JP2009040646A - Method for manufacturing carbon material, and electric double-layer capacitor containing the carbon material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a carbon material that can be molded without a binder and that can be used for a negative electrode having an excellent dielectric capacitance per unit volume. <P>SOLUTION: The method for manufacturing a carbon material includes the following steps [1] to [5]. They are steps of: [1] preparing a wet gel by reacting an aqueous solution containing a phenolic compound, an aldehyde compound and a basic catalyst; [2] dehydrating the wet gel obtained in the step [1] to prepare a dried gel; [3] impregnating the dried gel obtained in the step [2] with an aqueous solution containing a phenolic compound, an aldehyde compound and a basic catalyst to react to obtain a re-wet gel; [4] dehydrating the re-wet gel obtained in the step [3] to prepare a re-dried gel; and [5] calcining the re-dried gel obtained in the step [4] to prepare a carbon material. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a carbon material useful as an electrode material for an energy storage device such as an electric double layer capacitor and a battery electrode material, a carrier for supporting a catalyst, a chromatographic material, and an adsorbent. About.

Electric double layer capacitors are capable of rapid charge and discharge, have a semi-permanent lifetime, and have a wide operating temperature range. For example, backup power supplies for personal computers, power supplies for electric vehicles, and storage of generated power It is expected to be used for devices. A carbon material is usually used as an electrode that gives the electric double layer capacitor a characteristic capable of charging a large amount of electricity with a small capacity, that is, a characteristic excellent in electrostatic capacity per unit volume.
The carbon material is usually formed by kneading activated carbon powder or the like with a binder (polytetrafluoroethylene or polyvinylidene fluoride), but when the binder is used, the resulting electrode has a large volume resistivity and charges the electric double layer capacitor. In some cases, a high voltage was necessary.
The present inventors have already proposed a method for producing a carbon material suitable for a binder-free electrode by reacting a phenol compound and an aldehyde compound in a tablet-like bowl-shaped container, and drying and baking the resulting gel. (Patent Document 1).

JP 2005-187320 A

The electric double layer capacitor is required to be compact, that is, to improve the electrostatic capacity per unit volume, and more than an electric double layer capacitor including a carbon material obtained by the manufacturing method described in Patent Document 1 as an electrode. Furthermore, there is a need for a carbon material that provides an electric double layer capacitor having an excellent capacitance per unit volume.
An object of the present invention is to provide a method for producing a carbon material that can be molded without a binder and that is applied to an electrode having excellent capacitance per unit volume, and an electric double layer capacitor including the carbon material. That is.

As a result of intensive studies, the present inventor has pores such as macropores and mesopores of the carbon material obtained by the production method of Patent Document 1, and therefore again with the phenol compound in the pores of the gel before firing. After reacting with the aldehyde compound and further filling the pores with gel, it was found that the calcined carbon material can solve this problem, and the present invention was completed.
That is, the present invention is a carbon material manufacturing method including the following steps [1] to [5], and an electric double layer capacitor including the carbon material.
[1] A step of producing a wet gel by reacting an aqueous solution containing a phenol compound, an aldehyde compound and a basic catalyst.
[2] A step of dehydrating the wet gel obtained in [1] to produce a dry gel.
[3] A step of preparing a rewet gel by impregnating and reacting the dry gel obtained in [2] with an aqueous solution containing a phenol compound, an aldehyde compound and a basic catalyst.
[4] A step of dehydrating the rewet gel obtained in [3] to produce a re-dried gel.
[5] A step of firing the redried gel obtained in [4] to produce a carbon material.

The electrode provided by the carbon material of the present invention is excellent in electrostatic capacity per unit volume and has a small volume resistivity.
In addition, in the electric double layer capacitor having the electrode, the capacitance per unit volume after repeated rapid charge / discharge is almost reduced as compared with the capacitance per unit volume before repeated rapid charge / discharge. In other words, excellent recycling characteristics.

Hereinafter, the present invention will be described in detail.
The step [1] of the present invention is a step of preparing a wet gel by reacting an aqueous solution containing a phenol compound, an aldehyde compound and a basic catalyst, and in a fluid liquid containing particles of colloidal size. Is a step of obtaining a wet gel having a three-dimensional network structure derived from the colloidal particles through a sol state in which the colloidal particles are in active Brownian motion.
[1] The wet gel obtained in the step may contain a liquid such as water or a gas such as air in a three-dimensional network structure.

