JP2013161835A - Electroconductive polymer/porous carbon material complex, and electrode material using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric double layer capacitor having high electrostatic capacitance and excellent cycle characteristics, a lithium ion secondary battery, a lithium ion capacitor, an electrode material whereby they can be obtained, and a complex used for the electrode material.SOLUTION: In this complex of an electroconductive polymer having nitrogen atoms and a porous carbon material, the electroconductive polymer is bonded to the surface of the porous carbon material; the total pore volume of a total pore having a diameter of 0.5-100.0 nm when measured by the Horvath-Kawazoe method and the BJH method is 0.3-3.0 cm/g; the ratio of the pore volume of a pore having a diameter of not less than 2.0 nm and less than 20.0 nm when measured by the BJH method is 10-30% to the total pore volume; and the ratio of the pore volume of a pore having a diameter of not less than 0.5 nm and less than 2.0 nm when measured by the Horvath-Kawazoe method and the BJH method is 70-90% to the total pore volume.

Description

  The present invention relates to a conductive polymer / porous carbon material composite, an electrode material using the same, an electric double layer capacitor, a lithium ion secondary battery, and a lithium ion capacitor.

Lithium ion secondary batteries and electric double layer capacitors are known as power storage devices.
In general, a lithium ion secondary battery has a higher energy density and can be driven for a long time as compared with an electric double layer capacitor.
On the other hand, the electric double layer capacitor can be rapidly charged / discharged and has a long use life as compared with the lithium ion secondary battery.
In recent years, lithium ion capacitors have been developed as power storage devices that combine the advantages of such lithium ion secondary batteries and electric double layer capacitors.

  For example, as an electric double layer capacitor, the present applicant has disclosed in Patent Document 1 “Polyaniline / polyaniline or a derivative thereof obtained by combining polyaniline or a derivative thereof with a carbon-based material selected from activated carbon, ketjen black, acetylene black, and furnace black. A carbon composite comprising a polyaniline / carbon composite, wherein the polyaniline or a derivative thereof is obtained by dedoping a conductive polyaniline or a derivative thereof dispersed in a nonpolar organic solvent by base treatment. An electrode material for a multilayer capacitor. ”In Patent Document 2,“ Polyaniline / polyaniline obtained by combining conductive polyaniline dispersed in a nonpolar organic solvent or a derivative thereof with a porous carbon material ” Porous carbon composites ".

  In addition, as a lithium ion capacitor, the present applicant, in Patent Document 3, includes (i) a positive electrode, (ii) a negative electrode including an active material capable of reversibly occluding and releasing lithium ions, and (iii) a lithium salt supporting electrolyte. In an electric double layer capacitor comprising an electrolyte composed of an aprotic organic solvent, a composite of conductive polyaniline or a derivative thereof dispersed in a state where the positive electrode is doped in a nonpolar organic solvent and a porous carbon material An electrode active material using a conductive polyaniline / porous carbon composite formed as an active material, a current collector, and, if necessary, an electric double layer capacitor comprising a conductive auxiliary agent and a binder. " Has been proposed.

Japanese Patent No. 4294667 JP 2008-72079 A Japanese Patent Laid-Open No. 2008-300639

  As a result of studying the electrode materials and polyaniline / porous carbon composites described in Patent Documents 1 to 3, the present inventor has found that the molecular weight of polyaniline, the concentration of polyaniline dispersion for preparing the composite, the presence or absence of dedoping, the dedoping The specific surface area of the polyaniline / carbon composite may be reduced or the pore distribution may be changed depending on the above methods and combinations thereof. As a result, the capacitance and cycle characteristics may vary. It was clear.

  Therefore, the present invention has an electric double layer capacitor, a lithium ion secondary battery, and a lithium ion capacitor (hereinafter collectively referred to as “electric double layer capacitor etc.”) having high capacitance and excellent cycle characteristics. ), And an electrode material from which an electric double layer capacitor or the like can be obtained and a composite used for the electrode material.

  As a result of intensive studies, the inventor uses a porous carbon material in which a predetermined conductive polymer is bonded to the surface and a pore volume having a predetermined diameter is a specific ratio as an electrode material. Thus, the inventors have found that an electric double layer capacitor having a high capacitance and excellent cycle characteristics can be obtained, and the present invention has been completed. That is, the present invention provides the following (1) to (8).

(1) A composite of a conductive polymer having a nitrogen atom and a porous carbon material,
The conductive polymer is bonded to the surface of the porous carbon material;
The total pore volume of all the pores having a diameter of 0.5 to 100.0 nm measured by Horvath-Kawazoe method and BJH method is 0.3 to 3.0 cm ³ / g,
The ratio of the pore volume of pores having a diameter of 2.0 nm or more and less than 20.0 nm measured by the BJH method is 10 to 30% with respect to the total pore volume,
The composite_body | complex whose ratio of the pore volume of the pore which has the diameter of 0.5 nm or more and less than 2.0 nm measured by Horvath-Kawazoe method and BJH method is 70 to 90% with respect to the said total pore volume.

