JP2676173B2 - Carbon electrode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a carbon electrode, and more specifically to a carbon electrode containing a large number of layered structure parts and improved to have sufficient strength as an electrode.

[0002]

2. Description of the Related Art With the miniaturization and power saving of electronic devices,
Secondary batteries using alkali metals such as lithium are drawing attention. By the way, in the case of using an alkali metal such as lithium alone in the negative electrode, charge / discharge is repeated, that is, the dissolution-precipitation process of the alkali metal causes the formation of dendrites (resin-like crystals) on the dissolution-precipitation surface of the metal, grow up.
This dendrite has a problem that it causes a short circuit inside the battery by penetrating the separator and coming into contact with the positive electrode.

It has been found that when an alkali metal alloy is used for the secondary battery negative electrode instead of the alkali metal, the generation of dendrites is suppressed and the charge / discharge cycle characteristics are improved as compared with the case of a single substance. However, the use of the alloy does not completely prevent the generation of dendrite, and may cause a short circuit inside the battery.

A negative electrode made of an alkali metal or its alloy is
It utilizes the dissolution-precipitation process or dissolution-precipitation-diffusion process in solids of these metals, but in recent years,
As a negative electrode, an organic material such as carbon or a conductive polymer utilizing an absorption-desorption process of alkali metal ions has been developed.
As a result, the generation of dendrites that occurred when an alkali metal or its alloy was used did not occur in principle, and the problem of short circuit inside the battery was drastically reduced.

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

[0006] Carbon is basically composed of a layered structure portion having a graphite structure and an amorphous portion different from the graphite structure such as a structure including sp ³ hybrid orbitals or a defect structure in which layers are distorted. Carbon can also be changed from easily graphitizable carbon to non-graphitizable carbon depending on the macro or micro arrangement, the ratio of these, the structural difference of the amorphous parts, and the ratio of impurities such as oxygen and sulfur. There are many types of carbon, up to carbon.

There are many methods for producing various carbons having different microstructures or macrostructures.

The method for producing carbon is classified according to the state of the starting material. They are solid-phase carbonization, liquid-phase carbonization, and gas-phase carbonization.

Solid-phase carbonization is carbonization using a solid as a starting material as a carbon source, and includes wood, resins such as furan resin and phenol resin, celluloses, PAN, pitch,
A polymer compound such as rayon is used as a starting material.

Liquid-phase carbonization is a method of producing carbon by firing using a liquid substance such as pitch or tar.

The vapor-phase carbonization is a method of producing carbon in the vapor phase or a method of depositing carbon on a substrate using various hydrocarbon gases as starting materials.

The main carbons that can be produced by gas phase carbonization are soot and pyrolytic carbon. In soot, raw materials decompose and combine in the gas phase to form aromatic polynuclear radicals, and these combine and combine.
It is generated by gathering. Pyrolytic carbon is, as with the formation of soot, those deposited via aromatic polynuclear radicals or aromatic radicals on a substrate placed in a reaction tube. When a metal is used as a substrate in the production of pyrolytic carbon, the deposition behavior may be different from the others.
For example, when titanium, tungsten, tantalum, or the like is used as the base, the base metal and carbon react with each other to generate a carbide, and carbon is deposited thereon. Also, nickel,
When cobalt or iron is used, it acts as a catalyst in carbon deposition, and it is recognized that carbon deposits at a low temperature of 300 to 500 ° C.

[0013]

The absorption and release of the electron-donating substance and the electron-accepting substance with respect to carbon is carried out by intercalation and deintercalation of the substance between the layers in the layered structure portion mainly present in carbon. Is happening by Therefore, when carbon is used as an electrode capable of absorbing and releasing an electron-donating substance or an electron-accepting substance, a substance having a large number of layered structure portions existing in carbon and having a good orientation It is necessary to select carbon.

