JP6320700B2 - Metal-carbon fiber composite and production method thereof, and carbon fiber and production method thereof - Google Patents

Description

  The present invention relates to a metal-carbon fiber composite, a method for producing the metal-carbon fiber composite, a carbon fiber, and a method for producing the carbon fiber.

  Conventionally, various researches on carbon materials have been made for the purpose of application to fields such as various gas storage materials, secondary battery electrode materials, electric double layer capacitor materials, and catalyst support materials.

  For example, Patent Document 1 below discloses carbon nanofibers having a high specific surface area obtained by optimizing the catalyst and reaction temperature. And it is described that this carbon nanofiber is expected to be used for a carrier for preparing a high-performance catalyst and an electric double layer capacitor.

  Patent Document 2 below describes a method of growing carbon nanotubes from a catalyst surface serving as a base material by a CVD method.

JP 2006-241651 A US2005 / 0112409A1

  However, the carbon nanofibers of Patent Document 1 and the carbon nanotubes of Patent Document 2 do not have mesopores or macropores in the carbon fibers themselves and need to be connected to the carbon nanofibers and the extraction electrode. Application to electrode materials of secondary batteries such as capacitors has been difficult.

  An object of the present invention is a metal-carbon fiber composite in which a plurality of pores are present in the carbon fiber itself and can be applied to an electrode material, a conductive paste or an electric double layer capacitor material of a secondary battery. To provide a body.

  The metal-carbon fiber composite according to the present invention includes two types of catalytically active materials dispersed in at least one of the first metal having no catalytic activity as a matrix and the surface and the inside of the first metal. A metal composite including the above-described second metal nanoparticle and a carbon fiber having a plurality of pores extending from the nanoparticle.

  In a specific aspect of the metal-carbon fiber composite according to the present invention, the first metal is a metal other than a transition metal of Group 8 to Group 10 of the periodic table.

  In another specific aspect of the metal-carbon fiber composite according to the present invention, the second metal is at least one transition metal belonging to Groups 8 to 10 of the periodic table.

  In the metal-carbon fiber composite according to the present invention, preferably, the first metal is copper.

In the metal-carbon fiber composite according to the present invention, preferably, the second metal is composed of two or more metals selected from the group consisting of iron, cobalt, nickel, or palladium.
The second metal is more preferably made of two or more metals selected from the group consisting of iron, cobalt, nickel or palladium, and more preferably iron and cobalt.

  In the metal-carbon fiber composite according to the present invention, preferably, the second metal is contained in the metal in a proportion of 0.3 to 18% by weight.

  In the metal-carbon fiber composite according to the present invention, preferably, the pores include mesopores or macropores. The diameter of the mesopores or macropores is more preferably 10 nm to 200 nm.

  In the metal-carbon fiber composite according to the present invention, preferably, the pores are present on both the side surface and the cross section of the carbon fiber.

  In the method for producing a metal-carbon fiber composite according to the present invention, the first metal and the second metal nanoparticles dispersed on at least one of the surface and the inside of the first metal are included. Including a step of preparing a metal complex and a step of bringing the nanoparticle into contact with a carbon source under heating.

  In the method for producing a metal-carbon fiber composite according to the present invention, the step of preparing the metal composite is performed by subjecting the first metal and the second metal to a heat treatment.

  In the method for producing a carbon fiber having a plurality of pores according to the present invention, a method of removing the metal composite from the metal-carbon fiber composite with acid or alkali, or a method of classifying the carbon fiber after cutting it by pulverization or the like A step of isolating the metal complex.

  The carbon fiber having a plurality of pores according to the present invention is obtained by a method of removing a metal complex from a metal-carbon fiber complex with an acid or an alkali, or a method of classifying a carbon fiber after being cut by pulverization or the like. It is a carbon fiber obtained by isolating the composite.

  According to the present invention, a metal-carbon fiber composite is obtained in which a plurality of pores are present in the carbon fiber itself.

  According to the method for producing a metal-carbon fiber composite according to the present invention, it is possible to provide a metal-carbon fiber composite in which a plurality of pores are present in the carbon fiber.

