JP2006286803A - Electrochemical capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrochemical capacitor capable of efficiently charging/discharging with a high output. <P>SOLUTION: A hybrid capacitor 1 includes a positive electrode 2 with a specific surface area of 100 m<SP>2</SP>/g or more, a negative electrode 3 made of a material capable of reversibly absorbing and discharging lithium ions, and an electrolyte 5 made of a lithium-ion-containing organic solvent. The negative electrode 3 is formed of an amorphous carbon material including holes with three-dimensional regularity and arranged in an array macroscopically corresponding to a crystalline structure, preferably an amorphous carbon material including holes exhibiting a spherical or approximately spherical form and successively arranged in an array corresponding to a face-centered cube with a size of the hole in the maximum longitudinal direction of 1-1,000 nm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrochemical capacitor, and more particularly, to a hybrid capacitor having both power storage by an electric double layer and power storage by an oxidation-reduction reaction.

  To date, nickel-metal hydride batteries have been commercially available as power storage devices for hybrid vehicles. However, application of lithium ion batteries with higher energy density and higher output density and longer life is being studied. However, secondary batteries including lithium ion batteries involve a chemical reaction (oxidation-reduction reaction) of electrode materials in the process of charging and discharging, so that their lifetime is relatively short and it is difficult to obtain a high output.

On the other hand, the electric double layer capacitor is charged and discharged by the adsorption and desorption of ions, so it does not involve the chemical reaction (oxidation-reduction reaction) of the electrode material in the charge and discharge process, has a relatively long life and high output. Obtainable. However, on the other hand, there is a problem that the capacity is small.
From the above, a long-life, high-output, large-capacity power storage device is required as a power storage device for hybrid vehicles. In recent years, a hybrid capacitor using activated carbon for the positive electrode and a carbon material capable of reversibly occluding and releasing lithium ions for the negative electrode has been studied in order to meet such demands (see, for example, Patent Document 1). .

Since such a hybrid capacitor uses activated carbon for the positive electrode, high output can be obtained, and a carbon material capable of reversibly occluding and releasing lithium ions is used for the negative electrode. is there.
Japanese Patent Laid-Open No. 8-1007048

However, in a high-capacity charge / discharge cycle, the reversible insertion / desorption of lithium ions at the negative electrode is slower than the adsorption / desorption of positive electrode ions, so charge / discharge at the negative electrode is rate limiting. Become. Therefore, in a hybrid capacitor, development of a negative electrode material having a large capacity even in charge and discharge of high output is eagerly desired.
Accordingly, an object of the present invention is to provide an electrochemical capacitor capable of efficiently performing high-power charge / discharge.

In order to achieve the above object, an electrochemical capacitor of the present invention comprises a positive electrode having a specific surface area of 100 m ² / g or more, a negative electrode made of a material capable of reversibly occluding and releasing lithium ions, and an organic solvent containing lithium ions. In the electrochemical capacitor comprising the electrolyte solution, the negative electrode is made of an amorphous carbon material in which vacancies have three-dimensional regularity and are arranged in a macroscopic arrangement corresponding to the crystal structure It is characterized by.

In the electrochemical capacitor of the present invention, it is preferable that the holes are spherical or substantially spherical and are continuously arranged in an arrangement corresponding to a face-centered cube.
In the electrochemical capacitor of the present invention, it is preferable that the size of the pores in the maximum length direction is in a range of 1 to 1000 nm.

  In the electrochemical capacitor of the present invention, since the negative electrode is made of the above-described amorphous carbon material, a large capacity can be ensured in high output charge / discharge. Therefore, high output charge / discharge can be performed efficiently.

