JP2016166113A - Carbon-metal complex - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material which can improve the performance of a storage battery.SOLUTION: A carbon-metal complex comprises carbon, oxygen, and a metal element as constituent elements. The carbon-metal complex has carbon binding to oxygen, and comprises a metal element of groups 3-14 in the periodic table in an amorphous state.SELECTED DRAWING: None

Description

The present invention relates to a carbon-metal composite. More specifically, the present invention relates to a carbon-metal composite that can be suitably used as an electrode active material of a battery.

In recent years, with the growing interest in environmental issues, energy sources have been shifting from oil and coal to electricity in various industrial fields. In addition to electronic devices such as mobile phones and laptop computers, automobiles and aircraft The use of power storage devices such as batteries and capacitors has been spreading in various fields. In response to such an increase in demand for power storage devices, research for realizing higher performance power storage devices is being actively conducted.

Among such power storage devices, lithium ion secondary batteries have a high energy density and a high operating voltage, and can be miniaturized, so mobile phones, smartphones, mobile PCs, digital cameras, electric vehicles, etc. Are used in various applications. Currently, in many lithium ion secondary batteries, graphite is used for the negative electrode. When graphite is used as the negative electrode of a lithium ion secondary battery, the composition when lithium ions are occluded in the graphite is LiC _6, and thus the theoretical electric capacity of graphite is 372 mAh / g. Attempts have been made to improve battery performance by improving the carbon material used as an electrode, and research has also been published on applying a composite of carbon material and metal oxide to the electrode material (Patent Literature). 1, 2, and non-patent documents 1 to 9).

International Publication No. 2012/172623 International Publication No. 2013/027686

H. Wang, et.al, Journal of American Chemical Society, 2010, 132, 13978-13980 S.Zhu, et.al, RSC Advances, 2013, 3, 6141-6146 X. Wang, et.al, CARBON, 2011, 49, 133-139 W. Gao, et.al, NATURE CHEMISTRY, 2009, 1, 403-408 J. Yea, et.al, Electrochimica Acta, 2013, 113, 212-217 G. Wang, et.al, Journal of Power Sources, 2013, 239, 37-44 Q. Su, et.al, ACS NANO, 2013, 7, 10, 9115-9121 H. Zhang, et.al, RSC Advances, 2014, 4, 495-499 Y. Matsumoto, et.al, APPLIED MATERIALS and INTERFACES, 2010, 2, 12, 3461-3466

The demand for the performance of storage batteries such as lithium ion secondary batteries is increasing with the spread of applications, and the development of materials that can improve the performance of storage batteries is required.

This invention is made | formed in view of the said present condition, and aims at providing the material which can further improve the performance of a storage battery.

The present inventor paid attention to graphite used as a negative electrode active material of a lithium ion secondary battery, and variously studied a material capable of further improving the characteristics, and has carbon bonded to oxygen, and We have succeeded in producing a carbon-metal composite containing a group 3-14 metal element in an amorphous state. The present inventors have found that when this carbon-metal composite is used as a negative electrode active material, a battery capacity higher than that of graphite can be realized, and the present invention has been achieved.

That is, the present invention is a carbon-metal composite containing carbon, oxygen, and a metal element as constituent elements, and the carbon-metal composite has carbon bonded to oxygen, and the periodic table 3-14. It is a carbon-metal composite characterized by containing a group metal element in an amorphous state.
The present invention is described in detail below.
A combination of two or more preferred embodiments of the present invention described below is also a preferred embodiment of the present invention.

The carbon-metal composite of the present invention is a carbon-metal composite containing carbon, oxygen, and a metal element as constituent elements, and a carbon material having carbon (C) bonded to oxygen (O) and a periodic rule. It is preferable that it is a complex with the simple substance of the metal element of Table 3-14, or the metal compound which has this metal element. The carbon-metal composite of the present invention is characterized in that it contains a metal element of Group 3-14 of the periodic table in an amorphous state. In the present invention, a metal element of Group 3-14 of the periodic table is in an amorphous state. “Contains” means that a metal atom (metal simple substance) or a metal compound containing a metal element is in an amorphous state.
In the carbon-metal composite of the present invention, it is sufficient that at least a part of a metal element of the periodic table group 3-14 included in the composite or at least a part of the metal compound containing the metal element is in an amorphous state. .
The fact that the simple substance of the metal element of the group 3 to 14 of the periodic table or the metal compound containing the metal element is in an amorphous state indicates that the metal element of the group 3 to 14 of the periodic table is measured by XRD measurement of the carbon-metal composite. That a peak attributed to a simple substance or a metal compound containing the metal element is not observed, or from a peak attributed to a simple substance of a group 3-14 metal element or a metal compound containing the metal element, Scherrer's formula It can be confirmed that the crystallite diameter calculated by is less than 1 nm.

The carbon material is not particularly limited as long as it has carbon (C) bonded to oxygen (O), but is preferably a material in which oxygen is bonded to a graphitic carbon material such as graphene or graphite. More preferably, it is graphene oxide in which oxygen is bonded to a carbon atom of graphene.
The carbon-metal composite of the present invention may contain other elements as constituent elements as long as it contains carbon, oxygen, and metal elements as constituent elements, but only carbon, oxygen, and metal elements. A constituent element is preferred.
In general, graphene refers to a sheet composed of one layer of atoms in which carbon atoms bonded by sp ² bonds are arranged in a plane, and a stack of graphene sheets is referred to as graphite. The graphene includes not only a sheet composed of only one carbon atom layer but also one having a structure in which about several to 20 layers are laminated.

As a metal element used for the carbon-metal composite of the present invention, among the metal elements of Group 3 to 14 of the periodic table, metal elements of Group 5 to 11 of the periodic table are preferable. By using these as metal elements, the carbon-metal composite obtained is more excellent in characteristics when used as an electrode active material. More preferably, it is one of V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo, and W.
The carbon-metal composite of the present invention may contain one kind of metal element or may contain two or more kinds.

The carbon-metal composite of the present invention preferably contains a metal element of Groups 3 to 14 of the periodic table in a proportion of 1 to 40% by mass with respect to the entire carbon-metal composite. By including the metal elements of Groups 3 to 14 in the periodic table in such a ratio, the effect of being a carbon-metal composite can be more fully exhibited. The proportion of the metal atoms belonging to Groups 3 to 14 of the periodic table is more preferably 3 to 35% by mass, and further preferably 5 to 30% by mass with respect to the entire carbon-metal composite.
The ratio of the metal elements of Groups 3 to 14 of the periodic table in the carbon-metal composite can be measured by thermogravimetric analysis (TG).

