JP5098195B2 - Carbon material, composite material, method for producing carbon material, and method for producing composite material - Google Patents

Description

  The present invention relates to a carbon material, a composite material, a carbon material manufacturing method, and a composite material manufacturing method.

  In recent years, since the discovery of fullerenes and nanotubes, carbon materials have attracted a great deal of interest not only as substances but also from the viewpoint of application. In particular, carbon materials are considered to be important materials for devices related to environmental and energy problems. For example, the negative electrode of a lithium ion battery used as a power source for mobile devices such as mobile phones has been put into practical use only after there is a carbon material. Lithium ion batteries are expected to be greatly applied to electric vehicles and hybrid electric vehicles in the future. In addition, an ultracapacitor that makes use of the charge / discharge capacity on the surface of activated carbon or the like cannot be described without a carbon material. Furthermore, development of fuel cells for automobiles has been actively carried out to prevent global warming, and applications therefor are also considered as catalyst carriers, separators, and catalysts themselves.

In order to improve the performance of devices using these carbon materials, development of carbon materials in which some of the carbon atoms are substituted with hetero atoms such as nitrogen atoms is expected. In particular, carbon materials substituted with nitrogen atoms are expected to impart various functions. As a method for synthesizing this carbon material containing nitrogen, a method is known in which a so-called polyimide is baked and carbonized in an inert gas atmosphere (see Patent Document 1).
JP 2004-41748 A

  However, the carbon material synthesized by the above method has a small amount of nitrogen.

The present invention has been made to solve the above problems, and the carbon material according to the present invention is a carbon material containing carbon and nitrogen, and a part of the hexagonal mesh surface of carbon is substituted with nitrogen. The composition is characterized in that the mass ratio of nitrogen to carbon is larger than 5.6 [% by mass].

  A composite material according to the present invention includes the carbon material according to the present invention and a base material having at least a carbon material on a surface thereof.

The method for producing a carbon material according to the present invention comprises a diimine molecular skeleton represented by the general formula (I)

And a polymer is fired at a temperature in the range of 500 [° C.] to 1200 [° C.] in an atmosphere not containing oxygen.

The method for producing a composite material according to the present invention comprises a diimine molecular skeleton represented by the general formula (I)

And a polymer coated with the polymer is baked at a temperature in the range of 500 ° C. to 1200 ° C. in an oxygen-free atmosphere. And

  According to the present invention, a carbon material having a stable basic skeleton and excellent corrosion resistance is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the outstanding composite material with which the high function was expressed is provided.

  According to the present invention, a carbon material containing a large amount of nitrogen, having a stable basic skeleton, and excellent corrosion resistance can be easily produced.

  ADVANTAGE OF THE INVENTION According to this invention, the outstanding composite material with which the high function was expressed can be manufactured easily.

  Hereinafter, a carbon material, a composite material, a carbon material manufacturing method, and a composite material manufacturing method according to embodiments of the present invention will be described.

  FIG. 1 is an image diagram of a carbon material according to an embodiment of the present invention. The carbon material is a collection of carbon fine particles 1 shown in FIG. As shown in the surface schematic diagram of FIG. 1, the carbon fine particles 1 contain carbon and nitrogen, and the mass ratio of nitrogen to carbon is larger than 5.6 [% by mass]. Nitrogen is effective for functionalizing the carbon material. For this reason, when the mass ratio of nitrogen to carbon is larger than 5.6 [% by mass], a carbon material having a stable basic skeleton and excellent corrosion resistance is provided. Such carbon materials can be applied to oxygen reduction catalysts for fuel cells, catalyst carriers, electrode materials for electrochemical capacitors, negative electrode active materials for lithium ion batteries, and the like.

  The carbon material according to the embodiment of the present invention includes carbon and nitrogen, and includes low energy nitrogen and high energy nitrogen. Low energy nitrogen has a peak in the vicinity of 397.5 [eV] in the N1S spectrum by X-ray photoelectron spectroscopy (XPS). Further, high energy nitrogen has a peak in the vicinity of 400.5 [eV] in the binding energy in the N1S spectrum by XPS. As shown in FIG. 1, the carbon fine particles 1 have a configuration in which a part of the carbon hexagonal network surface 2 is replaced with low energy nitrogen 3 or high energy nitrogen 4. By including both low-energy nitrogen and high-energy nitrogen, the carbon material according to the embodiment of the present invention has a stable basic skeleton and excellent corrosion resistance. Such carbon materials can be applied to oxygen reduction catalysts for fuel cells, catalyst carriers, electrode materials for electrochemical capacitors, negative electrode active materials for lithium ion batteries, and the like.