(2) The composite according to (1), wherein the total specific surface area is 500 to 2500 m ² / g.

  (3) The conductive polymer according to (1) or (2), wherein the conductive polymer is at least one selected from the group consisting of polyaniline, polypyrrole, polypyridine, polyquinoline, polythiazole, polyquinoxaline, and derivatives thereof. Complex.

  (4) The composite according to any one of (1) to (3), wherein the porous carbon material is activated carbon and / or graphite.

  (5) An electrode material using the composite according to any one of (1) to (4) above.

  (6) An electric double layer capacitor having a polarizable electrode using the electrode material according to (5).

  (7) A lithium ion secondary battery having a negative electrode using the electrode material according to (5).

  (8) A lithium ion capacitor having a positive electrode and / or a negative electrode using the electrode material according to (5).

As described below, according to the present invention, an electric double layer capacitor having a high capacitance and excellent cycle characteristics, an electrode material capable of obtaining an electric double layer capacitor and the like, and the electrode material A composite used in the above can be provided.
Moreover, since the electrostatic capacity of the negative electrode material is usually very large compared to the electrostatic capacity of the positive electrode material, the lithium ion capacitor has an electrode material of the present invention that can improve the electrostatic capacity of the positive electrode material. This is very useful because the overall capacity can be increased and the mass of the positive electrode material can be reduced.

[Composite]
The composite of the present invention is a composite of a conductive polymer having a nitrogen atom and a porous carbon material, wherein the conductive polymer is bonded to the surface of the porous carbon material, and Horvath-Kawazoe. The total pore volume of all the pores having a diameter of 0.5 to 100.0 nm measured by the BJH method is 0.3 to 3.0 cm ³ / g. A pore volume ratio (hereinafter also referred to as “pore volume ratio”) of pores having a diameter of less than 0.0 nm (hereinafter also referred to as “mesopores”) is 10 with respect to the total pore volume. The pore volume ratio of pores having a diameter of 0.5 nm to less than 2.0 nm (hereinafter also referred to as “micropores”) measured by the Horvath-Kawazoe method and the BJH method is -30%. 70-90% of the pore volume That is a composite.

Here, “the conductive polymer is bonded to the surface of the porous carbon material” means the nitrogen atom (amino group or imino group) of the conductive polymer and the hydroxyl group of the surface of the porous carbon material. A state in which a chemical bond is formed by reaction (acid-base reaction) with an acidic functional group such as carboxy group.
The “Horvath-Kawazoe method” is a method for calculating the pore volume of small pores having a diameter of 0.5 nm to 1 nm (J. Chem. Eng. Jpn., 1983, Vol. 16, p. 470), “BJH method” is a method of determining the pore volume distribution with respect to the cylindrical pore diameter (diameter: 1 nm to 100.0 nm) according to the Barrett-Joyner-Halenda standard model (J. Amer. Chem. Soc., 1951, 73, p.373-377).
Further, “total pore” refers to all pores having a diameter of 0.5 to 100.0 nm, and “total pore volume” refers to a total value of pore volumes of all pores.

In the present invention, the conductive polymer is bonded to the surface of the porous carbon material, and the total pore volume and the pore volume ratio of mesopores and micropores satisfy the above-described range. It becomes a composite (electrode material) having a high electrostatic capacity and capable of obtaining an electric double layer capacitor having excellent cycle characteristics.
This is the size that the mesopores can diffuse without sterically hindering the solvated ions, and the micropores that absorb the ions and greatly contribute to the capacitance are maintained. Furthermore, it is considered that deterioration starting from free acidic functional groups present on the surface of the porous carbon material could be suppressed.

  In the present invention, the pore volume ratio of mesopores is preferably 10% or more with respect to the total pore volume because the electrostatic capacity of an electric double layer capacitor or the like is higher. From the viewpoint of maintaining the capacitance per volume, it is preferably 20% or less with respect to the total pore volume.

  Furthermore, in the present invention, the pore volume ratio of micropores is more preferably 75 to 85% because the electrostatic capacity of an electric double layer capacitor or the like becomes higher.

Complexes of the present invention, for reasons of excellent balance between the capacitance per capacitance and unit volume per unit mass, is preferably total specific surface area of 500~2500m ² / g, 1500~2000m ² / G is more preferable.
Here, the “specific surface area” refers to a measured value measured using a BET method based on nitrogen adsorption according to a method defined in JIS K1477.