In the carbon-metal composite of the present invention, the peak area derived from the C—O—C bond in the O1s spectrum obtained by XPS measurement is such that the peak area derived from the C═O bond and the peak area derived from the C—O bond. Preferably it is smaller. As described later, the carbon-metal composite of the present invention is preferably produced by mixing and reducing a carbon material having carbon bonded to oxygen with a metal compound. By reducing the carbon material bonded to oxygen, C—O—C bonds, C═O bonds, and C—O in the structure of the carbon material are reduced, but the carbon-metal composite of the present invention. Is the one in which the area of the peak derived from C—O—C bond in the XPS measurement is smaller than the area of the peak derived from C═O bond and the peak derived from C—O bond, that is, C—O—. It is preferable that the C bond is relatively more sufficiently reduced than the C═O bond or the C—O bond. When the carbon-metal composite is such, it exhibits more excellent characteristics as an electrode active material.
In the O1s spectrum obtained by the XPS measurement, a peak derived from a C—O—C bond is observed in the vicinity of 532 eV, and a peak derived from a C═O bond and a peak derived from a C—O bond are in the vicinity of 531 eV, respectively. Observed around 5 eV.

In the carbon-metal composite of the present invention, the ratio of the total peak area of the O1s region and the total peak area of the C1s region obtained by XPS measurement is preferably 1/20 to 1/1. When the ratio of these peak areas is within such a range, the carbon-metal composite exhibits more excellent characteristics as an electrode active material. The ratio of the total peak area of the O1s region and the total peak area of the C1s region is more preferably 1/10 to 1 / 1.2, more preferably 1/5 to 1 / 1.5, Particularly preferably, it is 1/40 to 1 / 1.8.
Here, the total peak area of the O1s region is the sum of the areas of all peaks observed in the O1s region, and is the sum of the areas of all peaks that are at least twice as high as the noise width of the baseline. It is. The same applies to the total peak area of the C1s region.

The carbon-metal composite of the present invention has a peak area derived from a C—O bond in a C1s spectrum obtained by XPS measurement and a peak area derived from a bond between carbon atoms (C—C bond and C═C bond). Is preferably 1/10 to 10/10. When the ratio of these peak areas is within such a range, the carbon-metal composite exhibits more excellent characteristics as an electrode active material. The ratio of the area of the peak derived from the C—O bond and the area of the peak derived from the bond between carbon atoms is more preferably 1/10 to 8/10, and further preferably 2/10 to 8/10. It is.
A peak derived from the C—O bond in the C1s spectrum obtained by XPS measurement is observed near 285 to 287 eV, and a peak derived from the bond between carbon atoms is observed near 284 to 285 eV.
The peak area can be obtained by performing a background correction by the Shirley method and performing peak fitting (peak separation) using a Voigt function as a fitting function.

It is preferable that the carbon-metal composite is a composite of a carbon material and a metal simple substance in the group 3 to 14 of the periodic table or a metal compound having the metal element. In graphene oxide, a peak is observed in a region smaller than 2θ = 26 °, particularly in the vicinity of 2θ = 10 ° in XRD measurement. Therefore, when graphene oxide is used as the carbon material constituting the carbon-metal composite, 2θ = 26. If no peak is observed in a region smaller than °, it can be said that the compound is sufficiently complex. Thus, it is one of the preferred embodiments of the present invention that the carbon-metal composite of the present invention is such that no peak is observed in a region smaller than 2θ = 26 ° in XRD measurement.
Here, the fact that a peak is not observed means that a peak having a height of twice or more the width of the baseline noise is not observed.

It is preferable that the metal elements of Groups 3-14 of the periodic table in the carbon-metal composite of the present invention have a positive valence greater than zero. It is preferable that the metal element has a positive valence greater than zero, that is, in the state of a compound rather than a single metal. More preferably, the compound is a compound having a bond of metal and oxygen. When the carbon-metal composite is such, the carbon-metal composite exhibits more excellent characteristics as an electrode active material. The valence of the metal element depends on the type of metal element and the type of metal compound, but is preferably 1-7. More preferably, it is 2-5.
Moreover, it is preferable that the metal element of the 3-14 group of the periodic table in the carbon-metal composite of this invention is a mononuclear state. By being in a mononuclear state, the carbon-metal composite can exhibit more excellent characteristics as an electrode active material. That the metal element is in a mononuclear state means that the compound containing the metal element is a compound containing only one metal atom in the structure.
Whether the metal element is in a valence or mononuclear state can be confirmed by XAFS measurement.

As described above, the carbon-metal composite of the present invention includes a carbon material having carbon (C) bonded to oxygen (O) and a metal simple substance in the periodic table group 3 to 14 or a metal compound having the metal element. It is preferably a composite, and the carbon material having carbon (C) bonded to oxygen (O) is preferably graphene oxide, as a metal simple substance or a metal compound having the metal element of Group 3-14 of the periodic table Is preferably a compound having a bond of metal and oxygen. That is, it is a preferred form of the carbon-metal composite of the present invention that the carbon-metal composite of the present invention is a composite of graphene oxide and a compound having a bond of metal and oxygen.

The method for producing the carbon-metal composite of the present invention is not particularly limited, but a carbon material having carbon (C) bonded to oxygen (O) and a metal element having a group of 3 to 14 metals or a metal having the metal element. A production method comprising a mixing step of mixing a compound and a reduction step of reducing a mixture of the carbon material and a metal simple substance of Group 3 to 14 of the periodic table or a metal compound having the metal element is preferable. The reduction step may be performed after the mixing step, and the reduction step may be started before the end of the mixing step. In addition, this manufacturing method may include other steps as long as the two steps are included.

Although the amount of the metal simple substance of the periodic table group 3-14 used for the manufacturing method of the said carbon-metal composite_body | complex or the metal compound which has this metal element is not restrict | limited especially as long as a carbon-metal composite_body | complex will be manufactured. It is preferable that it is 0.1-10g with respect to 1g of carbon materials which have carbon couple | bonded with oxygen. By using at such a ratio, the metal element is likely to exist in an amorphous state. More preferably, it is 0.3-5g, More preferably, it is 0.5-3g.