FIG. 1 is a schematic configuration diagram of a hybrid capacitor 1 schematically showing one embodiment of an electrochemical capacitor of the present invention.
In FIG. 1, the hybrid capacitor 1 includes a positive electrode 2, a negative electrode 3 disposed opposite to the positive electrode 2 with a space therebetween, a separator 4 interposed between the positive electrode 2 and the negative electrode 3, and the positive electrode 2. And a cell tank 6 containing a negative electrode 3 and a separator 4 and filled with an electrolytic solution 5 so as to immerse them. The hybrid capacitor 1 schematically shows battery cells employed on a lab scale. Industrially, the hybrid capacitor 1 is appropriately scaled up by a known technique. The

The positive electrode 2 reversibly adsorbs / desorbs (or occludes / releases) anions, and is formed from an electrode material having a specific surface area of 100 m ² / g or more. Such electrode material is not particularly limited, for example, a specific surface area of 100 m ² / g or more, preferably 1000 m ² / g or more, more preferably, activated carbon 1500~3000m ² / g is used.
The positive electrode 2 is formed, for example, by forming a mixture containing activated carbon, a conductive agent and a binder into an electrode shape and then drying it.

Examples of the activated carbon include ashigara activated carbon and petroleum coke activated carbon. The mixing ratio of the activated carbon is, for example, 30 to 98.5% by weight in the mixture.
Examples of the conductive agent include carbon black, ketjen black, and acetylene black. Moreover, the mixture ratio of a electrically conductive agent is 1 to 50 weight% in a mixture, for example.

Examples of the binder include polyvinylidene fluoride, fluoroolefin copolymer crosslinked polymer, fluoroolefin vinyl ether copolymer crosslinked polymer, carboxymethylcellulose, polyvinylpyrrolidone, polyvinyl alcohol, and polyacrylic acid. Moreover, the mixture ratio of a binder is 0.5-30 weight% in a mixture, for example.
To form into an electrode shape, for example, a mixture containing activated carbon, a conductive agent and a binder is stirred and mixed in a solvent, applied onto a metal foil, dried, punched into an electrode shape, and then dried. Let In addition, metal foil consists of aluminum foil etc. and is used as a collector.

Examples of the solvent include N-methylpyrrolidone, dimethylformamide, toluene, xylene, isophorone, methyl ethyl ketone, ethyl acetate, methyl acetate, ethyl acetate, dimethyl phthalate, ethanol, methanol, butanol, water, and the like.
The negative electrode 3 reversibly occludes / releases lithium ions, and is formed of an electrode material that can reversibly occlude / release lithium ions. In the negative electrode 3, an amorphous carbon material in which vacancies have a three-dimensional regularity and are arranged in an arrangement corresponding to a crystal structure macroscopically is used as such an electrode material.

Such an amorphous carbon material is prepared by mixing a polymerizable monomer into a colloidal crystal in accordance with, for example, the methods described in JP-A-9-67405 and JP-A-2001-2131992. Then, the monomer can be polymerized first, then calcined at 800 to 3000 ° C., and then the colloidal crystals can be removed.
The polymerizable monomer is not particularly limited as long as it can polymerize a polymer (resin) that can be converted into a carbon material by firing. For example, furfuryl alcohol capable of obtaining a furfuryl alcohol resin by polymerization. Phenol and formaldehyde capable of obtaining a phenol-aldehyde resin by polymerization, styrene and divinylbenzene capable of obtaining a styrene-divinylbenzene resin by polymerization, furfuryl alcohol capable of obtaining a phenol resin by polymerization, and Phenol is mentioned.

The colloidal crystal can be prepared by a method described later from a colloidal solution in which colloidal particles are dispersed in a dispersion medium.
Examples of colloidal particles include alkaline earth metal carbonates, silicates, phosphates, metal oxides, metal hydroxides, other metal silicates or other metal carbonates, and natural product particles. An inorganic compound is mentioned. More specifically, examples of the alkaline earth metal carbonate include calcium carbonate, barium carbonate, and magnesium carbonate. Examples of alkaline earth metal silicates include calcium silicate, barium silicate, and magnesium silicate. Examples of alkaline earth metal phosphates include calcium phosphate, barium phosphate, and magnesium phosphate. Examples of the metal oxide include silica, titanium oxide, iron oxide, cobalt oxide, zinc oxide, nickel oxide, manganese oxide, and aluminum oxide. Examples of the metal hydroxide include iron hydroxide, nickel hydroxide, aluminum hydroxide, calcium hydroxide, and chromium hydroxide. Examples of other metal silicates include zinc silicate and aluminum silicate. Examples of other metal carbonates include zinc carbonate and basic copper carbonate. Examples of natural products include shirasu balloon and perlite.