In addition, the composite of the present invention can obtain an electric double layer capacitor or the like having better cycle characteristics, and therefore a spectrum by X-ray photoelectron spectroscopy (hereinafter also referred to as “XPS”) (hereinafter referred to as “XPS”). The peak derived from nitrogen in the spectrum is also referred to as an imine-derived peak (398.5 ± 0.75 ev), an amine-derived peak (399.5 ± 0.75 ev), and a quaternary nitrogen (401.0 ± 0). .75 ev) and oxide (402.9 ± 0.75 ev) are preferably separated from the imine-derived peak (hereinafter, also simply referred to as “imine ratio”) by 40% or less. .
This is presumably because the porous carbon material was electrochemically stabilized by the strong bonding of the conductive polymer to the surface of the porous carbon material.

Here, the “XPS spectrum” is a spectrum measured using X-ray photoelectron spectroscopy, and a nitrogen-derived peak is a peak area calculated from a spectrum measured under the following conditions, and is derived from nitrogen. The peak derived from imine (398.5 ± 0.75ev), the peak derived from amine (399.5 ± 0.75ev), quaternary nitrogen (401.0 ± 0.75ev), and oxide (402.9) The ratio (%) to ± 0.75ev) refers to a value obtained by separating nitrogen-derived peaks under the condition that an asymmetric Gauss-Lorentz complex function having four peaks as vertices is mixed.
In addition, “the ratio of imine-derived peaks is 40% or less” means that the surface ratio of the porous carbon material is an acidic functional group such as a hydroxyl group or a carboxy group as compared with a peak ratio exceeding 40%. This shows that more conductive polymers are bonded and nitrogen atoms have higher energy.
X-ray source: Monochromated Al Kα (1486.6 eV)
・ X-ray beam diameter: 100 μm
・ X-ray intensity: 12.5W, 15kV
・ Pass energy: 69eV (common to each element)
・ Measurement elements: C1s, N1s, O1s

  Next, the conductive polymer and the porous carbon material used for the production of the composite of the present invention, and the production method of the composite of the present invention using these will be described in detail.

<Conductive polymer>
The conductive polymer used in the production of the composite of the present invention is not particularly limited as long as it is a polymer having a nitrogen atom that exhibits conductivity by introducing a dopant, and is a polymer doped with a dopant. Alternatively, a polymer obtained by dedoping it may be used, and examples thereof include a P-type conductive polymer and an N-type conductive polymer having an electric conductivity of 10 ⁻⁹ Scm ⁻¹ or more.
Specific examples of the P-type conductive polymer include polyaniline, polypyrrole, and derivatives thereof, and these may be used alone or in combination of two or more.
Specific examples of the N-type conductive polymer include polypyridine, polyquinoline, polythiazole, polyquinoxaline, and derivatives thereof. These may be used alone or in combination of two or more. You may use together.
Of these, polyaniline, polypyridine, and derivatives thereof are preferred because they are inexpensive and easy to synthesize.

Here, examples of the polyaniline derivative include, for example, an alkyl group, an alkenyl group, an alkoxy group, an alkylthio group, an aryl group, an aryloxy group, an alkylaryl group, an arylalkyl group, and an alkoxyalkyl group at positions other than the 4-position of the aniline. And an aniline derivative (monomer) having at least one as a substituent.
Similarly, examples of the polypyridine derivative include an alkyl group, an alkenyl group, an alkoxy group, an alkylthio group, an aryl group, an aryloxy group, an alkylaryl group, and an arylalkyl group in at least one of the 3-position, 4-position, and 6-position. And a pyridine derivative (monomer) having an alkoxyalkyl group as a substituent having a high molecular weight.

In the present invention, the conductive polymer is chemically polymerized with a monomer in a nonpolar solvent (so-called in-situ polymerization) in the presence of a porous carbon material, as shown in the method for producing a composite described later. By making it, it can produce | generate on the surface of a porous carbon material.
Specifically, when polyaniline is used as a monomer, it can be prepared, for example, by oxidative polymerization of aniline in a nonpolar solvent to which a dopant is added together with a porous carbon material.

Here, the concentration of the monomer in the nonpolar solvent is preferably 0.1 to 10% by mass, more preferably 0.2 to 8% by mass, and 0.3 to 6% by mass. Is more preferable.
Similarly, the concentration of the porous carbon material in the nonpolar solvent is preferably 0.1 to 20% by mass, more preferably 0.2 to 16% by mass, and 0.3 to 12% by mass. More preferably.
On the other hand, any of the dopants described above, the oxidizing agent for chemical polymerization (oxidation polymerization), the molecular weight modifier, the phase transfer catalyst, and the like can be those described in Patent Document 1.

