HK1223345B - Composite conductive material, power storage device, conductive dispersion, conductive device, conductive composite and thermally conductive composite and method of producing a composite conductive material - Google Patents

Abstract

The present invention provides composite conductive raw materials with excellent conductivity.A composite conductive raw material characterized in that it is a composite conductive raw material in which at least graphene like graphite obtained by peeling off a graphite based carbon raw material and a conductive raw material are dispersed in a base material. The graphite based carbon raw material has a rhombohedral graphite layer (3R) and a hexagonal graphite layer (2H), and the ratio Rate (3R) defined by the following equation (1) obtained by X-ray diffraction of the rhombohedral graphite layer (3R) and the hexagonal graphite layer (2H) is 31% or more.Rate (3R)=P3/(P3+P4) × 100oooo (Formula 1) In Formula 1, P3 is the peak intensity of the (101) plane obtained by X-ray diffraction of the rhombohedral graphite layer (3R), and P4 is the peak intensity of the (101) plane obtained by X-ray diffraction of the hexagonal graphite layer (2H).

Description

Composite conductive material, electricity storage device, electrically conductive dispersion, electrically conductive device, electrically conductive composite, thermally conductive composite, and method for producing composite conductive material

Technical Field

The present invention relates to a composite conductive material, an electric storage device, an electrically conductive dispersion, an electrically conductive device, an electrically conductive composite, a thermally conductive composite, and a method for producing a composite conductive material.

Background

In recent years, the addition of various nanomaterials has been studied in various fields for the purpose of size reduction and weight reduction. In particular, among environmental and resource problems, carbon materials such as graphene, CNT, and fullerene have attracted attention as non-metallic nanomaterials. For example, lithium ion batteries that have been put to practical use are improving the capacity of active materials themselves. However, its capacity is significantly lower than the theoretical capacity, and a further improvement is expected.

Therefore, acetylene black has been conventionally used as a conductive aid for lithium ion batteries, but in recent years, in order to further secure conductivity, a novel high-conductivity material such as carbon nanofibers (VGCF (vapor grown carbon fiber): registered trademark) manufactured by showa electrical corporation has been studied (patent document 1: japanese patent application laid-open No. 2013-77475).

In addition, a method of improving the cycle characteristics (reproducibility) of a battery by directly applying a positive electrode active material to a conductor has been studied; a method for producing a high-capacity and high-output lithium ion battery by focusing attention on ion conductivity (patent document 2: Japanese patent application laid-open No. 2013-513904) and (patent document 3: International publication No. 2014/115669).

In recent years, the active material itself of a lithium ion battery has been studied to be made nano-sized (non-patent document 5).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2013-77475 ([0031] - [0039])

Patent document 2: japanese patent laid-open publication No. 2013-513904 ([0016])

Patent document 3: international publication No. 2014/115669 ([0017] - [0018])

Patent document 4: international publication No. 2014/064432 (page 19, lines 4-9)

Non-patent document

Non-patent document 1: structural changes associated with graphite grinding; the method comprises the following steps: the long branches of the rice-Yuandao, the Maidao and the thin Sichuan are healthy and defective; 1973, 2 months and 1 day (Accept)

Non-patent document 2: the change in probability P1, PABA, and PABC associated with the carbon heat treatment; the method comprises the following steps: ji, Shifu Zhengming and Daorhidao; 1966, 9, 16 th month (accepted)

Non-patent document 3: spectroscopic and X-ray differentiation students on fluidized rhombohedrial graphics from the easter n Ghats Mobile Belt, India; G.Parthasarath, Current Science, Vol.90, No.7,10April 2006

Non-patent document 4: classification and respective structural features of the solid carbon material; kawasaki jin of famous ancient house industrial university

Non-patent document 5: LiCoO₂Synthesis of nanoparticles and application to lithium secondary batteries (52),13-18,2009, HOSOKAWA POWDER TECHNOLOGY RESEARCH INSTITUTE (ISSN:04299051)

Non-patent document 6: single-walled carbon nanotube/carbon fiber/rubber composite having thermal conductivity similar to that of titanium (http:// www.aist.go.jp/aid _ j/press _ release/pr2011/pr 20111006.htm l)

Disclosure of Invention

Problems to be solved by the invention

However, it is considered that the methods described in patent documents 2 and 3 and non-patent document 5 fail to provide fundamental measures against capacity, and have other problems. In order to conduct electricity or the like between substances, it is sufficient to bridge the substances with a conductive material, but generally, a resistance exists at a contact portion between a conductor and the conductive material. Further, the curved surfaces have a small contact area with each other, and often become point contacts, which causes an increase in contact resistance. In other words, it is considered that the more contacts, the higher the resistance.

In the case of applying these to a lithium ion battery, since the positive electrode active material, the conductive additive (conductor) such as acetylene black or VGCF is spherical or ribbon-shaped, has a curved surface shape, and has a size of nanometer to micrometer, a large amount of the conductive additive is interposed between the positive electrode active materials, and thus there are many contacts. In other words, it is considered that the theoretical capacity is not reached due to the contact resistance.

As described above, patent documents 1 to 3 and non-patent document 5 do not reach the theoretical capacity.

On the other hand, for the thermal conductivity, it is proposed to obtain a highly thermally conductive sheet with a low addition amount by compounding carbon fibers with CNTs. (non-patent document 6). However, in this method, since the band-shaped substances are in point contact with each other as in the above method, thermal resistance occurs as in the case of electric conduction, and thus a high effect cannot be obtained.

In view of the above, studies have been made to use graphene as a flexible carbon material such as a conductor or a planar material, with a view to reducing contact resistance and maximizing conductor performance.

In general, even when natural graphite is directly treated, the amount of exfoliated graphene is small, which is problematic. However, as a result of intensive studies, a graphite-based carbon material (graphene precursor) which can be easily exfoliated into graphene and has a high concentration or high dispersion is obtained by subjecting graphite as a material to a predetermined treatment.

The graphene precursor is partially or completely exfoliated by ultrasonic waves, stirring, and kneading, and a mixture "graphene-like graphite" from the graphene precursor to graphene is obtained. The graphene-like graphite is not limited because the size, thickness, and the like vary depending on the amount of the added graphene precursor, the process time, and the like, but is preferably further flaked.

That is, graphite that is easily exfoliated/dispersed into graphene-like graphite by a conventional stirring, kneading process or apparatus is a graphite-based carbon material (graphene precursor).

It was found that graphene graphite of this type has excellent conductivity and therefore, when highly dispersed, can be used in the positive electrode of a lithium ion 2-order battery, for example, to approach the theoretical capacity.

The present invention has been made in view of such problems, and an object thereof is to provide a composite conductive material having excellent conductivity, an electric storage device, an electrically conductive dispersion, an electrically conductive device, an electrically conductive composite, a thermally conductive composite, and a method for producing a composite conductive material.

Means for solving the problems

In order to solve the above problems, a composite conductive material of the present invention is a composite conductive material in which at least graphene-like graphite peeled from a graphite-based carbon material and a conductive material are dispersed in a matrix,

the graphite-based carbon material has a rhombohedral graphite layer (3R) and a hexagonal graphite layer (2H), and the ratio Rate (3R) of the rhombohedral graphite layer (3R) to the hexagonal graphite layer (2H) defined by the following (formula 1) obtained by X-ray diffraction is 31% or more.

Rate (3R) ═ P3/(P3+ P4). times.100. cndot. (formula 1)

In the formula 1, the reaction mixture is,

p3 represents the peak intensity of the (101) plane of the rhombohedral graphite layer (3R) obtained by X-ray diffraction,

p4 is the peak intensity of the (101) plane of the hexagonal graphite layer (2H) obtained by the X-ray diffraction method.

According to this feature, the composite material is excellent in conductivity. This is presumably because, since graphene-like graphite obtained by exfoliation from a graphite-based carbon material exists in a thin state, the graphene-like graphite contacts the base material and the conductive material at a plurality of positions. Further, it is also presumed that this contact is due to the surface-based contact because graphene-like graphite is thin and easily deformed.

Wherein the conductive material is a band-shaped, straight-chain, linear or scaly fine particle.

According to this feature, since graphene-like graphite exists around the fine particles, the conductivity of the fine particles can be sufficiently exhibited.

Characterized in that the aspect ratio of the fine particles is 5 or more.

This feature makes it possible to further fully utilize the conductivity of the fine particles.

Characterized in that the weight ratio of the graphite-based carbon material to the conductive material is not less than 1/50 and less than 10.

This feature enables the conductivity of the fine particles to be effectively exhibited.

The base material is an active material of a battery.

This feature makes it possible to obtain an electrode having excellent charge/discharge characteristics.

The active material is a positive electrode active material.

This feature makes it possible to obtain a positive electrode having excellent charge/discharge characteristics.

Wherein the base material is a polymer.

This feature makes it possible to obtain a composite conductive material having excellent electrical, thermal, and ionic conductivities.

The base material is a material which disappears by vaporization or the like.

According to this feature, the graphene-like graphite can be uniformly dispersed in the conductive material by dispersing the graphene-like graphite using the base material and then removing the base material.

An electric storage device such as a primary battery, a secondary battery, or a capacitor is characterized by using the composite conductive material.

With this feature, a power storage device having excellent power storage properties can be obtained.

The conductive dispersion liquid such as conductive ink, conductive paste, or the like is characterized by using the composite conductive material.

This feature makes it possible to obtain a conductive dispersion liquid having excellent conductivity.

Conductive devices such as transparent electrodes, transparent conductive films, conductive circuits, and substrates are characterized by being coated or printed with the conductive dispersion.

With this feature, a conductive device having excellent conductivity can be obtained.

The conductive composite is characterized by using the composite conductive material, and has resistance to electrification, static electricity, electromagnetic wave blocking, and the like.

This feature makes it possible to obtain a conductive composite having excellent conductivity.

The heat conductive compound such as a heat sink or a heat dissipating paste is characterized by using the composite conductive material.

This feature makes it possible to obtain a thermally conductive compound having excellent thermal conductivity.

Further, the method is characterized by comprising a step of kneading at least a graphite-based carbon material and a conductive material in a matrix,

the graphite-based carbon material has a rhombohedral graphite layer (3R) and a hexagonal graphite layer (2H), wherein the ratio (3R) of the rhombohedral graphite layer (3R) to the hexagonal graphite layer (2H) defined by the following formula (1) obtained by X-ray diffraction is 31% or more,

rate (3R) ═ P3/(P3+ P4). times.100. cndot. (formula 1)

In the formula 1, the reaction mixture is,

p3 represents the peak intensity of the (101) plane of the rhombohedral graphite layer (3R) obtained by X-ray diffraction,

p4 is the peak intensity of the (101) plane of the hexagonal graphite layer (2H) obtained by the X-ray diffraction method.