（式中、Ｒ¹は、ハロゲン原子若しくは置換基で置換されていてもよいアルキル基、又は水素原子を表す。ｎは２〜５の整数を表し、ｍは０〜３の整数を表すが、ｎとｍの和は５である。）
などが挙げられる。 Examples of the phenol compound used in the step [1] of the present invention include a formula (1)

(In the formula, R ¹ represents a halogen atom or an alkyl group which may be substituted with a substituent, or a hydrogen atom. N represents an integer of 2 to 5, and m represents an integer of 0 to 3, (The sum of n and m is 5.)
Etc.

Examples of the substituent on the alkyl group represented by R ₁ in the formula (1) include hydroxy, cyano, alkoxy, carbamoyl, carboxy, alkoxycarbonyl, alkylcarbonyloxy, sulfo and sulfamoyl.
The alkyl group and alkoxy, alkoxycarbonyl and alkylcarbonyloxy which are substituents of the alkyl group may be linear or branched.

In R ₁ , examples of the alkyl group which may be substituted with a halogen atom or a substituent include, for example, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, s-butyl group, octyl group, nonyl group, t-butyl group, 2-hydroxyethyl group, 2-hydroxypropyl group, 3-hydroxypropyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxybutyl Group, 2,3-dihydroxypropyl group, 3,4-dihydroxybutyl group, cyanomethyl group, 2-cyanoethyl group, 3-cyanopropyl group, methoxymethyl group, ethoxymethyl group, 2-methoxyethyl group, 2-ethoxyethyl Group, 3-methoxypropyl group, 3-ethoxypropyl group, 2-hydroxy-3-methoxypropyl group, chloromethyl Group, bromomethyl group, 2-chloroethyl group, 2-bromoethyl group, 3-chloropropyl group, 3-bromopropyl group, 4-chlorobutyl group, 4-bromobutyl group, carboxymethyl group, 2-carboxyethyl group, 3- Carboxypropyl group, 4-carboxybutyl group, 1,2-dicarboxyethyl group, carbamoylmethyl group, 2-carbamoylethyl group, 3-carbamoylpropyl group, 4-carbamoylbutyl group, methoxycarbonylmethyl group, ethoxycarbonylmethyl group 2-methoxycarbonylethyl group, 2-ethoxycarbonylethyl group, 3-methoxycarbonylpropyl group, 3-ethoxycarbonylpropyl group, 4-methoxycarbonylbutyl group, 4-ethoxycarbonylbutyl group, methylcarbonyloxymethyl group, ethylcarbo Nyloxymethyl group, 2-methylcarbonyloxyethyl group, 2-ethylcarbonyloxyethyl group, 3-methylcarbonyloxypropyl group, 3-ethylcarbonyloxypropyl group, 4-methylcarbonyloxybutyl group, 4-ethylcarbonyloxy Butyl, sulfomethyl, 2-sulfoethyl, 3-sulfopropyl, 4-sulfobutyl, sulfamoylmethyl, 2-sulfamoylethyl, 3-sulfamoylpropyl and 4-sulfamoylbutyl Groups and the like.
R ₁ is more preferably a hydrogen atom or an unsubstituted alkyl group, particularly preferably hydrogen, a methyl group, an ethyl group, or an octyl group.

  In the formula (1), m is preferably 1 or 2, and 1 is particularly preferable.

Specific examples of the compound represented by the formula (1) include o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, and 2,6-xylenol. 3,4-xylenol, 3,5-xylenol, o-ethylphenol, i-propylphenol, butylphenol, pt-butylphenol, p-octylphenol, p-nonylphenol, 2-chlorophenol, 4-methoxyphenol, 2 , 4-dichlorophenol, 3,5-dichlorophenol, 4-chloro-3-methylphenol, catechol, 3-methylcatechol, 4-t-butylcatechol, resorcinol, 2-methylresorcinol, 4-ethylresorcinol, 4- Chlororesorcinol, 5-methylresorcin Lumpur, 2,5-dimethyl resorcinol, 5-methoxy resorcinol, may be mentioned 5-pentyl Relais sol maytansinol and pyrogallol.
In the step [1] of the present invention, the above phenol compounds may be used alone or in combination of two or more.