It is a figure which shows an example of the temperature profile of the process with which a heat treatment process and a carbon source are made to contact. It is a figure which shows the transmission micrograph of the nanoparticle (iron, cobalt) which precipitated in the metal complex, 1 is an electron micrograph of a metal-carbon fiber composite material obtained in Example 1. FIG. It is a figure which shows the electron micrograph of the enlarged view of the metal-carbon fiber composite material obtained in Example 1. FIG. It is a figure which shows the electron micrograph of the metal-carbon fiber composite material obtained in Example 2. FIG. It is a figure which shows the electron micrograph of the metal-carbon fiber composite material obtained in Example 3. FIG. It is a figure which shows the electron micrograph of the metal-carbon fiber composite material obtained in Example 4. FIG. It is a figure which shows the electron micrograph of the metal-carbon fiber composite material obtained in Example 5. FIG. It is a figure which shows the electron micrograph of the metal-carbon fiber composite material obtained in the comparative example 1. It is a figure which shows the electron micrograph of the metal-carbon fiber composite material obtained in the comparative example 2. It is a figure which shows the electron micrograph of the metal-carbon fiber composite material obtained in the comparative example 3.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention.

(Metal-carbon fiber composite)
The metal-carbon fiber composite according to the present invention includes a metal and a plurality of carbon fibers extending from the surface of the metal. The shape of the metal is not particularly limited, and for example, a powder shape, a foil shape, or a linear shape can be used. In the case of powder, the number average particle diameter is preferably 0.5 to 45 μm. The metal is a metal complex including a first metal having no catalytic activity as a matrix and two or more second metals having catalytic activity. The second metal is a nanoparticle dispersed on at least one of the surface and the inside of the first metal. The nanoparticles are preferably dispersed on both the surface and the inside of the first metal or only on the surface. The nanoparticle acts as a catalyst, and the carbon fiber can take a structure extending from the nanoparticle.

  As the first metal, for example, copper, niobium, tantalum, aluminum, silver, chromium, molybdenum, manganese, magnesium, tungsten, gold, or titanium can be used. And it is preferable to use copper or silver, and it is more preferable to use copper.

  Although it does not specifically limit as said 2nd metal, The transition metal of the periodic table group 8-10 used as a catalyst seed | species can be used suitably. Examples of the transition metal of Group 8 to Group 10 of the periodic table include iron, nickel, cobalt, and palladium, and iron or cobalt is preferable. It is preferable to use a combination of iron and cobalt.

  The total content of the second metal with respect to the entire metal composite is preferably 0.03 to 18% by weight, and more preferably 0.1 to 12% by weight. More preferably, it is 0.3-8 weight%. When the content is in the above range, it is preferable because the nanoparticles are likely to precipitate by a simple heat treatment.

  In the present invention, the surface of the metal composite may be etched in order to disperse more nanoparticles on the surface. The area occupied by the nano-particles on the surface of the metal composite is preferably 3 to 50%. If this area is too small, the catalytic reaction is weak, and if it is too large, the nanoparticles may come into contact with each other and become coarse.

  The combination of the first metal and the second metal forming the metal composite is not particularly limited, but copper is used for the first metal and iron or cobalt is used for the second metal. Is preferred. This is because when iron and cobalt are used in combination in a copper matrix, the iron and cobalt are mixed in a self-organized form as nanoparticles in a matrix by heat treatment or the like.

  You may contain a 3rd metal as a structural component of the said metal complex. Examples of such components include silicon, phosphorus, magnesium, aluminum, manganese, niobium, vanadium, zinc, and tin. The third metal can be mixed with the second metal to form nanoparticles, and the catalytic ability of the nanoparticles can be further increased and the generation of pores can be further increased. It is preferable that the third metal is contained in the same proportion as the second metal.

  The carbon fiber extends from the surface of the metal composite. As said carbon fiber, a carbon nanotube, a carbon filament, a carbon nanofilament, a carbon nanocoil can be used, for example. The shape of the cross section of the carbon fiber is not particularly limited, and examples thereof include a circular shape and a rectangular shape, and a rectangular shape is preferable. The carbon fiber may be a single fiber or a fiber bundle composed of a plurality of fibers. The fiber diameter of the single fiber is preferably 5 to 100 nm. Moreover, it is preferable that the fiber diameter of the said fiber bundle is 20-2000 nm.