The carbon material used in the method for producing the carbon-metal composite is not particularly limited as long as it has carbon (C) bonded to oxygen (O), but oxygen is added to graphitic carbon materials such as graphene and graphite. Are preferably bonded. More preferably, it is graphene oxide in which oxygen is bonded to a carbon atom of graphene.
When graphene oxide is used as the carbon material, it is preferably obtained by adding an oxidizing agent having a mass of 1 to 10 times the mass of graphite when the graphite is oxidized. More preferably, it is obtained by adding an oxidizing agent having a mass 1 to 5 times the mass of graphite.
Graphene oxide can be produced by adding an oxidizing agent to graphite and oxidizing it, and the amount of oxygen atoms introduced into graphene oxide can be adjusted by changing the amount of the oxidizing agent added. When the metal element used for the production of the carbon-metal composite is a specific element such as Sn, the battery capacity when the carbon-metal composite is used as the electrode active material is the amount of the metal element introduced. In some cases, the battery capacity becomes higher when many metal atoms are introduced. Since the amount of the metal element introduced into the composite is affected by the amount of oxygen contained in the graphene oxide, the carbon-metal composite obtained by adjusting the addition amount of the oxidizing agent depending on the type of the metal element It is possible to adjust the battery capacity when using as an electrode active material.

The same metal elements as those described above are preferred as the metal elements of Groups 3 to 14 of the periodic table used in the method for producing the carbon-metal composite.
Examples of the metal compound having a metal element belonging to Groups 3-14 of the periodic table used in the method for producing a carbon-metal composite include oxides, hydroxides, chlorides, sulfates, nitrates, carbonates of these metal elements, In addition to the organic acid salt, a compound having a structure in which 1 to 4 alkyl groups or alkoxy groups having 1 to 10 carbon atoms are bonded to a metal atom or metal oxide can be used.

In the mixing step, the method for mixing the carbon material having carbon bonded to oxygen and the metal compound having a metal element of Groups 3 to 14 of the periodic table is not particularly limited, and the metal compound is added to the carbon material and stirred. The method can be used. When mixing, if necessary, a solvent may be added and stirred.

The solvent added in the mixing step is not particularly limited as long as the carbon-metal composite is produced. Water, ethanol, DMF, DMSO, ethylene glycol, N-methylpyrrolidone, isopropanol, acetone, methanol, tetrahydrofuran 1 type, or 2 or more types can be used.
Moreover, you may perform the said mixing process, adding an acid as needed. As the acid, hydrochloric acid, sulfuric acid, nitric acid, acetic acid and the like can be used.

The method of reducing the carbon material having a carbon atom bonded to an oxygen atom in the reduction step is not particularly limited as long as the carbon material is reduced, but a method using a reducing agent, heating in an inert gas atmosphere Any one of the method of irradiating and the method of irradiating light is preferable. Any of these may be used, or two or more methods may be used in combination.
In addition, in order to make the reduction reaction proceed efficiently, a solvent is added to the carbon material and the metal compound in the mixing step to prepare a mixed solution of the carbon material and the metal compound, and a thin film is formed with the obtained mixed solution to reduce it. You may perform a process.

The reducing agent is not particularly limited as long as it can reduce the carbon material, but one or two of hydrazine, sodium borohydride, dimethylamine borane, ascorbic acid, oxalic acid, formaldehyde, acetaldehyde and the like. The above can be used.
The reducing agent is preferably used at a ratio of 0.1 to 10 g with respect to 1 g of the carbon material having carbon atoms bonded to oxygen atoms. More preferably, it is used at a ratio of 0.5 to 5 g with respect to 1 g of the carbon material.

When reducing using the above reducing agent, heating and / or stirring may be performed as necessary in order to sufficiently proceed the reduction reaction after adding the reducing agent.
Although the temperature and time in the case of heating can be suitably set according to the kind of reducing agent, etc., it is preferable that heating temperature is 20-200 degreeC. More preferably, it is 40-100 degreeC. The heating time is preferably 10 to 600 minutes. More preferably, it is 30 to 180 minutes.

When a method of heating in an inert gas atmosphere is used as a method for reducing the carbon material, the heating temperature is not particularly limited as long as the carbon material is reduced, but is preferably 100 to 500 ° C. More preferably, it is 200-400 degreeC.
Moreover, it does not restrict | limit especially as an inert gas, Any inert gas, such as nitrogen, helium, and argon, may be used.

When using the method of irradiating light as a method of reducing the carbon material, the light to be irradiated is not particularly limited, but it is preferable to irradiate light of large energy. Among light irradiations, it is preferable to use a light source that can irradiate light of large energy in a short time because a complex in which a carbon material and a metal compound are sufficiently complexed can be efficiently produced. As such a light source, for example, a camera strobe capable of producing 300 to 20000 kW of light with a small amount of power is suitable.

As described above, the carbon-metal composite of the present invention can exhibit excellent performance when used as an electrode active material, and can be suitably used as a material for an electrode active material. Such an electrode active material containing the carbon-metal composite of the present invention is also one of the present invention, and an electrode configured using the electrode active material of the present invention, and using the electrode A battery configured as described above is also one aspect of the present invention.
The type of battery configured using the electrode active material of the present invention is not particularly limited. However, since graphite is currently used as the negative electrode active material in many lithium ion secondary batteries, The use of the carbon-metal composite of the present invention as a negative electrode active material of a lithium ion secondary battery is one of the preferred embodiments of the present invention, and the carbon-metal composite of the present invention is used as a negative electrode active material for a lithium ion secondary battery. A lithium ion secondary battery used as a substance is also one aspect of the present invention.

Although the manufacturing method of the electrode of the present invention is not particularly limited, a method of forming an electrode mixture containing a carbon-metal composite and a binder on a current collector is preferable.
Examples of the binder include poly (meth) acrylate-containing polymers, polyvinyl alcohol-containing polymers, cellulose, cellulose acetate, hydroxyalkyl cellulose, carboxymethyl cellulose, polyvinylidene fluoride-containing polymers, polypentafluoroethylene-containing polymers, and polymaleates. -Containing polymer, polyitaconate-containing polymer, ion exchange membrane polymer, sulfonate-containing polymer, quaternary ammonium salt-containing polymer, quaternary phosphonium salt polymer and the like.
As the current collector, an aluminum current collector, a copper foil, or the like can be used.