[1] Examples of the aldehyde compound used in the step include formaldehyde, paraformaldehyde, acetaldehyde, butyraldehyde, salicylaldehyde, benzaldehyde and the like.
As the aldehyde compound, formaldehyde is preferable.

  The ratio of phenol compound / aldehyde compound is usually in the range of 0.1 to 3 (mol / mol), preferably in the range of 0.2 to 1. When the ratio of the phenol compound / aldehyde compound is in the range of 0.1 to 3 (mol / mol), mesopores develop, and as a result, the capacitance per unit volume of the resulting carbon material tends to increase. This is preferable.

[1] The amount of water used in the step is usually in the range of 50 to 6000 parts by weight, preferably in the range of 50 to 2000 parts by weight per 100 parts by weight of the total amount of the phenol compound and the aldehyde compound. Preferably, it is the range of 50-1000 weight part. For example, when an aqueous solution such as formalin is used as the raw material compound, water contained in the aqueous solution is also included in the amount used.
When the amount of water used is 50 parts by weight or more, it is preferable because it gives a sufficient reaction time for preparation of a wet gel, and when it is 6000 parts by weight or less, the dehydration time of the wet gel described later tends to be shortened. Therefore, it is preferable.

[1] The basic catalyst in the step includes, for example, sodium carbonate, potassium carbonate, lithium carbonate, sodium hydroxide, potassium hydroxide, lithium hydroxide, barium carbonate, sodium phosphate, lithium phosphate and potassium phosphate. Among them, a weakly basic catalyst is preferable because of easy control of mesopore characteristics, and sodium carbonate is particularly preferable.
The amount of the basic catalyst used is such that the number of phenolic hydroxyl groups per mole of cation of the basic catalyst is usually in the range of 10 to 2000 mol, preferably in the range of 100 to 1000 mol. When the number of phenolic hydroxyl groups is 10 mol or more, it is preferably in the range of 100 to 1000 mol. When the number of phenolic hydroxyl groups is 10 mol or more, mesopores develop, and as a result, the capacitance per unit volume of the resulting carbon material tends to increase, and is preferably 2000 mol or less. And gelation tends to occur easily.

[1] The reaction temperature in the step is usually in the range of 0 to 100 ° C, preferably in the range of 30 to 90 ° C. A reaction temperature of 100 ° C. or lower is preferable because it gives a sufficient reaction time for preparation of a wet gel. A temperature of 0 ° C. or higher is preferable because the reaction time of the step [1] tends to be shortened.
Especially, it is made to react at 0-40 degreeC until it gels or just before it, Preferably it is made about 10-35 degreeC, and after gelatinization can be confirmed, it is made to react at 30-100 degreeC, Preferably it is 40-80 degreeC. And a fine structure including pores such as micropores (micropores having a diameter of less than 2 nm), mesopores (pores having a diameter of 2 to 20 nm), and macropores (pores having a diameter of more than 20 nm) in the gel In step [3], which will be described later, the pores are filled again with gel, and the gel has a fine structure mainly composed of micropores. As a result, the capacitance per unit volume is excellent. This is preferred because it provides an electrode.
In this way, by performing the reaction at a temperature of about 0 to 40 ° C., reacting in a closed system, or reacting in a humidification system until gelling, the water is not evaporated in the step [1]. , It is possible to suppress the generation of holes due to dehydration.

  [1] As a specific method of the step, (i) a concave portion of a disk-shaped bowl-shaped container having a concave portion in a disk shape or a rectangular parallelepiped is filled with an aqueous solution containing a phenol compound, an aldehyde compound and a basic catalyst, and left standing. A method for producing a wet gel in the recess by reacting, and (ii) mixing an aqueous solution containing a phenol compound, an aldehyde compound and a basic catalyst to obtain a flowable sol, and then a smooth support substrate A method of applying the sol using a coater such as a dip coater, bar coater, spin coater, etc., and further heating and reacting to obtain a wet gel, (iii) smooth support of the sol obtained in the same manner as described above Extrusion coating method, direct gravure coating method, reverse gravure coating method, CAP coating method and die coating method are used on the substrate. Coated, further heated, and a method of obtaining a wet gel can be given by the reaction.

