JP3131408B2 - Carbon body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates also relates to a carbon material, more particularly, can be used in the nonaqueous secondary battery carbons
About the body .

[0002]

2. Description of the Related Art With the miniaturization and power saving of electronic devices,
A secondary battery using an alkali metal such as lithium has attracted attention. When an alkali metal such as lithium is used alone for the negative electrode, repetition of charge and discharge generates dendrites on the metal, which causes a short circuit inside the battery. It has been found that when an alkali metal alloy is used for a negative electrode for a secondary battery instead of an alkali metal, the generation of dendrite is suppressed as compared with a simple substance. However, even if an alloy is used, dendrite does not completely stop being generated, and a short path inside the battery may occur. In recent years, the anode has been used to dissolve metals such as alkali metals and alloys.
Instead of using a precipitation reaction or a dissolution / precipitation / diffusion reaction in a solid, organic materials such as carbon and conductive polymers using an absorption / release reaction of an alkali metal ion have been developed.
As a result, the generation of dendrite, which occurs when an alkali metal or alloy is used, hardly occurs, and the problem of a short circuit inside the battery has been drastically reduced.

[0003] Since carbon is chemically stable and can be doped with both an electron donating substance and an electron donating substance, it is a promising material as an electrode, particularly as a battery electrode.

[0004] Carbon is basically composed of a layered structure part, SP
^It consists of an amorphous part containing ^three hybrid orbitals,
There are many types of carbon ranging from graphitizable carbon to non-graphitizable carbon depending on the arrangement or ratio of these. There are many methods for producing many types of carbon having such different microstructures. The main production methods for carbonization include solid-phase carbonization, liquid-phase carbonization, and gas-phase carbonization. In solid-phase carbonization, that is, carbonization using a solid organic compound as a starting material, wood, resins such as furan resin and phenol resin, celluloses, and high molecular compounds such as PAN, pitch and rayon are used. I have. In liquid phase carbonization, liquid substances such as pitches and tars are well known. In the gas-phase carbonization, various hydrocarbon gases can be used as starting materials, but the main ones are methane, propane, and benzene.

[0005] The main carbon that can be produced by carbonization from the gas phase is pyrolytic carbon. Soot is generated via polynuclear aromatic radicals formed by the decomposition and bonding of raw materials in the gas phase. It is considered that pyrolytic carbon is generated by depositing on a substrate installed in a reaction tube via an aromatic polynuclear radical or an aromatic radical, similarly to the generation of soot. In the production of pyrolytic carbon, when a metal or a metal oxide is used for a substrate, some of them exhibit different deposition behavior. For example, if Ti, Zn, Ta is used for the substrate,
The substrate itself reacts with the carbon to form carbides, on which carbon is deposited. When nickel, cobalt and iron are used, they act as catalysts for carbon deposition,
Carbon is deposited from a low temperature of 300 to 500 ° C.

[0006]

The absorption and emission of an electron-donating substance and an electron-accepting substance with respect to carbon are mainly caused by intercalation and intercalation between the above-mentioned substances in a layered structure existing in carbon. Is believed to be happening by. Therefore, when using carbon as an electrode capable of absorbing and emitting an electron-donating substance and an electron-accepting substance, a substance having a large number of layered structure parts existing in carbon, and further, having a good orientation You need to choose carbon.

However, in the solid-phase carbonization, for example, when a woody material or a phenol resin is used, the carbon produced is subjected to the shape in the solid as a starting material as it is, and becomes carbon having many amorphous portions. There is an inconvenience.
In liquid-phase carbonization, droplets composed of aromatic polynuclears called mesophases are generated during carbonization, and are repeatedly grown and coalesced to become carbonized. Although carbon having more layered structure parts is generated than carbon to be formed, the orientation is not good.

On the other hand, in the case of gas phase carbonization, if a substrate is placed in a reaction tube, carbon is deposited on the substrate, and pyrolytic carbon having a large number of layered structure portions and good orientation is generated. Although it can be used as an excellent electrode, it tends to peel off when the film thickness is increased, and there is a problem in strength.

In view of the above, the present invention provides a carbon electrode having good adhesion between a substrate and a carbon body, high strength as an electrode, and having a large number of layered structures in the carbon body, and a method for producing the same. The purpose is to:

[0010]

SUMMARY OF THE INVENTION The present invention provides a carbon material used for an electrode of a non-aqueous secondary battery , in the presence of a metal which combines with carbon to form a carbide or a solid solution with carbon. Provided is a carbon body obtained by calcining a solid or liquid organic compound.

More specifically, the carbon body is a metal
A carbon body characterized by including a layered structure obtained by the interaction with the carbonaceous material.