The shape of the colloidal particles is preferably spherical (true sphere) or substantially spherical, and the size is, for example, in the range of 1 to 1000 nm, preferably 100 to 500 nm as the size in the maximum length direction. Range.
Examples of the colloidal particle dispersion medium include a fluorine compound solution such as hydrofluoric acid, an alkaline aqueous solution, and an acidic aqueous solution.

The colloid solution is prepared by mixing colloidal particles with a dispersion medium. The solid content concentration (particle concentration) of the colloidal solution is, for example, 1% by weight or more, preferably 10% by weight or more.
A colloidal crystal is a state in which colloidal particles are aggregated to form a three-dimensionally ordered macroscopic crystal structure. For example, after applying an electric field to a colloidal solution, the dispersion medium is removed. Can be obtained. Also, for example, the lower part of the substrate is immersed in a relatively dilute colloidal solution having a solid content concentration of 1 to 5% by weight with a gap of several tens of μ, and a capillary phenomenon causes The colloidal solution can be obtained by rising between the substrates and evaporating and removing the dispersion medium to precipitate colloidal crystals between the substrates. Alternatively, for example, the colloidal solution can be left standing, the colloidal particles can be naturally settled and deposited, and then the dispersion medium can be removed. Moreover, it can obtain by well-known methods, such as an advection accumulation method.

  Furthermore, as another method, the colloidal solution can be dropped on the substrate and the dispersion medium can be distilled off. The dispersion medium is distilled off at room temperature or by heating to a temperature equal to or higher than the boiling point of the dispersion medium. Alternatively, the colloidal solution can be dropped on a preheated substrate to distill off the solvent. The substrate can also be rotated when or after the colloidal solution is dropped onto the substrate.

  In this method, the operation of dropping the colloid solution and removing the dispersion medium is repeated, the concentration of the colloid solution is adjusted, the amount of colloid solution to be dropped is adjusted, and the above is arbitrarily combined. Thus, the film thickness and area of the obtained colloidal crystal can be freely controlled. In this method, it is possible to easily increase the area or the volume while maintaining regularity. Therefore, it is possible to increase the area or the volume of the amorphous carbon material in accordance with it.

  Further, in this method, if a colloid solution having a solid content concentration of 10% by weight or more is used, a colloidal crystal having a considerable film thickness can be formed on the substrate by one dropping, and by repeating the dropping and drying, The film thickness can be freely controlled. Further, in this method, for example, by using a monodispersed colloidal solution, the obtained colloidal crystal can be made into a colloidal crystal having a single crystal structure (colloidal single crystal). Amorphous carbon material obtained using colloidal single crystal has regularity and continuity in the arrangement of pores in the macro, and there is no variation in the wavelength of reflected light, and the wavelength of selective reflected light is unified as a whole. be able to.

As another method, the colloidal solution is sucked under reduced pressure using a suction funnel or the like, the dispersion medium is sucked and removed, and colloidal particles are deposited on the filter paper or filter cloth on the suction funnel. It can also be obtained. Also in this method, for example, a colloidal single crystal can be obtained by using a monodispersed colloidal solution.
The concentration of the dispersion medium used for suction and removal can be appropriately selected depending on the volume of the colloidal crystal to be obtained by one operation. Further, once all the solvent is removed by suction, a dispersion medium is added again and the same operation is repeated, whereby a colloidal crystal having an arbitrary volume can be obtained. In this method, as in the above-described method, it is possible to increase the area or volume while maintaining regularity.