For the purpose of improving conductivity, a wet gel may be prepared by mixing fine carbon fibers with an aqueous solution containing a phenol compound, an aldehyde compound and a basic catalyst. Here, the fine carbon fiber is usually a carbon fiber having an average fiber diameter (diameter) of 2 μm or less, and preferably a carbon fiber of 500 nm or less. The average fiber diameter of the fine carbon fiber in the present invention, when the fiber cross-sectional shape of the fine carbon fiber is circular, shows an average value obtained by dividing the total of the cross-sectional diameters of the individual fibers by the number, the fiber cross-sectional shape When is not circular, an average value obtained by dividing the sum of the equivalent circle diameters determined from the cross-sectional areas of the individual fibers by the number of fibers is shown. From the viewpoint of conductivity, the purity of the fine carbon fiber is preferably 95% or more.
As the fine carbon fiber, it is preferable to use a carbon nanofiber which is a carbon fiber (vapor-grown carbon fiber) which is produced by a vapor growth method and has an extremely small fiber diameter and fiber length compared to a general carbon fiber. .
The amount of the fine carbon fiber used is usually 0.1 parts by weight or less, preferably 1 × 10 ^{−6 to} 0.01 parts by weight with respect to 1 part by weight of the phenol compound.

[1] The thickness of the wet gel obtained in the step is preferably 3 mm or less, and particularly preferably 0.3 to 2.8 mm or less. It is preferable that the thickness of the shortest side of the wet gel is 0.3 mm or more because the mechanical strength of the obtained carbon material tends to be improved. Further, when the thickness of the shortest side of the wet gel is 3 mm or less, the dehydration time of the [2] step described later tends to be shortened, and the impregnation time of the [3] step described later tends to be shortened. To preferred.
If the thickness of the wet gel is the method (i), the depth of the concave portion of the disc-shaped bowl-shaped container may be adjusted as appropriate. If the method is (ii), the height of the coater may be adjusted as appropriate. In the case of the method (iii), the thickness of the coating may be adjusted appropriately.

The step [2] of the present invention is a step of dehydrating the wet gel obtained in [1], and a dry gel can be obtained in this step. As a method for removing water from the wet gel, for example, direct water drying method, vacuum drying method, heat drying method at about 30 to 150 ° C., freeze drying method at 0 ° C. or less, or these drying methods As a preferred embodiment, a method of removing the hydrophilic organic solvent after replacing water in the wet gel with the hydrophilic organic solvent is recommended.
Examples of the hydrophilic organic solvent include alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol and t-butyl alcohol; aliphatic nitriles such as acetonitrile; aliphatic ketones such as acetone; dimethyl sulfoxide and the like. Aliphatic sulfoxides; and aliphatic carboxylic acids such as acetic acid.
Of these hydrophilic organic solvents, t-butyl alcohol, dimethyl sulfoxide or acetic acid is preferably used, and t-butyl alcohol is particularly preferably used.

Examples of the method for removing the hydrophilic organic solvent include a ventilation drying method, a vacuum drying method, a heat drying method at about 30 to 150 ° C., a freeze drying method at 0 ° C. or less, or a combination of these drying methods. The lyophilization method is preferable because it can retain the three-dimensional network structure of the particles constituting the wet gel made by the sol-gel reaction. That is, it is possible to remove a liquid such as a hydrophilic organic solvent in the wet gel while maintaining the properties of the freeze-drying method and the functionally three-dimensional network structure.
Furthermore, it is preferable to use a freeze-drying apparatus because the wet gel can be dried in a short time and the production cost of the dry gel can be reduced.
The freezing temperature in lyophilization is usually in the range of -70 to 0 ° C, preferably in the range of -30 to -5 ° C.