The carbon material according to the embodiment of the present invention is a 1,2-ethanediimine molecular skeleton represented by the general formula (I)

It is preferable to contain. As shown in FIG. 1, when the carbon material has the 1,2-ethanediimine molecular skeleton 5 represented by the general formula (I), the metal ions are easily coordinated by the 1,2-ethanediimine molecular skeleton 5. Become. For this reason, when such a carbon material is used as, for example, a catalyst carrier for a fuel cell, it triggers loading of catalyst fine particles.

  The carbon material which concerns on embodiment of this invention can be used as a composite material provided with the base material which has a carbon material and a carbon material on the surface at least. The base material used here is preferably a conductive material when applied to a catalyst or the like. When the conductive material has a carbon material on at least the surface, an excellent composite material exhibiting a high degree of function is provided by a combination of the function of the carbon material and the function of the base material. When applying to an electrode catalyst, it is preferable that the base material to be used has electroconductivity.

In order to obtain the above carbon material, a 1,2-ethanediimine molecular skeleton represented by the general formula (I)

The polymer is prepared by baking the polymer at a temperature in the range of 500 [° C.] to 1200 [° C.] in an atmosphere not containing oxygen. In this production method, by using a polymer containing a 1,2-ethanediimine molecular skeleton having a nitrogen atom, it contains a large amount of nitrogen effective for functionalization of the material in a small number of steps, and the basic skeleton is stable and excellent in corrosion resistance. A carbon material can be easily manufactured. This carbon material contains carbon and nitrogen, and the mass ratio of nitrogen to carbon is larger than 5.6 [% by mass]. The carbon material includes carbon and nitrogen, and includes low energy nitrogen and high energy nitrogen. Furthermore, by using a polymer containing a 1,2-ethanediimine molecular skeleton, a 1,2-ethanediimine molecular skeleton remains in the carbon material, and a carbon material having a stable basic skeleton and excellent corrosion resistance can be obtained. When firing, an atmosphere containing no oxygen is more preferable in terms of increasing the carbonization yield and preventing the introduction of unnecessary oxygen-containing functional groups on the surface of the carbon material. An inert gas atmosphere, a vacuum, etc. are raised. The firing temperature is more preferably in the range of 500 [° C.] to 1200 [° C.] in that the content of nitrogen atoms is not significantly reduced. When the firing temperature is lower than 500 [° C.], carbonization is insufficient and conductivity is inferior, which is not preferable. Moreover, when a calcination temperature is higher than 1200 [degreeC], it is unpreferable from the point that a contained nitrogen atom reduces significantly.

The polymer is preferably a polyimide containing a 2,2′-bipyridine molecular skeleton or a 1,10-phenanthroline molecular skeleton in the main chain. In this case, a carbon material containing a large amount of nitrogen in which a 1,2-ethanediimine molecular skeleton remains in the carbon material is obtained. The compound having a 2,2′-bipyridine molecular skeleton particularly has an amino group at the 4,4′-position or the 5,5′-position as represented by the general formula (II) or the general formula (III). It is preferable from the point of reacting with an acid anhydride to form an imide bond for polymerization.

As an example of a compound having an amino group at the 4,4 ′ position, 4,4′-diamino-2,2′bipyridine represented by the general formula (IV) is shown below.

The compound having a 1,10-phenanthroline molecular skeleton particularly has an amino group at the 3, 8 position or the 4, 7 position as represented by the general formula (V) or (VI). This is preferable in that it reacts with an anhydride to form an imide bond for polymerization.

  A polymer (polyimide) containing a 1,2-ethanediimine molecular skeleton is soluble by reacting an acid anhydride, for example, a tetracarboxylic acid anhydride, with 4,4′-diamino-2,2′bipyridine, which is a diamine. A polyamic acid is prepared, and the polyamic acid is produced by firing under vacuum. The polyimide obtained here is carbonized by firing in an argon atmosphere, and a carbon material containing a large amount of nitrogen effective for functionalization is obtained.