The suction method is not particularly limited, but suction is performed by, for example, an aspirator or a pump. The suction speed is not particularly limited, and examples thereof include a speed at which the interface of the dispersion medium in the funnel is constantly lowered at a reduced pressure of about 5320 Pa.
Alternatively, the substrate can be obtained by immersing the substrate in a colloidal solution and pulling it up or evaporating the dispersion medium. By adjusting the concentration of the colloid solution or repeatedly performing the same operation, a colloidal crystal having an arbitrary area and volume can be obtained. The pulling speed is not particularly limited, but is preferably pulled at a slow speed because crystals grow at the interface between the dispersion medium and the atmosphere. The speed of evaporating the dispersion medium is not particularly limited, but for the same reason, it is preferably evaporated at a slow speed. A colloidal single crystal can be obtained by using a monodispersed colloidal solution.

  In the above-described method, the above-described monomer is mixed with the above-described colloidal crystal. The concentration of the monomer with respect to the sum of the colloidal crystals and the monomer is 0.1% by weight to 99.9% by weight. Then, according to the type of polymerization, a known catalyst, polymerization initiator, crosslinking agent, etc. are dissolved in an organic solvent substituted with nitrogen, and this is impregnated in a mixture of colloidal crystals and monomers, and then an appropriate Heat to temperature or light. Then, in the colloidal crystal in which colloidal particles are regularly arranged three-dimensionally, the monomers are polymerized to obtain a polymer, thereby obtaining a colloidal crystal-polymer complex. The polymerization is a known solution such as a radical polymerization method or a polycondensation method using an acid, a block shape, an emulsification, a reverse phase suspension polymerization or the like. The polymerization temperature is, for example, 0 to 100 ° C., and the polymerization time is, for example, 10 Min to 48 hours.

Next, the colloidal crystal-polymer complex is fired at 800 to 3000 ° C. Firing can be carried out at a temperature in the range of 800 to 3000 ° C. in an inert atmosphere. The rate of temperature increase up to the firing temperature is set in a range where the structure does not collapse due to local heating.
Then, colloidal crystals are removed from the obtained fired product. For example, the colloidal crystal is removed by dissolving and removing the colloidal crystal. In order to dissolve and remove the colloidal crystals, for example, when the colloidal particles are inorganic compounds, an acidic solution, an alkaline solution, an acidic solution, or the like of a fluorine compound can be used as a solution for dissolution. For example, when the colloidal particles are silica, shirasu balloon or silicate, it can be obtained in an aqueous solution of hydrofluoric acid, an acidic solution such as ammonium fluoride, calcium fluoride or sodium fluoride or an alkaline solution such as sodium hydroxide. Immerse the fired product. The solution may be at least four times the amount of fluorine element relative to the silicon element of the fired product, and the concentration is preferably at least 10% by weight. The alkaline solution preferably has a pH of 11 or higher. When the colloidal particles are metal oxide or metal hydroxide, the fired product is immersed in an acidic solution such as hydrochloric acid. The acidic solution is preferably pH 3 or lower.

The amorphous carbon material obtained in this way is porous, and the pores resulting from the removed nanoscale colloidal particles have three-dimensional regularity and have a macroscopic crystalline structure. They are arranged in a corresponding arrangement.
Note that macroscopic means to exclude such arrangement only in a very small region. For example, the reflection spectrum is almost single regardless of the portion of the obtained amorphous carbon material. It exhibits wavelength absorption, meaning that the amorphous carbon material is monochromatic.

  The vacancies may be closed voids as long as they have a spherical shape (true sphere) or a substantially spherical shape corresponding to the colloidal particles and have regularity corresponding to the crystal structure. From the viewpoint of expressing optical characteristics, preferably they are continuously arranged. When the holes are continuously arranged, the voids may be voids whose periphery is closed with an amorphous carbon material, or voids having portions communicating with adjacent voids.