  In the metal-carbon fiber composite of the present invention, the carbon fiber has a plurality of pores. The presence of the pores is useful because the specific surface area can be increased.

  The pores are not particularly limited, and micropores having a diameter of 2 nm or less (micropores), mesopores having a diameter of 2 nm to 50 nm, and macropores having a diameter of 50 nm or more can be used. Of these, mesopores or macropores are preferable. The mesopores or macropores are preferably contained at a ratio of 50% or more of the entire pores. The pore diameter is preferably 10 to 200 nm. When it exists in the said range, the electrolyte of a secondary battery can adhere easily and can be used suitably. Moreover, it is preferable that the said pore exists not only in the cross section of a fiber but in a side surface. The presence of pores on the side surface can further increase the specific surface area.

  As described above, the metal-carbon fiber composite according to the present invention has a plurality of pores in the carbon fiber. Therefore, the specific surface area is large, and a specific size molecule is easily adhered and adsorbed. Therefore, various gas storage materials, secondary battery electrode materials, conductive pastes, electric double layer capacitor materials, electric wires, thermal conductive sheets, thermal conductive tubes, thermal conductive composite materials, etc. or catalyst support materials, It can be suitably used in a wide range of fields. For example, if linear or foil-like copper is used as the first metal of the metal composite of the metal-carbon fiber composite, an electrode made of mesoporous carbon fiber and the copper wired from the electrode are drawn out. An electrode material used as an electrode can be manufactured. The electrode material is useful because the internal resistance can be reduced. Moreover, since the metal-carbon fiber composite of the present invention has excellent wear resistance and high conductivity, it can be used as a contact material such as a carbon brush or a material for powder metallurgy.

(Method for producing metal-carbon fiber composite)
In the method for producing a metal-carbon fiber composite according to the present invention, first, a catalytically active 2 dispersed in at least one of the first metal serving as a matrix and the surface and the inside of the first metal. Step 1 of preparing a metal composite containing at least two kinds of second metal nanoparticles, and chemical vapor deposition (CVD method) in which a carbon source is brought into contact with the nanoparticles under heating, the metal- And a step 2 of producing a carbon fiber composite.

  As an example of step 1 for preparing the metal composite, first, the second metal is solid-dissolved in the first metal by melting or solution treatment. Next, the second metal, which is a catalyst species, is self-assembled to obtain nanoparticles. The self-assembly can be performed by heat treatment. And although it does not specifically limit as temperature of the said heat processing, It is preferable that it is 300 to 1050 degreeC.

  The heat treatment for obtaining the nano fine particles may be performed immediately before contacting the nano fine particles with the carbon source in Step 2 or may be performed in a separate step. Moreover, when the said metal is a powder form, you may carry out to the first half of the process 2. FIG. Further, in this method, the size of the nano fine particles can be adjusted by controlling the cooling rate.

  Another example of step 1 is a method in which the first metal and the second metal are subjected to a solution treatment, and then nanoparticles are deposited by heat treatment. Moreover, when a metal body is powder, you may produce by the atomizing method which melt | dissolves a 1st metal and a 2nd metal and sprays the obtained liquid, for example. Examples of the atomizing method include a water atomizing method, a gas atomizing method, and a centrifugal atomizing method. The metal body that has been subjected to the solution treatment or the atomization treatment is then subjected to heat treatment at 300 ° C. to 700 ° C. for several minutes to several hundred hours in an oxidation-preventing atmosphere, thereby precipitating nano-particles. Can be dispersed in the metal. The size and density of the nanoparticles can be controlled by the content of the second metal, the heat treatment conditions (temperature, time), and the like.

  The surface of the obtained metal composite may be etched so that more nanoparticles are exposed on the surface of the obtained metal composite. Etching can be carried out, for example, by treating the surface of the metal composite with a nital solution or an ammonium acetate-methanol solution.

  In step 2, the metal-carbon fiber composite is produced by a CVD method in which the nanoparticle is brought into contact with a carbon source under heating. Step 2 can be performed in a reaction vessel. The reaction vessel is not particularly limited as long as the carbon fiber having the pores is obtained. A rotary type, vertical type, fluidized bed type or free-fall type reaction vessel can be used as appropriate.

