KR20180031566A - Porous silicone composite cluster, carbon composite using the same, electrode, lithium battery, field emission device, biosensor, and semiconductor device including the same - Google Patents

Abstract

The present invention provides a porous silicon composite cluster comprising a core including porous silicon composite secondary particles and a shell including second graphene disposed on top of the core. The porous silicon composite secondary particles comprise: at least two aggregates of silicon composite primary particles, wherein said silicon composite primary particles are silicon; and silicon oxide (SiOx) (O < x < 2) disposed on the silicon, and first graphene disposed on the silicon oxide. The present invention also provides a carbon composite using the porous silicon composite cluster. Additionally, the present invention provides an electrode including the composite or the carbon composite, a lithium battery including the electrode, a biosensor including the composite or the carbon composite, a field emission device, a thermoelectric device, and a semiconductor device.

Description

TECHNICAL FIELD [0001] The present invention relates to a porous silicon composite cluster, a carbon composite using the same, a lithium cell, a field emission device, a biosensor, a semiconductor device and a thermoelectric device using the same, biosensor, and semiconductor device including the same}

Porous silicon composite clusters, carbon composites using them, electrodes containing them, lithium batteries, electric field extraction devices, biosensors, semiconductor devices, and thermoelectric devices.

Conventionally, among the anode active materials for lithium ion batteries, silicon has a theoretical capacity of 4200 mAh / g, which is high and low in price. However, silicon discharges when Li _{4 . 4} Si alloy is generated, which leads to volume expansion, resulting in an electrically isolated active material in the electrode, and an electrolyte degradation reaction due to an increase in the specific surface area of the active material. In order to overcome this problem, a method has been proposed in which a volume expansion of silicon is reduced and a structure with less crushing during volume expansion is developed, or a coating layer of carbon or the like is formed on the silicon surface.

However, when the silicon material developed so far is used, the volume expansion reduction effect and the charge / discharge efficiency of the battery have not reached a satisfactory level.

One aspect is to provide a porous silicon composite cluster.

Another aspect is to provide a carbon composite comprising the above-described porous silicon composite clusters and a carbon-based material.

Another aspect is to provide a lithium battery comprising the porous silicon composite cluster or the porous silicon composite cluster and an electrode containing a carbon composite material containing a carbon-based material.

Another aspect is to provide a field emission device comprising the porous silicon composite clusters or the carbon composite material comprising the porous silicon composite clusters and the carbon-based material.

According to another aspect, the side surface is provided with the porous silicon composite cluster or the porous silicon composite cluster and a carbon composite material containing the carbon-based material.

According to another aspect, there is provided a semiconductor device comprising a porous carbon composite material including the porous silicon composite clusters or the porous silicon composite clusters and the carbon-based material.

According to another aspect, there is provided a thermoelectric device including a porous carbon composite material comprising the porous silicon composite clusters or the porous silicon composite clusters and the carbon-based material.

On one side

A porous silicon composite cluster comprising a shell comprising a porous core comprising porous silicon composite secondary particles and a second graphene disposed on top of the core,

Wherein the porous silicon composite secondary particles comprise aggregates of two or more silicon composite primary particles,

The silicon composite primary particles may be silicon; There is provided a porous silicon composite cluster comprising silicon oxide (SiOx) (O < x < 2) disposed on the silicon and a first graphene disposed on the silicon oxide.

On the other side

Obtaining porous silicon secondary particles from a composition comprising silicon oxide (SiOx) (O < x < 2) formed on silicon and silicon, a composition comprising a dispersant and a solvent; And

And supplying the carbon source gas to the porous silicon secondary particles and heat treating the porous silicon secondary particles.

According to another aspect

There is provided a carbon composite material comprising the above porous silicon composite clusters and a carbon-based material.

According to another aspect there is provided a lithium battery comprising i) a porous silicon composite cluster as described above or ii) an electrode comprising a carbon composite comprising a porous silicon composite cluster and a carbon-based material.

Another aspect is to provide a field emission device comprising the i) the porous silicon composite cluster or ii) the carbon composite material comprising the porous silicon composite cluster and the carbon-based material.

According to another aspect, there is provided a biosensor comprising i) a porous silicon composite cluster or ii) a carbon composite comprising the porous silicon composite cluster and a carbon-based material.

According to another aspect, there is provided a semiconductor device comprising i) a porous silicon composite cluster or ii) a carbon composite comprising the porous silicon composite cluster and a carbon-based material.

According to another aspect there is provided a thermoelectric device comprising i) a porous silicon composite cluster or ii) a carbon composite comprising the porous silicon composite cluster and a carbon-based material.

The use of the porous silicon composite clusters according to one embodiment can reduce the expansion of the electrode plate during charging and discharging, improve the initial efficiency and the volume energy density as well as the conductivity and the high durability of the silicon protective layer, The charge and discharge durability can be improved.

1A schematically illustrates the structure of a porous silicon composite cluster according to one embodiment.
Figure IB is intended to illustrate the working principle of a cathode containing a porous silicon composite cluster according to one embodiment.
Figure 1c schematically illustrates the structure of graphene-grown silicon primary particles.
FIG. 1D is a view for explaining the state after charging / discharging of graphene-direct-growing silicon primary particles of FIG. 1C. FIG.
FIG. 1E illustrates a method of fabricating a porous silicon composite cluster according to one embodiment.
2A is a schematic view of a lithium battery according to an embodiment.
Figure 2B shows a schematic view of a thermoelectric module according to one embodiment.
2C is a schematic view showing thermoelectric cooling by the Peltier effect.
FIG. 2D is a schematic view showing the thermoelectric generation by the Seebeck effect. FIG.
FIG. 2E illustrates the structure of the electrode of the biosensor according to one embodiment.
3A to 3C are transmission electron microscope (TEM) photographs showing the outer and inner regions of the entire cluster shape and cluster in the porous silicon composite clusters prepared according to Preparation Example 1, respectively.
FIGS. 3D to 3F are TEM photographs showing the entire cluster shape and the outer and inner regions of the clusters in the porous silicon clusters prepared according to Production Example 2, respectively.
Figs. 3G to 3I and Figs. 14A to 14C are TEM photographs showing the entire cluster shape and the outer and inner regions of the clusters in the porous silicon clusters produced according to Production Example 3. Fig.
Figs. 4A and 4C show the inner regions of the materials prepared according to Comparative Preparation Examples 1 and 2, respectively.
Figs. 4B and 4D show the outer regions of the materials prepared according to Comparative Preparation Examples 1 and 2. Fig.
5A and 5B are TEM photographs of the materials prepared according to comparative preparation example 3. Fig.
6A to 6C are TEM photographs of the porous silicon composite clusters of Production Example 1. Fig.
Figs. 7A to 7C are TEM photographs of the porous silicon composite clusters of Production Example 2. Fig.
Figs. 8A to 8C are TEM photographs of the porous silicon composite clusters of Production Example 3. Fig.
9A to 9C are TEM photographs of the substance of Comparative Production Example 4. Fig.
FIGS. 10A and 10B are TEM photographs of the porous silicon composite clusters prepared according to Production Example 3. FIG.
Fig. 11 is a graph showing the results of the measurement of the La
The results are shown in Fig.
12A and 12B show SEM analysis results of the surface of the negative electrode active material of the cathode before and after charging in the coin cell manufactured according to the third embodiment.
12C to 12E are SEM analysis results of cross sections of the negative electrode active material of the cathode before and after charging in the coin cell manufactured according to the third embodiment.
13A to 13D show electron microscopic analysis results of the porous silicon composite clusters prepared according to Preparation Example 3. FIG.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features, and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the accompanying drawings, in which: FIG. .

A porous silicon composite cluster comprising a shell comprising a porous core comprising porous silicon composite secondary particles and a second graphene disposed on top of the core,

Wherein the porous silicon composite secondary particles comprise aggregates of two or more silicon composite primary particles, wherein the silicon composite primary particles are silicon; There is provided a porous silicon composite cluster comprising silicon oxide (SiOx) (O < x < 2) disposed on the silicon and a first graphene disposed on the silicon oxide.

As used herein, the term "cluster" refers to aggregates of at least one or more primary particles and may be interpreted substantially in the same sense as "secondary particles ".

As used herein, the term "graphene" may have a structure such as flake, nanosheet, membrane (or film) Here, the nanosheet refers to a case where the film is formed irregularly on the silicon oxide, and the film refers to a film shape formed continuously and uniformly on the silicon oxide. As such, graphene may have a number of layers or may have a layerless structure.

In a porous silicon composite cluster according to an embodiment, the core may have a size of 3 to 10 mu m and the shell may have a thickness of 10 to 5,000 nm, for example, 10 to 1,000 nm. Here, the size means the diameter or the major axis length.

1A shows a porous silicon composite cluster according to one embodiment.

The porous silicon composite cluster 11 comprises a shell 2 comprising a core 1 comprising porous silicon composite secondary particles and a second graphene 10b disposed on top of the core 1, .

The porous silicon composite secondary particles comprise aggregates of two or more silicon composite primary particles 10, wherein the silicon composite primary particles comprise silicon and at least one of silicon oxide (SiOx) (O <x <2) and silicon oxide And a first graphene 10a disposed on the silicon oxide. In the silicon composite primary particles, the first graphene forms a shell on the surface of the silicon oxide, and in the silicon composite secondary particles, the second a-lapping forms a shell on top of the core, so that the porous silicon composite cluster has a double core / shell structure . Having such a dual core / shell structure inhibits volume expansion and reduces side reactions with the electrolyte.

The number of layers of the first graphene 10a of the core 1 is equal to or different from that of the second graphenes 10b of the shell 2.

According to an embodiment, the second graphene 10b of the shell 2 may have a higher density than the first graphene 10a in the core 1. [ According to one embodiment, the number of first graphene layers in the core is in the range of 1 to 30 layers, for example 5 to 15 layers, specifically 10 layers, of the second graphene 10b in the shell 2 The number of layers is 1 to 50, for example 20 to 30.

According to one embodiment, an outer layer with a higher density than the core may be present. The thickness of such an outer layer is not limited, but may be, for example, 20 to 60 nm.

The core and shell may further comprise graphite.

The diameter ratio of the porous silicon composite secondary particles and the porous silicon composite clusters is 1: 1 to 1:30, for example, 1: 1 to 1:25, specifically 1:21. The diameter ratio of the clusters of the porous silicon composite secondary particles and the porous silicon composite exhibits a size ratio when both the porous silicon composite secondary particles and the porous silicon composite have a spherical shape. If the porous silicon composite secondary particles and the porous silicon composite are non-spherical, it may be a ratio of the major axis length.

According to another embodiment, the core in the porous silicon composite clusters has a diameter of 3 to 10 占 퐉, and the thickness of the shell is 10 to 5,000 nm (0.01 to 5 占 퐉), for example, 10 to 1,000 nm. The diameter of the core including the porous silicon composite clusters and the thickness of the shell (carbon coating film) are from 1: 0.001 to 1: 1.67, for example, 1: 001, 1: 1.67, 1: 0.0033, or 1: 0.5.