As the electrolytic solution constituting the battery of the present invention, those commonly used as the electrolytic solution of the battery can be used, and are not particularly limited. For example, the organic solvent-based electrolytic solution includes ethylene carbonate, propylene carbonate, dimethyl carbonate. , Diethyl carbonate, ethyl methyl carbonate, γ-butyrolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, dimethoxymethane, diethoxymethane, acetonitrile, dimethyl sulfoxide, sulfolane, fluorine group-containing carbonate, fluorine group-containing ether An ionic liquid, a gel compound-containing electrolytic solution, a polymer-containing electrolytic solution, and the like are preferable. Examples of the aqueous electrolytic solution include a potassium hydroxide aqueous solution, a sodium hydroxide aqueous solution, and a lithium hydroxide aqueous solution. You may use 1 type, or 2 or more types of said electrolyte solution. An inorganic solid electrolyte may be used.
When the battery of the present invention is a lithium ion secondary battery, the electrolytes include LiPF ₆ , LiBF ₄ , LiClO ₄ , LiN (SO ₂ F) ₂ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C _{2). F 5) 2, Li (BC} 4 O 8), LiF, LiB (CN) 4 and the like.

The separator constituting the battery of the present invention is not particularly limited, but polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, cellulose, cellulose acetate, hydroxyalkyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, cellophane, polystyrene, poly High molecular weight polymers having micropores such as acrylonitrile, polyacrylamide, polyvinyl chloride, polyamide, vinylon, poly (meth) acrylic acid, copolymers thereof, gel compounds, ion-exchange membrane polymers, copolymers thereof, rings Polymers, their copolymers, poly (meth) acrylate-containing polymers and their copolymers, sulfonate-containing polymers and their copolymers, quaternary ammonium salt-containing polymers and their copolymers, fourth Grade Phosphonium Salt-containing polymers and their copolymers.

As the active material of the positive electrode constituting the battery of the present invention, an active material corresponding to the type of battery is appropriately selected and used. In the case of a lithium ion secondary battery, lithium cobaltate, lithium manganate, phosphorus Various compounds that function as a positive electrode active material of a lithium ion secondary battery such as lithium iron oxide can be used.

The carbon-metal composite of the present invention has the above-described configuration, and exhibits excellent performance as an active material of an electrode constituting a battery. Various storage batteries, in particular, graphite is currently widely used as a negative electrode active material. It can be used suitably for the negative electrode active material of the lithium ion secondary battery currently used, the negative electrode active material of a sodium ion secondary battery, etc.

4 is a diagram showing a TEM observation result of the Si / rGO composite (1) manufactured in Example 1. FIG. FIG. 1b is an observation result observed at a higher magnification than in FIG. 1a. FIG. 3 is a diagram showing the XRD measurement results of the Si / rGO composite (1) produced in Example 1. The graph also includes graphene oxide used as a raw material for the composite and XRD measurement results of graphene oxide reduced with hydrazine. It is a diagram showing an XRD measurement result of Fe / rGO composites prepared in Comparative Example 1 (Comparative 1) (1 mmol use FeSO ₄ · 7H ₂ O). TEM observation result (FIG. 4a) of the Fe / rGO composite (Comparative 1) manufactured in Comparative Example 1 (using 1 mmol of FeSO ₄ .7H ₂ O), the Fe / rGO composite manufactured in Comparative Example 2 (Comparative 2) TEM observation result (FIG. 4 b) of FE observation (using 5 mmol of FeSO ₄ .7H ₂ O), TEM observation result of Fe / rGO complex (Comparative 3) manufactured in Comparative Example 3 (using 10 mmol of FeSO ₄ .7H ₂ O) It is the figure which showed (FIG. 4c). It is the figure which showed the XPS measurement result (O1s area | region spectrum (narrow scan, peak-separated)) of the Fe / rGO composite body manufactured by the comparative example 2 (comparative 2). It is the figure which showed the XPS measurement result (The spectrum (narrow scan, peak separation completed) of C1s area | region) of the Fe / rGO composite body (comparative 2) manufactured by the comparative example 2. It is the figure which showed the XPS measurement result (The spectrum (narrow scan, peak separation completed) of O1s area | region) of the Fe / rGO composite (2) manufactured in Example 2. FIG. It is the figure which showed the XPS measurement result (C1s area | region spectrum (narrow scan, peak-separated)) of the Fe / rGO composite (2) manufactured in Example 2. FIG. It is the figure which showed the XPS measurement result (The spectrum (narrow scan, peak separation completed) of O1s area | region) of the Fe / rGO composite (3) manufactured in Example 3. It is the figure which showed the XPS measurement result (The spectrum (narrow scan, peak separation completed) of the C1s area | region) of the Fe / rGO composite (3) manufactured in Example 3. In the Fe / rGO composite (2) produced in Example 2, the Fe / rGO composite (3) produced in Example 3, the Fe / rGO composite produced in Comparative Example 5 (Comparative 5), and Comparative Example 2 It is the figure which showed the XRD measurement result of the manufactured Fe / rGO composite (Comparative 2) and the carbon material (Comparative 6) manufactured by the comparative example 6. Fe / rGO composite (2) produced in Example 2, Fe / rGO composite (3) produced in Example 3, Fe / rGO composite produced in Comparative Example 5 (Comparative 5), and Comparative Example Fig. 12 shows the XPS measurement result (C1s region spectrum) of the Fe / rGO composite (Comparative 2) produced in Fig. 2 (Fig. 12a) and Fig. 12 shows the XPS measurement result (O1s region spectrum). is there. TEM observation result (FIG. 13a) of the Fe / rGO composite (Comparative 2) produced in Comparative Example 2, TEM observation result (FIG. 13b) of the Fe / rGO composite (Comparative 5) produced in Comparative Example 5, Example 2 shows a TEM observation result (FIG. 13 c) of the Fe / rGO composite (2) manufactured in FIG. 2 and a TEM observation result (FIG. 13 d) of the Fe / rGO composite (3) manufactured in Example 3. is there. Fe / rGO composite (2) produced in Example 2, Fe / rGO composite (3) produced in Example 3, Fe / rGO composite produced in Comparative Example 2 (Comparative 2), and Comparative Example 5 is a graph showing the results of evaluating the charge / discharge characteristics of the Fe / rGO composite (Comparative 5) manufactured in FIG. Fe / rGO composite (2) produced in Example 2, Fe / rGO composite (3) produced in Example 3, Fe / rGO composite produced in Comparative Example 2 (Comparative 2), and Comparative Example 6 is a graph showing the results of evaluating the charge / discharge characteristics of the carbon material (Comparative 6) manufactured in FIG. XRD of Fe / rGO complex (4) produced in Example 4, Fe / rGO complex produced in Comparative Example 7 (Comparative 7), and Fe / rGO complex produced in Comparative Example 2 (Comparative 2) It is the figure which showed the measurement result. TEM observation result (FIG. 17a) of the Fe / rGO composite (Comparative 8) produced in Comparative Example 8, TEM observation result (FIG. 17b) of the Fe / rGO composite (Comparative 7) produced in Comparative Example 7, Example TEM observation result (FIG. 17c) of the Fe / rGO composite (4) produced in FIG. 4 and TEM observation result (HAADF-STEM image) of the Fe / rGO composite (4) produced in Example 4 (FIG. 17d) ). Fe / rGO composite produced in Comparative Example 7 (Comparative 7), Fe / rGO composite produced in Comparative Example 8 (Comparative 8), Fe / rGO composite produced in Example 4 (4), and two valent FeSO _4, trivalent _α-Fe 2 _{O 3} and _γ-Fe 2 _{O 3} of XAFS measurement results (FIG. 18a), and a diagram showing the EXAFS spectrum analysis results (Figure 18b).