Drawings

Fig. 1 is a diagram showing a crystal structure of graphite, and fig. 1 (a) is a crystal structure of hexagonal crystal, and fig. 1 (b) is a crystal structure of rhombohedral crystal.

Fig. 2 is a diagram showing an X-ray diffraction pattern of a typical natural graphite.

Fig. 3 is a diagram illustrating a manufacturing apparatus a using a jet mill (jet mill) and plasma in example 1.

Fig. 4 is a diagram illustrating a manufacturing apparatus B using a ball mill and a magnetron in example 1, fig. 4 (a) is a diagram illustrating a state in which the graphite-based carbon material (precursor) is pulverized, and fig. 4 (B) is a diagram illustrating a state in which the graphite-based carbon material (precursor) is collected.

Fig. 5 is a diagram showing an X-ray diffraction pattern of the graphite-based carbon material of sample 5 produced by production apparatus B in example 1.

Fig. 6 is a diagram showing an X-ray diffraction pattern of a graphite-based carbon material of sample 6 produced by production apparatus a in example 1.

Fig. 7 is a diagram showing an X-ray diffraction pattern of the graphite-based carbon material of sample 1 of the comparative example.

Fig. 8 is a diagram showing a dispersion liquid production apparatus for producing a dispersion liquid using a graphite-based carbon material as a precursor.

Fig. 9 is a diagram showing the dispersion state of the dispersion liquid prepared by using the graphite-based carbon material of sample 1 representing the comparative example and sample 5 produced by the production apparatus B of example 1.

Fig. 10 is a TEM image of the graphite-based carbon material (graphene) dispersed in the dispersion liquid.

Fig. 11 is a diagram showing the distribution state of the graphite-based carbon material dispersed in the dispersion liquid prepared using the graphite-based carbon material (precursor) of sample 5, fig. 11 (a) is a diagram showing the distribution of the average size, and fig. 11 (b) is a diagram showing the distribution of the number of layers.

Fig. 12 is a diagram showing a distribution state of a graphite-based carbon material dispersed in a dispersion liquid prepared using a graphite-based carbon material representing sample 1 of a comparative example, fig. 12 (a) is a diagram showing a distribution of an average size, and fig. 12 (b) is a diagram showing a distribution of the number of layers.

Fig. 13 is a graph showing the distribution of the number of layers of the graphite-based carbon material dispersed in the dispersion liquid prepared using samples 1 to 7 as precursors.

Fig. 14 is a graph showing the ratio of 10 or less layers of graphene with respect to the content of rhombohedral crystals dispersed in the dispersion.

Fig. 15 is a graph showing the distribution state of graphite when the conditions for preparing a dispersion using the graphite-based carbon material (precursor) of sample 5 were changed in example 2, fig. 15 (a) is a graph showing the distribution when ultrasonic treatment and microwave treatment were used in combination, and fig. 15 (b) is a graph showing the distribution of the number of layers when ultrasonic treatment was performed.

Fig. 16 is a graph showing the resistance value when the graphite-based carbon material of example 3 was dispersed in the conductive ink.

Fig. 17 is a graph showing the tensile strength when the graphite-based carbon material of example 4 was kneaded into a resin.

Fig. 18 is a graph showing the tensile strength when the graphite-based carbon material of example 5 was kneaded into a resin.

Fig. 19 is a diagram showing a distribution state of a graphite-based carbon material dispersed in a dispersion liquid of N-methylpyrrolidone (NMP) for supplementary explanation of the dispersion state in example 5, fig. 19 (a) is a diagram showing a distribution state of sample 12, and fig. 19 (b) is a diagram showing a distribution state of sample 2.

FIG. 20 is a graph showing charge and discharge characteristics of the lithium ion secondary battery of example 6, FIG. 20 (a) is a graph showing examples 6-1 to 6-3 and comparative examples 6-1 to 6-2, and FIG. 20 (b) is a graph showing comparative example 6-3.

Fig. 21 is a schematic diagram showing a positive electrode of a lithium-ion secondary battery of example 6.

Fig. 22 is an SEM photograph (top view) of the graphene precursor.

Fig. 23 is an SEM photograph (side view) of the graphene precursor.

Fig. 24 is a graph showing charge and discharge characteristics of the lithium-ion secondary battery in example 7 to which carbon nanotubes were added.

Fig. 25 is a graph showing charge and discharge characteristics of the lithium ion secondary battery of example 8 in which the mixing ratio of the graphene precursors was changed.

Fig. 26 is an SEM image (cross-sectional view) of the resin in which graphene-like graphite is dispersed.

Fig. 27 is a side SEM photograph (side view) of the graphene-like graphite in fig. 26.

Fig. 28 is a schematic view for explaining the shape of the conductive raw material of example 11, (a) of fig. 28 is a schematic view for explaining the shape of acetylene black, (b) of fig. 28 is a schematic view for explaining the shape of carbon fiber, and (c) of fig. 28 is a schematic view for explaining the shape of metal particles.

Detailed Description

The present invention focuses on the crystal structure of graphite, and first, the contents of the crystal structure will be described. Natural graphite is known to be classified into three crystal structures of hexagonal, rhombohedral, and disordered according to the manner of overlapping layers. As shown in fig. 1, hexagonal crystal has a crystal structure in which layers are stacked in the order ABABAB · and rhombohedral crystal has a crystal structure in which layers are stacked in the order ABCABCABC · and.

Natural graphite has almost no rhombohedral at the stage of extraction, but is broken at the stage of purification, and thus about 14% of rhombohedral is present in a normal natural graphite-based carbon material. It is also known that the ratio of rhombohedral crystals is about 30% even when the refining is carried out for a long time by crushing (non-patent documents 1 and 2).

Further, a method of expanding graphite by heating to form a sheet is known in addition to physical force such as crushing, but even when graphite is treated by applying heat at 1600K (about 1300 degrees celsius), the ratio of rhombohedral is about 25% (non-patent document 3). Even if heat of 3000 degrees celsius at a very high temperature is further applied, it reaches about 30% at most (non-patent document 2).

In this way, the ratio of the rhombohedral crystal can be increased by treating the natural graphite with physical force or heat, but the upper limit is about 30%.

Hexagonal crystals (2H) contained in a large amount in natural graphite are very stable, and van der waals force between layers of graphene is expressed by (formula 3) (patent document 4). By applying energy exceeding the force, graphene exfoliation occurs. Since the energy required for exfoliation is inversely proportional to the third power of the thickness, graphene is exfoliated by weak physical force such as very weak ultrasonic waves in a thick state in which a plurality of layers are stacked, but a very large energy is required for exfoliation from graphite that is thin to a certain extent. In other words, even if graphite is treated for a long time, only a weak portion of the surface is peeled off, and most of the graphite remains in an un-peeled state.

Fvdw H/(6 pi. t 3. cndot. (formula 3)

Fvdw: van der waals force

H: hamaker constant

A: surface area of graphite or graphene

t: thickness of graphite or graphene

The inventors of the present application succeeded in increasing the proportion of rhombohedral crystals (3R) to a higher level, which could be increased only to about 30% by crushing and/or heating to ultrahigh temperature treatment, by subjecting natural graphite to a predetermined treatment as shown below. As a result of the experiment/study, the following findings were obtained: when the content of the rhombohedral crystal (3R) in the graphite-based carbon material is increased, particularly when the content is 31% or more, the graphite-based carbon material is used as a precursor, and thus the material tends to be easily exfoliated into graphene, and a graphene solution or the like having a high concentration and a high degree of dispersion can be easily obtained. This is considered to be because when a force such as shearing is applied to the rhombohedral crystal (3R), strain occurs between layers, that is, the strain of the entire structure of graphite increases, and exfoliation becomes easy, without depending on van der waals forces. Therefore, in the present invention, a graphite-based carbon material from which graphene can be easily exfoliated by subjecting natural graphite to a predetermined treatment and can be highly concentrated or highly dispersed is referred to as a graphene precursor, and hereinafter, in the examples described below, a method for producing a graphene precursor by a predetermined treatment, a crystal structure of the graphene precursor, and a graphene dispersion liquid using the graphene precursor will be described in order.

Here, in the present specification, the graphene refers to a sheet-like or sheet-like (sheet-like) graphene which is a crystal having an average size of 100nm or more, not a microcrystal having an average size of several nm to several tens of nm, and has 10 or less layers.

Since graphene is a crystal having an average size of 100nm or more, it is impossible to obtain graphene even when artificial graphite or carbon black, which is an amorphous (microcrystalline) carbon material other than natural graphite, is treated (non-patent document 4).

In the present specification, the graphene composite refers to a composite prepared by using a graphite-based carbon material having a Rate (3R) of 31% or more, which is a graphite-based carbon material that can be used as a graphene precursor of the present invention (for example, samples 2 to 7 in example 1 and samples 2 and 21. cndot. in example 5, which will be described later).

Examples of composite conductive materials, power storage devices, electrically conductive dispersions, electrically conductive devices, electrically conductive composites, and thermally conductive composites for carrying out the present invention will be described below.

Example 1

< production of graphite-based carbon Material useful as graphene precursor >

A method for obtaining a graphite-based carbon material usable as a graphene precursor by using a manufacturing apparatus a using a jet mill and plasma as shown in fig. 3 will be described. In the manufacturing apparatus a, a case where plasma is applied as a process based on an electromagnetic force and a jet mill is used as a process based on a physical force is exemplified.

In FIG. 3, the reference numeral 1 denotes a natural graphite material (flake graphite ACB-50 manufactured by the Japan graphite industry) having particles of 5mm or less; 2 is a hopper containing natural graphite material 1; 3 is a venturi nozzle for spraying the natural graphite material 1 from the hopper 2; 4, a jet mill for injecting air pressurized and delivered from the compressor 5 at eight places to cause the natural graphite material to collide with the jet flow in the chamber; reference numeral 7 denotes a plasma generating device which generates plasma in the chamber of the jet mill 4 by ejecting gas 9 such as oxygen, argon, nitrogen, or hydrogen from the container 6 from the nozzle 8 and applying a voltage to a coil 11 wound around the outer periphery of the nozzle 8 by a high voltage power supply 10, and is provided at four positions in the chamber. Reference numeral 13 denotes a pipe connecting the jet mill 4 and the dust collector 14, 14 denotes a dust collector, 15 denotes a collecting container, 16 denotes a graphite-based carbon material (graphene precursor), and 17 denotes a blower.