However, in the above solid-phase carbonization, for example, if a wood material or a phenol resin is used,
The carbon produced has the disadvantage that the form in the solid, which is the starting material, is inherited as it is, resulting in carbon having a large amount of amorphous portions.

Further, in the above liquid-phase carbonization, a droplet called an mesophase, which is composed of an aromatic polynuclear body, is generated during the carbonization, and the droplets grow and coalesce to become larger, thereby repeating the carbonization. Therefore, compared with the carbon generated by solid-phase carbonization, carbon with more layered structure is generated, but on the other hand, it has a drawback that the orientation is not good.

In vapor-phase carbonization, if a substrate is placed in the reaction tube, carbon is deposited on the substrate, and as a result, pyrolytic carbon having many layered structure portions and good orientation is produced. As a result, an excellent electrode can be obtained. However, on the other hand, when the film thickness is increased, there is a problem in strength that the film is easily peeled off.

The present invention has been made to solve the above-mentioned problems, and includes many layered structure portions,
Moreover, it aims at providing the carbon electrode improved so that it might have sufficient strength as an electrode.

[0018]

A carbon electrode according to the present invention relates to a battery electrode which utilizes intercalation / deintercalation between layers of a carbon material. The carbon electrode is a composite of metal and carbon, and the metal is selected from the metals that interact with carbon in the process of carbonization of an organic compound.

In the above-mentioned carbon electrode manufacturing method, first, a composite plating film is formed on a substrate from a plating bath containing organic compound powder as dispersed particles. The composite plating film is peeled off from the substrate. The composite plating film is fired.

Organic compound powders that can be preferably used in the present invention are aliphatic compounds, alicyclic compounds, aromatic compounds, heterocyclic compounds, high molecular compounds such as resins, carboxylic acids and their derivatives, pitch and the like. In particular, resins such as furan resin and phenol resin, celluloses, PA
Organic polymer compounds such as N, pitch and rayon are preferably used.

As the metal obtained by plating, chromium, manganese, copper, silver, gold, iron, cobalt, nickel and the like and alloys containing these are preferably used. In particular, iron, nickel, and cobalt are preferable, or those containing iron, nickel, and cobalt as the main components are particularly preferable.

In electrolytic plating, chromium plating bath, manganese plating bath, copper plating bath, silver plating bath, gold plating bath, iron plating bath, cobalt plating bath, nickel plating bath and Co-Mn, Co-Mo, Co-Ni , Co-W,
Cu-Ni, Fe-Cr, Fe-Mn, Fe-Ni, F
e-Ni-Cr, Fe-W, Ni-Cr, Ni-Mo,
A plating bath such as Ni-W is preferably used.

In electroless plating, a copper plating bath, a silver plating bath, a gold plating bath, an acidic / neutral / basic nickel plating bath, a cobalt plating bath, a Ni-Co plating bath, a Ni-Fe plating bath, Ni-X-P plating baths, iron plating baths, and modified plating baths and other plating baths are used.

The method of baking the plating film is performed in a non-oxidizing atmosphere (for example, under reduced pressure or in an inert gas atmosphere).
The method of heating at a temperature of 300 ° C. or higher, decomposing, and carbonizing is preferably adopted.

In another method for producing the above carbon electrode,
An organic polymer foam or nonwoven fabric having a three-dimensional network structure is coated with a metal, thereby forming a composite of the organic polymer foam and the metal. The composite is fired.

As a method for coating a metal, vapor deposition, sputtering, electroless plating or the like is preferably adopted. In particular, electroless plating is preferable because it is easy to use in manufacturing.

As the metal to be coated, titanium, tungsten, chromium, niobium, molybdenum, vanadium, iron, cobalt, nickel and the like and alloys containing these are preferably used. Particularly, iron, nickel and cobalt alone or as a main component. Those containing iron, nickel and cobalt are preferable.