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by weight” and “%” means “mass%”.

Various measurements in the examples were performed with the following apparatuses.
<XRD measurement>
Measurement was performed with an X-ray diffractometer Rigaku RINT2000 (manufactured by Rigaku Corporation).
<XPS measurement>
Measured with AXIS-ULTRA DLD (manufactured by Shimadzu Crates).
In addition, the analysis of measurement data used XPS analysis software Common Date Processing System (COMPRO) version11.
<XAFS measurement>
Measured with PF-XAFS BL-9C.
<Electron microscope (TEM) photography>
It measured with the transmission electron microscope JEOLJEM-2100F (made by JEOL Ltd.).
<Electron microscope (STEM) photography>
The measurement was performed with a scanning transmission electron microscope JEOL2100F (manufactured by JEOL Ltd.).
<Charge / discharge test>
It measured with HOKUTO HJ1001SD8 charging / discharging apparatus (made by Hokuto Denko).
<Thermogravimetry (TG)>
It was measured with Rigaku TG8120 (manufactured by Rigaku Corporation).

Synthesis Example 1 (Production of graphene oxide (GO) dispersion (1))
A 1 L beaker placed in a water bath was charged with 300 ml of concentrated sulfuric acid and 12 g of scaly graphite (Z-5F manufactured by Ito Graphite Industries) and stirred with a stirring blade. 36 g of KMnO ₄ was gradually added while cooling around the beaker with ice, then the temperature was raised to 35 ° C. and stirring was continued at 35 ° C. for 2 hours. Thereafter, 300 ml of water was slowly added while cooling the beaker around with ice. Subsequently, 18 ml of hydrogen peroxide having a concentration of 30% (w / v) was added and stirred at 20 ° C. for 30 minutes. After completion of the stirring, the liquid in the beaker was divided into four centrifuge bottles (500 ml), centrifuged, and the supernatant was removed to obtain a precipitate. The operation of putting water into the centrifuge bottle in which the precipitate remains, dispersing the precipitate by stirring and shaking, and then performing centrifugation again is repeated 10 times until the pH reaches about 4 to obtain a carbon raw material (graphene oxide). A dispersion (1) dispersed in water was obtained.

Synthesis Example 2 (Production of graphene oxide (GO) dispersion (2))
A 1 L beaker placed in a water bath was charged with 300 ml of concentrated sulfuric acid and 12 g of scaly graphite (Z-5F manufactured by Ito Graphite Industries) and stirred with a stirring blade. 60 g of KMnO 4 was gradually added while cooling the beaker with ice, and then the temperature was raised to 35 ° C. and stirring was continued at 35 ° C. for 2 hours. Thereafter, 300 ml of water was slowly added while cooling the beaker around with ice. Subsequently, 30 ml of 30% (w / v) hydrogen peroxide solution was added and stirred at 20 ° C. for 30 minutes. After completion of the stirring, the liquid in the beaker was divided into four centrifuge bottles (500 ml), centrifuged, and the supernatant was removed to obtain a precipitate. The operation of putting water into the centrifuge bottle in which the precipitate remains, dispersing the precipitate by stirring and shaking, and then performing centrifugation again is repeated 10 times until the pH reaches about 4 to obtain a carbon raw material (graphene oxide). Dispersion (2) dispersed in water was obtained.

Example 1 (Production of Si / rGO composite (1))
Dispersion (1) obtained in Synthesis Example 1 containing a carbon raw material equivalent to 0.4 g was dispersed in 53 mL of ethanol, and further 25 mg of (C ₁₆ H ₃₃ ) N (CH ₃ ) ₃ Br (CTAB) and 16 mL of water , 6 mL of Si (OC ₂ H ₅ ) ₄ (TEOS) was added and stirred at room temperature for 4 hours. Thereafter, ₂ mL of H ₂ NNH ₂ (hydrazine) was added and stirred at 85 ° C. for 4 hours. Centrifugation was performed and the supernatant was removed to obtain a precipitate. The operation of washing the precipitate with water and obtaining the precipitate again by centrifugation was repeated three times, and the resulting precipitate was dried under reduced pressure at 50 ° C. overnight. The dried product was pulverized with a mortar to obtain a composite (1). From the TG measurement, it was estimated that the composite (1) contained silicon. In the TEM observation (FIGS. 1a and 1b), many amorphous particles were observed. From this, it was considered that amorphous SiO ₂ particles were generated. When the composite (1) was evaluated by XRD measurement, no peak attributed to a simple substance of silicon or a compound containing silicon was observed in XRD (FIG. 2). From this, it was confirmed that silicon was contained in an amorphous state.