  The operation of step 2 can be performed by, for example, catalytic chemical vapor deposition (Cat-CVD method). Specifically, after a predetermined amount of the metal composite is filled in the reaction tube, the reaction tube is heated to a predetermined temperature, and a carbon source that is a raw material of carbon fiber is supplied onto the surface of the nanoparticle. The heating temperature is preferably 300 ° C to 900 ° C, more preferably 400 ° C to 800 ° C. More preferably, it is 450 degreeC-750 degreeC. The carbon source may be supplied alone on the catalyst, or may be supplied on the catalyst together with the carrier gas. As such a carrier gas, for example, an inert gas or a reducing gas can be used, or a mixed gas of the reducing gas and the inert gas can be used. It is preferable to use it. More preferably, nitrogen, argon, hydrogen, or helium can be used. These gases can control the linear velocity and concentration of the carbon-containing compound. Note that oxygen gas may be used as long as it is outside the explosion range. Moreover, when supplying on a catalyst independently, it can carry out under pressure reduction with a vacuum pump etc.

  Although it does not specifically limit as a carbon containing compound which is the said carbon source, A C1-C30 compound can be used and it is preferable that it is C1-C7. More preferably, it is C1-C4, More preferably, a C1-C2 compound is used. Further, the hydrocarbon may be aromatic or non-aromatic. In addition, oxygen-containing carbon compounds such as alcohols, ketones, aldehydes, and ethers can be used. Examples of these carbon-containing compounds include methane, ethane, propane, butane, pentane, hexane, heptane, ethylene, propylene, acetylene, benzene, toluene, xylene, cumene, ethylbenzene, diethylbenzene, trimethylbenzene, naphthalene, phenanthrene, anthracene. , Methanol, ethanol, propanol, butanol, acetone, formaldehyde, acetaldehyde, trioxane, dioxane, dimethyl ether, diethyl ether, ethyl acetate, carbon monoxide or a mixture thereof. Among these, a carbon compound selected from methane, ethane, ethylene, acetylene, propane and propylene is preferable in that a carbon nanotube with high purity can be obtained. And since these are gases in normal temperature and a normal pressure, supply amount can be prescribed | regulated as gas and it can use for reaction. On the other hand, when other carbon-containing compounds are reacted at normal pressure, it is necessary to add a process such as vaporization.

  A heat profile as an example of the step 1 and the step 2 is shown in FIG. Here, the steps 1-A and 1-B in the drawing are the step 1 and the step 1-C in the drawing shows the step 2. In the drawing, the shaded portion is treated in an ethylene gas atmosphere, and the other portions are treated in a nitrogen gas atmosphere.

  In step 1-A in FIG. 1, the copper powder is brought into contact with ethylene gas at 300 to 400 ° C. (aggregation preventing step). Next, in the figure, in step 1-B, the nanocatalyst is deposited in the copper powder and on the surface of the copper powder while being kept at 400 ° C. to 650 ° C. in an inert gas (catalyst deposition step). In the figure, a carbon allotrope is generated from the nanoparticles in the step 1-C (carbon generation step).

  The metal-carbon fiber composite obtained by this production method is preferably used as it is, but the metal composite may be isolated from the metal-carbon fiber composite and used depending on the form of use. For example, the metal composite can be removed from the metal-carbon fiber composite with acid or alkali. Moreover, the carbon fibers extending from the foil-like or linear metal composite can be separated by scraping. The carbon fibers extending from the powdered metal composite can be separated by wind classification, sedimentation, and magnetic field after pulverization.

  Next, specific examples will be described. In addition, this invention is not limited to a following example.

(Examples 1-5 and Comparative Examples 1-3)
(Production of metal composite)
Each metal fine particle (powder) such as Cu—Fe—Co and Cu—Co was produced from the melted metal composite having the composition shown in Table 1 by a water atomizing method or a gas atomizing method.

(Production of metal-carbon fiber composite by CVD method)
4 g of the above metal composite powder was put into a quartz cell having an inner diameter of 26 mm and a length of 70 mm, and a copper carbon composite CVD reactor (rotary kiln) using a rotary cylindrical quartz tube having an inner diameter of 32 mm and a length of 700 mm was used. Carbon fiber was produced | generated on the metal composite on 1 conditions, and the metal-carbon fiber composite of Examples 1-5 shown in Table 1 and Comparative Examples 1-3 was produced.