The following describes the manufacturing method. Conditions of the jet mill and plasma are as follows.

The conditions of the jet mill were as follows.

Pressure: 0.5MPa

Air volume: 2.8m³Per minute

Nozzle bore diameter: 12mm

Flow rate: about 410 m/s

The plasma conditions are as follows.

Output power: 15W

Voltage: 8kV

Gas species: ar (purity 99.999 vol%)

Gas flow rate: 5L/min

It is considered that the natural graphite materials 1 fed into the chamber of the jet mill 4 from the venturi nozzle 3 are accelerated to the sonic velocity or higher in the chamber, and are pulverized by the impact of collision of the natural graphite materials 1 with each other and with the wall, and at the same time, the plasma 12 discharges and excites the natural graphite materials 1 to directly act on atoms (electrons) and increase the strain of crystals to promote pulverization. When the natural graphite material 1 is formed into fine powder having a particle diameter of about 1 to 10 μm, the mass is reduced and the centrifugal force is weakened, and the fine powder is drawn out from the pipe 13 connected to the center of the chamber.

The gas mixed with the graphite-based carbon material (graphene precursor) flowing from the pipe 13 into the cylindrical container of the chamber of the dust collector 14 forms a swirling flow, the graphite-based carbon material 16 colliding with the inner wall of the container falls into the lower collection container 15, and an updraft is generated at the center of the chamber by the conical container portion below the chamber, and the gas is discharged from the blower 17 (so-called cyclone separation (cyclone) action). About 800g of a graphite-based carbon material (graphene precursor) 16 usable as a graphene precursor was obtained from 1kg of a natural graphite material 1 as a raw material by the production apparatus a in this example (recovery efficiency: about 8).

Next, a method for obtaining a graphite-based carbon material usable as a graphene precursor by using a manufacturing apparatus B using a ball mill and microwaves as shown in fig. 4 will be described. In the manufacturing apparatus B, a case where microwave is performed as a process based on electromagnetic force and a ball mill is used as a process based on physical force is exemplified.

In fig. 4 (a) and 4 (b), reference numeral 20 denotes a ball mill, 21 denotes a microwave generator (magnetron), 22 denotes a waveguide, 23 denotes a microwave inlet, 24 denotes a medium, 25 denotes a natural graphite material (flake graphite ACB-50 manufactured by the japan graphite industry) having particles of 5mm or less, 26 denotes a collection container, 27 denotes a filter, and 28 denotes a graphite-based carbon material (graphene precursor).

The following describes the manufacturing method. The conditions of the ball mill and the microwave generating apparatus are as follows.

The conditions of the ball mill are as follows.

Rotating speed: 30rpm

Medium size:

the kind of the medium: zirconia ball

And (3) crushing time: 3 hours

The conditions of the microwave generating apparatus (magnetron) are as follows.

Output power: 300W

Frequency: 2.45GHz

The irradiation method comprises the following steps: intermittent type

1kg of a natural graphite-based carbon material 25 and 800g of a medium 24 were charged into a chamber of the ball mill 20, and the chamber was sealed and treated at 30rpm for 3 hours. In this process, the chamber was irradiated with microwaves intermittently (20 seconds at intervals of 10 minutes). It is considered that the irradiation with the microwave directly acts on atoms (electrons) of the raw material to increase the strain of the crystal. After the treatment, the medium 24 is removed by the filter 27, whereby a graphite-based carbon material (precursor) 28 of about 10 μm powder can be collected in the collection container 26.

< X-ray diffraction Pattern on graphite-based carbon raw Material (precursor) >

Referring to fig. 5 to 7, the X-ray diffraction patterns and crystal structures of the graphite-based natural materials (sample 6 and sample 5) produced by the production apparatus A, B and the graphite-based natural material (sample 1: comparative example) obtained as a powder of about 10 μm by using only the ball mill of the production apparatus B will be described.

The measurement conditions of the X-ray diffraction apparatus are as follows.

Line source: CuKalpha ray

Scanning speed: 20 DEG/min

Tube voltage: 40kV

Tube current: 30mA

Each sample was described as showing peak intensities P1, P2, P3 and P4 on the surface (100) of hexagonal crystal 2H, the surface (002), the surface (101) and the surface (101) of rhombohedral crystal 3R, respectively, by X-ray diffraction (Ultima IV, a sample horizontal multi-purpose X-ray diffraction apparatus manufactured by Rigaku co., ltd.).

In recent years, so-called normalized values have been used for the measurement of X-ray diffraction patterns both at home and abroad. The sample horizontal multi-purpose X-ray diffraction apparatus Ultima IV manufactured by Rigaku corporation is an apparatus capable of measuring an X-ray diffraction pattern based on JIS R7651: 2007 "method for measuring lattice constant and crystallite size of carbon material". Note that the Rate (3R) is a ratio of diffraction intensities obtained by setting the Rate (3R) to P3/(P3+ P4) × 100, and the value of the Rate (3R) does not change even if the diffraction intensity changes. In other words, the ratio of diffraction intensities is normalized, usually to avoid identification of the substance in absolute values, which are independent of the measurement device.

As shown in fig. 5 and table 1, in the sample 5 produced by the production apparatus B which applied the ball mill treatment and the microwave treatment, the ratio of the intensities of the peak intensity P3 and the peak intensity P1 was high, and the Rate (3R) defined by (formula 1) indicating the ratio of P3 to the sum of P3 and P4 was 46%. The intensity ratio P1/P2 was 0.012.

Rate (3R) ═ P3/(P3+ P4). times.100. cndot. (formula 1)

Here, the number of the first and second electrodes,

p1 represents the peak intensity of the (100) plane of the hexagonal graphite layer (2H) by X-ray diffraction,

p2 represents the peak intensity of the (002) plane of the hexagonal graphite layer (2H) obtained by X-ray diffraction,

p3 represents the peak intensity of the (101) plane of the rhombohedral graphite layer (3R) obtained by X-ray diffraction,

p4 is the peak intensity of the (101) plane of the hexagonal graphite layer (2H) obtained by the X-ray diffraction method.

TABLE 1

Similarly, as shown in fig. 6 and table 2, in sample 6 produced by the production apparatus a in which the jet mill treatment and the plasma treatment were performed, the ratios of the intensities of the peak intensity P3 and the peak intensity P1 were high, and the Rate (3R) was 51%. The intensity ratio P1/P2 was 0.014.

TABLE 2

As shown in fig. 7 and table 3, the peak intensity P3 of sample 1, which is a comparative example and produced only by a ball mill, is smaller than those of samples 5 and 6, and the Rate (3R) is 23%. The intensity ratio P1/P2 was 0.008.

TABLE 3

As described above, sample 5 produced by the production apparatus B in example 1 and sample 6 produced by the production apparatus a in example 1 showed: the Rate (3R) was 46% or 51%, and was 40% or more or 50% or more as compared with the natural graphite shown in fig. 2 and sample 1 representing the comparative example.

Next, a graphene dispersion was prepared using the graphene precursor prepared as described above, and the ease of peeling of graphene was compared.

< graphene Dispersion >

A method for producing the graphene dispersion liquid will be described with reference to fig. 8. In fig. 8, a case where ultrasonic treatment and microwave treatment are used in combination in a liquid when preparing a graphene dispersion liquid is taken as an example.

(1) 0.2g of a graphite-based carbon raw material usable as a graphene precursor and 200ml of N-methylpyrrolidone (NMP) as a dispersion were charged into the beaker 40.

(2) The beaker 40 is placed in the chamber 42 of the microwave generator 43, and the ultrasonic transducer 44A of the ultrasonic horn 44 is inserted into the dispersion liquid 41 from above.

(3) The ultrasonic horn 44 was operated to continuously apply ultrasonic waves of 20kHz (100W) for 3 hours.

(4) While the ultrasonic horn 44 was operated, the microwave generator 43 was operated to intermittently apply microwaves (10 seconds per 5 minutes) at 2.45GHz (300W).

Fig. 9 shows a state in which the graphene dispersion liquid prepared as described above has elapsed for 24 hours.

It was confirmed that the graphene dispersion liquid 30 using sample 5 produced by production apparatus B was black in color as a whole, although a part of the graphene dispersion liquid was precipitated. This is considered to be because the graphite-based carbon material used as the graphene precursor is dispersed in a state of being exfoliated into graphene in many cases.

It was confirmed that most of the graphite-based carbon material precipitated in the dispersion 31 using the sample 1 representing the comparative example, and a part of the graphite-based carbon material floated in the state of a supernatant liquid. From this, it is considered that a very small portion is exfoliated into graphene and floats in the form of a supernatant.

The graphene dispersion prepared as described above was diluted at a concentration that enables observation, applied on a sample stage (TEM grid), dried, and the size and number of layers of graphene were observed from an image taken by a Transmission Electron Microscope (TEM) as shown in fig. 10. The supernatant was diluted and applied to sample 1. For example, in the case of fig. 10, the maximum length L of the sheet (flake)33 is determined to be about 600nm from fig. 10 (a), and the number of graphene layers is determined to be 6 (the region indicated by the reference numeral 34) by observing the end face of the sheet 33 and counting the number of graphene layers from fig. 10 (b). The size and number of layers of each sheet (the number of sheets is N) were measured in this manner, and the number of graphene layers and the size shown in fig. 11 and 12 were obtained.

Referring to fig. 11 (a), the particle size distribution (size distribution) of the flaky sheet (flake) contained in the graphene dispersion of sample 5(Rate (R3) 46%) produced by the production apparatus B in example 1 is a distribution having a peak of 0.5 μm. In fig. 11 (b), the number of layers is a distribution with 3 layers as a peak and 68% or less of graphene.

Referring to fig. 12, the particle size distribution (size distribution) of the flake-like flakes contained in the dispersion of sample 1 (23% Rate (R3)) of the comparative example is a distribution with a peak of 0.9 μm. The number of layers is 30 or more and the majority thereof, and 10% or less of graphene is distributed.

From the results, it is understood that when sample 5 produced by production apparatus B is used as a graphene precursor, a graphene dispersion liquid having a large amount of 10 or less layers of graphene, excellent in graphene dispersibility, and high in concentration can be obtained.