Moreover, in this invention, it is preferable that the number average molecular weights of the said conductive polymer are 400-20000, It is more preferable that it is 1000-15000, It is still more preferable that it is 5000-10000.
Here, the adjustment of the number average molecular weight of the conductive polymer can be adjusted by the amount of the molecular weight modifier (end-capping agent), specifically, when polymerizing the conductive polymer, the molecular weight It is preferable to add 0.1 to 1 equivalent of the amount of the adjusting agent (terminal blocking agent) with respect to the monomer.
The number average molecular weight of the conductive polymer is determined by immersing a porous carbon material (composite) having a conductive polymer bonded to the surface in an N-methyl-2-pyrrolidone solvent, and then N-methyl-2-pyrrolidone. After collecting a part of the conductive polymer dissociated from the surface of the porous carbon material by the exchange reaction with the water, it can be measured by gel permeation chromatography (GPC) and converted to polystyrene having a known molecular weight. .

<Porous carbon material>
The specific surface area of the porous carbon material used for production of the composite of the present invention is not particularly limited, but from the viewpoint of setting the total pore volume of the composite of the present invention to 0.3 to 3.0 cm ³ / g. The carbon material preferably has a specific surface area of 1500 to 3000 m ² / g.

Specific examples of the porous carbon material include activated carbon, graphite, boron-containing porous carbon material, nitrogen-containing porous carbon material, and the like. You may use the above together.
Among these, activated carbon and / or graphite is preferable because of easy availability.
The activated carbon is not particularly limited, and activated carbon particles used in known carbon electrodes and the like can be used. Specific examples thereof include coconut shell, wood powder, petroleum pitch, phenol resin, etc., water vapor, various chemicals, alkali Activated carbon particles activated using the above, etc., and these may be used alone or in combination of two or more.
Further, the graphite is not particularly limited, and those used for negative electrode active materials of known lithium ion secondary batteries can be used. Specific examples thereof include natural graphite, artificial graphite, graphitized mesocarbon micro Examples thereof include beads and graphitized mesophase pitch carbon fibers, and these may be used alone or in combination of two or more.

<Method for producing composite>
As described above, the composite of the present invention is obtained by chemically polymerizing a monomer in a nonpolar solvent (so-called in-situ polymerization) in the presence of the porous carbon material, and converting the conductive polymer into the porous carbon material. It can be produced by generating on the surface of the material.

In addition, the composite of the present invention has high electrochemical stability when used as an electrode material, so that the conductive polymer formed on the surface of the porous carbon material is dedoped to remove the dopant. It is preferable.
Here, the method of dedoping is preferably a method of performing a base treatment for neutralizing the dopant from the viewpoint that the chemical polymerization (oxidation polymerization) of the monomer can be stopped simultaneously with the dedoping.

Specific examples of the base treatment include a method of allowing a basic substance to act on the complex; a method of mixing the complex with water and / or an organic solvent in which the basic substance is dissolved; and a complex and a base. And the like.
Specific examples of the basic substance include metal hydroxides such as ammonia water, sodium hydroxide, potassium hydroxide, lithium hydroxide, magnesium hydroxide, and calcium hydroxide; methylamine, ethylamine, Amines such as triethylamine; alkylammonium hydroxides such as tetramethylammonium hydroxide and tetraethylammonium hydroxide; hydrazine compounds such as hydrazine and phenylhydrazine; hydroxylamine compounds such as diethylhydroxylamine and dibenzylhydroxylamine; and the like.
The organic solvent is not particularly limited as long as it dissolves the basic substance. Specific examples thereof include aromatic hydrocarbons such as toluene and xylene; aliphatics such as hexane, heptane and cyclohexane. Hydrocarbons; halogenated hydrocarbons such as chloroform and dichloromethane; esters such as ethyl acetate and butyl acetate; alcohols such as methanol and ethanol; sulfoxides such as dimethyl sulfoxide; amides such as dimethylformamide; propylene carbonate and dimethyl carbonate And carbonate esters such as diethyl carbonate; lactones such as γ-butyrolactone and γ-valerolactone; nitriles such as acetonitrile and propiononitrile; N-methyl-2-pyrrolidone; and the like.

[Electrode material]
The electrode material of the present invention is an electrode material using the composite of the present invention described above as an active material. Specifically, the material of the polarizable electrode of the electric double layer capacitor of the present invention described later, a lithium ion secondary battery It can be used as a negative electrode material and a positive electrode and / or negative electrode material of a lithium ion capacitor.

[Electric double layer capacitor]
The electric double layer capacitor of the present invention is an electric double layer capacitor having a polarizable electrode formed using the electrode material of the present invention described above.

[Lithium ion secondary battery]
The lithium ion secondary battery of the present invention is a lithium ion secondary battery having a negative electrode formed using the electrode material of the present invention described above.

[Lithium ion capacitor]
The lithium ion capacitor of the present invention is a lithium ion capacitor having a positive electrode and / or a negative electrode formed using the electrode material of the present invention described above.