Comparative Examples 1 to 4 (Production of Fe / rGO composites (Comparative 1 to 4) (hydrazine reduction))
Four types of sample mixed solutions obtained by adding 1, 5, 10, 20 mmol of the dispersion (1) obtained in Synthesis Example 1 containing 1 g of carbon raw material in 100 mL of water and FeSO ₄ .7H ₂ O, respectively. Created. These sample mixtures were stirred at room temperature for 2 hours in air. Thereafter, each sample mixture was centrifuged and the supernatant was removed to obtain a precipitate. The operation of washing the precipitate with water and obtaining the precipitate again by centrifugation was repeated three times. The obtained precipitate was dispersed in 100 mL of water, 1 mL of hydrazine was added, and the mixture was heated and stirred at 90 ° C. for 2 hours. Then, after repeating centrifugation and washing three times, the sample was collected by suction filtration, dried by vacuum lyophilization, and pulverized in a mortar to obtain composites (Comparative 1) to (Comparative 4). XRD was used to identify the metal oxide produced in the composite (Comparative 1) obtained from the sample mixture added with 1 mmol of FeSO ₄ · 7H ₂ O, and 1, 5 and 10 mmol of FeSO ₄ · 7H ₂ O were added. The shape and particle size of the produced particles in the composites (Comparative 1) to (Comparative 3) obtained from the sample mixture were analyzed using TEM.
As a result of XRD measurement (FIG. 3), it was found that the product of a 1 mmol sample was γ-Fe ₂ O ₃ . As a result of TEM observation (FIGS. 4a to 4c), in the samples of 1 mmol and 5 mmol, fine particles of several nm and particles of about 50 nm were mixed, and some of them were considerably aggregated. On the other hand, in the 10 mmol sample, acicular particles were uniformly dispersed.
In XRD, a peak derived from γ-Fe ₂ O ₃ was confirmed in all of the composites (Comparative 1) to (Comparative 4), and the crystallite diameter calculated from the peak by the Scherrer equation was all 1 nm or more. Therefore, it was confirmed that Fe ₂ O ₃ was not in an amorphous state in these samples.
FIG. 5 shows a spectrum (narrow scan, peak-separated) of the O1s region of the complex (Comparative 2) obtained by XPS measurement, and FIG. 6 shows a spectrum (narrow scan, peak-separated) of the C1s region. 5 and 6, the ratio of the total peak area of the O1s region to the total peak area of the C1s region in the XPS spectrum of the composite (Comparative 2) is 0.222 (1 / 4.50), The ratio of the peak area derived from the C—O bond to the peak area derived from the bond between carbon atoms was 0.407 (4.07 / 10). In the XPS spectrum of the composite (Comparative 2), the ratio between the total peak area of the Fe2p region and the total peak area of the O1s region and the C1s region was 0.040 (1 / 25.00).

Example 2 (Production of Fe / rGO composite (2) (heat reduction))
Dispersion (1) obtained in Synthesis Example 1 containing 1 g of carbon raw material was dispersed in 100 ml of water, 5 mmol of iron sulfate (FeSO ₄ · 7H ₂ O) was further added, and the mixture was stirred at room temperature for 2 hours. Thereafter, centrifugation was performed, and the supernatant was removed to obtain a precipitate. The operation of washing the precipitate with water and centrifuging it was repeated three times. The obtained paste-like precipitate was freeze-dried and then pulverized in a mortar. An alumina boat containing 0.5 g of the crushed sample is placed in a firing furnace, heated to 300 ° C. at a rate of 5 ° C./min in a nitrogen atmosphere, and after the temperature reaches 300 ° C., the temperature is kept as it is. The baking treatment was performed by holding for 1 hour. After the baking treatment, the sample was taken out after the temperature in the furnace reached room temperature, and pulverized in a mortar to obtain a composite (2). As a result of TG measurement, the iron content of the composite (2) was 9.4 wt% (13.4 wt% as Fe ₂ O ₃ ). The spectrum (narrow scan, peak separated) of the O1s region of the complex (2) obtained by XPS measurement is shown in FIG. 7, and the spectrum (narrow scan, peak separated) of the C1s region is shown in FIG. 7 and 8, the ratio of the total peak area of the O1s region to the total peak area of the C1s region in the XPS spectrum of the composite (2) is 0.448 (1 / 2.23), and the C1s spectrum C The ratio of the area of the peak derived from the —O bond and the area of the peak derived from the bond between carbon atoms was 0.450 (4.50 / 10). In the XPS spectrum of the composite (2), the ratio between the total peak area of the Fe2p region and the total peak area of the O1s region and the C1s region was 0.122 (1 / 8.20).

Example 3 (Production of Fe / rGO complex (3) (photoreduction))
Dispersion (1) obtained in Synthesis Example 1 containing 1 g of carbon raw material was dispersed in 100 ml of water, 5 mmol of iron sulfate (FeSO ₄ · 7H ₂ O) was further added, and the mixture was stirred at room temperature for 2 hours. Thereafter, centrifugation was performed, and the supernatant was removed to obtain a precipitate. The operation of washing this precipitate with water and centrifuging it was repeated three times, and the obtained paste-like precipitate was applied onto an aluminum foil using a doctor blade (100 mm). After air drying, the coated part was cut to an area of 1.5 × 5 cm. The cut coating film was irradiated with light using a camera strobe (MINOLTA PROGRAM 4000AF). After light irradiation, the sample was peeled off from the aluminum foil, collected, and pulverized in a mortar to obtain a composite (3). As a result of TG measurement, the iron content of the composite (3) was 9.5 wt% (13.6 wt% as Fe ₂ O ₃ ). The spectrum (narrow scan, peak separated) of the O1s region of the complex (3) obtained by XPS measurement is shown in FIG. 9, and the spectrum (narrow scan, peak separated) of the C1s region is shown in FIG. 9 and 10, the ratio of the total peak area of the O1s region to the total peak area of the C1s region in the XPS spectrum of the composite (3) is 0.389 (1 / 2.57), and the C1s spectrum C The ratio of the peak area derived from the —O bond and the peak area derived from the bond between carbon atoms was 0.630 (6.30 / 10). In the XPS spectrum of the composite (3), the ratio of the total peak area of the Fe2p region to the total peak area of the O1s region and the C1s region was 0.094 (1 / 10.64).

Comparative Example 5 (Production of Fe / rGO Composite (Comparative 5) (NaBH ₄ Reduction))
Dispersion (1) obtained in Synthesis Example 1 containing 1 g of carbon raw material was dispersed in 100 ml of water, 5 mmol of iron sulfate (FeSO ₄ · 7H ₂ O) was further added, and the mixture was stirred at room temperature for 2 hours. Thereafter, centrifugation was performed, and the supernatant was removed to obtain a precipitate. The operation of washing this precipitate with water and centrifuging it was repeated three times. The obtained precipitate was dispersed in 100 mL of water, and NaCO ₃ was added with stirring to adjust the pH to 9-10. Subsequently, 800 mg of NaBH ₄ was added and stirred with heating at 80 ° C. for 2 hours. Thereafter, centrifugation and washing were repeated three times, and then the sample was collected by suction filtration, dried by vacuum lyophilization, and pulverized in a mortar to obtain a composite (Comparative 5).