Next, referring to fig. 13, a relationship between the ratio Rate (3R) of the graphene precursor and the number of layers in the graphene dispersion liquid will be described. Samples 1, 5 and 6 in fig. 13 are the above-mentioned samples. Samples 2, 3, and 4 were produced by the production apparatus B which performed the ball mill treatment and the microwave treatment, and the graphene dispersion liquid was produced using the graphene precursor produced by making the irradiation time of the microwave shorter than that of sample 5. Sample 7 was produced by using the production apparatus a which applied the jet mill treatment and the plasma treatment, and a graphene dispersion liquid was prepared using a graphene precursor which was produced by applying plasma having an output higher than that of sample 6.

From fig. 13, the shape of the layer number distribution of samples 2 and 3 having rates (3R) of 31% and 38% is a shape close to a normal distribution having peaks around 13 layers (using the dispersions of samples 2 and 3). The number-of-layers distribution shape of samples 4 to 7 having a Rate (3R) of 40% or more is a shape of a so-called log-normal distribution having peaks in portions of several layers (thin graphene). On the other hand, sample 1 having a Rate (3R) of 23% has a peak shape in a portion where the number of layers is 30 or more (using the dispersion of sample 1). Namely, the following tendency is known: when the Rate (3R) reaches 31% or more, the layer number distribution shape differs from less than 31%, and further when the Rate (3R) reaches 40% or more, the layer number distribution shape differs from less than 40%. Further, it is understood that the ratio of 10 or less layers of graphene is 38% for the Rate (3R) of the dispersion liquid using sample 3, and 42% for the Rate (3R) of the dispersion liquid using sample 4, and that the ratio of 10 or less layers of graphene increases rapidly when the Rate (3R) is 40% or more.

From this, it is considered that graphene easily exfoliated to 10 layers or less when the Rate (3R) is 31% or more, and graphene easily exfoliated to 10 layers or less as the Rate (3R) increases to 40%, 50%, 60%. When attention is paid to the strength ratio P1/P2, the strength ratio P1/P2 is preferably in a narrow range of 0.012 to 0.016 for sample 2 to sample 7, and exceeds 0.01 which is considered to cause strain in the crystal structure and to be easily exfoliated into graphene.

Fig. 14 shows the results of comparing the Rate (3R) and the content ratio of graphene having 10 or less layers. Referring to fig. 14, it can be seen that when the Rate (3R) is 25% or more, 10 layers or less of graphene increases from near 31% (forming a slope that increases rightward), and at about 40% the 10 layers or less of graphene suddenly increases (the Rate (3R) of the dispersion using sample 3 is 38% for the Rate of 10 layers or less of graphene, while the Rate (3R) of the dispersion using sample 4 is 42% for the Rate of 10 layers or less of graphene, the Rate (3R) increases by 4%, and the Rate of 10 layers or less of graphene suddenly increases by 24%), and the total amount of 10 layers or less of graphene is 50% or more. The black squares in fig. 14 represent different samples, and include the above-mentioned samples 1 to 7 and other samples other than these samples.

Thus, when a graphene dispersion liquid is prepared using a sample having a Rate (3R) of 31% or more as a graphene precursor, the dispersion ratio of 10 or less layers of graphene starts to increase, and when a graphene dispersion liquid is prepared using a sample having a Rate (3R) of 40% or more as a graphene precursor, 50% or more of 10 or less layers of graphene are generated. That is, a graphene dispersion liquid in which graphene is highly dispersed at a high concentration can be obtained. Further, as described above, since the graphite-based carbon material (precursor) contained in the dispersion liquid is not substantially precipitated, a relatively concentrated graphene dispersion liquid can be easily obtained. By this method, a graphene dispersion liquid having a graphene concentration of more than 10% can be prepared without concentration. In particular, the Rate (3R) is more preferably 40% or more from the viewpoint of a sharp increase in the dispersion ratio of 10 or less layers of graphene to 50% or more.

From this, it is found that when the Rate (3R) is 31% or more, preferably 40% or more, and more preferably 50% or more, the ratio of the graphite-based carbon material separated into 10 or less layers and about 10 thin layers is high, and when these graphite-based carbon materials are used as the graphene precursor, a graphene dispersion liquid having excellent dispersibility of graphene and a high concentration can be obtained. As is apparent from example 5 described later, when the Rate (3R) is 31% or more, it is useful as a graphene precursor as a graphite-based carbon material.

It is not necessary to particularly limit the upper limit of the Rate (3R), but it is preferable to satisfy the intensity ratio R1/R2 of 0.01 or more at the same time, since graphene is easily separated when preparing a dispersion liquid or the like. In the case of the production method using the production apparatus A, B, the upper limit is about 70% from the viewpoint of ease of production of the graphene precursor. Further, the method of using a combination of a jet mill treatment and a plasma treatment in the manufacturing apparatus a is more preferable because a material having a high Rate (3R) can be easily obtained. Note that the Rate (3R) may be set to 31% or more by using the physical force processing and the electromagnetic force processing in combination.

Example 2

In example 1, a case where the ultrasonic treatment and the microwave treatment were used in combination when the graphene dispersion liquid was obtained was described, whereas in example 2, only the ultrasonic treatment was performed without performing the microwave treatment, and other conditions were the same as in example 1.

Fig. 15 (B) shows the distribution of the number of layers of the graphene dispersion liquid obtained by performing the ultrasonic treatment using the graphene precursor of sample 5(Rate (3R) ═ 46%) manufactured by the manufacturing apparatus B. Fig. 15 (a) is the same as the distribution shown in fig. 11 (B) of sample 5 produced by production apparatus B in example 1.

As a result, the distribution of the number of layers tended to be approximately the same, but the proportion of 10 layers or less of graphene was 64%, which was slightly lower than 68% of example 1. From this, it was found that, when the graphene dispersion liquid was prepared, it was more effective to perform both the physical force and the electromagnetic force.

Example 3

In embodiment 3, an example for the conductive ink will be described.

Ink 1, ink 3, ink 5, and ink 6 were prepared as graphene precursors at concentrations used as conductive inks in a mixed solution of water and an alcohol having 3 or less carbon atoms as a conductivity-imparting agent, using sample 1(Rate (3R) ═ 23%), sample 3(Rate (3R) ═ 38%), sample 5(Rate (3R) ═ 46%), and sample 6(Rate (3R) ═ 51%) of example 1 as graphene precursors, and the respective resistance values were compared. From this result, a result is obtained in which the resistance value decreases as the Rate (3R) increases.

Example 4

In example 4, an example of kneading into a resin will be described.

In the production of a resin sheet in which graphene is dispersed, the reason why the resin sheet containing glass fibers has very good tensile strength has been studied, and as a result, the following findings have been obtained: the addition of a compatibilizer simultaneously with the glass fibers aids in the graphitization of the precursor. Therefore, a case where a dispersant and a compatibilizer are mixed into a resin has been studied.

1 wt% of sample 5 of example 1(Rate (3R) ═ 46%) was added as a precursor directly to LLDPE (polyethylene), and kneaded with a kneader, a twin-screw kneader (extruder) or the like while applying shear (shearing force).

Since it is known that the tensile strength increases when a graphite-based carbon material in a resin undergoes graphitization and is highly dispersed, the degree of graphitization and dispersion can be relatively estimated by measuring the tensile strength of the resin. The tensile strength was measured under the condition of a test speed of 500 mm/min using a bench precision universal tester (AUTOGRAPH AGS-J) manufactured by Shimadzu corporation.

In addition, in order to compare the graphitization and dispersibility by the presence or absence of the additive, the following three comparisons (a), (b), and (c) were made.

(a) Without additives

(b) Conventional dispersant (Zinc stearate)

(c) Compatibilizer (graft-modified Polymer)

The results will be described with reference to fig. 17 showing the measurement results. In fig. 17, the circle mark is the resin material of sample 1 using the comparative example, and the square mark is the resin material of sample 5 using example 1.

In the case of (a) without adding the additive, the difference in tensile strength is small.

In the case where the dispersant is added to (b), it is found that the graphene formation of the graphene precursor of sample 5 is promoted to some extent.

When the compatibilizer is added to (c), it is found that the graphene formation of the graphene precursor of sample 5 is greatly promoted. This is considered to be because the compatibilizer not only has an effect of dispersing graphene but also acts as follows: when the graphene layer assembly is bonded to a resin and shear is applied in this state, the graphene layer assembly is torn.

The dispersant is exemplified by zinc stearate, but a dispersant having properties matching those of the compound may be selected. Examples of the dispersant include an anionic (anion) surfactant, a cationic (cation) surfactant, a zwitterionic surfactant, and a nonionic (nonion) surfactant. In particular, for graphene, anionic surfactants and nonionic surfactants are preferable. More preferably a nonionic surfactant. The nonionic surfactant is a surfactant which exhibits hydrophilicity due to hydrogen bonds with water, such as sugar chains of oxyethylene groups, hydroxyl groups, or glycosides, and does not dissociate into ions, and therefore has an advantage that it can be used in a nonpolar solvent, although it does not have strong hydrophilicity as in an ionic surfactant. And also because: by changing the chain length of the hydrophilic group, the property of the hydrophilic group can be freely changed from lipophilicity to hydrophilicity. As the anionic surfactant, an X acid salt (X acid is, for example, cholic acid, deoxycholic acid) is preferable, and for example, SDC: sodium deoxycholate, phosphate esters, and the like. The nonionic surfactant is preferably a fatty acid glyceride, a sorbitan fatty acid ester, a fatty alcohol ethoxylate, a polyoxyethylene alkylphenyl ether, an alkyl glycoside, or the like.

Example 5

In order to further verify that the graphene precursor is useful when the Rate (3R) is 31% or more as described in example 1, an example in which the graphene precursor is kneaded into a resin is used in example 5. The elastic modulus of a resin molded article using as a precursor a graphite-based carbon material of Rate (3R) shown in fig. 14 including samples 1 to 7 in example 1 will be described.

(1) The above-mentioned graphite-based carbon material as a precursor, LLDPE (20201J manufactured by Prime Polymer co., ltd.) 5 wt%, and a dispersant (nonionic surfactant) 1 wt% were mixed in ion-exchanged water, and the apparatus of fig. 8 was operated under the same conditions to obtain a graphene dispersion liquid in which the content of graphene and/or graphite-based carbon material was 5 wt%.