[0012] The metal is porous.
I do. A metal that can be used is a single metal that forms a solid solution with carbide or carbon , or an alloy containing these metals. For example, as a single metal, titanium, tungsten, tantalum, zirconium, chromium,
There are niobium, molybdenum, vanadium, iron, cobalt, nickel and the like. In addition, as alloys, there are binary (Ni-Cu, etc.), ternary, and multi-element alloys containing one or more of these. In particular, a simple substance of nickel, cobalt, or iron, an alloy thereof, or an alloy containing at least one of them is suitable. What can be used as a metal oxide is an oxide containing the above-mentioned metal as a component and a composite oxide containing one or more of these components. In particular, an oxide composed of nickel, cobalt or iron, a composite oxide thereof, or a composite oxide composed of one or more of these and another metal oxide is suitable.

The organic compound which can be used is a solid or a liquid, and can be used in various forms such as a paste or a solution , and may be a mixture of aliphatic compounds, alicyclic compounds, aromatic compounds and hetero compounds. Organic compounds containing heteroatoms such as ring compounds, polymer compounds such as resins , carboxylic acids and
And its dielectric and pitch .

The optimum mixing ratio of the metal powder or the mixture of the metal powder and the metal oxide powder to the organic compound varies depending on the particle size of the metal powder and the type of the organic compound. In consideration of the strength of the electrode body obtained by the above and the amount of carbon after firing, it is preferable that the volume ratio be between 1: 9 and 9: 1. As a method of firing this mixture, a method of heating and decomposing at a temperature of 300 ° C. or more in a non-acidic atmosphere (for example, under reduced pressure and an inert gas atmosphere) to carbonize can be used.

The electrodes manufactured by the above-described method may be, for example, a metal powder or a sintered body of a metal powder and a carbon body depending on the mixing ratio of the metal powder or the like and the organic compound, the type thereof, or other manufacturing conditions. And various types of electrodes such as an electrode in which a carbon body is bonded to a porous metal body made of a sintered body of a metal powder, or a mixed electrode in which the mixture is mixed. Then, in the electrode of any form, the interface between the metal body and the carbon body a compound or solid solution of the metal and the carbon constituting the metal body is formed <br/>.

[0016]

[0017]

[0018] Incidentally, the porous metal substrate is formed of a single metal or alloy described above, the following method as a method. First, a method of mechanically piercing a metal substrate, a method of sintering using one or more of the above metal powders or fibers, and a method of electrolessly or electrolytically plating a sponge-like polymer are used. A method of producing a foamed metal body by burning, a method of forming a dispersed plating film by subjecting dispersed particles to electroless or electrolytic plating using one or more of the above-described metals to form a dispersed plating film, and the like.

By the compound or solid solution of metal and carbon,
In particular, a carbon body having a large number of layered structures can be formed by a simple substance of nickel, cobalt, or iron, an alloy thereof, or an alloy containing at least one of them. This carbon body can absorb and release an electron donating substance and an electron donating substance. The interpretation of this is not clear, but the following may be considered. In the process of carbonizing the organic compound, if there is no metal, the organic compound is decomposed and combined to generate carbon. When a metal that combines with carbon to form a carbide or forms a solid solution is used as a substrate, the metal interacts with the metal when the organic compound is decomposed and combined. That is, carbon formed by the decomposition or combination of the organic compound interacts with the metal to form a compound or a solid solution. Thereafter, when the limit of carbon dissolution is exceeded, carbon precipitates on the compound or solid solution. In this case, especially when nickel, cobalt, or iron is used,
A dissolution-precipitation process in which the compounded carbon is precipitated is performed. Through this process, it is thought to become the high carbon bodies having more layered structure portion is completed.

When a metal oxide is used, oxygen, which is a constituent part of the oxide, is combined with carbon, sulfur, nitrogen or the like which is a constituent part of an organic compound, so that carbon dioxide, carbon monoxide or sulfur oxide, It becomes gas such as nitrogen and diffuses. It is believed that this reduces the metal oxide to a metal and acts as described above.

According to the electrode of the present invention comprising a mixture of a metal body and a carbon body, the metal body contributes to improving the conductivity of the electrode, and a compound or solid solution with carbon at the interface forms a bond between the metal body and the carbon body. And a form suitable for forming an electrode having a carbon body as described above using a solid or liquid organic compound.

In the electrode using the porous metal substrate,
Furthermore, the strength of the electrode itself, conductive both larger ing.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to examples.

Example 1 A mixture of 200 mesh nickel powder and carboxymethyl cellulose in a volume ratio of 1 to 1 was pressed into a pellet, and was heated to 900 ° C. at a heating rate of 20 ° C./hour in an argon atmosphere. The firing was performed by increasing the temperature and maintaining the temperature at 900 ° C. for 10 hours. The pellet thus formed had a diameter of 1.5 cm, a thickness of 3 mm, and a carbon content of 6.3 mg.