Comparative Example 6 (Production of carbon material (Comparative 6) (hydrazine reduction))
Dispersion (1) obtained in Synthesis Example 1 containing 1 g of carbon raw material was dispersed in 100 ml of water, 1 ml of hydrazine was added, and the mixture was heated and stirred at 90 ° C. for 2 hours. Thereafter, centrifugation and washing with water were repeated three times, and then the sample was collected by suction filtration, dried by vacuum lyophilization, and pulverized in a mortar to obtain a carbon material (Comparative 6). As a result of the XPS measurement, the ratio of the peak area derived from the C—O bond in the C1s spectrum to the peak area derived from the bond between carbon atoms in the XPS spectrum of the carbon material (Comparative 6) was 0.776 (7.76). / 10).

The composites (2), (3), and (Comparative 5) were evaluated by XRD, XPS, and TEM measurements. For comparison, the same measurement was also performed on the composite (Comparative 2) (obtained by hydrazine reduction of a sample mixed solution to which 5 mmol of FeSO ₄ · 7H ₂ O was added).
As a result of XRD measurement (FIG. 11), in the case of hydrazine reduction, γ-Fe ₂ O ₃ crystals were confirmed, but no iron oxide-based crystals were confirmed in other samples. In the NaBH ₄ reduced sample, a peak was detected in the vicinity of 2θ = 10 °. This is considered to be a peak derived from graphene oxide. From the XPS measurement results (FIG. 12), the NaBH ₄ reduced sample has a peak considered to be C—O around 286.6 eV of Cls and a peak considered to be C—O—C around 532 eV in the O1s region. It is thought that the reduction of graphene has not progressed sufficiently. On the other hand, the hydrazine-reduced sample has few peaks that are considered to be C—O and C═O (near 288 ev) even in the Cls region, and the entire peak is small in the O1s region and is well reduced. I understood. In thermal reduction and photoreduction, the peak considered to be C—O—C (near 532.5 eV) is significantly reduced in the O1s region, the peak considered to be C═O (near 531.5 eV), and the peak considered to be C—O. (533.5 eV) remained significantly. These reduction methods clearly differed from the hydrazine reduction, suggesting the possibility of selectively reducing C—O—C.
In the particle morphology observation by TEM (FIGS. 13a-d), particles were not confirmed in the thermally reduced sample (FIG. 13c), but the hydrazine reduced sample (FIG. 13a), the NaBH ₄ reduced sample (FIG. 13b), and the photoreduced sample (FIG. 13). The presence of particles was confirmed in 13d). The heat-reduced sample and the photoreduced sample had small particles uniformly scattered over a wide area compared to the hydrazine-reduced sample.
From the results of XRD measurement, the peak derived from γ-Fe ₂ O ₃ as in the case of hydrazine reduction is confirmed in the method of photoreduction by irradiating a strobe for a camera at 300 ° C. under N ₂ atmosphere. In addition, since no peak attributed to iron alone or other compounds containing iron was observed, it was confirmed that iron was in an amorphous state. In the reduction with NaBH _4, no peak derived from γ-Fe ₂ O ₃ was confirmed, and it was confirmed that iron was in an amorphous state.

Charge / Discharge Characteristic Evaluation Samples obtained in Examples 2 and 3 and Comparative Examples 5 and 6 were used as active materials to form a half cell, and a charge / discharge test was performed. The charge / discharge test was also performed on the hydrazine reduction sample of Comparative Example 2. The half cell fabrication method and the charge / discharge test method are as follows.
The result of the charging / discharging test implemented with the following method is shown in FIG.14 and FIG.15. 15 shows, Examples 2 and 3, the sample of Comparative Example 2 showed the results of a charge-discharge test of the Fe ₂ O ₃ complexed with non carbon material of Comparative Example 6 (Comparative 6). The photoreduction and thermal reduction samples in which iron was in an amorphous state exhibited good battery capacity and cycle characteristics. On the other hand, the hydrazine reduction and NaBH ₄ reduction samples resulted in low electric capacity. As for the cycle characteristics, the photoreduced sample had the largest capacity.
<Half cell manufacturing method>
About 100-150 mg of active material (composite sample) is weighed, 0.1-0.5 ml of 1-methyl-2-pyrrolidoneone (NMP, SIGMA-ALDRICH) is added, and a mixer (Awatori Nertaro, AR-100, (Sinky Co., Ltd.) pasted in polyvinylidene fluoride resin (PVDF, KF POLYMER # 9130, Kureha Co., Ltd.), weighed so that the active material: PVDF was 9: 1, and mixed with a mixer A paste was obtained. This paste was spread on a copper foil spread on a glass plate with a doctor blade (100 mm) and dried under reduced pressure at room temperature for 2 to 3 days. The dried body was punched with a 16 mmφ punch and pressed with a roll press to obtain an electrode. After measuring the weight of the electrode, the electrode was placed in the positive electrode can of the coin cell 2032, put in a Schlenk tube, and dried under reduced pressure at 120 ° C. overnight. While keeping the inside of the Schlenk tube in a vacuum, the tube was placed in a glove box under an argon atmosphere. In the glove box, the positive electrode can containing the electrode is taken out from the Schlenk tube, lithium foil is used as the counter electrode, glass fiber filter (257 nm, Whatman) is used as the separator, and 1M-LiPF _{6 is} used as the electrolyte (solvent is EC: DMC = 1: 1). ) Was used to assemble a coin cell. This was placed in the atmosphere at 25 ° C. overnight to form a measurement cell.
<Method of charge / discharge test>
The charge / discharge measurement was performed using a HOKUTO HJ1001SD8 charge / discharge device (manufactured by Hokuto Denko) at a constant current of 100 mA / g, the cut-off voltage was 0.01-3 V, and the rest time was 2 hours. Evaluation was performed in a 25 ° C. desiccator under the atmosphere.