(2) 0.6kg of the graphene dispersion liquid obtained in (1) was immediately kneaded with 5.4kg of a resin using a kneader (WDS 7-30, pressure type kneader manufactured by Moriyama Company Ltd.) to prepare pellets. The mixing conditions are described below. The blending ratio of the resin and the dispersion liquid is selected so that the amount of the final graphene and/or graphite-based carbon material added is 0.5 wt%.

(3) Using the pellets prepared in (2), a test piece JIS K71611A type (total length 165mm, width 20mm, thickness 4mm) was prepared by an injection molding machine.

(4) Based on JIS K7161, a bench precision universal tester (AUTOGRAPH AGS-J) manufactured by shimadzu corporation was used to perform the following tests at test rates: the elastic modulus (MPa) of the test piece produced in (3) was measured under the condition of 500 mm/min.

The kneading conditions are as follows.

Mixing temperature: 135 deg.C

Rotor speed: 30rpm

Mixing time: 15 minutes

Pressurizing in the furnace: 0.3MPa 10 min after the start, and the pressure is released to the atmospheric pressure 10 min after the end

Here, in the dispersion of the graphene dispersion liquid of the above (2) into a resin, water evaporates in the atmosphere because the melting point of the resin is generally 100 ℃ or higher, but a pressure kneader may pressurize a furnace. In the furnace, the boiling point of water is increased to keep the dispersion in a liquid state, whereby an emulsion of the dispersion and the resin can be obtained. After pressurization for a predetermined time, the pressure is gradually released, the boiling point of water is lowered, and water is gradually evaporated. At this time, the graphene confined in the water remains in the resin. It is considered that the graphene-based carbon material is highly dispersed in the resin.

In addition, since the graphene-based carbon material tends to settle over time in the graphene dispersion liquid, it is preferable to obtain the graphene dispersion liquid and immediately knead the graphene dispersion liquid into a resin.

The means for obtaining the emulsion of the dispersion and the resin may be a chemical propeller, a vortex mixer, a homomixer, a high-pressure homogenizer, a hydroshear (hydro), a jet mixer, a wet jet mill, an ultrasonic generator, or the like, in addition to the pressure kneader.

As the solvent of the dispersion, 2-propanol (IPA), acetone, toluene, N-methylpyrrolidone (NMP), N-Dimethylformamide (DMF), and the like can be used in addition to water.

Table 4 shows the relationship between the Rate (3R) at a Rate (3R) of about 30% and the elastic modulus of the resin molded article. In table 4, sample 00 is a blank sample in which the precursor is not kneaded, samples 11 and 12 are samples in which the Rate (3R) is between sample 1 and sample 2, and sample 21 is a sample in which the Rate (3R) is between sample 2 and sample 3.

TABLE 4

As can be seen from fig. 18 and table 4, the difference in elastic modulus (the increase ratio of elastic modulus) with respect to sample 00 (blank) is approximately 10% or so until the Rate (3R) reaches 31%, and is approximately constant, and the difference increases abruptly to 32% with the Rate (3R) 31% being the boundary, increases monotonically to 50% between the Rate (3R) 31% and 42%, and then slightly increases and converges to 60% or so after the Rate (3R) is 42%. When the Rate (3R) is 31% or more, a resin molded article having an excellent elastic modulus can be obtained. Further, since the amount of graphene and/or graphite-based carbon material contained in the resin molded product is small such as 0.5 wt%, the influence on the properties inherent in the resin is small.

This tendency is considered to be due to: a graphite-based carbon material having a thin layer containing 10 or less layers of graphene in contact with a resin is rapidly increasing in the range of Rate (3R) 31%. Here, in example 5, the number of graphene layers could not be confirmed even when observed by TEM due to the influence of the dispersant for dispersing in water. For reference, the reason for the above increase was examined based on the layer number distribution of the graphite-based carbon material when dispersed in NMP shown in table 4. In comparison between sample 12 and sample 2, the graphene (having 10 or less layers) was 25%. On the other hand, as shown in fig. 19, the proportion of the thin layers of less than 15 layers in sample 2 is larger than that of sample 12, which is considered to be because: the surface area of the graphite-based carbon material dispersed as the precursor is large, and the area in contact with the resin is rapidly increased.

As described above, according to example 5, when the Rate (3R) is 31% or more, the graphite-based carbon material that can be used as the graphene precursor clearly shows a tendency to be separated into 10 or less layers of graphene and/or a thin layer of the graphite-based carbon material.

Example 6

Experiments were conducted to obtain a positive electrode of a lithium ion secondary battery using the graphene precursor produced by the above method.

< conditions >

Solvent: NMP (N-methylpyrrolidinone; N-methylpyrrolidinone) (battery grade manufactured by Mitsubishi chemical Co., Ltd.),

Conductive auxiliary (conductive raw material): acetylene black (HS-100 manufactured by electrochemical chemical Co., Ltd., average particle diameter of 48nm, bulk density of 0.15g/ml, ash content of 0.01%)

Graphite-based carbon raw material: a graphene precursor (produced by the above-described method),

Adhesive: PVdF (Poly vinylidine; polyvinylidene) (Solvay corporation, Solef TA5130),

Positive electrode active material (base material): NCM Li (Ni1/3, Co1/3, Mn1/3) O2) (average particle size 30 μm) manufactured by Mitsui Metal Co., Ltd,

An ultrasonic treatment apparatus (UP 100S manufactured by Hielscher Co., Ltd.),

< treatment conditions: 20kHz, 100W >, (W),

< dispersion condition 1: the same procedure as in example 1 (fig. 8) was followed to prepare an exfoliated dispersion of graphene precursor. The conditions for applying the ultrasonic wave and the microwave are also the same. < CHEM > A

A mixer (ARE-310 manufactured by THINKY K.K.),

< stirring conditions 1: stirring at 2000rpm × 10 min at 25 ℃ at room temperature

< stirring conditions 2: stirring at the normal temperature of 25 ℃ for 2000rpm multiplied by 10 minutes, and defoaming after stirring at 2100rpm multiplied by 30 seconds >,

A separator (2400 manufactured by Celgard, Inc., having a plate thickness of 25 μm, made of PP (polypropylene)),

electrolyte solution: EC (ethylene carbonate; ethylene carbonate) containing 1.0mol/L of LiPF6(lithium hexafluoro phosphate): DEC (diethyl carbonate) (7: 3 vol%) (Kishida Chemical Co., Ltd.; manufactured by Ltd.), (,

Lithium foil (negative electrode): (thickness 0.2mm manufactured by Bencheng Metal Co., Ltd.)

< Experimental procedures >

Step 1. add 10g of graphene precursor (see samples 1, 2, 21, and 4 (samples used in examples 1 and 5)) to NMP (90g), and exfoliate/disperse the graphene precursor under dispersion condition 1 to obtain a dispersion having a concentration of 10 wt%.

Step 2. the dispersion (20g), PVdF (4g), and acetylene black (6g) were added, and stirring was carried out under stirring conditions 1 to obtain 30g of a mixture 1.

Step 3, the positive electrode active material in the ratio shown in table 5 was added to the mixture 1, and stirring was performed under the stirring condition 2 to obtain a mixture 2.

And 4, coating the mixture 2 on an aluminum foil with the film thickness of 0.25mm, performing vacuum drying at 100 ℃, and pressing under the pressure of 1.5MPa to adjust the thickness, thereby obtaining the positive electrode.

And 5, punching and cutting the positive electrode into the positive electrode with the diameter of 15 mm.

Step 6. a lithium foil pressure-bonded to a stainless steel plate was used as a negative electrode, and a separator, an electrolyte solution, and a positive electrode were sequentially stacked and assembled to a stainless steel HS cell manufactured by baoquan co.

Step 7. electrochemical evaluation was performed on HS cells under the following test conditions.

Here, in the above steps, the transition to the next step is performed sequentially without setting the standby time. The same applies to the following examples.

< test conditions >

Primary charging: CC-CV Charge 0.2C (0.01C cutoff)

Primary discharging: CC discharge 0.2C

Assembling environment: 25 ℃ and dew point temperature-64 ℃ under argon atmosphere (in glove box)

Voltage range: Li/Li + of 2.75V-4.5V vs

A measuring device: manufactured by NAGANO co, ltd, BTS2004W

Here, CC-CV charging is constant voltage and constant current charging, CC discharging is constant current discharging, 0.2C is a charge/discharge rate of 5 hours, and 0.01C cut off is a cut-off condition.

In order to confirm the effect of graphene-like graphite, experiments were carried out with rates (3R) of 23% (sample 1), 31% (sample 2), 35% (sample 21), and 42% (sample 4) according to the mixing ratios shown in table 5.

TABLE 5

According to table 5 and fig. 20, with respect to the charging characteristics, when the charging was carried out at a rate of 0.2C to a charging potential of 4.5V, examples 6-1, 6-2, and 6-3 and comparative example 6-1, and comparative example 6-2 in which graphene-like graphite was not dispersed, showed similar tendency. Examples 6-1, 6-2, and 6-3, particularly example 6-3, are more preferable because the charging voltage becomes higher. In comparative examples 6 to 3, no charging behavior was observed. This is presumably because, since a band-like substance such as acetylene black is not present, a conductive path cannot be formed only with nanoparticles such as graphene-like graphite.

In addition, with respect to the discharge characteristics, examples 6-1, 6-2, 6-3 were observed to have higher charge termination potentials than comparative examples 6-1, 6-2. Further, in each of examples 6-1, 6-2, 6-3 and comparative example 6-1 in which graphene-like graphite is dispersed, a larger capacity was observed as compared with comparative example 6-2 in which graphene-like graphite is not dispersed. In particular, in the case of examples 6-1, 6-2 and 6-3, a significant increase in capacity was observed. In comparative examples 6 to 3, no discharge behavior was observed.