  In addition, FIG. 2 is a figure which shows the transmission micrograph of the nanoparticle which the nanoparticle consisting of iron and cobalt precipitated in the copper matrix. It was confirmed from the EDS element image that the nano fine particles were composed of iron and cobalt.

(Evaluation of metal-carbon fiber composite)
1) Observation by SEM The metal-carbon fiber composites of Examples 1 to 5 and Comparative Examples 1 to 3 were observed by FE-SEM. The results are shown in FIGS. In Examples 1 to 5, it was observed that carbon fibers having pores on the side surfaces were generated.

  On the other hand, in Comparative Examples 1 and 3 in which iron or cobalt was not used as the second metal, no pores were observed on the side surfaces of the carbon fibers. In Comparative Example 2, thin fibers (10 to 50 nm) were observed at the tip of thick fibers (500 nm).

2) Specific surface area measurement The specific surface area of the mesoporous carbon fiber of the present invention, and the method for measuring mesopores and macropores are N ₂ (in the case of meso-macropores) used as a method for identifying porous materials. The pore distribution measurement method by the gas adsorption method used is used. The specific surface area measurement and pore distribution measurement of the present invention were performed using a constant volume gas adsorption method measuring apparatus BELSORP-mini manufactured by Shimadzu Corporation. As pretreatment of the target sample, degassing treatment was performed at 80 ° C. for 2 hours. N ₂ was used as the adsorption gas. The specific surface area is calculated by the BET method. In the case of mesopore-macropore measurement, isothermal adsorption measurement was performed at a liquid N ₂ temperature of −196 ° C. and a relative pressure of about 0.01 to 0.99. In the case of mesopores to macropores, the pore distribution of mesopores to macropores in the range of about 20 to 2000 mm was calculated by the DH analysis method of the same apparatus. The peak differential pore volume refers to the peak of the pore distribution of mesopores to macropores derived from the analysis software or the pore volume value of the shoulder center value. The peak diameter in the pore distribution of mesopores to macropores means a peak appearing in the pore distribution logarithmically expressed on the horizontal axis, a shoulder-like peak system, and the center value of the shoulder.

  The peak pore size is shown in the table. In addition, two points are entered for the two mountain distribution.

  The results are shown in Table 2.

  In Examples 1-5, it confirmed that the specific surface area was larger than Comparative Examples 1-3. In particular, in Example 1, it can be considered that the specific surface area increased because the step 1-B was performed for a long time. Moreover, although the average pore diameter and pore size are also measured in Comparative Examples 1 to 3, this is mainly a product in which the space between a plurality of fibers is measured as pores. Different.

Claims (8)

A metal composite comprising copper as a matrix, and nanoparticles formed of two or more metals including iron and cobalt, dispersed in the copper;
A metal-carbon fiber composite comprising a carbon fiber having a plurality of pores extending from the nanoparticle.   2. The metal-carbon fiber composite according to claim 1, wherein two or more kinds of metals including iron and cobalt are contained in the metal composite in a proportion of 0.3 to 18% by weight.   The metal-carbon fiber composite according to claim 1 or 2, wherein the pores include mesopores or macropores.   The metal-carbon fiber composite according to any one of claims 1 to 3, wherein a pore diameter of the mesopores or macropores is 10 nm to 200 nm.   The metal-carbon fiber composite according to any one of claims 1 to 4, wherein the pores are present on both a side surface and a cross section of the carbon fiber. A method for producing a metal-carbon fiber composite according to any one of claims 1 to 5,
Preparing a metal composite comprising the copper and nanoparticles of two or more metals including the iron and cobalt dispersed in the copper;
And a step of bringing a carbon source into contact with the nanoparticle under heating.   The method for producing a metal-carbon fiber composite according to claim 6, wherein the step of preparing the metal composite is performed by subjecting two or more kinds of metals including copper, iron, and cobalt to a heat treatment. The metal composite is simply separated from the metal-carbon fiber composite according to any one of claims 1 to 5 by a method of removing the metal composite with an acid or alkali, or a method of classifying after cutting the carbon fiber. A method for producing a carbon fiber having a plurality of pores, comprising a step of separating.