The total content of the first graphene and the second graphene in the porous silicon composite cluster is 0.1 to 2,000 parts by weight, for example, 0.1 to 300 parts by weight, for example, 0.1 to 90 parts by weight, based on 100 parts by weight of silicon, And 5 to 30 parts by weight. When the total content of the first graphene and the second graphene is in the above range, the volume suppression effect of silicon is excellent and the conductivity is excellent.

The first graphene in the composite primary particles extends at a distance of 10 nm or less in silicon of silicon oxide (SiOx) (O <x <2) and comprises at least one graphene layer, for example, 1 to 30 graphene layers And the total thickness of the first graphene is 0.3 to 50 nm, for example 0.6 to 50 nm, for example 1 to 30 nm, and the first graphene is oriented at an angle between 0 and 90 degrees with respect to the major axis of the silicon do.

The second graphene in the porous silicon composite clusters may be a silicon oxide (SiOx) (O < x < 2) of porous silicon composite secondary particles having a distance of less than 1,000 nm, for example a distance of less than 500 nm, Such as 1 nm or less, such as 0.00001 to 1 nm, and includes at least one graphene layer, for example, 1 to 30 graphene layers, and the total thickness of the second graphene is 0.6 to 50 nm For example between 1 and 50 nm, and the second graphene is oriented at an angle between 0 and 90 relative to the major axis of the silicon.

The thickness of the silicon oxide (SiOx) (O <x <2) is 30 μm or less, for example, 10 nm.

The silicon is not limited in shape, and may be at least one selected from, for example, a sphere, a nanowire, a needle, and a rod. The average particle diameter of silicon is 10 nm to 30 占 퐉, for example, 100 nm.

The average particle diameter (D50) of the porous silicon composite secondary particles is 200 nm to 50 탆, for example, 1 to 30 탆, for example, 1 to 10 탆, specifically 3 to 5 탆. The specific surface area of the porous silicon composite secondary particles is 0.1 to 100 m ² / g, for example, 1 to 30 m ² / g. And the density of the porous silicon composite secondary particles is 0.1 to 2.8 g / cc, for example, 0.5 to 2 g / cc.

The surface of the porous silicon composite cluster may further include a carbon coating film. When the carbon coating film is further formed, the initial efficiency is lowered, but the lithium battery having improved lifetime characteristics can be manufactured.

The thickness of the carbon coating film is, for example, 10 to 5000 nm.

The carbon coating film contains a carbon-based material. The carbon-based material uses at least one selected from graphene, amorphous carbon, carbon nanotube, carbon pitch, fullerene, and carbon fiber.

The particle size distribution characteristics of the porous silicon composite clusters are narrow. For example, the porous silicon cluster has a D50 of 1 to 30 占 퐉, a D10 of 0.001 to 10 占 퐉, and a D90 of 10 to 60 占 퐉. Porous silicon clusters can be seen as secondary particles.

The porous silicon composite clusters according to one embodiment have a narrow particle size distribution. On the other hand, the silicon composite secondary particles obtained from the conventional silicon composite primary particles are difficult to control with the particle size of the negative electrode active material exhibiting irregular size distribution of secondary particles and exhibiting optimal cell performance. The content of oxygen in the porous silicon composite clusters is 0.01 to 15 atomic%, for example, 3.5 to 5 atomic%, specifically 3.5 to 3.8 atomic%. The reason why the content of oxygen is smaller than that of the conventional silicon based material is that the oxidation of silicon is suppressed by using a dispersant such as stearic acid in the production of the porous silicon composite cluster. By minimizing the oxygen content, the silicon capacity can be maximized and the initial efficiency is improved.

FIGS. 1C and 1D show the state of a conventional graphene monocrystalline silicon primary particle 30 and a negative electrode containing the graphene monocrystalline silicon primary particle 30 'after charge and discharge using the same.

The graphene-grown silicon primary particles have a structure in which the first graphenes 20a are disposed on the acicular-shaped silicon particles 20. 1D, a graphite 34 is mixed with graphene-direct-grown silicon primary particles 30 to form a negative electrode active material layer on the copper current collector 32 to form a negative electrode.

As shown in FIG. 1 (d), the cathode expands and contracts due to volumetric expansion and contraction of the silicon, and the graphene-grown silicon primary particles 30 ', which is an active material, are desorbed and the capacity is lowered by the isolation of silicon. In addition, the unstable SEI layer continuously grows on the surface of the silicon primary particles, which may lead to a decrease in charge and discharge durability due to a large consumption of lithium.

The inventors of the present invention have found that, in order to solve the above-mentioned problems, the inventors of the present invention formed a uniform charge / discharge network using a porous silicon composite cluster having a dual core / shell structure to reduce the volume expansion and shrinkage of silicon during charging / And a stable SEI is formed on the surface of the porous silicon composite clusters. Thus, a cathode having improved durability during charging and discharging can be manufactured.

Referring to FIG. 1B, the operation principle of a negative electrode containing a porous silicon composite cluster 30 according to an embodiment as a negative electrode active material together with graphite 13 will be described.

The porous silicon composite clusters 30 are graphene straight-grown silicon particles, and the anode active material layer composed of the mixture with the graphite 13 is disposed on the copper current collector 32 as the anode current collector. Since the porous silicon composite clusters 30 have a small BET specific surface area, the electrolyte penetration is prevented and the side reaction area with the electrolyte is reduced, so that the side reaction with the electrolyte is effectively suppressed, so that the active material desorption and the electrode expansion are suppressed even after charging and discharging. As a result, a lithium battery employing an electrode containing a porous silicon composite cluster has improved initial efficiency and charge / discharge durability. The silicon particles in the porous silicon composite clusters are connected via graphene, and a sliding network is better formed. As a result, the volume expansion inhibiting effect is improved.

Graphene plays a role in suppressing the breakdown and crushing of particles occurring in conventional silicon particles. The graphene sliding layer serves as a clamping layer to prevent disintegration of the silicon particles. And the alloying reaction of lithium ions and Si proceeds to provide a very specific capacity and a continuous conductive path between the particles.

When the silicon particles are swollen, the graphene layers slide together and slide back to a relaxed position during delitihiation. This is due to the fact that the Bande Baalschim is larger than the interlayer friction.

The clamping effect of the graphene layer described above can be confirmed to be that the graphene layer remains as it is even after repeating the lithization / de-lithization cycle so that the graphene layer functions as a clamping layer for preventing decomposition of the silicon particles.

The porous silicon composite clusters according to one embodiment have very good capacity characteristics with a capacity of 600 to 2,000 mAh / cc.

Referring to FIG. 1E, a method of fabricating a porous silicon composite cluster according to one embodiment will be described.

First, the structure including silicon oxide (SiOx) (O < x < 2) formed on silicon and silicon is crushed to obtain crushed silicon primary particles 42.

The pulverized silicone primary particles 42, the dispersant and the solvent are mixed to obtain the composition 40. From the composition (40), porous silicon composite secondary particles (41) are obtained.

The porosity of the porous composite secondary particles is, for example, from 0.1 to 50% and the pore size is from 10 to 500 nm.

The method of preparing the porous silicon secondary particles from the above-described composition can be variously used by coprecipitation, spray drying, solid phase method and the like, and spray drying can be used according to one embodiment. In the case of preparing the particles according to the spray drying method, the particle diameter can be controlled by selecting the spraying type, the feed rate of the pressurized gas, the feed rate of the composition, and the drying temperature.

The spray drying is carried out at a temperature of room temperature (25 캜) to 500 캜, for example, 50 to 300 캜. The porosity of the silicone composite secondary particles is suitable when the temperature is within the above range while preventing the possibility of problems such as particle adhesion and clogging due to moisture condensation at the outlet of the particles during spray drying.

The spraying pressure of the spray drying during the spray drying may be 1 to 5 bar.

The surface area is greatly increased by such means as pulverizing the starting material before spray drying. For this purpose, disrupted silicon primary particles are used as the starting material.

For example, when spray drying is used, spherical porous silicon secondary particles 41 can be obtained. Part of the surface of the porous silicon secondary particles 41 may contain a dispersant such as stearic acid.

Thereafter, a porous silicon composite cluster including the step of supplying carbon source gas to the porous silicon secondary particles 31 and heat-treating the porous silicon composite particles may be manufactured.

The carbon source gas first grows outside the secondary particles after filling the pores of the porous silicon secondary particles.

As the solvent, ethanol, methanol, isopropyl alcohol or the like is used. When the alcohol-based solvent is used and the heat treatment is performed, the content of the dispersant in the porous silicon composite clusters is minimized along with the removal of the solvent. As a result, a porous silicon composite cluster having a minimized oxygen content can be obtained.

The dispersant plays a role of dispersing the silicon primary particles uniformly. The dispersing agent is at least one selected from, but not limited to, stearic acid, resorcinol, polyvinyl alcohol, and pitch. The content of the dispersant is 1 to 15 parts by weight, for example, 5 to 10 parts by weight, based on 100 parts by weight of the total composition. When the content of the dispersant is within the above range, silicon and graphene are uniformly dispersed without aggregation.

The carbon source gas is at least one selected from the group consisting of a compound represented by the following formula (1), a compound represented by the following formula (2), and an oxygen containing gas represented by the following formula (3).

[Chemical Formula 1]

C _n H _{(2n + 2-a)} [OH] _a

Wherein n is an integer of 1 to 20, a is 0 or 1,

(2)

C _n H _(2n)

Wherein n is an integer of 2 to 6,

(3)

CxHyOz

X is 0 or an integer of 1 to 20, y is 0 or an integer of 1 to 20, and z is 1 or 2.

The carbon source gas is at least one selected from the group consisting of, for example, methane, ethylene, propylene, methanol, ethanol and propanol.

Wherein the carbon source gas further comprises a second oxygen-containing compound represented by the following formula (3a), and the first oxygen-containing compound represented by the following formula (3a) differs from the oxygen-containing compound represented by the above formula (3).

[Chemical Formula 3]

CxHyOz

Wherein x is 0 or an integer of 1 to 20, y is 0 or an integer of 1 to 20, and z is 1 or 2.

For example, in Formula 3a, x may be 0 and the second oxygen containing compound may be water vapor (H ₂ O). The content of water vapor in the gas mixture is not particularly limited and can be, for example, 0.01 to 10% by volume based on 100% by volume of the total carbon source gas.

The carbon source gas may be a mixture of the above-described plurality of gases.

The heat treatment is performed at 600 to 1100 ° C, for example, at 700 to 1,000 ° C. When performed at this heat treatment temperature, graphene is formed at high density in the core and the shell.

As described above, the silicon composite primary particles may be silicon; Silicon oxide (SiOx) (O < x < 2) disposed on the silicon and graphene disposed on the silicon oxide. Silicon oxide (SiOx) (O <x <2) is an oxygen-deficient unstable material compared to silica (SiO ₂ ) and tends to react with other reactive materials such as carbon source gas to form a stable material. Taking advantage of this point, a silicon oxide (SiOx) (O <x <2) film is used as a seed layer material to form graphene.

The silicon oxide (SiOx) (O <x <2) formed on the silicon has a film shape. The thickness of the silicon oxide film has a very important influence on the shape and structure of the graphene.

The thickness of the silicon oxide (SiOx) (O < x < 2) film can be varied by using the carbon source gas composition necessary for forming the graphene, The thickness of such a silicon oxide (SiOx) (O < x < 2) film may be 300 m or less.