When the graphene-like graphite obtained by exfoliation of the graphene precursor having a Rate (3R) of 31% or more (examples 6-1, 6-2, and 6-3) was used in combination with AB, the obtained battery had a tendency to have a high charge termination potential and good discharge characteristics of the positive electrode, and particularly, a tendency to have a sharp increase in charge termination potential with a boundary of 31% was observed from fig. 20. It is presumed that, as shown in fig. 21, the conduction aids AB53, 53, ·, 53 having a band shape and a cross-sectional diameter of several tens of nm are present between the positive electrode active materials 52, 52 having a particle diameter of several tens of μm, and the graphene-like graphite 54 (for example, having a thickness of 50nm or less and a size of 100nm to 5 μm.) is dispersed between the positive electrode active material 52 and AB53, between AB53 and AB53, between the aluminum foil 51 and the positive electrode active material 52, and between the aluminum foil 51 and AB53, respectively. Further, since the graphene-like graphite 54 is planar and is relatively flexible compared to other materials such as the aluminum foil 51, the positive electrode active material 52, and AB53, it is considered that the aluminum foil 51, the positive electrode active material 52, and AB53 are brought into close contact with each other with the graphene-like graphite 54 interposed therebetween, and thus the discharge characteristics of the positive electrode become good. In the case of the graphene precursor having a Rate (3R) of less than 31% (comparative example 6-1), the amount of dispersed graphene-like graphite is considered to be small, and the effect of adding graphene-like graphite is not sufficiently exhibited.

As the Rate (3R) of the graphene precursor increased to 35% (example 6-2) or 42% (example 6-3), the discharge characteristics and capacity of the positive electrode were better than those below these values. This is considered to be because the number and contact area of the graphene-like graphite 54 in which the aluminum foil 51, the positive electrode active material 52, and the AB53 are in contact with each other are increased as compared with the case where the Rate (3R) is 31% (example 6-1).

In addition, since the graphene precursor is manufactured by the treatment based on the electromagnetic force and/or the treatment based on the physical force as described above, the oxidation and reduction treatment is not required. Further, since reduction treatment is not required in the production of the positive electrode, it is not necessary to set the temperature to a high temperature, and the production of the positive electrode is easy. The positive electrode is produced under the kneading conditions 1 and 2 and vacuum drying, and the production is simple.

Further, since the dispersion liquid in which the graphene-like graphite is dispersed under the dispersion liquid condition 1 is kneaded with AB53 before being kneaded with the positive electrode active material 52, the graphene-like graphite 54 and AB53 are well mixed under the kneading condition 1. Then, since the positive electrode active material 52 is kneaded, the graphene-like graphite 54 is uniformly dispersed.

Here, in the dispersion liquid obtained in step 1, a material exfoliated from the graphene precursor is dispersed. It is also stated at the outset that mixtures between graphene precursors and graphene, in which some or all of the graphene precursors are exfoliated, are referred to as "graphene-like graphites". The graphene-like graphite dispersed in the dispersion liquid can be observed by a Transmission Electron Microscope (TEM) in the same manner as the graphene shown in fig. 10, although not shown.

For reference, a Scanning Electron Microscope (SEM) photograph of the graphene precursor is explained. The graphene precursor obtained in example 1 is a laminate of thin-layer graphite having a length of 7 μm and a thickness of 0.1 μm, as shown in fig. 22 and 23, for example.

Example 7

Experiments were conducted to obtain a positive electrode of a lithium ion secondary battery using the graphene precursor produced by the above method.

In example 7, the carbon nanotubes were used as the conductive material, and the experiment was performed at the mixing ratio shown in table 6. Otherwise, the same procedure as in example 6 was repeated.

< conditions >

Carbon nanotube: VGCF-H manufactured by Showa Denko K.K. (fiber diameter 150nm, fiber length 10 to 20 μm)

TABLE 6

As shown in fig. 24, the same tendency as in example 6 was observed. By using the carbon nanotube, the charge/discharge characteristics are better than those of AB as a whole.

Example 8

Experiments were conducted to obtain a positive electrode of a lithium ion secondary battery using the graphene precursor produced by the above method.

In example 8, an experiment was performed under the conditions shown in table 7 with a mixing ratio of a graphene precursor with a Rate (3R) of 31% to a conductive raw material. Otherwise, the same procedure as in example 6 was repeated.

TABLE 7

As shown in fig. 25, regarding the charge and discharge characteristics, almost the same tendency was observed when the mixing ratio of the graphene precursor to the conductive material was more than 1 (example 8-2), and the characteristics were observed to be saturated. When the mixing ratio of the graphene precursors is 10 or more, the influence on the properties of the matrix becomes large. On the other hand, when the mixing ratio is less than 1/50 (example 8-7), the charging and discharging characteristics tend to be almost the same as the case where the graphene precursor is not mixed (comparative example 6-2), and when the mixing ratio is 1/10 (example 8-6) or more, the charging and discharging characteristics become good. Accordingly, the lower limit of the mixing ratio is 1/50 or more, preferably 1/10 or more, and the upper limit is 10 or less, preferably 1 or less.

Example 9

Next, an experiment was performed to obtain a resin molded article using the graphene precursor produced by the above method.

< conditions >

< raw Material >

Resin: LLDPE (polyethylene: Prime Polymer Co., Ltd., 20201J manufactured by Ltd.),

Solvent: water (ion-exchanged water),

Dispersing agent: 1% by weight (nonionic surfactant),

An ultrasonic treatment apparatus (UP 100S manufactured by Hielscher Co., Ltd.),

< treatment conditions: 20kHz, 100W >, (W),

< dispersion condition 2: the graphene precursor was mixed with 1 wt% of a dispersant (nonionic surfactant) into ion-exchanged water, and the apparatus shown in fig. 8 was operated under the same conditions to obtain a dispersion liquid in which graphene-like graphite was 10 wt%. < CHEM > A

< kneader >

A kneader: manufacture of pressure type kneader WDS7-30,

Mixing temperature: at 135 deg.C,

Rotor speed: 30 r/min,

Processing time: 15 minutes later,

Mixing ratio: 5340g of resin, 600g of AB (HS-100), 600g of dispersion liquid (making the graphene-like graphite 60g),

< volume resistance value >

Test piece:(ASTM D257)、

a measuring device: a device main body (R-503 manufactured by Chuangkou electric manufacturing), an electrode device (P-616 manufactured by Chuangkou electric manufacturing),

Voltage application: 500V,

The current after voltage application for 1 minute was measured,

< thermal conductivity >

Test piece:(ASTM E1530)、

a measuring device: UNITHERM 2021 manufactured by ANTER

< Experimental procedures >

Step 1, dispersions were obtained under dispersion conditions 2 using graphene precursors different in Rate (3R) shown in table 8.

And 2, putting the dispersion liquid obtained in the step 1 and the resin into a pressurizing kneader, and mixing at the mixing ratio.

Step 3. the kneaded product obtained in step 2 was molded into a test piece by an injection molding machine in accordance with ASTM D257, and the change in volume resistance value was observed.

Step 4. the kneaded material obtained in step 2 was molded into a test piece by an injection molding machine in accordance with ASTM E1530, and the change in thermal conductivity was observed by a static method.

TABLE 8

According to Table 8, examples 9-1, 9-2 and 9-3 all had small volume resistance and excellent conductivity.

In addition, the thermal conductivity was observed to be sufficiently high in examples 9-1, 9-2, 9-3 and comparative examples 9-1, 9-2, 9-3 and 9-4.

When the graphene-like graphite obtained by exfoliation of a graphene precursor having a Rate (3R) of 31% or more (examples 9-1, 9-2, and 9-3) was used in combination with AB, it was confirmed that the volume resistance and the thermal conductivity tended to be good, and particularly, the volume resistance and the thermal conductivity tended to be sharply good at a boundary of 31% from table 8. On the other hand, AB having a cross-sectional diameter of several hundred nm to several μm was present between polymers of LLDPE by the same principle as in example 6. It is presumed that graphene-like graphite is dispersed between LLDPE and AB, between AB and AB, and between LLDPE and LLDPE, respectively. Further, since graphene-like graphite is planar and is softer than other materials such as LLDPE and AB, it is considered that LLDPE and AB are in close contact with each other with graphene-like graphite interposed therebetween, and thus volume resistance and thermal conductivity are improved. When the Rate (3R) is less than 31% (comparative example 9-1), the amount of dispersed graphene-like graphite is considered to be small, and the effect of the dispersed graphene-like graphite is not sufficiently exhibited.

Further, as the Rate (3R) was increased to 35% (example 9-2) and 42% (example 9-3), the volume resistance and the thermal conductivity were better than those of the case of the values below these values. This is considered to be because the number and contact area of graphene-like graphite particles in which LLDPE and AB are in contact with each other were increased as compared with the case where the Rate (3R) was 31% (example 9-1).

Here, in the dispersion liquid obtained in step 1, a material exfoliated from the graphene precursor is dispersed. It is also stated at the outset that mixtures between graphene precursors and graphene, in which some or all of the graphene precursors are exfoliated, are referred to as "graphene-like graphites". The graphene-like graphite dispersed in the dispersion liquid can be observed by a Transmission Electron Microscope (TEM) in the same manner as the graphene shown in fig. 10, although not shown.

In addition, the graphene-like graphite dispersed in the resin can be observed as follows: the molded test piece was cut with a precision high-speed cutter (TechCut 5 manufactured by allid) or the like, and observed with a Scanning Electron Microscope (SEM) or the like. For example, fig. 26 shows a cross section of a resin in which carbon nanotubes and graphene-like graphite are dispersed, where linear portions are carbon nanotubes and white spot portions are graphene-like graphite. Such graphene graphite is a laminate of thin-layer graphite having a thickness of 3.97nm, for example, as shown in fig. 27.

Example 10

Next, an experiment was performed to obtain a resin molded article using the graphene precursor produced by the above method.

The experiment was performed according to the conditions shown in table 9 with a mixing ratio of the graphene precursor with a Rate (3R) of 31% to the conductive raw material.

< conditions >

< raw Material >

Resin: LLDPE (polyethylene: Prime Polymer Co., Ltd., 20201J manufactured by Ltd.),

A compatilizer: KAYABRID006PP (KAYAKU AKZO CO., LTD. manufactured maleic anhydride-modified PP),

Acetylene Black (HS-100 manufactured by electrochemical Industrial Co., Ltd., average particle diameter of 48nm, volume density of 0.15g/ml, ash content of 0.01%)

< < twin-screw extruder >)

A double-screw extruder: HYPERKTX 30 manufactured by Korea Steel works,

Mixing temperature: at 135 deg.C,

Screw rotation speed: 100 r/min,

< volume resistance value >

Test piece:(ASTM D257)、

a measuring device: a device main body (R-503 manufactured by Chuangkou electric manufacturing), an electrode device (P-616 manufactured by Chuangkou electric manufacturing),

Voltage application: 500V,

The current after voltage application for 1 minute was measured,

< thermal conductivity >

Test piece:(ASTM E1530)、

measuring apparatus UNITHERM 2021 manufactured by ANTER

< Experimental procedures >

Step 1, mixing graphene precursors and compatibilizers having different rates (3R) shown in table 9 with a twin-screw extruder to obtain a mixture 1 containing 40 wt% of graphene-like graphite. The graphene precursor becomes graphene-like graphite in the kneading process.