[3] The step is a step in which the dried gel obtained in the step [2] is impregnated with an aqueous solution containing a phenol compound, an aldehyde compound and a basic catalyst and reacted, and the dried gel has macropores and mesopores. The pores, particularly the mesopores, were impregnated with an aqueous solution containing a phenolic compound, an aldehyde compound and a basic catalyst, and colloidal particles were formed from the aqueous solution to further form a three-dimensional network structure in the pores in the dried gel. This is a step of obtaining a wet gel.
The aqueous solution may be impregnated with the prepared aqueous solution as it is, or may be impregnated into the pores in the dry gel as colloidal particles after the aqueous solution is stirred to form a sol.
About the phenol compound, aldehyde compound, and basic catalyst to be used, the phenol compound, the aldehyde compound and the basic catalyst exemplified in the step [1] may be used, and even if they are the same as those used in the step [1]. May be different.
Preferably, the gel obtained in the step [1] by appropriately adjusting the amounts of phenol compound, aldehyde compound, basic catalyst and water used, or by adjusting the stirring time (solation time) of the aqueous solution. It is preferable to adjust so that the nanoparticles derived from the colloidal particles and the nanoparticles derived from the colloidal particles formed in the step [3] have substantially the same diameter.
FIG. 1A shows an electron micrograph of a material (Comparative Example 4) obtained by carbonizing (baking) the dried gel obtained by performing the steps [1] and [2], and FIG. ) Shows an electron micrograph of the carbon material of the present invention (Example 15) obtained by subjecting the dried gel obtained by the steps [1] and [2] to the steps [3] to [5]. It was. As is clear from the photograph, it can be seen that the carbon material of the present invention has nanoparticles in the mesopores having the same particle size as the nanoparticles obtained by performing the steps [1] and [2]. .

The impregnation time varies depending on the amount of the dried gel obtained, the concentration of the aqueous solution comprising the phenol compound, aldehyde compound and basic catalyst used, and the viscosity, but is usually about 1 hour to 48 hours, preferably 5 hours to 30 hours. Degree.
In order to sufficiently impregnate, in the step [3], the reaction is carried out in a closed system or in a humidified system at 0 to 40 ° C., preferably about 10 to 35 ° C. [3] It is preferable not to evaporate water in the process.
When impregnating, a method of impregnating with a dry gel whose pressure is reduced by a vacuum pump or the like is also recommended.

After the impregnation, it is usually left at 30 to 100 ° C., preferably 40 to 80 ° C. for 1 to 48 hours, preferably 5 to 30 hours, so that the pores such as macropores and mesopores in the dried gel A three-dimensional network structure is formed in the hole.
[3] In the step, the three-dimensional network structure of the gel may be formed in the pores in the dried gel. After impregnation as in the embodiment, the gel may be left standing, or the impregnation and the standing are alternately performed. You may do it.
When the impregnation time is long, a low-density gel may be generated in the outer shell portion of the dried gel. The rewet gel containing this gel may be processed in the next step as it is, but from the viewpoint of improving the capacitance per unit volume, it is preferable to remove the gel in the outer shell portion by polishing.

  [4] The step is a step of dehydrating the impregnated gel obtained in the [3] step, and is a step of obtaining a re-dried gel. Specifically, it may be carried out in the same manner as the method exemplified in the section [2]. The [2] step and the [4] step may be performed under the same conditions or different conditions.

[5] The step is a step of baking (carbonizing) the re-dried gel obtained in the [4] step to obtain a carbon material. Usually, it is performed in an inert gas atmosphere, and nitrogen, argon, helium, hydrogen, etc. are preferable as the inert gas at the time of firing (carbonization). The firing (carbonization) temperature is usually in the range of 200 to 3000 ° C., and in order to reduce the volume resistivity, it is preferably 800 ° C. or higher that can remove a functional group such as a carboxyl group. In order to suppress, it is preferable that it is 1100 degrees C or less.
The firing time is usually in the range of several minutes to several hours.

The carbon material of the present invention may be activated in an oxidizing gas atmosphere containing H ₂ O, CO ₂ or O ₂ in addition to an inert gas. The activation temperature is usually preferably in the range of 800 to 1300 ° C from the viewpoint of reducing the volume resistivity in the range of 700 to 1500 ° C. The activation time is usually in the range of several minutes to several hours. The activation time is usually in the range of several minutes to several hours.
By the above activation, a carbon material with a large surface area per unit weight can be obtained by increasing the proportion of the fine structure, particularly the micropores.
In the activation treatment in the oxidizing gas atmosphere, a chemical may be used in combination. That is, after adding chemicals such as zinc chloride, phosphoric acid, potassium sulfide and potassium hydroxide to the carbon material obtained in the above step [4], an oxidizing gas atmosphere such as H ₂ O, CO ₂ or O ₂ is added. The activation process can be performed in step (b).