According to one embodiment, the thickness of the silicon oxide (SiOx) (O <x <2) film used in the composite battery is 10 nm or less, 0.1 to 10 nm, specifically 0.1 to 5 nm. When a composite having a silicon oxide (SiOx) (O < x < 2) film having such a thickness range is used, the capacity characteristics of the battery are excellent.

According to one embodiment, the process of forming graphene on a silicon oxide (SiOx) (O <x <2) film of silicon utilizes a catalyst-free vapor carbon deposition process.

The vapor-phase carbon deposition reaction is carried out in the presence of silicon oxide (SiOx) -coated silicon oxide (SiOx) in at least one gas atmosphere selected from the group consisting of a compound represented by the following formula (1), a compound represented by the following formula A heat treatment step is performed.

 [Chemical Formula 1]

C _n H _{(2n + 2-a)} [OH] _a

Wherein n is an integer of 1 to 20, a is 0 or 1,

(2)

C _n H _(2n)

Wherein n is an integer of 2 to 6,

(3)

CxHyOz

X is 0 or an integer of 1 to 20, y is 0 or an integer of 1 to 20, and z is 1 or 2.

The thickness of the silicon oxide (SiOx) layer can be controlled by controlling the process involved in graphene formation. For example, by controlling the composition of the carbon source gas used in the formation of the second graphene.

The above-described vapor carbon deposition reaction is not intended to be bound to the theory described later, but such a coating is formed by reforming the silicon covered with the silicon oxide (SiOx, 0 < x < 2) contained in the gas mixture by CO ₂ ).

According to the non-catalytic gaseous carbon deposition reaction described above, graphene is directly grown on the surface of silicon oxide (SiOx) disposed on silicon, and adhesion between silicon and first graphene and silicon and second graphene is high.

According to another embodiment, even though the SiOx layer does not exist on the Si layer, when a carbon mixed gas and an oxygen mixed gas are reacted, a silicon oxide (SiOx, 0 <x < 2) layer may be formed first, and a carbon mixed gas may be reacted on the layer to form a first graphene and a second graphene.

The adhesion between silicon and graphene can be evaluated by a scanning electron microscope between silicon and graphene of SiOx.

The first graphene of the silicon composite primary particles constituting the porous silicon composite clusters is extended in the silicon of the silicon oxide by a distance of 10 nm or less, for example, 0.5 to 10 nm. According to another embodiment, the first graphene is extended by a distance of 1 nm or less, for example 0.5-1 nm, in the silicon of the silicon oxide. And the first graphene is oriented at an angle between 0 and 90 relative to the major axis of the silicon. At least 1 to 20 graphene layers, and the total thickness of the first graphene is 0.6 to 12 nm. And the first graphene is oriented at an angle between 0 and 90 relative to the major axis of the silicon.

The shape of the silicon is non-limiting, for example, the silicon can be one selected from a sphere, a nanowire, a needle, a rod, a particle, a nanotube, a nanorod, a wafer, .

According to one embodiment, the silicon may be needle-shaped particle type. The length of the acicular silicon particles is about 100 to 160 nm, for example, about 108 to 125 nm, and the thickness is about 10 to 100 nm, for example, about 20 to 50 nm, specifically about 40 nm.

According to one embodiment, a film of silicon oxide (SiOx) (O < x < 2) may be formed on the acicular silicon and graphene may be formed thereon.

According to another embodiment, a silicon oxide (SiOx) (O < x < 2) film may be formed on the silicon nanoparticles and graphene may be formed thereon. Here, the average particle diameter of the silicon nanoparticles is 40 nm to 40 m, for example, 40 to 100 nm.

When the silicon is a wafer type, the thickness of the silicon wafer is 2 mm or less, for example, 0.001 to 2 mm.

The graphene is formed by connecting a plurality of carbon atoms to each other through a covalent bond to form a polycyclic aromatic molecule. The carbon atoms connected by the covalent bond form a 6-membered ring as a basic repeating unit, but a 5-membered ring and / It is also possible to include more. As a result, the graphene appears as a single layer of covalently bonded carbon atoms (usually sp ² bonds). The graphene may be composed of a single layer. However, it is also possible to form a plurality of layers by stacking a plurality of layers. For example, the graphenes may include one layer to 100 layers, or two layers to 100 layers, or three layers to 50 layers Lt; / RTI &gt;

Graphene may have a structure such as a nanosheet, a film (or film), a graphene nanosheet, a flake, or the like. The term "nanosheet " refers to a film formed in an irregular state on silicon oxide, and" film &quot; refers to a film shape formed continuously and uniformly on top of silicon oxide.

The porous silicon composite clusters according to one embodiment may further comprise a metal oxide. If such a metal oxide is further included, there is an advantage of preventing formation of SEI layer due to inhibition of side reaction.

The metal oxide includes at least one selected from the group consisting of magnesium oxide, manganese oxide, aluminum oxide, titanium oxide, zirconium oxide, tantalum oxide, tin oxide, hafnium oxide and aluminum fluoride (AlF ₃ ).

In a porous silicon composite cluster according to one embodiment, the graphene can serve as a SEI stabilizing clamping layer. The porous silicon composite clusters have a high specific surface area, which can prevent the initial efficiency and the volume energy density from deteriorating in the battery using the porous silicon composite clusters.

In porous silicon composite clusters, graphene can inhibit fracture and crushing of active materials such as silicon and improve the conductivity of the composite. Graphene plays a role in suppressing the breakdown and crushing of particles occurring in silicon particles. Graphene acts as a clamping layer to prevent the disintegration of silicon particles and alloying reaction of lithium ions and Si proceeds to provide a very good specific capacity and a continuous conductive path between particles. do.

When the silicon particles are swollen, the graphene layers slide together and slide back to a relaxed position during delitihiation. This is due to the fact that the Bande Baalschim is larger than the interlayer friction.

The clamping effect of the graphene layer described above is that the graphene layer remains intact after repeatedly performing about 200 lithium ionization / de-lithization cycles, thereby confirming that the graphene layer serves as a clamping layer to prevent decomposition of the silicon particles .

The porous silicon composite clusters according to an exemplary embodiment may form dense graphenes on the surface of the silicon composite primary particles to form nano-sized pores between the particles, and may act as a buffer when the primary particles and the secondary particles expand in volume. And the SEI layer can be stably formed through the heat treatment. And the graphenes of various layers present on the surface of the secondary particles are expanded in volume so that the primary particles are not exposed outside the secondary particles due to sliding between the graphenes during volume expansion and contraction of the silicon to reduce the contact of the primary particles of the silicon composite with the electrolyte .

According to another aspect, there is provided a carbon composite comprising the above-described porous silicon composite clusters and a carbon-based material. The porous silicon composite clusters according to an embodiment have a reduced specific surface area and an increased bulk density (non-capacity) as compared with the silicon composite primary particles, which can improve the bulk energy density when mixed with the carbon-based material, Can be further reduced.

The above-described carbon composite material is excellent in initial efficiency and non-capacity characteristics as compared with the composite, and the rate-limiting performance and durability are further improved.

The content of the carbon-based material is 0.001 to 99 parts by weight, for example, 10 to 97 parts by weight, for example, 50 to 97 parts by weight, based on 100 parts by weight of the carbon composite. When the content of the carbon-based material is within the above range, a carbon composite excellent in capacity and conductivity can be obtained.

The carbon-based material includes at least one selected from the group consisting of graphene, graphite, fullerene, carbon fiber, and carbon nanotube.

The carbon composite material may contain, for example, graphite and a porous silicon composite cluster formed on the graphite.

As the graphite, SFG6 graphite is used, for example, an average particle size of about 6 mu m. In the case of forming the electrode using the carbon composite material, the content of the carbon composite material in the electrode is, for example, 68 to 87 parts by weight, and the content of the binder is, for example, 13 to 32 parts by weight. The content of graphite in the carbon composite material is, for example, 1 to 20 parts by weight based on 100 parts by weight of the carbon composite material.

As the binder, for example, lithium polyacrylate is used.

The compound represented by Formula 1 and the compound represented by Formula 2 are at least one selected from the group consisting of methane, ethylene, propylene, methanol, ethanol, and propanol.

The oxygen-containing gas represented by the general formula (3) includes, for example, carbon dioxide (CO ₂ ) and carbon monoxide (CO), water vapor (H ₂ O), or a mixture thereof.

In addition to the carbon source gas, it may further comprise at least one inert gas selected from the group consisting of nitrogen, helium, and argon.

The oxygen-containing gas may be at least one selected from the group consisting of carbon monoxide, carbon dioxide, and water vapor.

When an oxygen-containing gas is used as a carbon source gas, the thickness of the silicon oxide film can be thicker than the thickness of the silicon oxide film, which is a natural oxide film. The thickness of the silicon oxide film can be controlled to 10 nm or less, for example, 0.5 to 5 nm. By using a silicon oxide film having such a thickness range, the shape and thickness of graphene can be controlled. More specifically, if the thickness of the silicon oxide layer is thicker than the thickness of the natural oxide layer, the graphene layer having a more dense structure than the graphene nanosheet formed thereon can be obtained. Here, the graphene layer has, for example, a 5 to 10 layer structure.

If the gas mixture comprises water vapor, the resultant complexes may exhibit higher conductivity. Without wishing to be bound by any particular theory, it is believed that the reaction between the gas mixture in the presence of water vapor deposits highly crystalline carbon on the silicon coated with silicon oxide, so that even when a smaller amount of carbon is coated, . The content of water vapor in the gas mixture is not limited, and is, for example, 0.01 to 10% by volume based on 100% by volume of the total carbon source gas.

The carbon source gas may be, for example, methane; A mixed gas comprising methane and an inert gas; An oxygen-containing gas; Or a mixed gas comprising methane and an oxygen-containing gas.

The carbon source gas according to one embodiment may be a CH ₄ : CO ₂ mixed gas or a CH ₄ : CO ₂ : H ₂ O mixed gas.

The CH ₄ : CO ₂ mixed gas may be provided in a molar ratio of about 1: 0.20-0.50, specifically about 1: 0.25-0.45, and more specifically about 1: 0.30-0.40 Lt; / RTI &gt;

The CH ₄ : CO ₂ : H ₂ O mixed gas may be provided in a molar ratio of about 1: 0.20-0.50: 0.01 to 1.45, and specifically in a molar ratio of about 1: 0.25-0.45: 0.10-1.35, More specifically from about 1: 0.30 to 0.40: 0.50 to 1.0.

The carbon source gas according to another embodiment may be carbon monoxide (CO) or carbon dioxide (CO ₂ ).

A carbon source gas according to another embodiment is a mixed gas of CH ₄ and N ₂ .

CH _4: N ₂ gas mixture is about 1: may be provided in a molar ratio of 0.20 ~ 0.50, in particular from about 1: may be provided in a molar ratio of 0.25 to 0.45, and more specifically about 1: mole ratio of 0.30 ~ 0.40 Lt; / RTI &gt; The carbon source gas according to one embodiment may not contain an inert gas such as nitrogen.

The heat treatment may be performed at 750 to 1100 ° C, for example, 800 to 1000 ° C.