FIG. 1 shows a schematic view of a cross section of the pellet. The nickel powder forms a sintered body 1, and a layer 3 made of a solid solution of nickel and carbon or a compound Ni ₃ C is formed at an interface between the sintered body 1 and the carbon body 2,
It has a structure having. Note that the formation of the sintered body 1 increases the strength of the pellet and facilitates use as an electrode body.

Table 1 shows the characteristics when the pellets were used as electrodes. The pellet was dried under reduced pressure at 200 ° C. for 10 hours, and then subjected to charge / discharge measurement. The measurement was performed by a triode method. Charge / discharge was performed using propylene carbonate containing Li / Li ^{+ for the} reference electrode and 1 M LiClO ₄ for the electrolyte, setting the discharge end voltage to 0 V and the charge end voltage to 2 V.

Example 2 A mixture of 200 mesh cobalt powder and naphthalene in a volume ratio of 1: 2 was pressed into pellets, which were heated to 900 ° C. at a rate of 20 ° C./hour in an argon atmosphere. Then, firing was performed by maintaining the temperature at 900 ° C. for 10 hours. The pellets obtained at this time are 1.5 cm in diameter and 4 in thickness.
mm, and the carbon content was 2.6 mg.

FIG. 2 shows a schematic sectional view of the pellet.
The cobalt powder forms a sintered body 1, and a layer 33 of a solid solution of cobalt and carbon is formed at an interface between the sintered body 1 and the carbon body 2, and has a structure having many holes 4. still,
The number of holes 4 in the sintered body 1 is smaller than in the first embodiment.

Table 1 shows the characteristics when the pellets were used as electrodes. The measuring method is the same as in Example 1.

Example 3 A 200-mesh nickel powder was mixed with a powdery phenol resin and a resole resin to form a paste, which was then mixed at a rate of 20 ° C./hour in an argon atmosphere. The temperature was raised to 900 ° C., and the firing was performed by maintaining the temperature at 900 ° C. for 10 hours. The resulting product had an apparent surface area of 3.3 cm ² , a thickness of 2 mm, and a carbon content of 7.6 m.
g.

FIG. 3 is a schematic cross-sectional view. It has the same structure as the pellet of the first embodiment.

Table 1 shows the characteristics when the same measurement as in Example 1 was carried out using this as an electrode.

Projection Example 4 A mixture of a 200-mesh nickel powder and a 150-mesh copper powder, an epoxy resin and a curing agent polyamide resin were mixed and cured, and the mixture was cured under argon atmosphere for 20 minutes.
The calcination was performed by maintaining the temperature at 900 ° C. for 10 hours at a rate of temperature rise of 10 ° C./hour. The resulting product had an apparent surface area of 2.8 cm ² , a thickness of 4 mm, and a carbon content of 5.3 mg.

FIG. 4 shows a schematic cross-sectional view of this. The nickel powder and the copper powder partially form an alloy, and form a sintered body 1. At the interface between the sintered body 1 and the carbon body 2, a nickel-copper alloy or a solid solution or a compound of nickel and carbon is formed. Ni
A layer 3 of ₃ C is formed, and has a structure having many holes 4.

Table 1 shows the characteristics when this was used as an electrode and the same measurement as in Example 1 was performed.

Example 5 A mixture of 5 parts by weight of 200 mesh nickel powder and 1 part of iron (III) oxide and a mixture of carboxymethylcellulose at a volume ratio of 1: 2 were pelletized under an argon atmosphere. The temperature was raised to 900 ° C. at a rate of 20 ° C./hour, and the firing was performed by maintaining the temperature at 900 ° C. for 10 hours. The resulting pellet had a diameter of 1.5 cm, a thickness of 3 mm, and a carbon content of 5.4 mg.

FIG. 5 is a schematic sectional view of this embodiment. The nickel powder and the iron oxide powder partially form an alloy and form a sintered body 1. An interface between the sintered body 1 and the carbon body 2 is formed of nickel, iron or a nickel-iron alloy and carbon. A layer 3 of a solid solution, compounds Fe ₃ C and Ni ₃ C is formed, and has a structure having many holes 4. Further, iron oxide is reduced in the firing process to become iron. When another metal oxide powder is used, it is reduced by firing to become a metal.

Table 1 shows the characteristics when this was used as an electrode and the same measurement as in Example 1 was performed.

Example 6 A mixture of 200 mesh nickel powder and a powdered phenol resin and resole resin which were made into a paste was mixed at a heating rate of 20 ° C./hour in an argon atmosphere at 900 ° C. The temperature was raised to 900C and the firing was performed by maintaining the temperature at 900C for 10 hours. This calcined product has an apparent surface area of 1.8 cm ² , a thickness of 0.75 mm, and a carbon content of 39.4 mg.
Met.

