JP4390601B2 - Electric double layer capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress phenomena that a discharge current is increased owing to the strong depression of electrodes to a packaging container or a sealing board at a high temperature, and to the adhesiveness of the electrodes to the packaging container and the sealing board is reduced at a low temperature, in an electric double layer capacitor constituted so that an electrode body in which a separator is formed between at least a pair of electrodes, and an electrolyte, are stored in the packaging container, and so that the aperture part of the packaging container is sealed by the sealing board. <P>SOLUTION: In the electric double layer capacitor constituted so that the electrode body 1 in which the separator 1c is formed between at least a pair of electrodes 1a, 1b and the electrolyte are stored in the packaging container 10, and so that the aperture 16 of the packaging container 10 is sealed by the sealing board 20, a board obtained by laminating two or more sorts of plate materials 21, 22 having respectively different linear expansion coefficients is used as the sealing board 20, and the sealing board 20 is fitted to the packaging container so that the plate material 21 having higher linear expansion coefficient is arranged on the opposite side to the aperture of the packaging container. <P>COPYRIGHT: (C)2005,JPO&amp;NCIPI

Description

  The present invention relates to an electric double layer capacitor, and in particular, an electrode body in which a separator is provided between at least a pair of electrodes and an electrolytic solution are accommodated in an outer container, and the opening of the outer container is sealed by a sealing plate. In addition, the electric double layer capacitor is characterized in that an increase in discharge current at high temperatures is suppressed and an increase in internal resistance at low temperatures is prevented.

  Conventionally, as a device for accumulating electric energy, in addition to a chemical battery, an electrode using an electrode material having a large specific surface area such as activated carbon and an electrolytic solution are used, and the electrodes are provided so as to face each other. There is known an electric double layer capacitor in which a dielectric layer called a Helmholtz layer is formed.

  Here, such an electric double layer capacitor has a merit that it can be charged / discharged more rapidly than a chemical battery with an oxidation-reduction reaction since a reaction occurs only by the movement of electrolyte ions. It has come to be used as a backup power source and auxiliary power source for electrical appliances.

  As such an electric double layer capacitor, generally, an electrode body in which a separator is provided between a pair of electrodes and an electrolytic solution are placed in a capacitor can made of a pair of circular metal can bodies. A coin-type electric double layer capacitor is used in which the cans are housed and coupled to each other through an insulating packing around the pair of cans.

  Here, when the electric double layer capacitor is used as a backup power source or auxiliary power source for a mobile phone or household electric appliance as described above, the electric double layer capacitor is soldered and mounted on the printed circuit board. .

  However, in the case of a coin-type electric double layer capacitor as described above, in order to solder this onto a printed circuit board, it is necessary to attach a terminal to each can body by welding or the like, which is expensive. Moreover, in the case of the coin type as described above, there is a problem that a wasteful area increases.

  For this reason, in recent years, a terminal is provided in an outer container using ceramic or the like, and an electrode body in which a separator is provided between a pair of electrodes and an electrolytic solution are accommodated in the outer container, and an opening of the outer container is provided. An electric double layer capacitor has been proposed in which a sealing plate is attached to the opening to seal the opening (see, for example, Patent Documents 1 and 2).

Here, in such an electric double layer capacitor, the electrode expands at a high temperature, and the electrode is strongly pressed against the outer container or the sealing plate to increase a discharge current. On the other hand, the electrode contracts at a low temperature. There has been a problem that the adhesion between the electrode and the outer container or the sealing plate is lowered, and the internal resistance is increased.
JP-A-11-54387 JP 2001-216852 A

  In the electric double layer capacitor according to the present invention, an electrode body in which a separator is provided between at least a pair of electrodes and an electrolytic solution are accommodated in an outer container, and the opening of the outer container is sealed with a sealing plate. As described above, the electrode is strongly pressed against the outer container or the sealing plate at a high temperature as described above, and the discharge current is increased. It is an object to suppress an increase in internal resistance due to a decrease in adhesion with a container or a sealing plate.