The pressure in the heat treatment step is not limited, and can be selected in consideration of the heat treatment temperature, the composition of the gas mixture, and the amount of the desired carbon coating. The pressure during the heat treatment can be controlled by adjusting the amount of the introduced gas mixture and the amount of the discharged gas mixture. For example, the pressure during heat treatment may be at least 1 atm, such as at least 2 atm, at least 3 atm, at least 4 atm, and at least 5 atm, but is not limited thereto.

The heat treatment time is not particularly limited and can be appropriately adjusted according to the heat treatment temperature, the pressure at the heat treatment, the composition of the gas mixture, and the amount of the desired carbon coating. For example, the reaction time may be 10 minutes to 100 hours, specifically 30 minutes to 90 hours, more specifically, 50 minutes to 40 hours, but is not limited thereto. While not intending to be bound by any particular theory, the longer the time, the greater the amount of deposited graphene (carbon), and thus the electrical properties of the composite can be improved. However, this tendency may not necessarily be directly proportional to time. for example. After a predetermined time has elapsed, graphene deposition may no longer occur or the deposition rate may be lowered.

The above described method of producing porous silicon composite clusters can provide a uniform coating of graphene on silicon coated with silicon oxide (SiOx) even at relatively low temperatures through the above-described gas phase reaction of the carbon source gas. And the desorption reaction of graphene formed on the silicon coated with the silicon oxide (SiOx) film does not substantially occur. By controlling the thickness of the silicon oxide film, the desorption reaction of graphene can be further suppressed. As described above, the thickness of the silicon oxide film that can effectively suppress the desorption of graphene is 10 nm or less, 0.1 to 10 nm, specifically 0.1 to 5 nm.

Also, since graphene is coated on silicon through a gas phase reaction, a coating film having high crystallinity can be formed. When such a porous silicon composite cluster is used as an anode active material, the conductivity of the anode active material can be increased without changing the structure.

The process for preparing the carbon composite material using the porous silicon composite clusters according to one embodiment is as follows.

The porous silicon composite clusters according to one embodiment are mixed with the carbon-based material and heat-treated.

The heat treatment is performed at 600 to 1100 ° C, for example, 700 to 1,000 ° C. When the heat treatment temperature is in the above range, a carbon composite excellent in capacity characteristics can be obtained.

The porous silicon composite clusters or carbon composites according to one embodiment may be usefully used in batteries, display luminous bodies, thermoelectric elements, biosensors, and the like.

According to another aspect, there is provided an electrode comprising the above-described porous silicon composite cluster or carbon composite. The electrode may be an electrode for a lithium battery.

The electrode may be a cathode.

The composite or carbon composite may be used as an electrode active material, for example, an anode active material. As such, when used as an anode active material, silicon volume expansion is reduced and the crushing is reduced. The conductivity can be improved and the high-rate characteristics can be improved. In addition, it is possible to coat graphene in a minimum amount on silicon coated with silicon oxide, thereby obtaining a negative electrode active material having an improved energy density per volume. The composite material or the lithium composite material containing the composite material and the carbon- Thereby providing a battery.

The negative electrode can be produced by the following method.

The negative electrode may be, for example, a composite or a carbon composite that is an anode active material,

The negative electrode active material composition containing the binder may be formed into a predetermined shape or the negative electrode active material composition may be applied to a current collector such as copper foil. It is not necessary to use a conductive agent in the composition.

Also, the negative electrode active material composition may be formed in the form of a film on the separator without the current collector.

Specifically, the negative electrode active material mixed with the negative electrode active material, the conductive agent, the binder and the solvent

A material composition is prepared. The negative electrode active material composition is directly coated on the metal current collector to produce a negative electrode plate. Alternatively, the negative electrode active material composition may be cast on a separate support, and then the film peeled off from the support may be laminated on the metal current collector to produce a negative electrode plate. The negative electrode is not limited to the above-described form, but may be in a form other than the above-described form.

The negative active material composition may further include a carbon-based negative active material other than the negative active material described above. For example, the carbonaceous anode active material may be at least one selected from the group consisting of natural graphite, artificial graphite, expanded graphite, graphene, carbon black, fullerene soot, carbon nanotube, But are not limited to, and can be used in the art.

As the conductive agent, metal powders such as acetylene black, Ketjen black, natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, copper, nickel, aluminum and silver, metal fibers and the like can be used , And polyphenylene derivatives may be used alone or in admixture of one or more. Any conductive material may be used as long as it can be used as a conductive material in the technical field of the art.

Examples of the binder include vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, polytetrafluoroethylene, styrene butadiene rubber-based polymer, polyacrylic liquid A seed, a polyamideimide, a polyimide, or a mixture thereof may be used, but is not limited thereto and can be used as long as it can be used as a bonding agent in the art.

As the solvent, N-methylpyrrolidone, acetone, water or the like may be used, but not limited thereto, and any solvent which can be used in the technical field can be used.

The content of the negative electrode active material, the conductive agent, the binder and the solvent is a level commonly used in a lithium battery. Depending on the application and configuration of the lithium battery, one or more of the binder and the solvent may be omitted.

A lithium battery according to another embodiment adopts the negative electrode. The lithium battery can be produced by the following method.

First, a negative electrode is prepared according to the negative electrode manufacturing method.

Next, a cathode active material composition in which a cathode active material, a conductive agent, a binder and a solvent are mixed is prepared. The positive electrode active material composition is coated directly on the metal current collector and dried to produce a positive electrode. Alternatively, the cathode active material composition may be cast on a separate support, and then a film peeled from the support may be laminated on the metal current collector to produce a cathode.

The positive electrode active material may include at least one selected from the group consisting of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, and lithium manganese oxide. However, May be used.

For example, the cathode active material is a lithium-containing metal oxide, and any of those conventionally used in the art can be used without limitation. For example, at least one of complex oxides of metal and lithium selected from cobalt, manganese, nickel, and combinations thereof may be used. Specific examples thereof include Li _a A _{1 - b} B _b D ₂ 0.90? A? 1, and 0? B? 0.5); Li _a E _{1 - b} B _b O _{2 - c} D _{c where} 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05; LiE _{2 - b} B _b O _{4 - c} D _{c where} 0? B? 0.5, 0? C? 0.05; Li _a Ni _{1 -b- c} Co _b B _c D _{? Wherein} 0.90? A? 1, 0? B? 0.5, 0? C? 0.05, 0 <?? 2; Li _a Ni _{1 -b- c} Co _b B _c O _{2 - ?} F _{? Where} 0.90? A? 1, 0? B? 0.5, 0? C? 0.05, 0 <? Li _a Ni _{1 -b- c} Co _b B _c O _{2 - ?} F ₂ wherein 0.90? A? 1, 0? B? 0.5, 0? C? 0.05, 0 <? Li _a Ni _{1 -b- c} Mn _b B _c D _? Wherein, in the formula, 0.90? A? 1, 0? B? 0.5, 0? C? 0.05, 0 <? Li _a Ni _{1 -b- c} Mn _b B _c O _{2 - ?} F _? Wherein? 0.90? A? 1, 0? B? 0.5, 0? C? 0.05, 0 <? Li _a Ni _{1 -b- c} Mn _b B _c O _{2 - ?} F ₂ wherein 0.90? A? 1, 0? B? 0.5, 0? C? 0.05, 0 <? Li _a Ni _b E _c G _d O ₂ wherein 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, and 0.001 ≤ d ≤ 0.1; Li _a Ni _b Co _c Mn _d GeO ₂ wherein 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, and 0.001 ≤ e ≤ 0.1; Li _a NiG _b O ₂ (in the above formula, 0.90? A? 1, and 0.001? B? 0.1); Li _a CoG _b O ₂ (in the above formula, 0.90? A? 1, 0.001? B? 0.1); Li _a MnG _b O ₂ (in the above formula, 0.90? A? 1, 0.001? B? 0.1); Li _a Mn ₂ G _b O ₄ (in the above formula, 0.90? A? 1, 0.001? B? 0.1); QO _2; QS ₂ ; LiQS ₂ ; V ₂ O ₅ ; LiV ₂ O ₅ ; LiIO ₂ ; LiNiVO _4; Li _(3-f) J ₂ (PO ₄ ) ₃ (0? F? 2); Li _(3-f) Fe ₂ (PO ₄ ) ₃ (0? F? 2); A compound represented by any one of the formulas of LiFePO ₄ can be used.

In the above formula, A is Ni, Co, Mn, or a combination thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or combinations thereof; Q is Ti, Mo, Mn, or a combination thereof; I is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

Of course, a compound having a coating layer on the surface of the compound may be used, or a compound having a coating layer may be mixed with the compound. The coating layer may comprise an oxide, a hydroxide of the coating element, an oxyhydroxide of the coating element, an oxycarbonate of the coating element, or a coating element compound of the hydroxycarbonate of the coating element. The compound constituting these coating layers may be amorphous or crystalline. The coating layer may contain Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr or a mixture thereof. The coating layer forming step may be any coating method as long as it can coat the above compound by a method that does not adversely affect physical properties of the cathode active material (for example, spray coating, dipping, etc.) by using these elements, It will be understood by those skilled in the art that a detailed description will be omitted.

For example, LiNiO ₂ , LiCoO ₂ , LiMn _x O _2x (x = 1, 2), LiNi _{1 - x} Mn _x O ₂ (0 <x <1), LiNi _{1 - x -} yCo _x Mn _y O ₂ 0? X? 0.5, 0? Y? 0.5), LiFeO ₂ , V ₂ O ₅ , TiS, MoS and the like can be used.

As the conductive agent, binder and solvent in the positive electrode active material composition, the same materials as those for the negative electrode active material composition may be used. It is also possible to add a plasticizer to the cathode active material composition and / or the anode active material composition to form pores inside the electrode plate.

The content of the cathode active material, the conductive agent, the binder, and the solvent is a level commonly used in a lithium battery. At least one of the conductive agent, the binder and the solvent may be omitted depending on the use and configuration of the lithium battery.

Next, a separator to be inserted between the positive electrode and the negative electrode is prepared. The separator can be used as long as it is commonly used in a lithium battery. A material having a low resistance against the ion movement of the electrolyte and an excellent ability to impregnate the electrolyte may be used. For example, selected from glass fiber, polyester, Teflon, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), or a combination thereof, and may be nonwoven fabric or woven fabric. For example, a rewindable separator such as polyethylene, polypropylene, or the like is used for the lithium ion battery, and a separator having excellent organic electrolyte impregnation capability can be used for the lithium ion polymer battery. For example, the separator may be produced according to the following method.

A polymer resin, a filler and a solvent are mixed to prepare a separator composition. The separator composition may be coated directly on the electrode and dried to form a separator. Alternatively, after the separator composition is cast and dried on a support, a separator film peeled from the support may be laminated on the electrode to form a separator.

The polymer resin used in the production of the separator is not particularly limited, and any material used for the binder of the electrode plate may be used. For example, vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate or mixtures thereof may be used.

The separator may comprise a ceramic component to improve the performance of the membrane. For example, an oxide may be coated on the separator or ceramic particles may be prepared when the separator is manufactured.

Next, the electrolyte is prepared.