For electroless plating, acidic, neutral and basic nickel plating baths, cobalt plating baths, Ni-Co plating baths, Ni-Fe plating baths, Ni-X-P plating baths, iron plating baths, and these An improved plating bath or other plating bath is preferably used, which enables coating of an organic polymer foam or nonwoven fabric having a three-dimensional network structure.

As a method for firing a composite made of an organic polymer foam or a non-woven fabric having a three-dimensional network structure coated with a metal, a non-oxidizing atmosphere (for example, under reduced pressure,
Heating in an inert gas atmosphere) at a temperature of 300 ° C or higher,
A method of decomposing and carbonizing is preferably used.

In still another method for producing the above carbon electrode, a solid organic compound formed by coating a metal is molded to form a composite of the metal and the solid organic compound. The composite is fired.

Solid organic compounds which can be used in the present invention are aliphatic compounds, alicyclic compounds, aromatic compounds, heterocyclic compounds, polymer compounds such as resins, carboxylic acids and their derivatives, pitch and the like. In particular, resins such as furan resin and phenol resin, celluloses, organic polymer compounds such as PAN, pitch and rayon are preferably used.

As a method for coating the metal, there are vapor deposition, sputtering, electroless plating and the like. In particular, electroless plating is preferably used because it is easy to use in manufacturing.

As the metal to be coated, titanium, tungsten, chromium, niobium, molybdenum, vanadium, iron, cobalt, nickel and the like and alloys containing these are preferably used. In particular, iron, nickel, and cobalt are preferable, or those containing iron, nickel, and cobalt as the main components are preferable.

In electroless plating, acidic / neutral / basic nickel plating baths, cobalt plating baths, Ni--Co
A plating bath, a Ni-Fe plating bath, a Ni-X-P plating bath, an iron plating bath, and a plating bath improved from these and other plating baths are preferably used, whereby an organic compound can be coated with a metal. .

As a method for firing the molded composite,
A method of heating at a temperature of 300 ° C. or higher in a non-oxidizing atmosphere (for example, under reduced pressure, in an inert gas atmosphere) to decompose and carbonize is adopted.

[0036]

According to the carbon electrode of the present invention, since the metal and carbon are compounded, the electrode has excellent electrode strength. Moreover, since the metal is selected from the metals that interact with carbon in the process of carbonization of the organic compound, it becomes a carbon body with many layered structures. As a result, the conductivity of the electrode is improved.

According to the above method for producing a carbon electrode, a dispersed plating film formed by using a metal as a matrix and dispersing organic compound powder as dispersed particles therein is fired. According to this method, a composite electrode of metal and carbon containing a carbon body having many layered structure portions can be obtained. As for the interpretation of this, although the details are not clear, the following may be considered. In the process of carbonizing an organic compound, if no metal is present, the organic compound decomposes and bonds to form carbon. On the other hand, in the process of carbonizing an organic compound, when a metal is present, that is, when a metal forming a solid solution, particularly a metal containing iron, nickel, or cobalt as a main component, is used, the decomposition and bonding of the organic compound , Carbon interacts with metals. It is considered that due to this interaction, a carbon body having many layered structure portions is formed during carbon deposition.

Further, the dispersion plating film obtained by carrying out dispersion plating with the organic compound powder as dispersed particles has a form in which the dispersed particles are taken into the inside thereof, and therefore this itself is electrically conductive. Have sex. By firing this, the metal is sintered and the carbon and the metal body are bonded to each other. As a result, it is possible to ensure the improvement of the conductivity of the carbon electrode and the increase of the strength of the electrode itself.

According to another method of manufacturing the carbon electrode, a composite made of an organic polymer foam or non-woven fabric having a three-dimensional network structure coated with a metal is fired. According to this method, a composite electrode of metal and carbon containing a carbon body having many layered structure portions can be obtained. As for the interpretation of this, although the details are not clear, the following may be considered. In the process of carbonization of an organic polymer, when a metal is not present, the organic polymer decomposes into a low molecular weight organic compound such as hydrogen, carbon monoxide, or methane, or the polymer dissociates into a lower molecular weight, Further, the remaining carbon and heteroatoms combine to form a carbon body. On the other hand, when a metal that binds to carbon to form a compound or forms a solid solution is used, carbon interacts with the metal when the organic polymer is decomposed into low molecular weight molecules and when carbon is bound. . It is considered that this interaction produces a carbon body having many layered structure portions at the time of carbon generation.