  The size of the holes is not particularly limited, but the size in the maximum length direction is preferably in the range of 1 to 1000 nm. If it is less than 1 nm, the void is excessively small and there is no significant difference from the bulk carbon material. On the other hand, if it exceeds 1000 nm, the void is excessively large, and the density of carbon in the electrode may be reduced. In consideration of the surface area, the electrode density, and the like, the size of the pores in the maximum length direction is more preferably in the range of 50 to 500 nm.

Further, the regularity in the arrangement of the holes is not particularly limited as long as it is an arrangement corresponding to the crystal structure, and examples thereof include a face-centered cube, a body-centered cube, and a simple cube. Preferably, they are continuously arranged in an arrangement corresponding to a face-centered cubic. Since the face-centered cubic has a close-packed structure, the surface area is large and pores are densely arranged.
Further, in the case of including holes of different sizes, a more complicated pattern can be formed. In the preparation method described above, the arrangement of the holes is determined by the colloidal particle packing arrangement, and the structure capable of arranging the colloidal particles is reflected in the regularity of the arrangement of the holes.

More specifically, the obtained amorphous carbon material preferably has a (1,1,1) plane orientation in which the vacancies are macroscopically face-centered cubic lattices on the surface of the amorphous carbon material. Are arranged. This means that, for example, even when an amorphous carbon material is cut on an arbitrary surface, the surface always has the above orientation.
The negative electrode 3 is formed, for example, by forming a mixture containing the amorphous carbon material, the conductive agent and the binder obtained as described above into an electrode shape and then drying the mixture.

As the conductive agent, the same conductive agent as described above is used. Moreover, the mixture ratio of a electrically conductive agent is 1 to 50 weight% in a mixture, for example.
As the binder, the same binder as described above is used. Moreover, the mixture ratio of a binder is 0.5-20 weight% in a mixture, for example.
In order to form an electrode shape, for example, a mixture containing an amorphous carbon material, a conductive agent and a binder is stirred and mixed in a solvent, applied onto a metal foil, dried, and punched into an electrode shape. Then dry. In addition, as a solvent, the thing similar to the above is mentioned. The metal foil is made of copper foil or the like and used as a current collector.

The separator 4 is made of an insulating material. Examples of the insulating material include glass fibers, silica and alumina fibers, whisker and other inorganic fibers, for example, natural fibers such as cellulose, and organic materials such as polyolefin and polyester. Examples include fibers.
Moreover, the separator 4 is shape | molded, for example in plate shape.
The electrolytic solution 5 is made of an organic solvent containing lithium ions, and is prepared by dissolving a lithium salt in the organic solvent.

Examples of the lithium salt include LiClO ₄ , LiCF ₃ SO ₃ , LiC (SO ₂ CF ₃ ) ₃ , LiB (C ₆ H ₅ ) ₄ , LiC ₄ F ₉ SO ₃ , LiC ₈ F ₁₇ SO ₃ , LiB [C _{6 H 3 (CF 3) 2} -3,5] 4, LiB (C 6 F 5) 4, LiB [C 6 H 4 (CF 3) -4] 4, LiBF 4, LiPF 6, LiAsF 6, LiSbF 6 LiCF ₃ CO ₂ , LiN (CF ₃ SO ₂ ) ₂ . In the above formula, [C ₆ H ₃ (CF ₃ ) ₂ -3, 5] is the 3rd and 5th positions of the phenyl group, and [C ₆ H ₄ (CF ₃ ) -4] is the 4th position of the phenyl group. Each of which is substituted with —CF ₃ .

  Examples of the organic solvent include propylene carbonate, propylene carbonate derivatives, ethylene carbonate, ethylene carbonate derivatives, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, γ-butyrolactone, 1,3-dioxolane, dimethyl sulfoxide, sulfolane, and formamide. , Dimethylformamide, dimethylacetamide, dioxolane, phosphate triester, maleic anhydride, succinic anhydride, phthalic anhydride, 1,3-propane sultone, 4,5-dihydropyran derivative, nitrobenzene, 1,3-dioxane, 1 , 4-dioxane, 3-methyl-2-oxazolidinone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydro Rofuran derivatives, sydnone compounds, acetonitrile, nitromethane, alkoxy ethane, and toluene. These can be used alone or in combination of two or more.