For example, the electrolyte may be an organic electrolyte. In addition, the electrolyte may be a solid. For example, boron oxide, lithium oxynitride, and the like, but not limited thereto, and any of them can be used as long as they can be used as solid electrolytes in the art. The solid electrolyte may be formed on the cathode by a method such as sputtering.

For example, an organic electrolytic solution can be prepared. The organic electrolytic solution can be prepared by dissolving a lithium salt in an organic solvent.

The organic solvent may be any organic solvent which can be used in the art. Examples of the solvent include propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, dibutyl carbonate N, N-dimethylformamide, N, N-dimethylformamide, tetrahydrofuran, tetrahydrofuran, Dimethylacetamide, N, N-dimethylsulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether or mixtures thereof.

The lithium salt may also be used as long as it can be used in the art as a lithium salt. For example, LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , LiAlO ₂ , LiAlCl ₄ , _x F _{2x + 1} SO ₂ ) (C _y F _{2y + 1} SO ₂ ) (where x and y are natural numbers), LiCl, LiI, or a mixture thereof.

2A, the lithium battery 121 includes a cathode 123, a cathode 122, and a separator 124. The anode 23, the cathode 122 and the separator 124 described above are wound or folded and housed in the battery case 125. Then, an organic electrolytic solution is injected into the battery case 125 and the cap assembly 126 is sealed to complete the lithium battery 121. The battery case may have a cylindrical shape, a rectangular shape, a thin film shape, or the like. For example, the lithium battery may be a thin film battery. The lithium battery may be a lithium ion battery.

A separator may be disposed between the anode and the cathode to form a battery structure. The cell structure is laminated in a bi-cell structure, then impregnated with an organic electrolyte solution, and the obtained result is received in a pouch and sealed to complete a lithium ion polymer battery.

In addition, a plurality of battery assemblies may be stacked to form a battery pack, and such battery pack may be used for all devices requiring high capacity and high output. For example, a notebook, a smart phone, an electric vehicle, and the like.

The lithium battery is suitable for an electric vehicle (EV) because it has a high rate characteristic and a good life characteristic. For example, it is suitable for a hybrid vehicle such as a plug-in hybrid electric vehicle (PHEV).

Another aspect provides a field emission device comprising the complex or the carbon composite material comprising the complex and the carbon-based material.

Field emission devices are devices that utilize the movement of electrons. A typical field emission device includes at least a reducing electrode, an emitter tip, and an oxidizing electrode spaced from the reducing electrode. (See U.S. Patent Nos. 7,009,331, 6,976,897, 6,911,767, and U.S. Patent Application 2006/0066217, the contents of each of which are incorporated herein by reference), a voltage is applied between the reduction electrode and the oxide electrode, Lt; / RTI &gt; The electrons proceed from the reducing electrode toward the oxidizing electrode. The device may be used in a variety of applications such as, but not limited to, ultrasonic vacuum tube devices (e.g., X-ray tubes), power amplifiers, ion guns, high energy accelerators, free electron lasers and electron microscopes, particularly flat panel displays. Flat panel displays can be used for replacing conventional cathode tubes. These flat panel displays are therefore applied to televisions and computer monitors

As the emitter tip, a composite according to one embodiment or a carbon composite using the composite may be used.

Conventional emitter tips are made of a metal such as molybdenum or a semiconductor such as silicon. One of the concerns associated with using a metal emitter tip is that the control voltage required for emission is relatively high, e.g., on the order of 100 V. In addition, due to the fact that these emitter tips have no uniformity, the current density between the pixels becomes non-uniform.

When the emitter tips using the porous silicon composite clusters or carbon composites described above are used, the field emission characteristics are excellent.

The above-described porous silicon composite clusters or carbon composites are usable in manufacturing electroluminescent devices.

According to another aspect, there is provided a biosensor comprising a porous silicon composite cluster according to one embodiment, or a carbon composite comprising the porous silicon composite cluster and a carbon-based material.

A porous silicon composite cluster or carbon composite according to one embodiment is usable for forming an electrode for a biosensor.

2E is a cross-sectional view illustrating an electrode structure of a biosensor according to one embodiment.

The biosensor electrode according to one embodiment includes a substrate 310, a first layer 320 including a porous silicon composite cluster or a carbon composite formed on the substrate 310, And a second layer 330 formed thereon. In the second layer 330, the bio material 340 is supported or fixed in various ways.

The substrate 310 may be selected from the group consisting of glass, plastic, metal, ceramic, and silicon. The substrate 310 may be formed of any type of substrate on which graphene can be deposited or formed, Is not particularly limited as long as graphene can be deposited or formed thereon.

Biomaterials selected from the group consisting of enzymes, platamers, proteins, nucleic acids, microorganisms, cells, lipids, hormones, DNA, PNAs, RNAs and mixtures thereof can be used as the biomaterial 340, It should be noted that various bio materials may be used.

Referring to FIG. 2E, a specific enzyme is used as the biomaterial 340, and the second layer 330 discloses an electrode for a biosensor in which the specific enzyme-supported or fixed membrane is used. Meanwhile, in FIG. 2E, the specific enzyme is shown to be supported or immobilized within the membrane. However, it should be noted that the position of the specific enzyme is not limited thereto, and some or all of the enzyme may protrude from the membrane. According to this structure, since the enzyme is excellent in substrate specificity and has a characteristic of selectively reacting only with a specific molecule even in a mixture, it is possible to selectively detect an analyte (for example, blood glucose) do.

According to another aspect, there is provided a semiconductor device containing the porous silicon composite cluster or the porous silicon composite cluster and a carbon composite material containing a carbon-based material.

The porous silicon composite clusters or carbon composites may be used as electrodes of semiconductor devices.

According to another aspect, there is provided a thermoelectric material containing the porous silicon composite clusters or the porous silicon composite clusters and the carbon composite material including the carbon-based material, and a thermoelectric element including the thermoelectric material.

The thermoelectric material has improved thermoelectric performance due to its excellent electrical properties. These thermoelectric materials can be usefully used in thermoelectric elements, thermoelectric modules or thermoelectric devices.

The performance of thermoelectric materials uses the ZT value of Equation 1, commonly referred to as a dimensionless figure of merit.

 [Equation 1]

ZT = (S ² σT) / k

In the equation (1), ZT represents a figure of merit, S represents a Seebeck coefficient,? Represents electrical conductivity, T represents absolute temperature, and? Represents thermal conductivity.

As shown in Equation (1), in order to increase the ZT value of the thermoelectric material

Should increase the Seebeck coefficient and electrical conductivity, ie, the power factor (S ² σ), and decrease the thermal conductivity.

The porous silicon composite clusters or carbon composites according to one embodiment contain graphene, so that when the characteristics of graphene is applied to the thermoelectric material, high electrical conductivity and low thermal conductivity are realized, and thus the performance of the thermoelectric material can be improved have.

The porous silicon composite clusters or carbon composites having one embodiment have improved crystallinity and electronic structure at the interface between graphene having a metallic property and silicon having a semiconducting property to increase the Seebeck coefficient and accelerate the transfer of the charged particles It is possible to induce an increase in electric conductivity and charge mobility. In addition, the phonon scattering at the interface between the graphene and the silicon is increased, and the thermal conductivity can be controlled.

As described above, the porous silicon composite clusters or carbon composites can be usefully used as thermoelectric materials. Therefore, the thermoelectric element can be manufactured by molding the thermoelectric material by a cutting method or the like. The thermoelectric element may be a p-type thermoelectric element. Such a thermoelectric element means that the thermoelectric material is formed in a predetermined shape, for example, a rectangular parallelepiped shape.

On the other hand, the thermoelectric element may be a component capable of exhibiting a cooling effect by being coupled with an electrode by applying an electric current, and exhibiting a power generation effect by a temperature difference.

2B shows an embodiment of a thermoelectric module employing the thermoelectric element. 2B, an upper electrode 212 and a lower electrode 22 are patterned and formed on the upper insulating substrate 211 and the lower insulating substrate 221, The p-type thermoelectric component 215 and the n-type thermoelectric component 16 are in contact with the upper electrode 212 and the lower electrode 222 with each other. These electrodes 212 and 222 are connected to the outside of the thermoelectric element by the lead electrode 24. The above-described thermoelectric element can be used as the p-type thermoelectric element 215. The n-type thermoelectric component 216 can be used without limitation as long as it is known in the art.

 As the insulating substrates 211 and 221, gallium arsenide (GaAs), sapphire, silicon, pyrex, and quartz substrates can be used. The electrodes 212 and 222 may be made of various materials such as copper, aluminum, nickel, gold, and titanium, and their sizes may be variously selected. As a method of patterning these electrodes 12 and 22, a conventionally known patterning method may be used without limitation. For example, a lift-off semiconductor process, a deposition method, a photolithography method, or the like can be used.

In one embodiment of the thermoelectric module, one of the first electrode and the second electrode may be exposed to a heat source, as shown in Figures 2c and 2d. In one embodiment of the thermoelectric device, one of the first electrode and the second electrode is electrically connected to a power source, or an electrical element (e.g., a battery) that consumes or stores power outside of the thermoelectric module, As shown in FIG.

In one embodiment of the thermoelectric module, one of the first electrode and the second electrode may be electrically connected to a power source.

Will be explained in more detail through the following examples and comparative examples. However, the examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Manufacturing example  One

The needle-shaped silicon was pulverized to obtain plate-shaped and needle-shaped silicon particles having a length of about 125 nm and a thickness of about 40 nm, in which a silicon oxide (SiO _x ) (o <x <2) film (thickness: about 0.1 nm) was formed on the surface.

25 parts by weight of the platelike and needle-shaped silicon particles, 10 parts by weight of stearic acid and 65 parts by weight of isopropyl alcohol was spray-dried and dried to obtain porous silicon secondary particles having an average particle size of about 3-6 탆.

Spray drying was performed using a spray dryer (model: MMSD Micro Mist Spray Dryers, Fujisaki electric). The clusters were prepared by adjusting the spray nozzle size and pressure under the N ₂ condition and adjusting the powder spraying atmosphere temperature (80 - 200 ° C) to dry the alcohols.

The porous silicon secondary particles were placed in a reactor. A gas mixture having a rate of 300 sccm of CH ₄ was flown into the reactor to form an atmosphere of the gas mixture in the reactor. The pressure produced by the flow of the gas mixture in the reactor is 1 atm. The internal temperature of the reactor was raised to 1000 캜 (temperature raising rate: about 23 캜 / min) in the gas mixture atmosphere, and the gas mixture was continuously heated to the reactor while maintaining the temperature for 1 hour. Subsequently, the resultant was allowed to stand for about 4 hours to form a graphene nanosheet on the needle-shaped silicon particles. Thereafter, the supply of the gas mixture is stopped and the reactor is cooled to room temperature (25 캜) to form a core comprising porous silicon composite secondary particles and a high crystalline graphene flake disposed on top of the core, Wherein the porous silicon composite secondary particles comprise aggregates of two or more silicon composite primary particles, wherein the composite primary particles are selected from the group consisting of silicon; A porous silicon composite cluster comprising silicon oxide (SiOx) (O <x <2) disposed on the silicon and first graphene disposed on the silicon oxide was obtained.