In order to obtain the above composite material, a 1,2-ethanediimine molecular skeleton represented by the general formula (I)

And a base material coated with the polymer is baked at a temperature in the range of 500 ° C. to 1200 ° C. in an oxygen-free atmosphere. To manufacture. In this production method, an excellent composite that has developed high functions in a small number of steps by applying a polymer containing a 1,2-ethanediimine molecular skeleton having nitrogen as a raw material of a carbon material to a base material and baking it. The material can be manufactured easily.

  The polymer is preferably a polyimide containing a 2,2′-bipyridine molecular skeleton or a 1,10-phenanthroline molecular skeleton in the main chain. In this case, a composite material containing a large amount of nitrogen in which a 1,2-ethanediimine molecular skeleton remains in the composite material is obtained.

  Hereinafter, the present invention will be described more specifically with reference to Examples 1 to 6 and Comparative Examples 1 to 2, but the scope of the present invention is not limited thereto.

  First, the manufacturing method of the carbon material which concerns on embodiment of this invention is demonstrated from Example 1- Example 5, the comparative example 1, and the comparative example 2. FIG.

1. Preparation of Sample In order to synthesize a carbon material containing a large amount of nitrogen in bulk, a polyimide containing a 1,2-ethanediimine molecular skeleton was synthesized, and the obtained polyimide was carbonized under an argon atmosphere. FIG. 2 is a flowchart showing the manufacturing methods of Examples 1 to 5, Comparative Example 1 and Comparative Example 2. The carbon material includes a polyamic acid preparation step S1 for preparing a polyamic acid, a film forming step S2 for obtaining a film using the obtained polyamic acid, and a solvent drying step S3 for drying a solvent contained in the obtained film formation. And a polyimide forming step S4 for polyimideizing the sample obtained in the solvent drying step S3 at 300 [° C.] under vacuum, and a carbonizing step S5 for firing and carbonizing the obtained polyimide in an argon atmosphere. Is done. In Examples 1 to 5, 5,5′-diamino-2,2′-bipyridine was used as a diamine containing a 1,2-ethanediimine molecular skeleton and serving as a raw material for polyimide. The method for synthesizing 5,5′-diamino-2,2′-bipyridine was referred to J. Heterosyslic Chem., 14 (1977) 191. Pyromellitic anhydride was used as the acid anhydride raw material for polyimide. As the solvent, sufficiently dried dimethylacetamide (moisture 5 ppm or less) was used.

Example 1
The reaction of Example 1 is shown in FIG. First, in order to prepare polyamic acid, 2.33 [g] 5,5′-diamino-2,2′-bipyridine 12 may be added to 70 [g] dimethylacetamide in a glove box in a nitrogen atmosphere. The solution was stirred to dissolve, and 5,5′-diamino-2,2′-bipyridine 12 and equimolar pyromellitic acid 11 were added to this solution and stirred for half a day to prepare a polyamic acid. Next, this mixed solution (polyamic acid solution) is taken out of the glove box and applied onto a glass plate, and the solvent is dried on a digital hot plate set at a temperature of 90 to 100 [° C.] did. This film was peeled off from the glass substrate, collected, put into a vacuum container, and heat-treated at 300 [° C.] under vacuum for 1 [hour] to be polyimideized. This polyimide 13 is put into a sealed quartz tube, vacuuming and leaking with high-purity argon gas (99.9999 [%]) are repeated three times, and then the quartz tube joint is made to allow argon gas to flow through the quartz tube. The argon gas was kept flowing at a flow rate of 30 to 50 [ml / min]. A quartz tube with a polyimide sample placed in the center is placed in a tubular electric furnace, and the electric furnace is heated to 900 [° C.] at a heating rate of 400 [° C./hour] and 1 [hour] at 900 [° C.]. Retained. Thereafter, the argon flow rate was slightly increased and then the temperature was lowered. After the temperature became close to room temperature, the argon gas was stopped, and the carbonized polyimide was taken out to obtain a sample of Example 1.

Example 2
A sample of Example 2 was obtained in the same manner as in Example 1 except that 25 [mol%] of 5,5′-diamino-2,2′-bipyridine in Example 1 was replaced with diaminodiphenyl ether.

Example 3
A sample of Example 3 was obtained in the same manner as in Example 1 except that 50 [mol%] of 5,5′-diamino-2,2′-bipyridine in Example 1 was replaced with diaminodiphenyl ether.