  In this invention, in order to solve the above-described problems, an electrode body in which a separator is provided between at least a pair of electrodes and an electrolytic solution are accommodated in an outer container, and an opening of the outer container is formed by a sealing plate. In the sealed electric double layer capacitor, the above-mentioned sealing plate is a laminate of two or more types of plates having different linear expansion coefficients, and a plate having a high linear expansion coefficient is placed on the side opposite to the opening of the outer container. The sealing plate is attached to the outer container.

  Then, as described above, the sealing plate is a laminate of two or more types of plates having different linear expansion coefficients, and a plate having a high linear expansion coefficient is placed on the side opposite to the opening of the outer container, and the sealing plate is used as the outer container. When attached, at high temperatures, the plate material having a high coefficient of linear expansion extends larger than the plate material having a low coefficient of linear expansion located on the opening side of the outer container, and the sealing plate is convex with respect to the opening part of the outer container. Thus, the electrode is prevented from being strongly pressed against the outer container or the sealing plate, and the discharge current is prevented from increasing at a high temperature. On the other hand, at a low temperature, the plate material having a high linear expansion coefficient contracts more than the plate material having a low linear expansion coefficient located on the opening side of the outer container, and the sealing plate is recessed with respect to the opening portion of the outer container. As a result, the adhesiveness between the electrode and the outer container or the sealing plate is prevented from decreasing, and the internal resistance is prevented from increasing at low temperatures.

  Here, as the two or more types of plate materials having different linear expansion coefficients used for the sealing plate, various types of plate materials having different linear expansion rates can be used. As such plate materials, resins having different linear expansion rates can be used. It is preferable to use a plate or to use a resin plate and a metal plate having different linear expansion coefficients.

  This is because the resin plates with different linear expansion coefficients are bonded together, or the resin plates and metal plates with different linear expansion coefficients are bonded to each other, compared to the metal plates with different linear expansion coefficients bonded to each other. The difference in coefficient of linear expansion in the plate material can be increased, the deformation as described above at high temperature and low temperature can be increased, the discharge current at high temperature and the internal resistance at low temperature can be increased. This can be further prevented. In addition, those in which resin plates with different linear expansion coefficients are bonded together, or those in which resin plates and metal plates with different linear expansion coefficients are bonded together are plate materials compared to those in which metal plates with different linear expansion coefficients are bonded together. When the mutual adhesive force is weak and the sealing plate is greatly deformed, the plates are separated from each other before the sealing plate is detached from the outer container, and the sealing plate is prevented from being detached from the outer container.

  Here, as the resin constituting the resin plate, for example, polyimide amide, polyether ether ketone, polyimide, polyphenylene sulfite, and the like can be used, and in particular, with respect to the heat resistance and the electrolyte used for the electric double layer capacitor. It is preferable to use a liquid crystal polymer that has excellent corrosion resistance and can easily adjust the linear expansion coefficient.

  Moreover, as said metal plate, what was comprised with various metals can be used, for example, it comprised with ceramic materials, such as aluminum excellent in the corrosion resistance with respect to the electrolyte solution used for an electrical double layer capacitor, and alumina. It is preferable to use Fernico or the like that has a small difference in linear expansion coefficient from the outer container and is difficult to come off from the outer container. In addition, since said Fernico is not enough corrosion resistance with respect to electrolyte solution, when using the board | plate material which consists of Fernico, it is preferable to provide protective layers, such as aluminum, in the surface of this board | plate material.

  In the electric double layer capacitor according to the present invention, as described above, a sealing plate in which two or more kinds of plates having different linear expansion coefficients are bonded together is used, and a plate having a high linear expansion coefficient is placed on the side opposite to the opening of the outer container. Since the sealing plate is attached to the outer container, an increase in the discharge current is suppressed at a high temperature, and an increase in internal resistance is prevented at a low temperature.

  Further, in the electric double layer capacitor according to the present invention, as the two or more kinds of plate materials having different linear expansion coefficients used for the sealing plate, resin plates having different linear expansion coefficients are used, or resin plates having different linear expansion coefficients are used. When a metal plate is used, an increase in discharge current at a high temperature and an increase in internal resistance at a low temperature can be further prevented, and the sealing plate can be prevented from coming off from the outer container. .

