaterials prepared with a 10% by weight graphene and a molar ratio of Si: Mg of 1: 3, and FIG. 56B shows the capacity retention characteristics of 12.5% by weight graphene 56C shows the rate capability of the silicon nanomaterial prepared under the condition of Si: Mg molar ratio of 1: 2 under F1EC-free conditions. FIG. 56C shows the molar ratio of Si: Mg Is a graph showing the charge-discharge profile of a silicon nanomaterial prepared under the condition of 1: 2 under an F1EC-free condition. According to the above graphs, the capacity at the current density of 0.05 C was stable during charging and discharging, but the capacity was low at about 600 mAh / g.

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 interpreted as being included in the scope of the present invention .

Claims (16)

Comprising reducing the silica contained in said clay to a silicon nanosheet by heat treating a mixture comprising clay and an alkaline earth metal,
Method of manufacturing silicon nanosheet.
The method according to claim 1,
Further comprising obtaining the silicon nanosheet by etching the heat-treated mixture using an acidic solution.
3. The method according to claim 1 or 2,
Wherein the clay comprises a layered clay.
4. The method according to any one of claims 1 to 3,
The clay may be selected from the group consisting of montmorillonite, nontronite, beidellite, bentonite, hectorite, laponite, saponite, And a smectite-based mineral selected from the group consisting of sauconite, vermiculite, and combinations thereof.
5. The method according to any one of claims 1 to 4,
Wherein the heat treatment is carried out at a temperature of 300 ° C to 1,000 ° C, preferably 400 ° C to 800 ° C, more preferably 550 ° C to 750 ° C.
6. The method according to any one of claims 1 to 5,
The molar ratio of silicon contained in the clay and the alkaline earth metal in the mixture is 1: 0.1 to 1:10, preferably 1: 0.5 to 1: 5, more preferably 1: 0.5 to 1: 3 , A method for producing a silicon nanosheet.
7. The method according to any one of claims 1 to 6,
Adding a cation of an alkaline earth metal to the clay before heat treating the mixture comprising the clay and the alkaline earth metal to restack the clay or lyophilizing the clay. Method of manufacturing silicon nanosheet.
8. The method according to any one of claims 1 to 7,
Wherein the mixture comprising the clay and the alkaline earth metal further comprises graphene oxide.
The method of claim 8, wherein
The mixture of the clay and the alkaline earth metal, which further comprises the graphene oxide, is heat-treated to reduce the silica contained in the clay and the graphene oxide to silicon nano-sheet and graphene, respectively, To form a composite of a silicon nanosheet.
A silicon nanosheet comprising a layered structure substantially similar to clay.
11. The method of claim 10,
A silicon nanosheet, which is produced by the method of any one of claims 1 to 9.
The method according to claim 10 or 11,
And a BET surface area of 20 m ² / g to 300 m ² / g.
13. The method according to any one of claims 10 to 12,
A silicon nanosheet having a size of 10 nm to 300 nm and an aspect ratio of 1: 1 to 1:10.
14. The method according to any one of claims 10 to 13,
The silicon nanosheets may be formed of a material selected from the group consisting of carbon black, acetylene black, active carbon, carbon nanotube (CNT), graphite, graphene, &Lt; / RTI &gt; wherein at least one of the carbon nanotubes is hybridized with at least one conductive carbon compound.
14. An electrode comprising a silicon nanosheet according to any one of claims 10 to 14.
A lithium ion battery comprising an anode, a cathode, and an electrolyte comprising an electrode according to claim 15.

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