Example 4
A sample of Example 4 was obtained by treating in the same manner as in Example 1 except that 75 [mol%] of 5,5′-diamino-2,2′-bipyridine in Example 1 was replaced with diaminodiphenyl ether.

Example 5
A sample of Example 5 was obtained in the same manner as in Example 1 except that the temperature of the tubular electric furnace was raised to 800 [° C.] in Example 1.

Comparative Example 1
The reaction of Comparative Example 1 is shown in FIG. In Example 1, instead of 5,5′-diamino-2,2′-bipyridine 12, diaminodiphenyl ether 22 was used as a diamine as a raw material for standard polyimide, and the amount of dimethylacetamide used as a solvent was 40 [g]. To make a mixed solution (polyamic acid solution). When this mixed solution was slightly stirred, the viscosity of the solution increased. After stirring for about 1 [hour], a film was formed by coating on a glass plate in the same manner as in Example 1. The film was peeled off from the glass substrate and collected, and placed in a vacuum container at 300 [° C.] under vacuum. [Time] Heat treatment was performed to obtain polyimide 23. The obtained polyimide 23 was carbonized in the same manner as in Example 1 to obtain a sample of Comparative Example 1.

Comparative Example 2
A sample of Comparative Example 2 was obtained in the same manner as in Example 1 except that the temperature of the tubular electric furnace was increased to 1300 [° C.] in Example 1.

  Several analyzes were performed on the obtained samples. As the analysis, XRD (X-ray diffraction), XPS (X-ray photoelectron spectroscopy), and elemental analysis (carbon, hydrogen, and nitrogen) were performed. The result of XRD is shown in FIG. 4, and the spectrum of XPS N1s is shown in FIG. Table 1 shows the mass ratio of nitrogen to carbon by elemental analysis.

2. Confirmation of crystal structure (XRD)
In order to confirm the crystal structure of the obtained sample, X-ray diffraction measurement was performed. The apparatus used was an X-ray diffractometer (MXP18VAHF) manufactured by Max Science. The measurement was performed using a voltage of 40 [kV], a current of 300 [mA], and a source of CuKα rays.

3. Confirmation of nitrogen binding state (XPS)
Confirmation of the binding state of nitrogen on the obtained sample surface was performed by XPS. The apparatus used was a composite surface analyzer Quantum-2000 manufactured by PHI. Measurement is performed using Monochromated-AL-kα ray (voltage 1486.6 [eV], 40 [W]) as an X-ray source, photoelectron extraction angle 45 [°], measurement depth of about 4 [nm], and measurement area φ200 [μm]. ] Was performed by irradiating the surface of the sample from which X-rays were obtained.

4). Confirmation of composition The composition of the synthesized sample was confirmed by elemental analysis. An organic element analyzer CHN CORdER MT-6 manufactured by Yanaco Co., Ltd. was used for confirmation of carbon, hydrogen and nitrogen.

  The XRD results of the samples obtained in Example 1, Example 3 and Comparative Example 1 are shown in FIG. As shown in FIG. 4, in each sample obtained in Example 1, Example 3, and Comparative Example 1, spectra having broad peaks 31 and 32 were observed. From the peaks 31 and 32, it was found that the samples obtained in Example 1, Example 3 and Comparative Example 1 were formed with a layer structure having a hexagonal mesh surface.

  Next, the XPS N1S spectra of the samples obtained in Example 1, Example 3 and Comparative Example 1 are shown in FIG. From FIG. 5, in each sample, a peak 41 derived from low energy nitrogen is observed near a binding energy of 397.5 [eV], and a peak 42 derived from high energy nitrogen is observed near a binding energy of 400.5 [eV]. It was done. In each sample, the peak 42 derived from high energy nitrogen was strong, and it was found that each sample contained a large amount of high energy nitrogen. On the other hand, the peak 41 derived from low energy nitrogen relative to the peak 42 derived from high energy nitrogen was the strongest in Example 1. In Example 3 in which 50 [mol%] of diamine which is one of the raw materials of the carbon material is 5,5′-diamino-2,2′-bipyridine, the peak derived from low energy nitrogen with respect to peak 42 derived from high energy nitrogen 41 was weaker than Example 1. Moreover, in the comparative example 1 which uses diamino diphenyl ether as a diamine, the peak 41 derived from low energy nitrogen with respect to the peak 42 derived from high energy nitrogen was weaker than Example 3. From this result, it was found that the higher the proportion of 5,5'-diamino-2,2'-bipyridine as the raw material for the carbon material, the higher the content of low energy nitrogen in the obtained carbon material.