By coating an organic polymer foam or nonwoven fabric having a three-dimensional network structure with a metal, a three-dimensional network structure of metal is formed. This metal three-dimensional network structure itself has conductivity. When this is fired, the coating metal is sintered and carbon and metal are bonded. As a result, a carbon electrode having improved conductivity and increased strength of the electrode itself can be obtained.

According to still another method for producing the above-mentioned carbon electrode, a solid organic compound coated with a metal is molded and then fired. According to this method, a composite electrode of metal and carbon containing a carbon body having many layered structure portions can be obtained. The interpretation of this is not clear, but the following may be considered.

In the process of carbonizing an organic compound, if no metal is present, the organic compound decomposes and bonds to form carbon. On the other hand, when a metal that bonds with carbon to form a compound or forms a solid solution is used, the carbon and the metal interact with each other when the organic compound is decomposed and bonded. It is considered that due to this interaction, a carbon body having many layered structure portions is formed during carbon deposition.

Further, according to this method, since the solid organic compound coated with metal is sintered, carbon and metal are bound to each other during sintering of the metal, and a carbon electrode having improved conductivity can be obtained. . Further, as a result of the carbon and the metal body being bonded, the strength of the carbon electrode itself is increased.

[0044]

Hereinafter, the present invention will be described with reference to examples.
The present invention is not limited to this.

Example 1 5 g / l of dispersed particles of powdered phenolic resin were added to a Watts bath which is an electrolytic nickel plating bath, and nickel was used as an electrode to carry out dispersion plating at a current density of 5 mA / cm ^2. It was Peel the composite thus created from the electrode,
In an argon atmosphere, this was heated to 900 ° C. at a heating rate of 20 ° C./hour, and kept at 900 ° C. for 10 hours to be fired. The carbon electrode thus produced had a carbon amount of 7.3 mg and a metal amount of 34.5 mg. Table 1 shows the characteristics when the pellet was used as an electrode. The pellet was dried under reduced pressure at 200 ° C. for 10 hours and then subjected to charge / discharge measurement. A three-pole method was used for charge / discharge measurement. Li / Li ⁺ was used as the reference electrode, propylene carbonate containing 1 M LiClO ₄ was used as the electrolytic solution, and the charge end potential was set to 0 V and the discharge end potential was set to 2 V to perform charge / discharge.

Example 2 20 g / l of powdery phenol resin dispersed particles were added to a neutral nickel sulfate bath which is an electroless nickel plating bath, and dispersion plating was performed on a nickel substrate. The composite thus produced was peeled off from the nickel substrate and fired in the same manner as in Example 1. The carbon content of the resulting electrode was 9.
The amount was 2 mg and the amount of metal was 20.3 mg. Table 1 shows the characteristics when the pellet is used as an electrode. The measuring method was the same as in Example 1.

Example 3 Prior to electroless nickel plating on a urethane foam resin, the resin was degreased with alcohol, treated with a solvent, etched,
Palladium catalyzed treatment was applied. The electroless nickel plating was performed using a neutral nickel sulfate bath. The plating reaction was carried out by incorporating it in the resin. The composite thus formed is molded into pellets, heated to 900 ° C. at a heating rate of 20 ° C./hour in an argon atmosphere,
It was fired by keeping it at 900 ° C. for 10 hours. The carbon amount of the produced carbon electrode was 25.2 mg and the amount of metal was 20.3 mg. The characteristics when this pellet is used as an electrode are shown in Table 1.
Shown in The pellet was dried under reduced pressure at 200 ° C. for 10 hours and then subjected to charge / discharge measurement. The charging / discharging measurement method is the same as in the first embodiment.

