JP2001230154A - Electrochemical capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrochemical capacitor which can improve the strength reliability and airtightness of its package and, at the same time, can contribute to resistance and weight reduction of electrode terminals. SOLUTION: This electrochemical capacitor is constituted in such a way that at least one laminated body in which polarizable electrodes 2 and 3 formed by using a carbon material as a chief material are respectively set up on paired current collecting bodies made of a metallic material and an electronic insulating separator is sandwiched between the polarizable electrodes is sealed in the package 60 in a state where the laminated body is dipped in an organic or inorganic electrolytic solution. The electrodes 2 and 3 are housed in the package 60 and the electrode terminals 2 and 3 are stuck to the internal surface of the package 60 except their connecting sections 4 and 5 which are used for connecting the terminals 2 and 3 to an external circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an electrochemical capacitor using a carbon material as a polarizable electrode material.

[0002]

2. Description of the Related Art Electrochemical capacitors (hereinafter, referred to as “capacitors”) have farad-class large capacities and excellent charge / discharge cycle characteristics. In addition to being used as batteries for transport aircraft, from the viewpoint of effective use of energy, use in applications such as storage of nighttime power is also being studied.

As shown in FIG. 5, a single-electrode cell 10, which is one of the basic structures of such a capacitor, generally has polarizers on the positive electrode side on current collectors 20 and 22 each made of a metal material. An electrode 24 and a polarizable electrode 26 on the negative electrode side are formed, and have a structure in which the polarizable electrodes 24 and 26 are separated by a separator 28. The liquid is impregnated.

FIG. 6 shows the structure of a single capacitor cell 12 in which a plurality of single electrode cells 10 are connected to a current collector 20.
・ Electrode extraction portions 30 and 32 formed at 22 are electrically connected in parallel. Relatively large capacitors used for automobiles, etc.
Such a single capacitor cell 12 is preferably used.
Each of the single electrode cell 10 and the single capacitor cell 12 is a flat plate type, and has a feature that high filling and large area can be easily performed.

When a capacitor as described above is actually used, strict packaging suitability (sealability, barrier property, abrasion resistance, etc.) except for the electrode terminals is required to prevent the intrusion of moisture that causes leakage or deterioration of the electrolyte from outside air. It is important to package in a manner such as resistance and expansion resistance. For this reason, as shown in FIG. 4, for example, as shown in FIG. 4, a single electrode cell 10 or a single capacitor cell 12 is provided in a package 60 which is a pouch made of an aluminum laminated film or the like.
And an organic electrolyte solution, and the electrode terminals 44 and 46 covered with the heat-sealing film are taken out of the package 60, and then heat-sealed together with the sealing part 62 of the package to seal. ing.

In the above-described package method, when the thickness of the electrode terminals 44 and 46 is too large, it is difficult to seal with the seal portion 62 of the package. Further, there is a problem that stress is concentrated on the sealing portion 62 of the package due to impact, vibration, or the like, and the strength reliability and airtightness of the package 60 are significantly reduced.

To solve this, for example, as shown in FIG. 4, electrode terminals 44 and 4 respectively connected to a current collector.
A packaging method has been proposed in which the electrode unit 50 in which the holding member 54 is integrated with the holding member 54 is interposed in the package 60 and sealed.

By the way, in the capacitor shown in FIG. 4, when a large current is applied to the electrode terminal, it is necessary to increase the sectional area of the electrode terminal in order to reduce the resistance of the electrode terminal. However, when the cross-sectional area of the electrode terminal is increased,
There is a problem that the weight of the electrode terminal increases in proportion thereto. In addition, an increase in the cross-sectional area of the electrode terminal leads to an increase in the sealing area, so that the airtightness becomes insufficient, and there is a problem that deterioration of the electrolyte due to moisture permeation cannot be ignored.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of such problems of the related art,
It is an object of the present invention to provide an electrochemical capacitor capable of improving strength reliability and airtightness of a package and contributing to reduction in resistance and weight of an electrode terminal.