  Hereinafter, the electric double layer capacitor according to the present invention will be described in detail with reference to examples, and in the electric double layer capacitor in this example, the internal resistance increases at a high temperature and the discharge current is suppressed. A comparative example will clarify that the internal resistance decreases at room temperature. The electric double layer capacitor according to the present invention is not limited to those shown in the following examples, and can be implemented with appropriate modifications within a range not changing the gist thereof.

Example 1
In Example 1, in preparing an electrode, 100 parts by weight of activated carbon powder having a specific surface area of 2000 m ² / g, 5 parts by weight of acetylene black, and 5 parts by weight of polytetrafluoroethylene (PTFE) were added. This was kneaded and molded to produce a square electrode having a side length of 3.5 mm and a thickness of 0.5 mm.

In preparing the electrolytic solution, propylene carbonate was used as a solvent, and the solute (C ₂ H ₅ ) ₄ NBF ₄ was dissolved to a concentration of 1 mol / l to prepare an electrolytic solution.

Further, the exterior container is made of alumina having a linear expansion coefficient of 7 × 10 ⁻⁶ , a square shape with a side length of 5 mm, and a frame body with a height of 1.3 mm. A container in which a container having a square shape with a length of 3.6 mm and a depth of 1.1 mm is formed, as shown in FIG. 1, the bottom of the container 11 in the outer container 10. A current collector 12 in which tungsten is gold-plated is provided, one connection terminal 15a extending through the side wall 13 to the bottom surface 14 so as to come into contact with the current collector 12, and the above-described housing A portion provided with the other connection terminal 15 b extending from the edge of the opening 16 on the top surface of the portion 11 to the bottom surface 14 is used.

As the sealing plate, as shown in FIG. 2, a sealing plate 20 in which two types of plate materials 21 and 22 having different linear expansion coefficients are bonded together is used. In this embodiment, a resin plate made of a liquid crystal polymer having a linear expansion coefficient of 8 × 10 ⁻⁵ and a thickness of 0.2 mm is used as the plate material 21 having a large linear expansion coefficient, and the linear expansion coefficient is small. As the plate 22, a metal plate made of aluminum having a linear expansion coefficient of 2 × 10 ⁻⁵ and a thickness of 0.25 mm was used.

  And in producing an electric double layer capacitor, as shown in FIG. 3, the electrode which made the glass fiber separator 1c interpose between the two electrodes 1a and 1b produced as mentioned above, and was made to oppose. The body 1 is accommodated in the accommodating portion 11 of the outer casing 10, and one electrode 1 a is brought into contact with the current collector 12 provided at the bottom of the accommodating portion 11. The electrolyte solution was poured into the electrode 1a and 1b so that the electrolyte solution was sufficiently impregnated. Next, the plate material 21 having a large linear expansion coefficient in the sealing plate 20 is placed on the side opposite to the outer container 10, and the plate material 22 having a small linear expansion coefficient in the sealing plate 20 is replaced with the opening 16 of the outer container 10. An electric double layer capacitor was manufactured by heat-sealing to the edge and sealing the opening 16 of the outer container 10 with the sealing plate 20.

(Example 2)
In Example 2, as the plate material 21 having a large linear expansion coefficient in the sealing plate 20 described above, a resin plate made of a liquid crystal polymer having the same linear expansion coefficient as in Example 1 and a thickness of 0.2 mm is 8 × 10 ^−5. On the other hand, as the plate material 22 having a small linear expansion coefficient, a metal plate made of Fernico having a linear expansion coefficient of 5 × 10 ⁻⁶ and a thickness of 0.25 mm is used. An electric double layer capacitor was produced in the same manner as in the case.