The electrolytic solution 5 is prepared so that the concentration of the lithium salt in the organic solvent is, for example, 0.1 to 2.5 mol / liter, preferably 0.2 to 2.0 mol / liter. Moreover, it prepares so that the moisture content in the electrolyte solution 5 may be 150 ppm or less, for example, Preferably it is 50 ppm or less so that a high withstand voltage may be obtained.
And in this hybrid capacitor 1, since the negative electrode 3 consists of an amorphous carbon material mentioned above, a big capacity | capacitance can be ensured in charge / discharge of high output. Therefore, high output charge / discharge can be performed efficiently.

[Production of amorphous carbon material]
1) Production of Amorphous Carbon Material A A colloidal solution was prepared from a silica colloid suspension aqueous solution (manufactured by Nissan Chemical Co., Ltd., silica spherical fine particles, colloid particle diameter (40-50 nm)) as a 3% solid content aqueous solution.
The colloidal solution is put in a 30 mm diameter SPC filter holder (manufactured by Shibata Kagaku) covered with a filter cloth (nitrocellulose membrane filter manufactured by MILLIPORE, filter pore size: 25 nm), and filtered under reduced pressure with an aspirator (about 5320 Pa). A silica thin film was obtained on the cloth. After peeling off the filter cloth, it was sintered in air at 1000 ° C. for 2 hours to obtain a silica colloid single crystal film.

  A mixture of 10.0 g of furfuryl alcohol and 0.0500 g of oxalic acid hexahydrate (both manufactured by Wako Pure Chemical Industries, Ltd.) was dropped onto a silica colloid single crystal film on a Teflon (registered trademark) sheet, and silica colloid The excess mixture overflowing from the crystals was wiped off and polymerized in the air at 80 ° C. for 48 hours. The obtained silica-furfuryl alcohol resin composite was subjected to moisture removal and polymer re-curing process at 200 ° C. for 1 hour in a tube furnace under an argon atmosphere, and then heated to 1000 ° C. at 5 ° C./min. Then, the silica-furfuryl alcohol resin composite was fired by firing at 1000 ° C. for 1 hour and naturally cooling.

Thereafter, the obtained fired product was immersed in a 48 wt% hydrofluoric acid solution overnight at room temperature to dissolve the silica colloid single crystal. The hydrofluoric acid solution was changed every 12 hours. Thereafter, washing with pure water was repeated until neutrality, and amorphous carbon material A was obtained.
A scanning electron microscope (SEM) photograph of the surface of the obtained amorphous carbon material A is shown in FIG. From FIG. 2, the holes are spherical with a diameter of about 50 nm.
2) Manufacture of amorphous carbon material B Amorphous carbon material except that monodispersed silica colloid suspension aqueous solution (manufactured by Nippon Shokubai Co., Ltd., monodispersed silica spherical fine particles KE-P30, colloidal particle size (280 nm)) was used. By the same operation as A, an amorphous carbon material B was obtained.

A scanning electron microscope (SEM) photograph of the surface of the obtained amorphous carbon material B is shown in FIG. From FIG. 3, the holes are spherical with a diameter of 280 nm, and are connected to adjacent holes through through holes of approximately 40 nm. Further, the holes are arranged in a face-centered cubic shape, In FIG. 2, it was confirmed that the layers were arranged in (1,1,1) plane orientation.
Further, the amorphous carbon material B was placed in a dark place, irradiated with white light at a viewing angle of 0 °, and the wavelength of reflected light was measured. Since the obtained reflection spectrum shows unimodal absorption only in the vicinity of 450 nm, even in the amorphous carbon material B, the vacancies have three-dimensional regularity and are regularly arranged macroscopically. It was confirmed that
[Manufacture of carbon electrodes]
Using the carbon materials A to D shown below, carbon electrodes of Examples 1 and 2 and Comparative Examples 1 and 2 corresponding to them were produced by the method described below.