Here, as the polarizable electrode, the positive electrode and the negative electrode in the electric double layer capacitor, lithium ion secondary battery and lithium ion capacitor of the present invention (hereinafter referred to as “the electric double layer capacitor of the present invention”), for example, It can be comprised with the composite_body | complex of invention and a collector (for example, platinum, copper, nickel, aluminum, etc.).
Moreover, since the polarizable electrode contains the above-described conductive polymer, a binder and a conductive auxiliary agent are not necessarily required, but may be used as necessary. In addition, when using a binder and a conductive support agent, it is good also as an electrode material of this invention using a binder and a conductive support agent with the conductive polymer and porous carbon material which were mentioned above.

Specific examples of the binder include polyvinylidene fluoride, polytetrafluoroethylene, a fluoroolefin copolymer, carboxymethyl cellulose, polyvinyl alcohol, polyacrylic acid, polyvinyl pyrrolidone, and polymethyl methacrylate.
Specific examples of the conductive auxiliary include carbon black (especially acetylene black and ketjen black), natural graphite, thermally expanded graphite, carbon fiber, nanocarbon material, ruthenium oxide, metal fiber (for example, aluminum) And nickel).

  Further, the electric double layer capacitor of the present invention can reversibly occlude / release lithium ions except that the above-described electrode material (composite) of the present invention is used for the polarizable electrode. An electrolytic solution composed of a negative electrode containing an active material such as graphite and an aprotic organic solvent containing a lithium salt supporting electrolyte can be employed, and can be produced by a conventionally known production method.

  Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.

<Reference Example 1: Production of composite 1>
(Preparation of polyaniline toluene dispersion)
In 200 g of toluene, 1.2 g of aniline, 2.6 g of dodecylbensulfonic acid, and 0.26 g of 2,4,6-trimethylaniline (0.15 equivalent to aniline) as a molecular weight regulator (end-capping agent) are dissolved. Thereafter, 100 g of distilled water in which 2.2 mL of 6N hydrochloric acid was dissolved was added.
After adding 0.36 g of tetrabutylammonium bromide to this mixed solution and cooling to 5 ° C. or lower, 80 g of distilled water in which 3.52 g of ammonium persulfate was dissolved was added.
After oxidative polymerization at 5 ° C. or less for 6 hours, 100 g of toluene and then a methanol / water mixed solvent (water / methanol = 2/3 (mass ratio)) were added and stirred.
After the stirring, polyaniline toluene dispersion 1 was obtained by removing only the aqueous layer from the reaction solution obtained by separating the toluene layer into the aqueous layer.
A part of the polyaniline toluene dispersion 1 was collected and the toluene was distilled off under vacuum. As a result, the dispersion contained 1.2% by mass of solids (polyaniline content: 0.4% by mass, polyaniline number average molecular weight: 7800). It was.
Moreover, when this dispersion was filtered with a filter having a pore size of 1.0 μm, clogging did not occur, and the particle size of the polyaniline particles in the dispersion was measured using an ultrasonic particle size distribution analyzer (APS-100, manufactured by Matec Applied Sciences). As a result, it was found that the particle size distribution was monodisperse (peak value: 0.19 μm, half width: 0.10 μm).
Furthermore, this dispersion was stable without agglomeration and precipitation even after 1 year at room temperature. From the elemental analysis, the molar ratio of dodecylbenzenesulfonic acid per aniline monomer unit was 0.45. The yield of polyaniline obtained was 95%.

(Preparation of composite 1)
Mixing by adding 8 g of activated carbon (NK260, specific surface area: 2000 m ² / g, acidic functional group content: 0.1 mmol, manufactured by Kuraray Chemical Co., Ltd.) to 300 g of polyaniline toluene dispersion (polyaniline content: 1.2 g) A dispersion was obtained.
6 mL of a 2 mol / liter triethylamine methanol solution was added to the mixed dispersion, and the mixture was stirred and mixed for 5 hours.
After completion of the stirring, the precipitate was collected by filtration and washed with methanol. The filtrate and washing liquid at this time were colorless and transparent.
The washed and purified precipitate was vacuum dried to prepare a polyaniline / activated carbon composite (hereinafter referred to as “composite 1”).

<Reference Example 2: Production of composite 2>
A mixed dispersion obtained by adding 40 g of activated carbon (NK260, specific surface area: 2000 m ² / g, amount of acidic functional group: 0.1 mmol, manufactured by Kuraray Chemical Co., Ltd.) to 300 g of polyaniline toluene dispersion (polyaniline content: 1.2 g) A polyaniline / activated carbon composite (hereinafter referred to as “composite 2”) was prepared in the same manner as in Reference Example 1 except that was used.