The content of the first graphene and the second graphene in the porous silicon composite clusters is about 20 parts by weight based on 100 parts by weight of the total weight of the porous silicon composite clusters.

Manufacturing example  2

Except that the internal temperature of the reactor was raised to 1000 占 폚 (temperature raising rate: about 23 占 폚 / min) in a gas mixture atmosphere, and the gas mixture was continuously fed to the reactor while being maintained at the above temperature for 2 hours , And Production Example 1 to obtain a porous silicon composite cluster.

The total content of the first graphene and the second graphene in the porous silicon composite clusters is about 30 parts by weight based on 100 parts by weight of the total weight of the porous silicon composite clusters.

Manufacturing example  3

Except that the internal temperature of the reactor was raised to 1000 占 폚 (temperature raising rate: about 23 占 폚 / min) in a gas mixture atmosphere and the gas mixture was continuously fed to the reactor and maintained at the above temperature for 3 hours , And Production Example 1 to obtain a porous silicon composite cluster.

The total content of the first graphene and the second graphene in the porous silicon composite clusters is about 30 parts by weight based on 100 parts by weight of the total weight of the porous silicon composite clusters.

Manufacturing example  4-6

Except that plate-shaped and needle-shaped silicon particles having a length of about 108 nm and a thickness of about 40 nm were used in place of the plate-shaped and needle-shaped silicon particles having a length of about 125 nm and a thickness of about 40 nm, in the same manner as in Production Examples 1 to 3 Thereby preparing a porous silicon composite cluster.

Manufacturing example  7

A porous silicon composite cluster was produced in the same manner as in Production Example 4, except that a composition containing 25 parts by weight of plate-shaped and needle-shaped silicon particles, 5 parts by weight of stearic acid and 70 parts by weight of isopropyl alcohol was used.

Comparative Manufacturing Example  One

A slurry containing needle-shaped silicon particles was prepared by crushing a composition containing 10 탆 of granular silicon in granular form, 10 parts by weight of stearic acid and 20 parts by weight of isopropyl alcohol 70 silicone, and dried without spraying. The secondary particle clusters were prepared by spray drying using the slurry. .

The resultant product was pulverized to obtain needle-shaped silicon particles having a length of about 125 nm formed on the surface of a silicon oxide (SiO _x ) (o <x <2) film (thickness: about 0.1 nm).

The acicular silicon primary particles were placed in a reactor. A gas mixture having a ratio of nitrogen (N ₂ ) of 300 sccm was flowed into the reactor to form an atmosphere of the gas mixture in the reactor. The pressure produced by the flow of the gas mixture in the reactor is 1 atm. The inside temperature of the reactor was raised to 950 캜 (temperature raising rate: about 23 캜 / min) in the gas mixture atmosphere, and the gas mixture was continuously heated to the reactor while keeping it at the above temperature for 3 hours. The resultant was left for about 4 hours to obtain porous silicon primary particles. The structure of the silicon primary particles has a needle shape.

Comparative Manufacturing Example  2

The granules of 10 mu m in granule form were pulverized to obtain a plate-like and needle-like form having a length of about 125 nm and a thickness of about 40 nm formed on the surface of a silicon oxide (SiO _x ) (o <x <2) Silicon particles were obtained.

The platelike and needle-shaped silicon particles were placed in a reactor. A gas mixture having a rate of 300 sccm of CH ₄ was flown into the reactor to form an atmosphere of the gas mixture in the reactor. The pressure produced by the flow of the gas mixture in the reactor is 1 atm. The internal temperature of the reactor was raised to 1000 캜 (temperature raising rate: about 23 캜 / min) in the gas mixture atmosphere, and the gas mixture was continuously heated to the reactor while maintaining the temperature for 1 hour. Subsequently, the resultant was allowed to stand for about 4 hours to form a graphene nanosheet on the plate-shaped and needle-shaped silicon particles. Thereafter, the supply of the gas mixture was stopped, and the reactor was cooled to room temperature (25 캜) to prepare silicon composite primary particles.

The silicon composite primary particles may be selected from the group consisting of plate-shaped and needle-shaped silicon; And a structure comprising silicon oxide (SiOx) (O < x < 2) disposed on the silicon and graphene disposed on the silicon oxide.

The content of graphene in the silicon composite primary particles is about 85 parts by weight based on 100 parts by weight of the total weight of the silicon composite primary particles.

Comparative Manufacturing Example  3

A silicon oxide (SiO _x ) (o < x < 2) film (thickness: about 0.1 nm) formed on the surface was ground to about 125 nm and a thickness of about 40 nm, Silicon particles were obtained.

20 parts by weight of the plate-shaped and needle-shaped silicon particles and 80 parts by weight of graphite were mixed to obtain a mixture, and the mixture was heat-treated at about 1,000 캜 to prepare a silicone composite.

Comparative Manufacturing Example  4

Shaped silicon particles having a length of about 125 nm formed on the surface of the silicon oxide (SiO _x ) (o <x <2) film (thickness: about 0.1 nm) were obtained by pulverizing the plate-shaped silicon.

10 parts by weight of stearic acid and 90 parts by weight of isopropyl alcohol was spray-dried on acicular silicone particles and dried to obtain silicone secondary particles having an average particle diameter of about 5 mu m.

The silicon secondary particles were placed in a reactor. A gas mixture having a ratio of nitrogen (N ₂ ) of 300 sccm was flowed into the reactor to form an atmosphere of the gas mixture in the reactor. The pressure produced by the flow of the gas mixture in the reactor is 1 atm. The inside temperature of the reactor was raised to 950 캜 (temperature raising rate: about 23 캜 / min) in the gas mixture atmosphere, and the gas mixture was continuously heated to the reactor while keeping it at the above temperature for 3 hours. The resultant was allowed to stand for about 4 hours to obtain porous silicon secondary particles.

The porous silicon secondary particles had a structure in which a carbon coating layer originated from stearic acid existed on the surfaces of the platelike and needle-shaped silicon particles.

Comparative Manufacturing Example  5

The silicone composite primary particles prepared according to Comparative Preparation Example 2 were further left for about 3 hours to prepare silicone composite secondary particles.

According to Comparative Preparation Example 5, it was difficult to obtain a silicon composite secondary comparative particle having a uniform and micrometer particle size. The resultant product thus obtained did not have a double core shell structure.

Example  1: cathode and Coin cell  Produce

A slurry was prepared by mixing porous silicon composite clusters, graphite, carbon black (KB600JD), lithium polyacrylate (Li-PAA) and NMP as a solvent prepared according to Preparation Example 1. In the slurry, the mixture ratio of the porous silicon composite clusters prepared in Preparation Example 1 and graphite, carbon black (KB600JD) and lithium polyacrylate was in a weight ratio of 91: 1: 8. The weight ratio of the porous silicon composite clusters to the graphite in the mixture of the porous silicon composite clusters prepared according to Preparation Example 1 and graphite was 7:84 (1:12) by weight.

The slurry was coated on a copper foil (Cufoil) and then formed into a film having a coating thickness of 40 탆 by using a doctor blade, followed by vacuum drying at 120 캜 for 2 hours, followed by rolling to prepare a negative electrode.

The anode is LiNi _{0 . 6} Co _{0 . 2} Mn _{0 . 2} O ₂ , Super P, and lithium polyacrylate (Li-PAA) as a binder and NMP as a solvent were mixed to prepare a slurry. The mixing weight ratio of LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , Super P, and lithium polyacrylate (Li-PAA) as a binder in the slurry was 93: 5: 2.

A coin cell was fabricated using the negative electrode and the positive electrode. The slurry was applied to an aluminum foil, and then formed into a film having a coating thickness of 40 탆 by using a doctor blade, followed by vacuum drying at 120 캜 for 2 hours, followed by rolling to prepare a positive electrode.

A polypropylene film (Cellgard 3510) was used as the separator and 1.3M LiPF ₆ EC (ethylene carbonate): DEC (diethyl carbonate): FEC (fluoroethylene carbonate) (2: 6: 2 volume ratio) Respectively.

Example  2-7: cathode and Coin cell  Produce

A negative electrode and a coin cell were prepared in the same manner as in Example 1, except that the porous silicon composite cluster according to Production Example 2-7 was used in place of the porous silicon composite cluster according to Production Example 1.

Example  8: cathode and Coin cell  Produce

A porous silicon composite cluster prepared according to Preparation Example 1, carbon black (KB600JD), AST9005 (aekyung) and NMP as a solvent were mixed to prepare a slurry. The solid content ratio of the porous silicon composite clusters, carbon black (KB600JD) and AST9005 (aekyung) prepared in Preparation Example 1 in the slurry was 79: 1: 20 by weight.

The slurry was coated on a copper foil (Cufoil), coated with a doctor blade to a coating thickness of 40 microns, vacuum dried at 120 ° C for 2 hours, and rolled to prepare a negative electrode.

A coin cell (CR2032) was fabricated using the negative electrode and lithium metal as a counter electrode.

A polypropylene film (Cellgard 3510) was used as the separator and 1.3M LiPF ₆ EC (ethylene carbonate): DEC (diethyl carbonate): FEC (fluoroethylene carbonate) (2: 6: 2 volume ratio) Respectively.

Example  9-14: cathode and Coin cell  Produce

A negative electrode and a coin cell were prepared in the same manner as in Example 8 except that the porous silicon composite cluster according to Production Example 2-7 was used in place of the porous silicon composite cluster according to Production Example 1.

Example  15: cathode and Coin cell  Produce

Except that the solid content ratio of the porous silicon composite clusters prepared in Preparation Example 1, carbon black (KB600JD) and lithium polyacrylate was changed to 82.8: 9.2: 8 by weight instead of the 91: 1: 8 weight ratio. The negative electrode and the coin cell were produced in the same manner.

Example  16: cathode and Coin cell  Produce

A negative electrode and a coin cell were produced in the same manner as in Example 1, except that the mixture ratio of the porous silicon composite clusters prepared in Preparation Example 1 and graphite was changed to 1:99 by weight instead of the 1:12 weight ratio Respectively.

Example  17: cathode and Coin cell  Produce

A negative electrode and a coin cell were produced in the same manner as in Example 1, except that the mixture ratio of the porous silicon composite clusters prepared according to Preparation Example 1 and graphite was changed to a weight ratio of 3:97 instead of the 1:12 weight ratio Respectively.

Example  18: cathode and Coin cell  Produce

A negative electrode and a coin cell were produced in the same manner as in Example 1, except that the mixing ratio of the porous silicon composite clusters prepared according to Production Example 1 and graphite was changed in a 1: 1 weight ratio instead of the 1:12 weight ratio Respectively.

Comparative Example  1-4: cathode and Coin cell  Produce

A negative electrode and a coin cell were fabricated in the same manner as in Example 1, except that the material prepared according to Comparative Production Example 1-4 was used in place of the porous silicon composite cluster prepared according to Production Example 1.

Comparative Example  5-8: cathode and Coin cell  Produce

A negative electrode and a coin cell were fabricated in the same manner as in Example 8, except that the material prepared according to Comparative Production Example 1-4 was used in place of the porous silicon composite cluster prepared according to Production Example 1.