Step 2. the mixture 1 obtained in step 1, the resin, AB were compounded in the same twin-screw extruder in the proportions shown in table 9.

Step 3. the kneaded product obtained in step 2 was molded into a test piece by an injection molding machine in accordance with ASTM D257, and the change in volume resistance value was observed.

Step 4. the kneaded material obtained in step 2 was molded into a test piece by an injection molding machine in accordance with ASTM E1530, and the change in thermal conductivity was observed by a static method. .

The volume resistance and thermal conductivity of the compatibilizer do not greatly change from those of the resin that is the base material, and therefore, this embodiment does not take into consideration.

TABLE 9

As shown in table 9, when the mixing ratio of the graphene precursor to the conductive material was more than 1 (examples 10 to 5), the volume resistance and the thermal conductivity became almost the same values, and the characteristics were observed to be saturated. When the mixing ratio of the graphene precursors is 10 or more, the influence on the properties of the base material becomes large. On the other hand, when the mixing ratio is less than 1/50 (comparative example 10-9), the volume resistance and thermal conductivity are almost the same as those in the case where the graphene precursor is not mixed (comparative example 9-2). Accordingly, the lower limit of the mixing ratio is 1/50 or more, preferably 1/10 or more, and the upper limit is 10 or less, preferably 1 or less.

Example 11

Next, an experiment was performed to obtain a resin molded article using the graphene precursor produced by the above method.

In example 11, the conductive raw material mixed with the graphene precursor having a Rate (3R) of 31% was changed, and the influence of the shape was confirmed. Otherwise, the same procedure as in example 9 was repeated.

As shown in fig. 28, Acetylene Black (AB), which is one of carbon blacks, is a band-shaped and/or linear carbon black having a diameter of several tens of nm and a length of several to several tens of μm as a conductive material. The Carbon Fibers (CF) are linear fibers having a diameter of several tens μm and a length of several hundreds μm. The diameter of the metal particles is several tens nm to several μm.

Watch 10

As shown in Table 10, the bulk resistivity and the thermal conductivity were good in both of example 9-1 to which AB was added and example 11-1 to which CF was added. On the other hand, in example 11-2 in which the metal particles were added, the volume resistance and the thermal conductivity were not good, although the graphene precursor was added and the graphene-like graphite was dispersed. From this, it is found that it is preferable to use a graphene precursor in combination with a conductive material in a band, straight chain, or linear form. In addition, although not shown as an example, the volume resistance and the thermal conductivity of the scale-like conductive material are also good. It is presumed that the tape-like, straight-chain, linear, or flaky nano-conductive material has a large surface area per unit mass due to its shape, and therefore, comes into contact with a large amount of graphene-like graphite, and has a good affinity for graphene-like graphite. Further, it has been found that the conductive material is particularly preferably in a band-like, straight-chain, linear or scaly shape, and has an aspect ratio of 5 or more. The aspect ratio of the average diameter to the longest portion of the raw material branched like acetylene black may be determined. In addition, the aspect ratio of the scaly raw material may be determined as the ratio of the average thickness to the longest portion.

Example 12

Next, an experiment was performed to obtain a resin molded article using the graphene precursor produced by the above method. In example 12, an experiment was performed using a graphene paste produced from a graphene precursor under the dispersion condition 3.

< conditions >

< raw Material >

Diacetone alcohol: manufactured by Wako pure chemical industries, Ltd,

Methyl paraben: manufactured by Wako pure chemical industries, Ltd,

A stabilizer: 30-50 parts of nitrocellulose DLX (Nobel NC Co. Ltd.),

Acetylene black (HS-100 manufactured by electrochemical chemical Co., Ltd., average particle diameter of 48nm, bulk density of 0.15g/ml, ash content of 0.01%)

< stirring >

Mixer (ARE-310 made by THINKY)

< stirring conditions 3 >: stirring at 25 deg.C for 2000rpm × 10 min at room temperature, and defoaming at 2100rpm × 30 sec after stirring

< coating Condition 1>

A bar coating machine: no.16 manufactured by first physical chemical Co., Ltd,

Coating film thickness: 36.6 μm (25.4 μm in dry state),

Drying conditions are as follows: 30 minutes at 130℃,

Substrate: quartz glass (t2mm),

Coating area: 50mm multiplied by 50mm,

< sheet resistance measuring device >

LORESTA GP MCP-T610 model Mitsubishi Chemical Analyticech Co., Ltd,

The measurement conditions were as follows: JIS K7194

< Experimental procedures >

Step 1. the apparatus of fig. 8 was operated under the same conditions in diacetone alcohol (4-Hydroxy-4-methyl-2-pentanone; 4-Hydroxy-4-methyl-2-pentanone) using graphene precursors having different rates (3R) shown in table 11, to obtain a dispersion liquid in which graphene-like graphite was 10 wt%. (Dispersion Condition 3)

Step 2. the graphene dispersion obtained in step 1, Methyl paraben (Methyl 4-hydrooxybenzoate), stabilizer, and AB were added in the proportions shown in table 11 to obtain a mixture 3 under stirring condition 3.

Step 3. the mixture 3 was coated under the coating condition 1 using a bar coater, and the sheet resistance was measured by a four-probe method according to JIS K7194.

TABLE 11

As shown in Table 11, in examples 12-1, 12-2 and 12-3, a low sheet resistance was observed as compared with comparative examples 12-1 and 12-2. In addition, it was observed that the sheet resistance of comparative example 12-1 in which the Rate (3R) was 23% was substantially equal to that of comparative example 12-2 in which no graphene precursor was added. It is thus presumed that the graphene-like graphites in examples 12-1, 12-2, and 12-3 sufficiently contribute to the reduction in sheet resistance together with AB. It was also found that the sheet resistance of the graphene paste using a graphene precursor having a Rate (3R) of 31% or more (examples 12-1, 12-2, and 12-3) was drastically reduced as compared with the graphene paste using a graphene precursor having a Rate (3R) of 23% (comparative example 12-1).

In the present embodiment, in order to eliminate the disturbance factor, only basic raw materials are used. In practical conductive inks and pastes, an antioxidant, a viscosity modifier, and various conductive materials are usually added to achieve a desired ink and a reduced resistance value.

While the embodiments of the present invention have been described above with reference to the drawings, the specific embodiments are not limited to these embodiments, and modifications and additions within the scope not departing from the gist of the present invention are also included in the present invention.

In the above-described embodiments, the production apparatus a using a jet mill and plasma and the production apparatus B using a ball mill and microwave were described as the production apparatus for producing a graphene precursor, but it is preferable to use a combination of a treatment based on electromagnetic force such as microwave, millimeter wave, plasma, electromagnetic Induction Heating (IH) and a magnetic field and a treatment based on physical force such as a ball mill, jet mill, centrifugal force, or supercritical because a precursor having a higher Rate (R3) can be obtained. The physical force-based processing and the electromagnetic force-based processing are used in combination, and the types of the individual processing of the physical force-based processing and the electromagnetic force-based processing are not limited. In particular, it is preferable to cause the electromagnetic force and the physical force to act simultaneously as in the manufacturing apparatuses a and B, and the electromagnetic force and the physical force may be caused to act alternately at predetermined time intervals. Further, as for the electromagnetic force, for example, different electromagnetic forces such as microwave and plasma treatments may be alternately applied, and 1 or 2 or more kinds of physical force-based treatments may be applied in parallel thereto. Further, as for the physical force, for example, different physical forces such as a jet mill and supercritical processing may be alternately applied, and 1 or 2 or more types of processing by electromagnetic force may be applied in parallel therewith.

For example, the following materials can be used as a base material for dispersing the conductive material and the graphite-based carbon material. However, the base material may be smaller than the conductive material or the graphite-based carbon material. In addition, the water may disappear by combustion, oxidation, vaporization, evaporation, or the like during use. For example, the base material such as the conductive paste or the conductive ink disappears when the base material is a volatile solvent. The base material may contain a conductive material in addition to the base material.

As the positive electrode active material, a layered oxide-based active material (LiCoO)₂、LiNiO₂、Li(Ni_xCo_y)O₂(wherein x + y is 1), Li (Ni)_xCo_yAl_z)O₂、Li(Ni_xMn_yCo_z)O₂、Li(Ni_xMn_y)O₂、Li₂MnO₃-Li(Ni_xMn_yCo_z)O₂(wherein x + y + z ═ 1), etc.), olivine active material (LiMPO)₄、Li₂MPO₄F、Li₂MSiO₄(wherein M is at least 1 metal element selected from the group consisting of Ni, Co, Fe and Mn), a lithium excess system active material, and a spinel type positive electrode active material (LiMn)₂O₄) And the like.

Examples of the resin include thermoplastic resins such as Polyethylene (PE), polypropylene (PP), Polystyrene (PS), polyvinyl chloride (PVC), ABS resin (ABS), acrylic resin (PMMA), polyamide/nylon (PA), Polyacetal (POM), Polycarbonate (PC), polyethylene terephthalate (PET), cyclic polyolefin (COP), Polyphenylene Sulfide (PPs), Polytetrafluoroethylene (PTFE), Polysulfone (PSF), Polyamideimide (PAI), thermoplastic Polyimide (PI), polyether ether ketone (PEEK), and Liquid Crystal Polymer (LCP). Among the synthetic resins, examples of the thermosetting resin or the ultraviolet curable resin include epoxy resin (EP), phenol resin (PF), melamine resin (MF), Polyurethane (PUR), unsaturated polyester resin (UP), examples of the conductive polymer include fibers such as PEDOT, polythiophene, polyacetylene, polyaniline, polypyrrole, fibrous nylon, polyester, acrylic resin, vinylon, polyolefin, polyurethane, rayon, and examples of the elastomer include Isoprene Rubber (IR), Butadiene Rubber (BR), Styrene Butadiene Rubber (SBR), Chloroprene Rubber (CR), nitrile rubber (NBR), polyisobutylene rubber/butyl rubber (IIR), ethylene propylene rubber (EPM/EPDM), chlorosulfonated polyethylene (CSM), acrylic rubber (ACM), epoxy rubber (CO/ECO), and the like, examples of the thermosetting resin-based elastomer include a part of urethane rubber (U), silicone rubber (Q), Fluororubber (FKM), and examples of the thermoplastic elastomer include styrene-based, olefin-based, polyvinyl chloride-based, polyurethane-based, and amide-based elastomers.