Example 4 Prior to electroless nickel-cobalt plating on linear polyester, pretreatment was carried out in the same manner as in Example 3, and plating was performed using a sulfuric acid bath. This was fired in the same manner as in Example 3. The carbon content of the electrode is 1
The amount was 0.3 mg and the amount of metal was 9.7 mg. Table 1 shows the characteristics when the pellet is used as an electrode. The charging / discharging measurement method is the same as in the first embodiment.

Example 5 A powdered phenolic resin was subjected to alcohol degreasing, solvent treatment, etching and palladium catalyzed treatment prior to electroless nickel plating. For electroless nickel plating, a neutral nickel sulfate bath was used. The plating reaction was performed while stirring the bath. The composite thus formed is molded into pellets, heated to 900 ° C. at a heating rate of 20 ° C./hour in an argon atmosphere,
It was fired by keeping it at 900 ° C. for 10 hours. The carbon amount of the produced carbon electrode was 11.5 mg, and the metal amount was 7.9 mg.
Met. Table 1 shows the characteristics when this pellet is used as an electrode.
Shown in The pellet was dried under reduced pressure at 200 ° C. for 10 hours and then subjected to charge / discharge measurement. The measuring method is the same as in the first embodiment.

Example 6 Prior to electroless nickel-cobalt plating of a powdery phenolic resin, the resin was pretreated in the same manner as in Example 5 and plated with a sulfate bath.
This was fired in the same manner as in Example 5. The carbon amount of the produced carbon electrode was 13.2 mg and the amount of metal was 21.4 mg. Table 1 shows the characteristics when the pellet is used as an electrode. The measuring method is the same as in the first embodiment.

Example 7 A polyester cloth was pretreated in the same manner as in Example 5 and nickel-plated using a neutral nickel sulfate bath. This was fired in the same manner as in Example 5. The carbon amount of the produced carbon electrode was 5.8 mg and the metal amount was 7.6 mg. Table 1 shows the characteristics when this is used as an electrode. The measuring method is the same as in Example 1.

Comparative Example A phenol resin was fired in an argon atmosphere at a heating rate of 20 ° C./hour up to 900 ° C. and kept at 900 ° C. for 10 hours. From this, 10.3 mg was taken and formed into pellets. Table 1 shows the characteristics when the pellet is used as an electrode. The measuring method is the same as in the first embodiment. In addition, in order to collect the current, the measurement was performed by sandwiching it between nickel meshes.

[0053]

[0054]

As described above, the carbon electrode according to the present invention is composed of a composite of metal and carbon, so that an electrode having excellent electrode strength can be obtained.
Further, since the metal is selected from the metals that interact with carbon in the process of carbonization of the organic compound, a carbon body having many layered structures can be obtained. As a result, the conductivity of the electrode is improved.

[0055]

Front page continuation (72) Kazuo Yamada, Inventor Kazuo Yamada, 22-22 Nagaike-cho, Abeno-ku, Osaka, Osaka (56) References JP-A-60-97553 (JP, A)

Claims (4)

(57) [Claims] 1. In a battery electrode utilizing intercalation / deintercalation between layers of a carbon material, a metal and carbon are compounded, and the metal is mixed with carbon in the process of carbonization of an organic compound. A carbon electrode characterized by being selected from metals that interact with each other. 2. The carbon electrode according to claim 1, wherein the carbon electrode formed by combining the metal and the carbon is formed by firing a composite of the metal and the organic material. 3. The metal is chromium, manganese, copper, silver,
Gold, iron, cobalt, nickel, titanium, tungsten,
The carbon electrode according to claim 1 or 2, which is one or more kinds of metal selected from niobium, molybdenum and vanadium or an alloy thereof. 4. The carbon electrode according to claim 1, wherein the metal is at least one selected from iron, cobalt and nickel or an alloy thereof.