FIG. 6 shows a schematic sectional view of this. It has the same structure as the pellet of the first embodiment, but the carbon body 2 occupies more than the sintered body 1.

Table 1 shows the characteristics when the same measurement as in Example 1 was performed using this as an electrode.

Comparative Example 1 A phenol resin was heated to 900 ° C. at a rate of 20 ° C./hour in an argon atmosphere, and calcined at 900 ° C. for 10 hours. From this, 5.7 mg was taken. Table 1 shows the characteristics when the same measurement as in Example 1 was performed. In addition, in order to collect electricity, the measurement was carried out by sandwiching between nickel meshes.

[0043]

[Table 1]

EXAMPLE 7 50 mg of carboxymethylcellulose was immersed in a foamed nickel substrate (apparent surface area: 1.5 cm ² , thickness: 5 mm) having a porosity of about 95% at a rate of 20 ° C./hour in an argon atmosphere. The temperature is raised to 900 ° C at a rate of 900
Calcination was performed by maintaining at 10 ° C. for 10 hours. At this time,
The obtained carbon was 4.2 mg.

FIG. 7 shows a schematic sectional view of this. The carbon body 2 is bonded to the surface of the foamed nickel substrate 11, and a layer 3 made of a solid solution or a compound of nickel and carbon is formed at the interface between them.

Table 2 shows the characteristics when this was used as an electrode and the same measurement as in Example 1 was performed.

Example 8 A Watts bath (NiSO _{4.
7H 2 O 300g / l, NiC1} 2 · 6H 2 O 45g
/ L, with H ₃ BO ₃ 35g / l, the bath temperature 60 ° C.),
The nickel porous body (apparent surface area 4 cm ² , thickness 2 mm) incorporating the cobalt particles was impregnated several times with an aqueous solution of polyacrylic acid. This is heated at 20 ° C. in an argon atmosphere.
The temperature is raised to 900 ° C at a heating rate of
The calcination was performed by keeping 0 hours. The carbon obtained at this time was 1.3 mg.

Table 2 shows the characteristics when this was used as an electrode and the same measurement as in Example 7 was performed.

Example 9 A mixture of a phenol resin and a resole resin (liquid phenol resin) was applied to a substrate (apparent surface area: 2 cm ² , thickness: 5 mm) obtained by sintering nickel powder and having a porosity of about 50%. Then, in an argon atmosphere, the temperature was raised to 900 ° C. at a rate of 20 ° C./hour, and the temperature was maintained at 900 ° C. for 10 hours, thereby firing. The carbon obtained at this time is 1
1.5 mg.

Table 2 shows the characteristics when this was used as an electrode and the same measurement as in Example 7 was performed.

Specific Softening Example 2 The phenol resin was heated to 900 ° C. at a heating rate of 20 ° C./hour in an argon atmosphere, and calcined at 900 ° C. for 10 hours. From this, 10 mg was taken in particular.

Table 2 shows the characteristics when the same measurement as in Example 7 was performed. In addition, in order to collect electricity, the measurement was carried out by sandwiching between nickel meshes.

[0053]

[Table 2]

[0054]

According to the present invention, there is provided an electrode which is excellent in strength and can absorb and discharge a large amount of an electron donating substance and an electron accepting substance.

According to the manufacturing method of the present invention, the electrode of the present invention can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a first embodiment of the electrode of the present invention.

FIG. 2 is a schematic sectional view showing a second embodiment of the electrode of the present invention.

FIG. 3 is a schematic sectional view showing a third embodiment of the electrode of the present invention.

FIG. 4 is a schematic sectional view showing a fourth embodiment of the electrode of the present invention.

FIG. 5 is a schematic sectional view showing a fifth embodiment of the electrode of the present invention.

FIG. 6 is a schematic sectional view showing a sixth embodiment of the electrode of the present invention.

FIG. 7 is a schematic sectional view showing a seventh embodiment of the electrode of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sintered body 2 Carbon body 3 Solid solution or compound layer 4 Void 11 Foamed nickel substrate 33 Solid solution layer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01M 4/00-4/04

Claims (3)

(57) [Claims] 1. A carbon material used for an electrode of a non-aqueous secondary battery, wherein a solid or liquid organic compound is calcined in the presence of a metal which combines with carbon to form a carbide or a solid solution with carbon. A carbon body characterized in that it is obtained by: 2. The method according to claim 1, wherein the carbon body interacts with the metal.
The carbon body according to claim 1 , further comprising a layered structure obtained by the method . 3. The carbon body according to claim 1, wherein the metal is a porous body.