Example 4 (Production of Fe / rGO Complex (4) (Photoreduction))
Dispersion (2) obtained in Synthesis Example 2 containing 1 g of carbon raw material was dispersed in 100 ml of water, and 10 mmol of iron sulfate (FeSO ₄ · 7H ₂ O) was further added, followed by stirring at room temperature for 2 hours. Thereafter, centrifugation was performed, and the supernatant was removed to obtain a precipitate. The operation of washing this precipitate with water and centrifuging it was repeated three times, and the obtained paste-like precipitate was applied onto an aluminum foil using a doctor blade (100 mm). After air drying, the coated part was cut to an area of 5 × 8 cm. The cut coating film was irradiated with light using a strobe light for stage illumination (ST-3000 DMX (PS LASER)). After light irradiation, the sample was peeled off from the aluminum foil, collected, and pulverized in a mortar to obtain a composite (4). As a result of TG measurement, the iron content of the composite (4) was 16.0 wt% (22.9 wt% as Fe ₂ O ₃ ).

Comparative Example 7 (Production of Fe / rGO complex (Comparative 7) (hydrazine reduction))
Dispersion (2) obtained in Synthesis Example 2 containing 1 g of carbon raw material was dispersed in 100 ml of water, and 10 mmol of iron sulfate (FeSO ₄ · 7H ₂ O) was further added, followed by stirring at room temperature for 2 hours. Thereafter, centrifugation was performed, and the supernatant was removed to obtain a precipitate. The operation of washing this precipitate with water and centrifuging it was repeated three times. The obtained precipitate was dispersed in 100 ml of water, 1 ml of hydrazine was added, and the mixture was heated and stirred at 90 ° C. for 2 hours. Thereafter, centrifugation and washing were repeated three times, and then the sample was collected by suction filtration, dried by vacuum lyophilization, and pulverized in a mortar to obtain a composite (Comparative 7). As a result of TG measurement, the iron content of the composite (Comparative 7) was 9.5 wt% (13.6 wt% as Fe 2 O 3).

Comparative Example 8 (Production of Fe / rGO composite (Comparative 8) (no reduction treatment))
Dispersion (2) obtained in Synthesis Example 2 containing 1 g of carbon raw material was dispersed in 100 ml of water, and 10 mmol of iron sulfate (FeSO ₄ · 7H ₂ O) was further added, followed by stirring at room temperature for 2 hours. Thereafter, centrifugation was performed, and the supernatant was removed to obtain a precipitate. The operation of washing this precipitate with water and centrifuging it was repeated three times, and the resulting precipitate was dried by vacuum lyophilization and pulverized in a mortar to obtain a composite (Comparative 8).

The composites (4), (Comparative 7), and (Comparative 8) were analyzed using XRD, TEM, STEM, and XAFS.
As a result of the XRD measurement (FIG. 16), in the complex (4), only broad peaks are detected around 2θ = 24 ° and 43 °, and no iron oxide peak as in hydrazine reduction appears, Since no peaks attributed to iron alone or other compounds containing iron were observed, it was confirmed that iron was in an amorphous state. When performing the hydrazine reduction, complex (Comparison 2) In the _gamma-Fe 2 _{O 3} generated by the complex (Comparison 7) In the _alpha-Fe 2 _{O 3} was produced. Since the crystallite diameter calculated by the Scherrer equation from the α-Fe ₂ O ₃ peak of the composite (Comparative 7) was 1 nm or more, in this sample, Fe ₂ O ₃ was not in an amorphous state. It was confirmed. In the complex (Comparative 7), unknown peaks were detected at 2θ = 13 ° and around 20 °. In TEM observation (FIGS. 17a-d), no particles were first observed in the unreduced complex (Comparative 8) (FIG. 17a), and it is considered that iron oxide particles are not formed before reduction. It was.
In the composite (4) (FIG. 17c), it was observed that the dim round particles were scattered. This was different from the particle morphology of the hydrazine reduced sample (FIG. 17b) and from the particle morphology of the complex (3) photoreduced with a camera strobe (FIG. 13d). In the HAADF-STEM image (FIG. 17d), it is observed that a large amount of Fe is dispersed, and some exist as 5-10 nm particles, but many exist in a state that cannot be observed by TEM. I found out. Therefore, the presence state of Fe was analyzed by XAFS (FIGS. 18a and b). Comparing the value of the absorption edge E0 of the XANES spectrum (FIG. 18 a) with divalent FeSO ₄ , trivalent α-Fe ₂ O ₃ and γ-Fe ₂ O ₃ , the valence is 3 for both the photoreduced sample and the hydrazine sample. I found out that it was worth. In addition, since the order coordination is not seen in the second coordination sphere of the EXAFS spectrum (FIG. 18 b) after the Fourier transform processing of the complex (4) as compared with α-Fe ₂ O ₃ and γ-Fe ₂ O ₃ . In the complex (4), Fe was not present in the second coordination sphere, and it was confirmed that Fe was in a mononuclear state.
From these measurement results, it was confirmed that the Fe / rGO composite produced by photoreduction is in an amorphous state.

Claims (9)

A carbon-metal composite containing carbon, oxygen, and a metal element as constituent elements,
The carbon-metal composite has carbon bonded to oxygen,
A carbon-metal composite comprising a group 3-14 metal element in the periodic table in an amorphous state. The carbon-metal composite according to claim 1, wherein the carbon-metal composite contains a metal element belonging to groups 3 to 14 of the periodic table in a ratio of 1 to 40 mass% with respect to the entire carbon-metal composite. Metal composite. The carbon-metal composite has a ratio of the total peak area of the O1s region and the total peak area of the C1s region obtained by XPS measurement to 1/20 to 1/1. A carbon-metal composite as described in 1. In the carbon-metal composite, the ratio of the peak area derived from the C—O bond in the C1s spectrum obtained by XPS measurement to the peak area derived from the bond between carbon atoms is 1/10 to 10/10. The carbon-metal composite according to any one of claims 1 to 3. 5. The metal element of Groups 3 to 14 of the periodic table is any one of V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo, and W. A carbon-metal composite as described in 1. The carbon-metal composite according to any one of claims 1 to 5, wherein the metal element of groups 3 to 14 of the periodic table in the carbon-metal composite has a positive valence greater than zero. body. The carbon-metal composite according to any one of claims 1 to 6, wherein the metal element of groups 3 to 14 of the periodic table in the carbon-metal composite is in a mononuclear state. An electrode active material comprising the carbon-metal composite according to claim 1. A battery comprising the electrode active material according to claim 8.