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to an Example.

Example 1
[1] Step 10 g of distilled water ([weight of resorcinol] / [weight of water] = 0.5 g / ml, hereinafter sometimes referred to as R / W = 0.5 g / ml), 48 mg of sodium carbonate ([phenolic Mole number of hydroxyl group] / [Mole number of sodium cation] = 100 mol / mol, hereinafter referred to as R / C = 100 mol / mol), 5.0 g of resorcinol and 7.37 g of 37 wt% formalin were charged ([ Mole number of resorcinol] / [Mole number of formalin] = 0.5 mol / mol) were sequentially mixed to prepare an aqueous solution.

[2] Step A disc-shaped bowl-shaped container (2) having a disc-shaped recess having a thickness of 1 mm and an inner diameter of 17 mm was placed in the shar (3) so that the opening of the recess became the upper surface. Subsequently, the aqueous solution (1) prepared in the step [1] was slowly poured into the petri dish (3) so as not to include bubbles in the concave portion (see FIG. 2 (a)). After the bowl-shaped container (2) is completely immersed in the aqueous solution (1) including the recess, the bottom surface of the petri dish (4) smaller than the petri dish (3) and the aperture so as to cover the aperture of the recess The two petri dishes were further sealed with wraps so that the water did not evaporate (see FIGS. 2B and 2C). Subsequently, after storing at 25 ° C. for 1 day, it was stored in an oven at 50 ° C. for 1 day to obtain a wet gel.

[2] Step The wet gel obtained in the step [1] was immersed in t-butyl alcohol for several hours and taken out. This operation was repeated 5 times or more in 3 days to replace the water in the wet gel with t-butyl alcohol. The gel substituted with t-butyl alcohol was freeze-dried at −10 ° C. for 3 days to obtain a dried gel.

[3] Step The dehydrated gel obtained in the step [2] was placed in a petri dish, and the aqueous solution prepared in the same manner as in the step [1] was slowly poured into the petri dish. After all of the dehydrated gel was immersed in the aqueous solution, the dehydrated gel was covered with a bottom surface of the petri dish smaller than the petri dish, and two petri dishes were sealed with wraps so that the water did not evaporate. Subsequently, after storing at 25 ° C. for 1 day, it was stored in an oven at 50 ° C. for 1 day to obtain a rewet gel.

[4] Step Water in the rewet gel obtained in [3] step is replaced with t-butyl alcohol in the same manner as in [2] step, freeze-dried at −10 ° C. for 3 days, A dry gel was obtained.

[5] Step [2] The re-dried gel obtained in the step is placed in a ceramic tube of an electric furnace (Kyoto Science Co., Ltd.), and nitrogen is circulated through the tube at 200 ml / min for 30 minutes at room temperature. Replaced with nitrogen. Subsequently, while flowing nitrogen in the same manner, the temperature was raised to 523 ° C. at 4.2 ° C./min, held at 523 ° C. for 2 hours, then again raised to 1000 ° C. at 4.2 ° C./min, and 4 ° C. at 1000 ° C. Holding for a time, a carbon material having a thickness of about 0.60 mm was obtained.

[Evaluation of pore characteristics and capacitance]
The adsorption and desorption isotherm of nitrogen at 77 degrees (absolute temperature) of the obtained carbon material was measured with an automatic gas adsorption device (Nippon Bell, BELSORP28), and the specific surface area (Brunauer-Emmett-Taylor method) was used. Hereinafter, it may be referred to as S _BET ), and it was 857 m ² / g.
Further, when the mesopore volume and mesopore distribution were determined from the above desorption isotherm by the Dollimore-Heal method, the mesopore volume (hereinafter sometimes referred to as Vmeso) 0.60 cm ³ / g, the mesopore distribution The peak radius (hereinafter sometimes referred to as Rp, meso) was 4.05 nm. Further, when the micropore volume (hereinafter sometimes referred to as Vmicro) was determined by the t-plot method using the desorption isotherm, it was 0.23 cm ³ / g.
Furthermore, 4M potassium hydroxide is used as the electrolyte, and the obtained carbon material is used as the working electrode of the triode cell as it is, the Ni electrode as the counter electrode, and the constant current charge / discharge measurement using the Ag / AgCl electrode as the reference electrode. The capacitance per unit weight of the electric double layer capacitor (hereinafter sometimes referred to as Cmas) was determined by (300 mA / g) and found to be 151.9 F / g, and the electrode density (the diameter, thickness, and thickness of the electrode used). Calculated as a cylinder from the mass, hereinafter referred to as ρ.) Since 0.89 g / cm ³ , the capacitance per unit volume of the electric double layer capacitor (hereinafter also referred to as Cvol) was 134.9. F / cm ³ .