(Example 3)
In Example 3, a resin plate made of a liquid crystal polymer having a linear expansion coefficient of 8 × 10 ⁻⁵ and a thickness of 0.25 mm is used as the plate material 21 having a large linear expansion coefficient in the sealing plate 20. As the plate material 22 having a small expansion coefficient, a resin plate made of a liquid crystal polymer having a linear expansion coefficient of 1 × 10 ⁻⁵ and a thickness of 0.25 mm is used. As shown in FIG. A current collector 23 made of aluminum having a thickness of 0.05 mm was formed on the surface 22, and an electric double layer capacitor was fabricated in the same manner as in Example 1 except for that.

(Comparative Example 1)
In Comparative Example 1, only the metal plate made of aluminum having a linear expansion coefficient of 2 × 10 ⁻⁵ and a thickness of 0.25 mm was used as the sealing plate. An electric double layer capacitor was produced in the same manner as in the case.

  Next, an alternating current (0.1 mA) having a frequency of 1 kHz is applied to each of the electric double layer capacitors of Examples 1 to 3 and Comparative Example 1 manufactured as described above, and each electric double layer capacitor is applied. The internal resistance (Ω) at room temperature and 150 ° C. was measured, and the results are shown in Table 1 below.

  As a result, the sealing plate 20 in which two types of plate materials 21 and 22 having different linear expansion coefficients are bonded to each other is used, and the plate material 21 having a high linear expansion coefficient is attached to the outer container 10 on the side opposite to the opening of the outer container 10. In each of the electric double layer capacitors of Examples 1 to 3, the internal resistance at room temperature is lower than that of the electric double layer capacitor of Comparative Example 1 using a sealing plate made of a single plate, but the high temperature of 150 ° C. The internal resistance at the time increased significantly, and the discharge current at high temperatures was suppressed.

It is a section explanatory view of the exterior container used in the electric double layer capacitor of Examples 1-3 of this invention. It is sectional explanatory drawing of the sealing board used in the electric double layer capacitor of Example 1, 2 of this invention. It is the schematic sectional drawing which showed the electric double layer capacitor of Example 1, 2 of this invention. It is the schematic sectional drawing which showed the electric double layer capacitor of Example 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrode body 1a, 1b Electrode 1c Separator 10 Exterior container 11 Storage part 12 Current collector 13 Side wall 14 Bottom face 15a, 15b Connection terminal 16 Opening part 20 Sealing board 21 Plate material with a large linear expansion coefficient 22 Plate material with a small linear expansion coefficient 23 Electric body

Claims (4)

In an electric double layer capacitor in which an electrode body in which a separator is provided between at least a pair of electrodes and an electrolytic solution are accommodated in an outer container, and an opening of the outer container is sealed by a sealing plate,
As the sealing plate, a laminate of two or more plate materials having different linear expansion coefficients is used,
The sealing plate is attached to the exterior container so that the plate material having a high linear expansion coefficient is on the side opposite to the opening of the exterior container, and the plate material having a low linear expansion coefficient is on the opening side of the exterior container. An electric double layer capacitor characterized in that the plate material having a low linear expansion coefficient is in contact with one electrode, and the current collector formed at the bottom of the housing portion of the outer container is in contact with the other electrode . In an electric double layer capacitor in which an electrode body in which a separator is provided between at least a pair of electrodes and an electrolytic solution are accommodated in an outer container, and an opening of the outer container is sealed by a sealing plate,
As the above-mentioned sealing plate, using a laminate of two or more types of resin plates having different linear expansion coefficients,
The sealing plate is attached to the exterior container so that the plate material having a high linear expansion coefficient is on the side opposite to the opening of the exterior container, and the plate material having a low linear expansion coefficient is on the opening side of the exterior container. The plate material having a low coefficient of linear expansion is in contact with the current collector formed between the plate material having a low coefficient of linear expansion and one electrode, and the current collector formed at the bottom of the housing portion of the outer container is the other. An electric double layer capacitor characterized in that it is in contact with the electrode.   2. The electric double layer capacitor according to claim 1, wherein a resin plate and a metal plate are used as two or more kinds of plate materials having different linear expansion coefficients used for the sealing plate. The electric double layer capacitor according to any one of claims 1 to 3, wherein the outer container is made of a ceramic material.