[0010]

Means for Solving the Problems According to the present invention, a pair of current collectors made of a metal material is provided with a polarizable electrode formed mainly of a carbon material, and the polarizable electrode is An electrochemical capacitor in which at least one laminate having an electronic insulating separator interposed therebetween is sealed in a package while being immersed in an organic or inorganic electrolytic solution, and the electrode terminals are respectively connected to the current collector. To
There is provided an electrochemical capacitor characterized in that a part other than a connection part for connecting to an external circuit of an electrode terminal is adhered to an inner surface of the package while being internal to the package. At this time, it is preferable that the electrode terminal has a shape that maximizes its cross-sectional area and a shape that maximizes the connection area with the current collector.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In an electrochemical capacitor according to the present invention, a pair of current collectors made of a metal material is provided with a polarizable electrode formed mainly of a carbon material, and an electron is provided between the polarizable electrodes. An electrochemical capacitor in which at least one laminate sandwiching an insulating separator is immersed in an organic or inorganic electrolytic solution and sealed in a package, wherein electrode terminals respectively connected to the current collector are included in the package. And a portion other than a connection portion for connecting the electrode terminal to an external circuit is adhered to the inner surface of the package. Thereby, the strength reliability and airtightness of the package are improved, and the resistance and the weight of the electrode terminals can be reduced.

Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 is a schematic perspective view showing an example of a package in the electrochemical capacitor of the present invention, and FIG.
FIG. 3 shows an example of the electrochemical capacitor of the present invention,
(A) is a front view, (b) is a side view, and (c) is A of (a).
It is -A sectional drawing. In this embodiment, the structure in which the electrode terminals 2 and 3 are arranged on one side surface of the single capacitor cell is shown. However, a structure in which the electrode terminals 2 and 3 are drawn out to both sides of the cell is also possible. As a result, the electrode terminals can be expanded to the same extent as the width of the polarization electrode, and the internal resistance of the cell can be further reduced.

Here, the main feature of the electrochemical capacitor of the present invention is that, as shown in FIGS. 1 and 2, electrode terminals 2 and 3 respectively connected to a current collector are provided inside a package 60,
Except for the connection parts 4 and 5 of the electrode terminals 2 and 3, a package 6
0 is attached to the inner surface. Thereby, since the electrode terminals 2 and 3 are integrated in the package 60,
The strength reliability and airtightness of the package 60 can be greatly improved, and the thickness and shape of the electrode terminals are not affected, so that the resistance and weight of the electrode terminals 2 and 3 can be reduced. At this time, the electrode terminals 2, 3
Must be electrically insulated, and insulation can be reliably maintained by interposing an insulating spacer between the electrode terminals 2 and 3.

Here, the electrode terminals 2 and 3 used in the present invention
Has a shape that maximizes the cross-sectional area of the electrode terminal and the connection area with the current collector, as shown in FIG.
This is preferable because it can contribute to lowering the resistance of the electrode terminal and lowering the connection resistance with the current collector.

In the example shown in FIG. 3, the connecting portions 4a and 4b are provided with through holes, and are electrically connected to external circuits by bolts. For this reason, the sealing surfaces of the electrode terminals 2 and 3 are both surfaces 6a and 6b in the sectional view of FIG. In the case where the connecting portion to be connected to the external circuit has a tap structure and does not penetrate the electrode terminal, the connecting portion is provided on only one side of each of 4a and 4b, so that only one sealing surface is required. Therefore, since the number of sealing surfaces is reduced, the amount of permeated water is reduced, and the long-term reliability is improved.

The electrode terminals 2 and 3 used in the present invention
Indicates the joint 6 with the package (see the hatched portion in FIG. 3).
It is important to previously cover with a heat sealing film.
This is because the reliability of the strength and airtightness of the electrochemical capacitor of the present invention can be maintained by ensuring the bonding between the electrode terminals 2 and 3 and the package 60 at the time of heat fusion.