<Comparative Example 1: Production of composite 3>
By dissolving 1.2 g of commercially available polyaniline powder (number average molecular weight: 3800, manufactured by Aldrich) in 298.8 g of N-methyl-2-pyrrolidone (NMP), a polyaniline NMP solution (polyaniline heavy content 0.4 mass%) ) Was prepared.
Mixing and dispersing by adding 8 g of activated carbon (NK260, specific surface area: 2000 m ² / g, acidic functional group amount: 0.1 mmol, manufactured by Kuraray Chemical Co., Ltd.) to 300 g of polyaniline NMP solution (polyaniline content: 1.2 g) A liquid was obtained.
A polyaniline / activated carbon composite (hereinafter, referred to as “composite 3”) was prepared by heating NMP from the mixed dispersion and vacuum distillation.

<Example 1: Production of composite 4>
In 200 g of toluene, 1.2 g of aniline, 2.6 g of dodecylbensulfonic acid and 0.26 g of 2,4,6-trimethylaniline (0.15 equivalents relative to aniline) as a molecular weight regulator (terminal blocking agent) are dissolved. After that, 100 g of distilled water in which 2.2 mL of 6N hydrochloric acid was dissolved was added.
After adding 0.36 g of tetrabutylammonium bromide to this mixed solution and cooling to 5 ° C. or lower, activated carbon (NK260, specific surface area: 2000 m ² / g, acidic functional group amount: 0.1 mmol, manufactured by Kuraray Chemical Co., Ltd.) 8 g Further, 80 g of distilled water in which 3.52 g of ammonium persulfate was dissolved was added.
After oxidative polymerization at 5 ° C. or less for 6 hours, 100 g of toluene and then a methanol / water mixed solvent (water / methanol = 2/3 (mass ratio)) were added and stirred.
After completion of the stirring, 1 g of triethylamine was added, followed by filtration and vacuum drying at 80 ° C. for 24 hours to prepare a polyaniline / activated carbon composite (hereinafter referred to as “complex 4”).

<Example 2: Production of composite 5>
A polyaniline / activated carbon composite (hereinafter, referred to as “composite 4”) was added in the same manner as composite 4 except that 40 g of activated carbon (NK260, specific surface area: 2000 m ² / g, acidic functional group: 0.1 mmol, manufactured by Kuraray Chemical Co., Ltd.) was added. "Composite 5") was prepared.

<Example 3: Production of composite 6>
In 200 g of toluene, 1.2 g of aniline, 2.6 g of dodecylbensulfonic acid and 0.26 g of 2,4,6-trimethylaniline (0.20 equivalent to aniline) as a molecular weight modifier (end-capping agent) are dissolved. After that, 100 g of distilled water in which 2.2 mL of 6N hydrochloric acid was dissolved was added.
After adding 0.36 g of tetrabutylammonium bromide to this mixed solution and cooling to 5 ° C. or lower, activated carbon (NK260, specific surface area: 2000 m ² / g, acidic functional group amount: 0.1 mmol, manufactured by Kuraray Chemical Co., Ltd.) 8 g Further, 80 g of distilled water in which 3.52 g of ammonium persulfate was dissolved was added.
After oxidative polymerization at 5 ° C. or less for 6 hours, 100 g of toluene and then a methanol / water mixed solvent (water / methanol = 2/3 (mass ratio)) were added and stirred.
After the completion of stirring, 1 g of triethylamine was added, followed by filtration and vacuum drying at 80 ° C. for 24 hours to prepare a polyaniline / activated carbon composite (hereinafter referred to as “complex 6”).

<Comparative Example 2: Production of composite 7>
50 g of a commercially available polyaniline dispersion (xylene solution, solid content concentration: 2 mass%, NX-B001 manufactured by Olmecon), activated carbon (NK260, specific surface area: 2000 m ² / g, acidic functional group amount: 0.1 mmol, Kuraray Chemical Co., Ltd.) A mixed dispersion was obtained by adding 8 g.
6 mL of a 2 mol / liter triethylamine methanol solution was added to the mixed dispersion, and then stirred and mixed for 5 hours. After completion of the stirring, the precipitate was collected by filtration and washed with methanol.
The washed and purified precipitate was vacuum-dried to prepare a polyaniline / activated carbon composite (hereinafter referred to as “complex 7”).

About the obtained composites 1-7, the nitrogen-derived peak of the XPS spectrum observed using a specific surface area (BET method) and an X-ray photoelectron spectrometer (model number: Quanta SMX, manufactured by ULVAC-PHI) The peak derived from imine (398.5 ± 0.75 ev), the peak derived from amine (399.5 ± 0.75 ev), quaternary nitrogen (401.0 ± 0.75 ev) and oxide (402.9 ± 0. The ratio of imine-derived peaks (imine ratio) when separated into 75 ev) was calculated. These results are shown in Table 1 below together with the contents (charge amounts) of activated carbon and polyaniline.
Moreover, about the obtained composites 1-7, the pore volume was measured using the high-speed specific surface area / pore distribution measuring apparatus (model number: Asap 2020, Shimadzu Micromeritic Co., Ltd.). Specifically, after drying at 150 ° C. for 6 hours, the total pore volume by the Horvath-Kawazoe method and the BJH method using a nitrogen gas as an adsorption gas and a liquid nitrogen as a refrigerant, a diameter of 2.0 nm or more and less than 20.0 nm The pore volume of each pore and the pore volume of a pore having a diameter of 0.5 nm or more and less than 2.0 nm were measured, and the pore volume ratio of each pore volume was calculated from these measurement results. These results are shown in Table 1 below.
In addition, since the pore volume of the pores having a diameter of 2.0 nm or more and less than 20.0 nm was small for the composite 3 and measurement was impossible, “−” is shown in Table 1 below.
In addition, the following Table 1 also shows the specific surface area (BET method) of activated carbon (NK260, specific surface area: 2000 m ² / g, acidic functional group amount: 0.1 mmol, manufactured by Kuraray Chemical Co., Ltd.) and the like as reference values. .