The results of elemental analysis of the samples obtained in Examples 1 to 5, Comparative Example 1 and Comparative Example 2 are expressed as N / C ratios representing the nitrogen content (mass) relative to the carbon content (mass). It is shown in 1.

From Table 1, it was found that the higher the proportion of 5,5'-diamino-2,2'-bipyridine as the raw material for the carbon material, the higher the nitrogen content in the obtained carbon material. Moreover, from the results of Comparative Example 2, it was found that the nitrogen content was low when the firing temperature was as high as 1300 [° C.]. This is thought to be due to the presence of nitrogen that begins to escape at high temperatures.

  Next, the composite material which concerns on embodiment of this invention is demonstrated from Example 6. FIG.

Example 6
FIG. 6 is a flowchart showing the manufacturing method of the sixth embodiment. The composite material includes a polyamic acid preparation step S11 for preparing a polyamic acid, a coating step S12 for coating the obtained polyamic acid on acetylene black, a solvent drying step S13 for drying a solvent contained in the obtained sample, a solvent The sample obtained in the drying step S13 is manufactured through a polyimide forming step S14 in which the sample is polyimideized at 300 [° C.] under vacuum and a carbonizing step S15 in which the obtained sample is baked and carbonized in an argon atmosphere. In Example 6, acetylene black was dispersed in the polyamic acid solution of Example 1, filtered and dried, and subjected to polyimide formation and firing under the same conditions as in Example 1. The obtained sample was subjected to XPS and elemental analysis.

  From the XPS N1S spectrum of the sample obtained in Example 6, the intensity was weaker than the spectrum of Example 1 shown in FIG. 5, but a peak derived from low energy nitrogen and a peak derived from high energy nitrogen were observed. From this result, it was found that low energy nitrogen and high energy nitrogen exist on the surface of acetylene black. From the results of elemental analysis, it was found that N / C was 0.102 and the nitrogen content was high.

  From the results of Examples 1 to 6 and Comparative Examples 1 to 2, in the method for producing a carbon material according to the embodiment of the present invention, carbon containing many nitrogen atoms, the basic skeleton is stable, and the corrosion resistance is excellent. It has been found that the material can be easily manufactured. Moreover, according to the manufacturing method of the composite material which concerns on embodiment of this invention, it turned out that the outstanding composite material which expressed the high function can be manufactured easily.

  Although the present embodiment has been described above, it should not be understood that the description and the drawings, which form part of the disclosure of the above embodiment, limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

It is an image figure of the carbon material which concerns on embodiment of this invention. It is a flowchart which shows the manufacturing method of Example 1- Example 5, the comparative example 1, and the comparative example 2. FIG. (A) It is a figure which shows reaction in Example 1. FIG. (B) It is a figure which shows the reaction in the comparative example 1. FIG. It is a figure which shows the result of XRD. It is a figure which shows the result of XPS. 10 is a flowchart showing a manufacturing method of Example 6. FIG.

Explanation of symbols

1 Carbon fine particles (carbon material)
2 Carbon hexagonal network 3 Low energy nitrogen 4 High energy nitrogen 5 1,2-ethanediimine molecular skeleton

Claims (6)

A carbon material containing carbon and nitrogen,
A portion of the carbon hexagonal mesh surface is substituted with the nitrogen;
A carbon material, wherein a mass ratio of the nitrogen to the carbon is larger than 5.6 [% by mass].   A carbon material containing carbon and nitrogen, wherein the carbon material contains low energy nitrogen and high energy nitrogen. Including carbon and nitrogen,
A mass ratio of the nitrogen to the carbon is greater than 5.6 [% by mass];
The carbon material, wherein the nitrogen includes low energy nitrogen and high energy nitrogen.
  A composite material comprising: the carbon material according to claim 1; and a base material having at least a surface of the carbon material. 1,2-ethanediimine molecular skeleton represented by the general formula (I)

A method for producing a carbon material, comprising: preparing a polymer containing a carbon, and firing the polymer at a temperature in a range of 500 [° C.] to 1200 [° C.] in an atmosphere not containing oxygen.   6. The method for producing a carbon material according to claim 5, wherein the polymer is a polyimide containing a 2,2′-bipyridine molecular skeleton or a 1,10-phenanthroline molecular skeleton in the main chain.