The heat sealing film used in the present invention is:
The resin is not particularly limited as long as it is a resin having excellent bonding properties with the electrode terminals 2 and 3 and the package 60 and has a solvent resistance to an organic or inorganic electrolytic solution. A modified resin to which a good functional group is added can be suitably used.

The material of the electrode terminals 2 and 3 used in the present invention is not particularly limited as long as it has high electric conductivity and high-temperature deformation resistance. For example, high-purity aluminum or the like is preferably used. it can.

Further, the package 60 used in the present invention
In order to have a function according to the purpose, a laminated film in which films with different characteristics are laminated is used,
In particular, an aluminum laminate film can be suitably used.

The aluminum laminated film used in the present invention is an aluminum foil film coated on both sides with a resin,
The aluminum foil blocks moisture permeation from the outside. The inner resin in contact with the organic or inorganic electrolyte is preferably a polyolefin resin having excellent solvent resistance, and the outer resin is preferably polyethylene or the like from the viewpoint of weather resistance.

Next, an example of the method for packaging an electrochemical capacitor according to the present invention will be described. For example, the electrode extraction portions 30, 32 of the single capacitor cell 12 shown in FIG.
And the electrode terminals 2 and 3 are connected respectively. Here, the connection between the two is preferably a method that minimizes the electric resistance of the joint, and ultrasonic welding, spot welding, electron beam welding, or the like can be employed. Among them, the ultrasonic welding method uses thin foil-like electrode extraction portions 30, 32 and block-like electrode terminals 2, 2.
3 was experimentally confirmed to be suitable for connection. The electrode take-out portions 30 and 32 are formed at portions where the electrode terminals 2 and 3 are bent into an L shape (portions without oblique lines in FIG. 3). this is,
If the welding surface is formed in the shaded portion in FIG. 3, the surface is roughened by welding, the joining property with the inner surface of the package 60 is reduced, and there is a high possibility that a sealing failure occurs.

Next, the single capacitor cell 12 connected to the electrode terminals 2 and 3 and the organic electrolyte are charged into a package 60 made of an aluminum laminated film or the like. Thereafter, the package 60 and the electrode terminals 2 and 3 are adhered to each other by performing heat fusion while keeping the electrode terminals 2 and 3 at predetermined positions of the package 60. At this time, it is important that the width of the seal surface of the joint 6 with the package (the hatched portion in FIG. 3) is equal to the seal width when the package 60 is manufactured. As a result, all the sealing surfaces of the capacitor cell shown in FIG. 1 have the same cross-sectional area per unit length of the sealing surface with the outside, so that the moisture permeating from the resin layer of the cross-section can be minimized. Experimentally, a seal width of 10
If it is about mm, a life of about 10 years can be secured as a capacitor.

After the single capacitor cell 12, the electrode terminals 2 and 3, and the organic electrolyte are sealed in the package, the aluminum laminate film of the connection portions 4 and 5 of the electrode terminals 2 and 3 is removed. As a result, FIGS.
As shown in the figure, the packaging of the electrochemical capacitor is completed. The capacitor shown in FIG. 1 is used by being housed in a capacitor container 70 shown in FIG.

Here, the single capacitor cell 12 which is one of the basic structures of the electrochemical capacitor of the present invention includes, for example, a pair of current collectors 2 made of a metal material as shown in FIG.
A positive electrode-side polarizable electrode 24 and a negative electrode-side electrode 26 each formed mainly of a carbon material are formed at 0 and 22, respectively, and a laminate in which an electronic insulating separator 28 is sandwiched between the polarizable electrodes 24 and 26. In this structure, a plurality of bodies (single electrode cells) 10 are stacked, and then electrically connected in parallel at electrode extraction portions 30 and 32 formed on the current collectors 20 and 22, respectively.

As the polarizable electrode material used in the present invention, activated carbon is generally used and widely used for capacitors. Using this carbon material as a main material, a polarizable electrode is produced. The production of the polarizable electrode is performed by adding a conductive agent such as an organic binder or carbon black to a carbon material, mixing, kneading, or the like, and processing into various shapes such as a plate shape or a sheet shape.