(Comparative Example 1)
The dried gel obtained in the step [2] of Example 1 was baked in the same manner as in the step [5] of Example 1. The results of the obtained carbon materials are summarized in Table 1 together with Example 1.
As is apparent from comparison between Comparative Example 1 and Example 1, it can be seen that Example 1 has a reduced mesopore volume and a marked increase in capacitance per unit volume. The volume resistivity was 2.67 Ω · cm.

(Examples 2 to 6)
Unlike the example 1 in which the aqueous solution prepared in the step [1] was used immediately in the step [3] of the example 1, in the steps [3] of the examples 2 to 6, the aqueous solution standing time in Table 1 was set. An aqueous solution prepared in the step [1] was allowed to stand for the indicated time and used to make a sol. The results are shown in Table 1. As is clear from comparison with Comparative Example 1, it can be seen that in Examples 2 to 6, the mesopore volume is reduced and the capacitance per unit volume is remarkably increased.

(Examples 7 and 8)
[3] A carbon material was prepared in the same manner as in Example 1 except that the R / C, R / W of the aqueous solution used in the step and the aqueous solution standing time described in Table 1 were used. The results are shown in Table 1. As is clear from comparison with Comparative Example 1, in Examples 7 to 16, the mesopore volume is reduced and the capacitance per unit volume is remarkably increased.
The volume resistivity of the carbon material obtained in Example 7 was 2.50 Ω · cm.

(Examples 9 to 22)
[1] The R / C and R / W of the aqueous solution used in the step are listed in Table 1, and the R / C, R / W and aqueous solution standing time of the aqueous solution used in the [3] step are shown. A carbon material was prepared in the same manner as in Example 1 except that the material described in 1 was used. The results are shown in Table 1.

(Comparative Examples 2-6)
[1] A carbon material was prepared in the same manner as in Comparative Example 1 except that R / C and R / W of the aqueous solution used in the step were those listed in Table 1. The results are shown in Table 1. Comparative Example 2 means that the dried gel obtained in Example 9 was baked as it is, Comparative Example 3 means that the dried gel obtained in Examples 10 to 13 was baked as it was, Comparative Example 4 means that the dried gels obtained in Examples 14 to 17 were baked as they were, Comparative Example 5 means that the dried gels obtained in Examples 18 to 19 were baked as they were, and Comparative Example 6 means that the dried gel obtained in Examples 20 to 22 was baked as it was.
The examples show that the mesopore volume is reduced and the capacitance per unit volume is significantly increased compared to the corresponding comparative examples.
The volume resistivity of the carbon material obtained in Comparative Example 3 was 2.84 Ω · cm.

(Example 23)
[5] A carbon material was prepared in the same manner as in Example 15 except that the final firing temperature in the step was 900 ° C. The results are shown in Table 2. The volume resistivity was 2.87 Ω · cm.
The capacitance was measured in the same manner as in Example 15 except that the constant current charge / discharge measurement was performed at a current density of 5 A / g.

(Example 24)
A carbon material was prepared in the same manner as in Example 23, except that carbon nanofibers (manufactured by Hyperion Co., Ltd.) were mixed with the aqueous solution in step [1] at a ratio of 1 × 10 ⁻⁵ parts by weight to 1 part by weight of resorcinol. The results are shown in Table 2. The volume resistivity was 1.58 Ω · cm.
The capacitance was measured in the same manner as in Example 23.