<Production of Evaluation Electrodes: Reference Examples 1-1 to 1-4, Comparative Examples 1-1 to 1-2, and Examples 1-1 to 1-3>
Conductivity for the above composites 1 to 7 or activated carbon (NK260, specific surface area: 2000 m ² / g, acidic functional group amount: 0.1 mmol, manufactured by Kuraray Chemical Co.) or graphite (bulk mesophase graphite, manufactured by JFE Chemical Co., Ltd.) An auxiliary agent (acetylene black, manufactured by Denki Kagaku Kogyo Co., Ltd.) and a binder (carboxymethyl cellulose, manufactured by Aldrich Co., Ltd.) were mixed and dispersed at the composition ratio shown in Table 2 below. Mixed to paste.
This paste was applied to an aluminum current collector foil (30 μm thickness) to a thickness of 60 μm, and then dried at 150 ° C. for 24 hours. This sheet-like electrode was pressure-treated at 20 MPa, and then cut into a disk shape (diameter 1 cm) to prepare evaluation electrodes A to I.

<Electric Double Layer Capacitors: Reference Examples 2-1 to 2-3, Comparative Examples 2-1 to 2-2, Examples 2-1 to 2-3>
In Reference Example 2-1, an electrode A for evaluation made of activated carbon was used for both electrodes.
Reference Examples 2-2 to 2-3 used evaluation electrodes C and D prepared from composites 1 and 2 as positive electrodes, respectively, and used evaluation electrodes A prepared from activated carbon as negative electrodes. .
In Comparative Example 2-1, an evaluation electrode E produced from the composite 3 was used as the positive electrode, and an evaluation electrode A produced from activated carbon was used as the negative electrode.
In Comparative Example 2-2, the evaluation electrode I made from the composite 7 was used as the positive electrode, and the evaluation electrode A made from activated carbon was used as the negative electrode.
In addition, Examples 2-1 to 2-3 used evaluation electrodes F to H prepared from the composites 4 to 6 as positive electrodes, and used evaluation electrodes A prepared from activated carbon as the negative electrodes. .
The positive and negative electrodes were opposed to each other through a glass fiber separator (manufactured by Nippon Sheet Glass Co., Ltd.), and an electric double layer capacitor was produced using a 1 mol / L tetraethylammonium tetrafluoroborate propylene carbonate solution as an electrolyte.

<Lithium ion capacitor: Reference Examples 3-1 to 3-3, Comparative Example 3-1, Examples 3-1 to 3-3>
In Reference Example 3-1, an evaluation electrode A made from activated carbon was used as the positive electrode, and an evaluation electrode B made from graphite was used as the negative electrode.
Reference Examples 3-2 to 3-3 used evaluation electrodes C and D made from composites 1 and 2 as the positive electrode, and used evaluation electrode B made from graphite as the negative electrode. .
In Comparative Example 3-1, an evaluation electrode E produced from the composite 3 was used as the positive electrode, and an evaluation electrode B produced from graphite was used as the negative electrode.
Examples 3-1 to 3-3 used evaluation electrodes F to H made from the composites 4 to 6 as the positive electrode, and used an evaluation electrode B made from graphite as the negative electrode. .
Specifically, first, the positive electrode and the negative electrode described above were laminated via a separator and vacuum-dried at 150 ° C. for 12 hours.
Next, one separator was placed on the outside of each electrode, and the four sides were sealed to produce a lithium ion capacitor element.
Next, metallic lithium capable of supplying ions with a doping amount of 350 mAh / g with respect to the mass of the negative electrode active material is pressure-bonded to a copper lath having a thickness of 70 μm, and the outermost portion of the lithium ion capacitor element is opposed to the negative electrode. One was placed in the.
After inserting the lithium ion capacitor element in which metallic lithium was arranged into the exterior laminate film, an electrolyte solution in which 1.2 M LiPF ₆ was dissolved in propylene carbonate was impregnated under vacuum conditions.
Thereafter, the exterior laminate film was heat-sealed and sealed under vacuum conditions to assemble a lithium ion capacitor cell.