The organic electrolyte used in the present invention is a solute, that is, an electrolyte, a quaternary ammonium tetrafluoroborate (BF ₄ ⁻ ) salt or hexafluorophosphoric acid (PF ₆ ⁻ ) salt, or tetraethylammonium (PF ₆ ⁻ ) salt. TEA ⁺⁾ or BF ₄ salt or PF ₆ salt of tetrabutylammonium (TBA ^+), BF ₄ salt or a PF ₆ salt of triethylmethylammonium (TEMA ^+), or quaternary phosphonium salt of BF ₄ salt or P
F ₆ salt, BF _{4 of} tetraethylphosphonium (TEP ⁺ )
Salt or PF ₆ salt, or general formula

[0027]

Embedded image

(Wherein R ₁ and R ₂ are an alkyl group having 1 to 5 carbon atoms, and R ₁ and R ₂ may be the same or different groups). _Four
Salts or PF ₆ salts, and BF ₄ salts or PF ₆ salts of 1-ethyl-3-methyliridazolium (EMI ⁺ ) can be suitably used.

Further, the organic electrolyte solution used in the present invention includes propylene carbonate (PC), γ-butyl lactone (GBL), and ethylene carbonate (E) as solvents.
Those containing at least one of C) and sulfolane (SL) are preferably used. In addition, the PC, GBL, EC,
It is also possible to use a solvent containing at least one of SL as a main solvent and a solvent containing at least one of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) as a secondary solvent. is there.

Here, the main solvent refers to a solvent capable of obtaining sufficient performance as an electrolyte solvent even when the substance is used alone, and the sub-solvent refers to a solvent having a low performance as an electrolyte solvent when used alone. It refers to a solvent that, when used in combination with the main solvent, can attain a performance higher than that of the main solvent alone or the auxiliary solvent alone. The amount of the auxiliary solvent added is not limited to, for example, 50% or less.

[0031]

As described above, according to the electrochemical capacitor of the present invention, not only the strength reliability and airtightness of the package can be improved, but also the resistance and the weight of the electrode terminals can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an example of a package in an electrochemical capacitor according to the present invention.

FIGS. 2A and 2B show an example of the electrochemical capacitor of the present invention, wherein FIG. 2A is a front view, FIG. 2B is a side view, and FIG.

FIG. 3 is a schematic perspective view showing an example of an electrode terminal used in the present invention.

FIG. 4 is a schematic perspective view showing an example of a package in a conventional electrochemical capacitor.

FIG. 5 is a perspective view showing an example of the structure of a single electrode cell.

FIG. 6 is a perspective view showing an example of the structure of a single capacitor cell.

[Explanation of symbols]

2,3 ... electrode terminal, 4,5 ... connecting part for connecting to external circuit, 6 ... joining part with package, 10 ... single electrode cell (laminated body), 12 ... single capacitor cell, 20,22 ... collection Electric body, 24, 26 ... Polarizable electrode, 28 ... Separator, 3
0,32 ... electrode extraction part, 44,46 ... electrode terminal, 5
0: electrode unit, 54: holding material, 60: package,
62: Seal part of package, 70: Capacitor container.

Claims (3)

[Claims] A pair of current collectors made of a metal material are provided with polarizable electrodes formed mainly of a carbon material, and at least one polarizer is provided with an electronic insulating separator interposed between the polarizable electrodes. An electrochemical capacitor in which two laminates are sealed in a package in a state of being immersed in an organic or inorganic electrolytic solution, wherein an electrode terminal connected to the current collector is provided inside the package, and an external electrode terminal is provided. An electrochemical capacitor characterized in that a portion other than a connection portion for connecting to a circuit is attached to an inner surface of a package. 2. The electrochemical capacitor according to claim 1, wherein the electrode terminal is shaped to maximize its cross-sectional area. 3. The electrochemical capacitor according to claim 1, wherein the electrode terminal has a shape that maximizes a connection area with the current collector.