(Cycle characteristics)
Except for using the carbon material of Example 15 as the working electrode of the triode cell as it is, using the Ni electrode as the counter electrode, the Ag / AgCl electrode as the reference electrode, and the current density of 300 mA / g, the same as described above The constant current charge / discharge measurement was repeated 10,000 times. The results on the way are shown in FIG. Ultimately, the capacitance per unit volume decreased by 1.8% and the density decreased by 2%.

  The carbon material obtained by the production method of the present invention is used for, for example, carbon black and activated carbon having a solid shape, but is used for an electrode such as a lithium secondary battery or an electric double layer capacitor because of excellent conductivity. it can.

(A) Electron micrograph of the carbon material obtained in Comparative Example 4 (b) Electron micrograph of the carbon material obtained in Example 15 [2] Explanatory drawing of a process (a) The pot-shaped container (2) which has the recessed part which the opening part has faced on the upper surface is set | placed on a petri dish (3), and the aqueous solution (1) containing a phenol compound, an aldehyde compound, and a basic catalyst Was added. (B) Place the petri dish (4) in the bowl-shaped container (2). (C) State before putting petri dish (4) and sealing with wrap Results of cycle characteristics with the constant current charge / discharge count on the horizontal axis and the capacitance on the vertical axis

Claims (11)

The manufacturing method of the carbon material including the following [1]-[5] processes.
[1] A step of producing a wet gel by reacting an aqueous solution containing a phenol compound, an aldehyde compound and a basic catalyst.
[2] A step of dehydrating the wet gel obtained in [1] to produce a dry gel.
[3] A step of preparing a rewet gel by impregnating and reacting the dry gel obtained in [2] with an aqueous solution containing a phenol compound, an aldehyde compound and a basic catalyst.
[4] A step of dehydrating the rewet gel obtained in [3] to produce a re-dried gel.
[5] A step of firing the redried gel obtained in [4] to produce a carbon material. The production method according to claim 1, wherein the phenol compound is a compound represented by the formula (1).

(In the formula, R ¹ represents a halogen atom or an alkyl group which may be substituted with a substituent, or a hydrogen atom. N represents an integer of 2 to 5, and m represents an integer of 0 to 3, (The sum of n and m is 5.)   [1] The step is a step of producing a wet gel in the recess by reacting an aqueous solution containing a phenol compound, an aldehyde compound and a basic catalyst in the recess of the disc-shaped bowl-shaped container having the recess. 2. The production method according to 2.   [1] The production method according to any one of claims 1 to 3, further comprising a step of mixing fine carbon fibers with the aqueous solution used in the step.   [1] The process according to any one of claims 1 to 4, wherein the step includes a step in which an aqueous solution containing a phenol compound, an aldehyde compound and a basic catalyst reacts at 0 to 40 ° C, and subsequently reacts at 30 to 100 ° C. Manufacturing method.   [2] The production method according to any one of claims 1 to 5, wherein the step includes a step of replacing water in the wet gel with a hydrophilic organic solvent and then lyophilizing to remove the hydrophilic organic solvent. .   [3] After impregnating the dried gel in an aqueous solution containing a phenolic compound, an aldehyde compound and a basic catalyst at 0 to 40 ° C. for 1 to 48 hours, the obtained gel is pulled up, The manufacturing method in any one of Claims 1-6 including the process left still for 5 to 48 hours at 30-100 degreeC.   [4] The production according to any one of claims 1 to 7, wherein the step includes a step of replacing water in the rewet gel with a hydrophilic organic solvent and then lyophilizing to remove the hydrophilic organic solvent. Method.   [5] The manufacturing method according to any one of claims 1 to 8, wherein the step includes a step of baking the re-dried gel in an inert gas atmosphere. An electrode obtained through the following steps [1] to [5].
[1] A step of producing a wet gel by reacting an aqueous solution containing a phenol compound, an aldehyde compound and a basic catalyst.
[2] A step of dehydrating the wet gel obtained in [1] to produce a dry gel.
[3] A step of preparing a rewet gel by impregnating and reacting the dry gel obtained in [2] with an aqueous solution containing a phenol compound, an aldehyde compound and a basic catalyst.
[4] A step of dehydrating the rewet gel obtained in [3] to produce a re-dried gel.
[5] A step of firing the redried gel obtained in [4] to produce a carbon material.   An electric double layer capacitor comprising the electrode according to claim 10.

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