Comparative Example  9: cathode and Coin cell  Produce

A negative electrode was prepared in the same manner as in Example 1, except that the material prepared according to Comparative Preparation Example 5 was used in place of the porous silicon composite cluster prepared according to Preparation Example 1.

Evaluation example  One: Charging and discharging  characteristic

(1) Initial efficiency, rate performance, Coulomb efficiency and discharge capacity measurement

1) Examples 1-3, 8-10, Comparative Examples 1-8

Charge and discharge characteristics of each of the coin cells were evaluated according to the following method using the coin cells prepared according to Examples 1-3, 8-10 and Comparative Example 1-8.

Examples 1-3 and Comparative Examples 1-4 Charging conditions (Charge: 1.0C / Cutoff: 4.2V-0.01C, Discharge: 1.0C / Cutoff: 2.5V)

Examples 8-10 and Comparative Examples 5-8 Charge and discharge conditions (Charge: 1.0C / Cutoff: 0.01V-0.01C, Discharge: 1.0C / Cutoff: 1.5V)

The evaluation results of the charge-discharge characteristics are shown in Table 1 below.

Non-capacity (mAh / g) Volume Capacity (mAh / cc) Initial efficiency (%) life span(%) Example 1 2200 2200 83.9 76.2 Example 2 1900 2090 85.0 78.5 Example 3 1880 2068 86.5 81.5 Example 8 2200 2200 90.8 96.3 Example 9 1900 2090 90.8 96.2 Example 10 1880 2068 91.1 96.1 Comparative Example 1 2100 630 67 45.1 Comparative Example 2 2300 1196 70.2 74.0 Comparative Example 3 800 800 65.2 76.2 Comparative Example 4 2200 1980 69.3 52.2 Comparative Example 5 2100 630 54.7 60.2 Comparative Example 6 2300 1196 86.2 94.4 Comparative Example 7 800 800 85.0 95.2 Comparative Example 8 2200 1980 72.0 72.0

With reference to Table 1, The coin cell of 1-3 improved the initial efficiency as compared to the coin cell of Comparative Example 1-4. The coin cells of Examples 8-10 were improved in initial efficiency as compared to the coin cells of Comparative Examples 5-8.

2) Examples 3-7 and 10-14

Charging and discharging characteristics were evaluated using the coin cells manufactured according to Examples 3-7 and 10-14 according to the following methods. The evaluation results of charging and discharging characteristics are shown in Table 2 below.

Example 3-7 Charge (Charge: 1.0C / Cutoff: 4.2V-0.01C, Discharge: 1.0C / Cutoff: 2.5V)

Examples 10-14: charge and discharge conditions (Charge: 1.0C / Cutoff: 0.01V-0.01C, Discharge: 1.0C / Cutoff: 1.5V)

division Non-capacity (mAh / g) Volume Capacity (mAh / cc) Initial efficiency (%) life span(%) Example 3 1880 2068 86.5 81.5 Example 4 1880 2068 85.8 89.6 Example 5 1900 1805 85.0 82.5 Example 6 1690 1521 84.5 81.2 Example 7 1510 1329 80.8 83 Example 10 1630 1190 91.1 96.1 Example 11 1900 1805 89.4 98.2 Example 12 1690 1521 89.0 97.5 Example 13 1510 1329 88.7 97.5 Example 14 1630 1190 82.4 97.0

Referring to Table 2, it can be seen that the porous silicon composite clusters according to Examples 3, 4-7, and 11-14 are excellent in the durability of coin cells. Also, the coin cells of Examples 4, 7, and 11-14 were somewhat reduced in initial efficiency as compared to the coin cells prepared according to Example 3-10. The charge / discharge characteristics of the coin cell prepared in Example 16-18 were evaluated in the same manner as in Example 1.

As a result of the evaluation, the coin cells of Examples 16-18 exhibited excellent results at an equivalent level as compared with the case of Example 1 in terms of initial efficiency and life characteristics.

Evaluation example  2: oxygen and carbon content

1) Production Examples 1-3 and Comparative Examples 1-4

The porous silicon composite clusters prepared according to Production Example 1-3 and the materials prepared according to Comparative Production Example 1-4 were subjected to XPS analysis to analyze the content of oxygen and carbon. The results of the analysis are shown in Table 3 below .

XPS analysis was performed using Quantum 2000 (Physical Electronics, Inc.) (acceleration voltage: 0.5 to 15 kV, 300 W, energy resolution: about 1.0 eV, sputter rate: 0.1 nm / min).

division Oxygen(%) carbon(%) Production Example 1 3.75 20.0 Production Example 2 3.70 30.0 Production Example 3 3.67 30.0 Comparative Preparation Example 1 8.9 ~ 10 Comparative Production Example 2 4.8 20 Comparative Production Example 3 3.5 ~ 85 Comparative Production Example 4 6.6 ~ 10

In Table 3, the carbon content defines the carbon content corresponding to the C1s peak, and the oxygen content indicates the content of oxygen corresponding to the O1s peak.

Referring to Table 3, it was found that the porous composite silicon clusters prepared according to Production Example 1-3 had a reduced oxygen content as compared with Comparative Production Examples 1-2 and 4.

2) Preparation Example 3, 4-7

In the porous silicon composite clusters prepared according to Production Examples 3 and 4-7,

The content of bovine and carbon was evaluated in the same manner as in Production Example 1 described above and is shown in Table 4 below.

division Oxygen(%) carbon(%) Production Example 3 3.67 30.0 Production Example 4 5.81 23.0 Production Example 5 5.21 29.0 Production Example 6 5.18 34.0 Production Example 7 8.81 26.0

Referring to Table 4, the porous silicon composite clusters prepared according to Production Example 4-7 had an increased oxygen content as compared to that of Production Example 3. As shown in Table 2, using the porous silicon composite clusters having increased oxygen content, the initial efficiency and capacity characteristics of the coin cell tended to decrease.

Evaluation example  3: Raman analysis

1) Preparation Example 1-3

The Raman analysis of the porous silicon composite clusters of Production Example 1-3 was performed. Raman analysis was carried out using Raman 2010 Spectra (NT-MDT Development Co.) (Laser system: 473, 633, 785 nm, Lowest Raman shift: ~ 50 cm -1, Spatial resolution: about 500 nm) Respectively.

The ratio of the intensity of the D peak to the intensity of the G peak was measured based on the Raman analysis result, and it is shown in Table 5 below.

Graphene shows peaks at 1350 cm ^-1 , 1580 cm ^-1 and 2700 cm ^-1 in the Raman spectroscopy spectrum, which gives information on the thickness, crystallinity and charge doping state of graphene. The peak at 1580 cm ^-1 is called the G mode, which is due to the oscillation mode corresponding to the stretching of the carbon-carbon bond, and the energy of the G-mode is determined by the density of the surplus charge doped into the graphene. And the peak at 2700 cm ^-1 is useful for evaluating the thickness of graphene as a 2D-mode peak. The peak at 1350 cm &lt; ^-1 &gt; is a peak called D mode, which is a peak when the SP ² crystal structure is defective. And the D / G intensity ratio gives information on the disorder of the graphene crystal.

division D / G intensity ratio Production Example 1 1.25 Production Example 2 1.21 Production Example 3 1.10

Referring to Table 5, in the porous silicon composite prepared according to Production Example 1-3, as the CVD time gradually increased, the graphene quality serving as a protective cell was improved and the D / G was decreased.

2) Preparation Example 3, 4-7

Raman analysis was performed on the porous silicon composite clusters of Production Examples 3 and 4-7

Respectively. The results of the Raman analysis are shown in Table 6.

division D / G intensity ratio Production Example 3 1.1 Production Example 4 1.22 Production Example 5 1.11 Production Example 5 1.06 Production Example 7 1.23

3) Preparation Example 3

The porous silicon composite clusters were repeatedly manufactured according to Production Example 3 and Raman analysis was performed on the clusters. The results of the Raman analysis are shown in FIG. 11 and Table 7. In FIG. 12, B, C and D are repeated three times.

division D / G intensity ratio Production Example 3

1.05 1.15 1.09

Referring to FIG. 11 and Table 7, it was found that the porous silicon composite clusters of Production Example 3 contain high crystalline graphene. In the porous silicon composite clusters of Production Example 3, the D / G intensity ratio was found to be in the range of 1.10 ± 0.05.

Evaluation example  4: Transmission electron microscope ( TEM )

1) Production Example 1-3, Comparative Production Example 1-3

The complexes of Preparation Examples 1-3 and the materials of Comparative Preparation Examples 1-3 were analyzed using a transmission electron microscope. As the TEM analysis, Titan cubed G2 60-300 manufactured by FEI Co. was used as an analyzer.

The analysis photographs are shown in Figs. 3A to 5B.

FIGS. 3A to 3C are TEM photographs showing the outer clusters and the inner and outer regions of the clusters in the porous silicon composite clusters prepared according to Production Example 1, respectively. And FIGS. 3D to 3F are TEM photographs showing the outer clusters and the inner and outer regions of the clusters in the porous silicon clusters prepared according to Production Example 2, respectively. And Figs. 3g to 3i and Figs. 14a to 14c are TEM photographs showing the outer clusters and the outer and inner regions of the clusters in the porous silicon clusters produced according to Production Example 3. Fig. Figs. 4A to 4D, Figs. 5A and 5B relate to the materials prepared according to Comparative Preparations 1 to 3, respectively. Figs. 4A and 4C show the inner regions of the materials prepared according to Comparative Preparation Examples 1 and 2, respectively, and Figs. 4B and 4D show the outer regions of the materials prepared according to Comparative Preparation Examples 1 and 2. Fig. Referring to FIG. 4d, the presence of graphene was confirmed in the outer region.

The number of graphene layers in the inside and outside of the porous silicon composite clusters prepared according to Production Examples 1 to 3 was examined and is shown in Table 8 below.

division External graphene layer number Number of internal graphene layers Production Example 1 <Floor 3 - Production Example 2 3-7 floors 3-7 floors Production Example 3 10-20 floors 3-7 floors

Referring to Table 8, it can be seen that as the CVD time becomes longer, the number of graphenes formed on the outside increases gradually after graphenes are formed inside the clusters. In accordance with Production Example 1, the presence of the number of internal graphene layers was confirmed, but it was difficult to confirm the number of layers.

Figures 5A and 5B are TEM photographs of the materials prepared according to Comparative Preparation Example 3, respectively.

Referring to these results, it was found that, in the case of Production Examples 1 to 3, the number of grains outside the graphene was larger than that of Comparative Production Examples 1 and 2, and the density was increased overall. In the case of Production Examples 1 to 3, it was found that the density of graphene was increased as the CVD time was increased.

2) Production Examples 1-3 and Comparative Production Example 4

The porous silicon composite clusters prepared according to Preparation Example 1-3 and the materials of Comparative Preparation Example 4 were analyzed using a transmission electron microscope. Titan cubed 60-300 manufactured by FEI Co., Ltd. was used as an analyzer for the TEM analysis.

The analysis photographs are shown in Figs. 6A to 9C.

TEM images of the porous silicon composite clusters of Production Example 1 are shown in Figs. 6A to 6C, and TEM photographs of the porous silicon composite clusters of Production Example 2 are shown in Figs. 7A to 7C. And TEM photographs of the porous silicon composite clusters of Production Example 3 are shown in Figs. 8A to 8C.