Further, as the mineral oil, as a lubricating oil, a grease, or a rubber compounding oil, paraffin mineral oil, naphthene mineral oil, aromatic mineral oil, and the like can be cited.

Further, examples of the nonpolar substance include hexane, benzene, toluene, chloroform, ethyl acetate, etc., examples of the polar aprotic substance include acetone, N-Dimethylformamide (DMF), N-methylpyrrolidone (NMP), acetonitrile, etc., and examples of the polar protic substance include acetic acid, ethanol, methanol, water, 1-butanol, 2-propanol, formic acid, etc.

As the conductive material, the following materials can be mentioned. Examples of the metal material include silver nanoparticles, copper nanoparticles, silver nanowires, copper nanowires, scaly silver, scaly copper, iron powder, and zinc oxide. Examples of the carbon material include carbon black, carbon fiber, CNT, graphite, and activated carbon. Examples of the conductive polymer include PEDOT, polythiophene, polyacetylene, polyaniline, and polypyrrole. In particular, a chain-like, ribbon-like, or scaly fibrous substance is excellent in conductivity.

Further, as natural graphite used for producing a graphite-based carbon material used as a graphene precursor, a natural graphite material having particles of 5mm or less (flake graphite ACB-50 produced by the graphite industry of japan) is exemplified, but from the viewpoint of easy availability, natural graphite which is flake graphite and is pulverized to 5mm or less, and has a Rate (3R) of less than 25% and a strength ratio P1/P2 of less than 0.01 is preferable. With recent technological development, artificial natural graphite-like graphite (graphite in which crystals are layered) can be synthesized, and thus the raw material of graphene and graphene-like graphite is not limited to natural graphite (mineral). For applications such as batteries where the metal content needs to be controlled, it is preferable to use synthetic graphite having high purity.

The graphene-based carbon material used as the graphene precursor is generally referred to as graphene, a graphene precursor, Graphene Nanosheets (GNPs), few-layer graphene (FLG), nanographene, and the like, but is not particularly limited.

Industrial applicability

The present invention is directed to a conductive composite material, and the application field thereof is not limited. In the present invention, the conductive means at least one of electrical conduction, ionic conduction, and thermal conduction. For example, there are the following fields.

(1) Examples of electrical conductors (electrical conductors)

(1-1) electric storage device

(1-1-1) Battery

As a conductive material used for a positive electrode material, a negative electrode material, and the like of a battery represented by a lithium ion battery, both conductivity and ion conductivity are preferable. The following materials are exemplified as the materials constituting the battery, but are not limited thereto.

Positive electrode active material: LiCoO₂、LiMn₂O₄、LiNiO₂、LiFeO₄、Li₂FePO₄F、Li(Cox,Niy,Mnz)O₂

Conductive assistant: graphite powder, acetylene black, VGCF, CNT

Anode material: graphite powder, hard carbon, activated carbon, titanate (Li)₄Ti₅O₁₂)、Si

Electrolyte solution: PC (polycarbonate), EC (ethylene carbonate), DEC (diethyl carbonate)

Supporting electrolyte: LiPF₆、LiBF₄、LiTFSI

Current collector: aluminum foil, copper foil and lithium foil

(1-1-2) capacitor, condenser

As a lithium ion capacitor, an electric double layer capacitor, a capacitor such as a condenser, and a condenser, it is desirable that the electric conduction is good. As a material constituting the capacitor and the condenser, the following materials are exemplified, but not limited to them.

Collector electrode: aluminum foil

Polarizable electrodes: activated carbon

Conductive auxiliary materials: carbon black and CNT

Electrolyte: tetraethylammonium ion, boron tetrafluoride ion, bis (trifluoromethylsulfonyl) imide

Electrolyte solution: propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate

(1-2) conductive Dispersion

The conductive particles are preferably used as a conductive dispersion liquid such as a conductive ink, a conductive paste, or a conductive paste used for a transparent/opaque conductive film or a conductive device for an electronic circuit board (printing or photo-etching). The following materials are exemplified as the material constituting the conductive dispersion liquid, but are not limited thereto.

Solvent: water, anti-drying agent (glycerol, glycol, etc.), penetrating agent (alcohol, glycol ether, etc.), alcohol, NMP (N-methylpyrrolidone), DMF, toluene, ethyl acetate, and ketone

The colorant: dyes and pigments

Resin: thermoplastic resins such as acrylic block copolymer, acrylic resin, maleic acid, rosin, epoxy resin, silicone, and butyral

Additives: pH regulator, chelating agent, surfactant, antibacterial and antifungal agent, antioxidant, ultraviolet absorbent, and plasticizer

Conductive raw materials: graphite powder, carbon black (ketjen black, acetylene black, etc.), carbon fiber, CNT (SWNT, MWNT), fine metal powder (copper/silver nanoparticles), metal oxide (ITO, zinc oxide), metal fiber (copper/silver nanowires), conductive polymer (PEDOT, polyacetylene, etc.)

(1-3) conductive composite

As the conductive composite having resistance to conduction, static electricity, electrification, electromagnetic wave blocking property, and the like, good conduction is preferable. The following materials are exemplified as the material constituting the conductive dispersion liquid, but are not limited thereto.

Conductive raw materials: the metal includes Fe and Ni. Carbon fibers, isotropic graphite, and carbon black are used as carbon materials.

The polymer species: PE, PP, PS, PC, PVC, ABS, PA6, PA66, PSS, PEEK, POM, epoxy resin, natural rubber, chloroprene rubber, NBR, silicone rubber.

(2) Examples of thermal conductivity

(2-1) thermally conductive Compound

(2-1-1) Heat sink made of thermal conductive film, thermal conductive Polymer, or the like

The heat sink which can increase the heat resistance time of the mixture by locally releasing heat is preferably excellent in heat conduction. The following materials are exemplified as the material constituting the heat sink, but are not limited thereto.

Conductive raw materials: the metal is Cu, Al, or W. Carbon fibers and isotropic graphite are used as the carbon material.

The polymer species: PE, PP, PS, PC, PVC, ABS, PA6, PA66, PSS, PEEK, POM, epoxy resin, natural rubber, chloroprene rubber, NBR, silicone rubber.

(2-1-2) Heat-dissipating paste and cataplasm

The thermal conductive paste or paste, which is a material for connecting a heat sink such as (2-1-1) to a heat sink, is preferably excellent in thermal conductivity. The materials constituting the heat dissipating paste and the paste are exemplified by, but not limited to, the following materials.

Solvent: silicon grease (polysiloxane compound)

Conductive agent: zinc oxide, silver nanoparticles, nanodiamond, carbon black, silicon nanoparticles

Description of the reference numerals

51 aluminum foil

52 Positive electrode active material (base material)

53 AB (conductive raw material)

Class 54 graphene graphite

Claims (17)

1. A composite conductive material, characterized in that a composite conductive material in which at least graphene-like graphite obtained by exfoliation from a graphite-based carbon material and a conductive material are dispersed in a matrix,

the graphite-based carbon material has a rhombohedral graphite layer (3R) and a hexagonal graphite layer (2H), wherein the ratio Rate (3R) of the rhombohedral graphite layer (3R) to the hexagonal graphite layer (2H) defined by the following formula (1) obtained by an X-ray diffraction method is 31% or more,

rate (3R) ═ P3/(P3+ P4). times.100. cndot. (formula 1)

In the formula 1, the reaction mixture is,

p3 represents the peak intensity of the (101) plane of the rhombohedral graphite layer (3R) obtained by X-ray diffraction,

p4 represents the peak intensity of the (101) plane of the hexagonal graphite layer (2H) by X-ray diffraction,

the graphene-like graphite is a mixture between the graphite-based carbon material and graphene, which is obtained by peeling off a part or all of the graphite-based carbon material,

the graphene is a flaky or flaky graphene which belongs to crystals with an average size of 100nm or more and has 10 or less layers.

2. The composite conductive raw material as claimed in claim 1, wherein the conductive raw material is a band-like, straight-chain, linear or scaly fine particle.

3. The composite conductive raw material as claimed in claim 2, wherein the aspect ratio of the fine particles is 5 or more.

4. The composite conductive raw material as claimed in claim 1 or 2, wherein a weight ratio of the graphite-based carbon raw material to the conductive raw material is 1/50 or more and less than 10.

5. The composite conductive raw material as claimed in claim 1, wherein the base material is an active material of a battery.

6. The composite conductive raw material as claimed in claim 5, wherein the active material is an active material of a positive electrode.

7. The composite conductive stock material of claim 1, wherein the parent material is a polymer.

8. The composite conductive raw material as claimed in claim 1, wherein the base material is a material which disappears in use.

9. An electricity storage device, characterized by using the composite conductive raw material according to claim 1.

10. An electroconductive dispersion liquid, characterized in that the composite conductive raw material according to claim 1 is used.

11. An electrically conductive device coated or printed with the electrically conductive dispersion liquid according to claim 10.

12. An electrically conductive composite, characterized in that the composite conductive raw material according to claim 1 is used.

13. A thermally conductive composite, characterized in that the composite conductive raw material according to claim 1 is used.

14. A method for producing a composite conductive material, comprising a step of kneading at least a graphite-based carbon material and a conductive material in a matrix,

the graphite-based carbon material has a rhombohedral graphite layer (3R) and a hexagonal graphite layer (2H), wherein the ratio Rate (3R) of the rhombohedral graphite layer (3R) to the hexagonal graphite layer (2H) defined by the following formula (1) obtained by an X-ray diffraction method is 31% or more,

rate (3R) ═ P3/(P3+ P4). times.100. cndot. (formula 1)

In the formula 1, the reaction mixture is,

p3 represents the peak intensity of the (101) plane of the rhombohedral graphite layer (3R) obtained by X-ray diffraction,

p4 is the peak intensity of the (101) plane of the hexagonal graphite layer (2H) obtained by the X-ray diffraction method.

15. The method for manufacturing a composite conductive material as set forth in claim 14, wherein the conductive material is a band-shaped, linear, or scaly fine particle.

16. The method of manufacturing a composite conductive raw material according to claim 15, wherein an aspect ratio of the fine particles is 5 or more.

17. The method for manufacturing a composite conductive raw material according to claim 14 or 15, wherein a weight ratio of the graphite-based carbon raw material to the conductive raw material is 1/50 or more and less than 10.