<Capacitance and cycle characteristics>
(Electric double layer capacitor)
A charge / discharge test of the produced electric double layer capacitor was performed using a charge / discharge tester (HJ1001SM8A, manufactured by Hokuto Denko Co., Ltd.). Charging was performed at 60 ° C. with a constant current of 2 mA. After the voltage reached 3.0 V, charging was performed with constant voltage charging for 1 hour. The discharge was performed at a constant current of 2 mA at 60 ° C., and the final voltage was 0V.
The charge / discharge test is repeated 5000 times, and the capacitance per positive electrode material in the 10th discharge is defined as the initial capacitance (capacitance per unit weight of the positive electrode), and the capacitance maintenance ratio with respect to the initial capacitance is obtained. It was. The results are shown in Table 3 below.
(Lithium ion capacitor)
The charge / discharge test of the lithium ion capacitor cell was performed using a charge / discharge tester (HJ1001SM8A, manufactured by Hokuto Denko).
Specifically, first, charging was performed at a constant current of 2 mA until the cell voltage reached 3.8 V, and then a constant voltage of 3.8 V was applied for 1 hour to perform constant current-constant voltage charging.
Next, the battery was discharged at a constant current of 2 mA until the cell voltage reached 2.2V.
Thereafter, a continuous charge test for 10,000 hours was performed under the conditions of a cell voltage of 3.8 V and 60 ° C. After 10,000 hours have passed, the voltage application was stopped, and the sample was allowed to stand at 25 ° C. for 10 hours. Then, the charge / discharge cycle of 3.8V-2.2V was performed 5000 times to calculate the capacitance, and the positive electrode material per discharge at the first discharge Was determined as an initial capacitance (capacitance per unit weight of the positive electrode), and a capacitance retention ratio with respect to the initial capacitance was determined. The results are shown in Table 3 below.

From the results shown in Tables 1 to 3, the composites 1 and 2 having a small pore volume ratio of micropores even when the total pore volume is in the range of 0.3 to 3.0 cm ³ / g. (Evaluation electrodes C and D) have a higher retention rate of capacitance than when activated carbon (evaluation electrode A) is used, but it is below 90%, indicating that there is room for improvement (reference) Example 2-2, Reference Example 2-3, Reference Example 3-2, Reference Example 3-3).
In addition, as described above, the composite 3 (evaluation electrode E), which has a small mesopore volume and was not measurable, has a lower capacitance than when activated carbon (evaluation electrode A) is used. It turned out that the maintenance rate is also inferior (Comparative Example 2-1 and Comparative Example 3-1).
Even when the total pore volume is in the range of 0.3 to 3.0 cm ³ / g, the composite 7 (evaluation electrode I) having a small pore volume ratio of mesopores and micropores is activated carbon ( It was found that the capacitance was rather lower than the case where the evaluation electrode A) was used, and the maintenance rate was inferior (Comparative Example 2-2).
On the other hand, when composites 4 to 6 (evaluation electrodes F to H) in which the total pore volume, the pore volume ratio of micropores, and the pore volume ratio of mesopores are all in a predetermined range are used, It turned out that an electrostatic capacitance becomes higher than the case where activated carbon (evaluation electrode A) is used, and it is excellent also in cycling characteristics (Examples 2-1 to 2-3, Examples 3-1 to 3-3). .

Claims (8)

A composite of a conductive polymer having a nitrogen atom and a porous carbon material,
The conductive polymer is bonded to the surface of the porous carbon material;
The total pore volume of all the pores having a diameter of 0.5 to 100.0 nm measured by Horvath-Kawazoe method and BJH method is 0.3 to 3.0 cm ³ / g,
The ratio of the pore volume of pores having a diameter of 2.0 nm or more and less than 20.0 nm measured by the BJH method is 10 to 30% with respect to the total pore volume,
The composite_body | complex whose ratio of the pore volume of the pore which has the diameter of 0.5 nm or more and less than 2.0 nm measured by Horvath-Kawazoe method and BJH method is 70 to 90% with respect to the said total pore volume. The composite according to claim 1, wherein the total specific surface area is 500 to 2500 m ² / g.   The composite according to claim 1 or 2, wherein the conductive polymer is at least one selected from the group consisting of polyaniline, polypyrrole, polypyridine, polyquinoline, polythiazole, polyquinoxaline, and derivatives thereof.   The composite according to any one of claims 1 to 3, wherein the porous carbon material is activated carbon and / or graphite.   The electrode material using the composite_body | complex in any one of Claims 1-4.   An electric double layer capacitor having a polarizable electrode using the electrode material according to claim 5.   A lithium ion secondary battery having a negative electrode using the electrode material according to claim 5.   A lithium ion capacitor having a positive electrode and / or a negative electrode using the electrode material according to claim 5.