On the other hand, TEM photographs of the material of Comparative Production Example 4 are as shown in Figs. 9A to 9C.

Referring to this, as the graphene grows further according to the CVD time, the density increases

.

3) Manufacturing Example  3

Permeation of porous silicon composite clusters prepared according to Preparation Example 3

Electron microscopic analysis was performed, and the results are shown in FIGS. 10A and 10B. 10B is an enlarged view of the square area of FIG. 10A.

Referring to this, it can be seen that the thickness of the graphene protection layer formed on the outside in the porous silicon composite cluster produced according to Production Example 3 is 20 to 60 nm.

Evaluation example  5: Expansion ratio

The coin cells prepared according to Examples 8-10 and Comparative Examples 5-8 were charged at a constant current (CC) of 0.1 C under a constant current / constant voltage (CC / CV) condition to 5 mV and then reached a current of 0.005 C (CV) until ready to use. Thereafter, the battery was allowed to stand for 20 minutes, and discharged at a constant current of 0.1 C to 1.5 V to carry out a first cycle charge / discharge. Thereafter, the electrode was allowed to stand for 20 minutes, and then the electrode was fully charged at 0.2 C, and the coin cell was disassembled to determine the thickness difference. The thickness expansion rate of the electrode was measured. The measurement results are shown in Table 9 below.

division Thickness Expansion Rate (%) Example 8 30-32 Example 9 28-30 Example 10 23-25 Comparative Example 5 65 Comparative Example 6 42 Comparative Example 7 83 Comparative Example 8 45

Referring to Table 9, it was found that the rate of change in electrode thickness was decreased in the coin cell manufactured according to Example 8-10, as compared with the case of Comparative Example 5-8.

Evaluation example  6: Charging and discharging After the reaction Electronic scanning microscope  analysis

The charge / discharge characteristics of the coin cell fabricated according to Example 3 were evaluated according to the following method, and 100 cycles were repeatedly performed.

Charging and discharging conditions (Charge: 1.0C / Cutoff: 4.2V-0.01C, Discharge: 1.0C / Cutoff: 2.5V)

The surface and the cross section of the negative electrode active material were examined using a scanning electron microscope after the charge and discharge cycles were repeated 100 times. SEM analysis results of the surface of the negative electrode active material are shown in Figs. 12A and 12B, and SEM analysis results of the cross section of the negative electrode active material are shown in Figs. 12C to 12E.

Referring to this, it can be seen that the secondary particles maintain their structure after 100 cycles. When a structurally stable negative electrode active material is used after charging and discharging, a battery having low expansion and excellent durability can be produced.

Evaluation example  7: Electronic scanning microscope

The porous silicon composite clusters prepared according to Preparation Example 3 were analyzed using an electron microscope and the results are shown in FIGS. 13A to 13D.

FIG. 13A is a SEM photograph showing a cross section of the porous silicon composite cluster, FIG. 13C is a cross-sectional view of the silicon composite cluster of FIG. 13D is a SEM image of a graphene or primary particle protective layer disposed on top of a primary particle as an SEM photograph, and FIG. 13D is a SEM image of a silicon composite cluster of FIG. As a photograph, it refers to the secondary particle protective layer present in the outer layers.

Referring to this, it was found that the thickness of the first protective film in the porous silicon composite cluster was about 20 nm.

Evaluation example 8: Porosity  The size (D50) of the silicon composite cluster particle, Specific surface area , Powder density and Graphene layer number  analysis

The particle size, specific surface area, powder density and number of graphene layers of the porous silicon composite clusters prepared according to Production Example 1-3 and the materials prepared according to Comparative Production Example 1-4 were analyzed and shown in Table 10 below.

The particle size was measured using a scanning electron microscope.

Powder density refers to the density for the sample before pressing. The number of graphene layers was examined by transmission electron microscopy.

division Particle size (D50) (占 퐉) (PSA) BET (m ² / g) Powder density Graphene layer number Production Example 1 4.2 35.0 1.0 ~ 3 Production Example 2 4.4 9.3 1.1 ~ 7 Production Example 3 4.8 6.3 1.1 7-20 Comparative Preparation Example 1 <1.2 153.5 0.3 - Comparative Production Example 2 - 85.0 0.52 1.2 Comparative Production Example 3 9.0 3 to 10 0.98 - Comparative Production Example 4 3.8 102.5 09.9 -

With reference to Table 10, the porous silicon composite clusters of Production Example 1-4 have an increased powder density as compared with Comparative Production Examples 1-4, and can produce an anode active material having an increased volume energy density. The porous silicon composite clusters of Production Example 1-4 had a BET specific surface area reduced as compared with Comparative Production Examples 1-2 and 4, indicating that the initial efficiency and durability characteristics can be improved.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the exemplary embodiments or constructions. It will be apparent to those skilled in the art that various modifications and variations are possible in light of the above teachings will be. Accordingly, the scope of protection of the invention should be determined by the appended claims.

10: silicon primary particles 10a, 10b: graphene
21: Lithium battery
22: cathode 23: anode
24: separator 25: battery case
26: Cap assembly

Claims (31)

A porous silicon composite cluster comprising a shell comprising a core comprising porous silicon composite secondary particles and a second graphene disposed on top of the core,
Wherein the porous silicon composite secondary particles comprise aggregates of two or more silicon composite primary particles,
The silicon composite primary particles may be silicon; A porous silicon composite cluster comprising silicon oxide (SiOx) (O < x < 2) disposed on the silicon and a first graphene disposed on the silicon oxide. The method of claim 1, wherein the first graphene in the core is of a different or equal number of layers than the second graphene of the shell and the second graphene of the shell is a porous silicon composite cluster. The method according to claim 1,
Wherein the porous silicon composite clusters have a dual core / shell structure. The method according to claim 1,
The porous silicon composite clusters may include a silicon composite primary
Wherein a first graphene of the particle is a double core / shell having a shell disposed on the silicon oxide
Porous silicon composite clusters. The method according to claim 1,
Wherein the porous silicon composite clusters further comprise an outer layer having a higher density than the core. The method according to claim 1,
Wherein the diameter of the core comprising the porous silicon composite clusters and the thickness ratio of the shell is from 1: 0.001 to 1: 1.67. The method according to claim 1,
Wherein the total content of the first graphene and the second graphene is 0.1 to 2,000 parts by weight based on 100 parts by weight of silicon. The method according to claim 1,
Wherein the first graphene in the silicon composite primary particles extends from the silicon of silicon oxide (SiOx) (O < x < 2) by a distance of less than 10 nm and comprises from 1 to 30 graphene layers, The thickness is 0.3 to 1,000 nm,
Wherein the first graphene is oriented at an angle between 0 and 90 relative to the major axis of the silicon. The method according to claim 1,
Wherein the second graphene in the porous silicon composite secondary particle extends from the silicon oxide (SiOx) (O < x < 2) by a distance of 1000 nm or less, comprises 1 to 30 graphene layers, To 50 nm,
Wherein the graphene is oriented at an angle between 0 and 90 relative to the major axis of the silicon. The method according to claim 1,
Wherein the thickness of the silicon oxide (SiOx) (O < x < 2) is 30 m or less. The method according to claim 1,
Wherein the silicon is at least one selected from the group consisting of sphere, nanowire, needle, rod, particle, nanotube, nanorod, wafer, and nanoribbons. The method according to claim 1,
The porous silicon composite an average particle diameter of the secondary particles is from 1 to 30㎛, the specific surface area is in the range of 0.1 to 100m ² / g and density of 0.1 to 2.57g / CC porous silicon composite cluster. The method according to claim 1,
Wherein the silicon is particles having an average particle size of 10 nm to 30 占 퐉. The method according to claim 1,
Wherein the porous silicon composite clusters have a D50 of 1 to 30 占 퐉, a D10 of 0.001 to 10 占 퐉, and a D90 of 10 to 60 占 퐉. The method according to claim 1,
Wherein the content of oxygen is 0.01 to 15 atomic%. Obtaining porous silicon secondary particles from a composition comprising silicon and a silicon oxide (SiOx) (O < x < 2) formed on the silicon, a composition comprising a dispersant and a solvent; And
15. A method for producing a porous silicon composite cluster according to any one of claims 1 to 15, comprising the step of supplying carbon source gas to the porous silicon secondary particles and heat treating the porous silicon composite particles. 17. The method of claim 16,
The solvent is an alcohol-based solvent,
Wherein the step of obtaining the porous silicon secondary particles from the composition is performed by spray drying the composition. 17. The method of claim 16,
Wherein the dispersing agent is at least one selected from the group consisting of stearic acid, resorcinol, polyvinyl alcohol, and pitch. 17. The method of claim 16,
Wherein the carbon source gas comprises at least one selected from the group consisting of a compound represented by the following formula (1), a compound represented by the following formula (2) and an oxygen-containing gas represented by the following formula (3).
[Chemical Formula 1]
C _n H _{(2n + 2-a)} [OH] _a
Wherein n is an integer of 1 to 20, a is 0 or 1,
(2)
C _n H _(2n)
Wherein n is an integer of 2 to 6,
(3)
CxHyOz
Wherein x is an integer of 1 to 20, y is 0 or an integer of 1 to 20, and z is 1 or 2. The method of claim 19, wherein
Wherein the carbon source gas further comprises a second oxygen-containing compound represented by the following formula (3a), and the first oxygen-containing compound represented by the following formula (3a) is a mixture of the oxygen- Way.
[Chemical Formula 3]
CxHyOz
Wherein x is 0 or an integer of 1 to 20, y is 0 or an integer of 1 to 20, and z is 1 or 2. 17. The method of claim 16,
Wherein the carbon source gas comprises at least one selected from the group consisting of methane, ethylene, propylene, methanol, ethanol and propanol. 17. The method of claim 16,
Wherein the heat treatment is performed at 750 to 1100 占 폚. 16. A carbon composite material comprising the porous silicon composite clusters according to any one of claims 1 to 15 and a carbon-based material. 24. The carbon composite material according to claim 23, wherein the content of the carbon-based material is 0.001 to 99 parts by weight based on 100 parts by weight of the carbon composite. 16. An electrode comprising a porous silicon composite cluster according to any one of claims 1 to 15 or a carbon composite comprising said porous silicon composite cluster and a carbon-based material. 26. The method of claim 25,
Wherein the carbon-based material is at least one selected from the group consisting of graphene, graphite, fullerene, carbon fiber, and carbon nanotube. 26. A lithium battery comprising the electrode of claim 25. 16. A field emission device comprising the porous silicon composite clusters according to any one of claims 1 to 15 or the porous silicon composite clusters and the carbon-based material. 16. A biosensor comprising the porous silicon composite clusters according to any one of claims 1 to 15 or the porous silicon composite clusters and the carbon-based material. 16. A semiconductor device comprising the porous silicon composite clusters of any one of claims 1 to 15 or the porous silicon composite clusters and the carbon-based material. 16. A thermoelectric device comprising the porous silicon composite clusters of any one of claims 1 to 15 or a carbon composite material comprising the porous silicon composite clusters and the carbon-based material.

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