Carbon material, conductive agent (manufactured by Lion: Ketjen black), binder (manufactured by Daikin: PVDF dispersion), carbon material: conductive agent: binder (solid content) = 85: 5: 10 After blending, pressing and mixing in a mortar, the mixture was rolled to 100 μm using a hand press, punched into a disk shape with a diameter of 5 mm, and further vacuum dried at 100 ° C. for 12 hours to produce a carbon electrode. .
Example 1: Carbon material A (amorphous carbon material A)
Example 2: Carbon material B (amorphous carbon material B)
Comparative Example 1: Carbon material C (manufactured by Kureha Chemical Co., Ltd .: Carbotron PS (F), SEM photograph is shown in FIG. 4 for reference)
Comparative Example 2: Carbon material D (Osaka Gas: MCMB25-28, SEM photograph is shown in FIG. 5 for reference)
[Assembly of test cell]
A lithium metal foil as a counter electrode (also serving as a reference electrode), carbon electrodes of Examples 1 and 2 and Comparative Examples 1 and 2 as working electrodes, and a 50 μm thick cellulose separator (manufactured by Nippon Kogyo Paper Co., Ltd.) punched to 24 mmφ A bipolar test cell (manufactured by Toyo System Co., Ltd.) shown in FIG. 6 was assembled using 1 mL of 1M LiPF ₆ ethylene carbonate / diethylene carbonate solvent (1: 1 volume ratio) as an electrolytic solution.
[Charge / discharge test]
Using TOSCAT (manufactured by Toyo System Co., Ltd.), a charge / discharge test was conducted under the conditions of potential range: 3 to 0 V · vs · Li / Li ⁺ , current density: 1 to 20 mA / cm ² , and evaluation of the carbon electrode single electrode Was done. FIG. 7 shows the relationship between current density and capacity in charge and discharge in each test cell using the carbon electrodes of Examples 1 and 2 and Comparative Examples 1 and 2.
[Test results]
From FIG. 7, Comparative Examples 1 and 2 (carbon materials C and D) can obtain only a very low capacity during high output charge / discharge, while Examples 1 and 2 (carbon materials A and B) are high. It can be seen that a high capacity can be obtained even during output charging and discharging.

It is a schematic block diagram of the hybrid capacitor which shows typically one Embodiment of the electrochemical capacitor of this invention. 3 is an image processing diagram of an SEM photograph of a carbon material A used in Example 1. FIG. 6 is an image processing diagram of an SEM photograph of carbon material B used in Example 2. FIG. 6 is an image processing diagram of an SEM photograph of a carbon material C used in Comparative Example 1. FIG. 6 is an image processing diagram of an SEM photograph of a carbon material D used in Comparative Example 2. FIG. It is a center sectional view showing a bipolar test cell used for a charge / discharge test. It is a correlation diagram which shows the relationship between a current density and a capacity | capacitance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hybrid capacitor 2 Positive electrode 3 Negative electrode 4 Separator 5 Electrolyte

Claims (3)

In an electrochemical capacitor comprising a positive electrode having a specific surface area of 100 m ² / g or more, a negative electrode made of a material capable of reversibly occluding and releasing lithium ions, and an electrolytic solution made of an organic solvent containing lithium ions,
The electrochemical capacitor characterized in that the negative electrode is made of an amorphous carbon material in which vacancies have three-dimensional regularity and are arranged in an arrangement corresponding to a crystal structure macroscopically.   2. The electrochemical capacitor according to claim 1, wherein the holes have a spherical shape or a substantially spherical shape, and are continuously arranged in an arrangement corresponding to a face-centered cube.   3. The electrochemical capacitor according to claim 1, wherein a size of the vacancies in a maximum length direction is in a range of 1 to 1000 nm.