JP2004296520A - Electrochemical capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrochemical capacitor that can be reduced in size and weight even when the capacitor is constituted to serially connect unit cells in a state where two or more unit cells are arranged in parallel with each other and, in addition, can sufficiently obtain a volume energy density on the basis of the volume of a space to be installed. <P>SOLUTION: The electrochemical capacitor 1 has elemental bodies 60A and 60B, an electrolytic solution 30, and a case 50. The elemental body 60A is composed of electrodes 10A and 20A faced to each other, and a separator 40A disposed between the electrodes 10A and 20A. The body 60A is provided with first and the second leads 12A and 22A, respectively, connected to the electrodes 10A and 20A. The elemental body 60B also has the same constitution. The element bodies 60A and 60B are serially electrically connected to each other through metallic wires 11. In the case 50, the elemental body sections 60A and 60B are arranged in parallel with each other and a partitioning section 56 is provided between the sections 60A and 60B. The partitioning section 56 bonds the facing portions of first and second films 51 and 52 to each other through thermal fusion. The thicknesses d of the films 51 and 52 and the thickness D of the whole body of the electrochemical capacitor are adjusted to simultaneously meet the following inequalties : (1): d≤100 μm, and (2): D≤4d. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrochemical capacitor such as an electric double layer capacitor, and more particularly, to an electrochemical capacitor having a configuration in which two or more unit cells are electrically connected in series in a state of juxtaposition.
[0002]
[Prior art]
Electrochemical capacitors such as electric double layer capacitors can be charged and discharged rapidly, have a semi-permanent life, can be charged and discharged with a relatively large current, and can be easily reduced in size and weight. For example, it is expected to be used as a backup power supply for a power supply of an electronic device or the like, or an auxiliary power supply for an electric vehicle or a hybrid vehicle, and various studies have been made to improve its performance. .
[0003]
Further, in addition to the above-described performance improvement, the electrochemical capacitor is also required to be reduced in size and weight. That is, the improvement of the energy density per unit weight and the improvement of the energy density per unit volume of the electrochemical capacitor are required at the same time.
[0004]
Therefore, one composite packaging film (laminate film) provided with a metal layer such as a synthetic resin layer or a metal foil is used, and this is folded in half, and the edges of the overlapped portions are heated together. A lightweight case (encapsulated bag) produced by sealing (heat fusion) or a lightweight case produced by superposing two sheets and heat-sealing the edges of the superimposed portions with one another Electrochemical capacitors having a configuration used as an outer container for enclosing components such as electrodes and electrolytes have been studied. In this case, one end is electrically connected to each of the pair of electrodes, and the other end is connected to a metal lead projecting to the outside of the case.
[0005]
In the present specification, the “heat seal (heat fusion)” of the surface (hereinafter referred to as “the inner surface” of each film) of each of the two films that are the materials of the case is to be heat sealed (heat fused). The area of the edge portion to be attached) is referred to as a “seal portion” as necessary.
[0006]
For example, as a case formed using a film, a non-aqueous electrolyte battery different from an electrochemical capacitor is provided, but a lead in a seal portion of a case formed from a composite packaging film (laminate film) is used. There has been known a case in which a projection area of a case is reduced by folding a portion other than a portion that is pulled out (for example, see Patent Document 1 below).
[0007]
[Patent Document 1]
JP 2000-138040 A
[0008]
[Problems to be solved by the invention]
However, the electrochemical capacitor is required to be able to be easily installed in a very small installation space in the above-mentioned device while sufficiently satisfying the charge / discharge characteristics (particularly output characteristics) required by the device to be mounted. When a specific configuration aiming at further miniaturization and weight reduction is intended, simply applying the configuration of the non-aqueous electrolyte battery described in Patent Document 1 to an electrochemical capacitor has the following problems. The present inventors have found that it is extremely difficult to obtain the effect. Note that the “specific configuration” is a configuration in which two or more thin-film unit cells having a thickness of 400 μm or less, as described below, are electrically connected in series in a state of juxtaposition.
[0009]
Electrochemical capacitors, including electric double layer capacitors, have a smaller unit capacity per unit cell compared to secondary batteries of the same size due to the operating principle and the restrictions on the structure of constituent elements (electrodes and separators) and constituent materials. Generally has low electric capacity and voltage (voltage between terminals, withstand voltage, etc.). Therefore, in order to satisfy a voltage value (for example, a voltage between terminals of 5 V or more) required by a device to be mounted, it is necessary to connect two or more unit cells in series.
[0010]
In this case, depending on the shape of the equipment to be mounted or the size and shape of the installation space in the equipment to be mounted, it is necessary to adopt a configuration in which two or more unit cells are connected in series without juxtaposition without stacking unit cells. There may be.
[0011]
From the viewpoint that the electrochemical capacitor is formed in a thin film shape and can be arranged in a smaller installation space, a configuration is adopted in which two or more unit cells are connected in series in a state of juxtaposition, and 1. As in the case described in Patent Document 1 (described as “exterior material” in Patent Document 1), a flexible film (for example, a composite packaging film) that is lightweight and easily thinned and has a thickness Use a case formed using a film having a thickness of 100 μm or less, and particularly when the thickness of the unit cell (including the thickness of the film constituting the case) is 400 μm or less, use FIGS. 10 and 11. The present inventors have found that there is a problem described below.
[0012]
FIG. 10 is a front view showing a conventional electrochemical capacitor employing a configuration in which two or more unit cells are connected in series in a state of juxtaposition. FIG. 11 is a schematic cross-sectional view when the electrochemical capacitor 100 shown in FIG. 10 is cut along the line X100-X100 in FIG. In particular, FIG. 11 shows a cross section on the side of the unit cell 101 shown in FIG. The cross section of the unit cell 102 not shown in FIG. 11 is the same as that of the unit cell 101 shown in FIG.
[0013]
The electrochemical capacitor 100 shown in FIG. 10 has two unit cells 101 and 102 arranged side by side on the same installation surface in an equipment (not shown) in which they are to be installed, and is electrically connected in series. It has a connected configuration.
[0014]
Here, the case 105 of the unit cell 101 is formed by folding one-half using a single flexible film (for example, the above-described composite packaging film) 104 and overlapping the inner surface. It is manufactured by heat sealing (thermal fusion) between the edges 104B. Further, inside the case 105 (a space formed by the non-heat-sealed partial region 104A of the film 104), an anode (not shown), a cathode (not shown), and an anode and a cathode which are opposed to each other are provided. (Hereinafter, referred to as a “capacitor body portion”) 108 including a separator (not shown) disposed therebetween and an electrolyte solution 109 (partially contained in the anode, the cathode, and the separator) And are housed. The anode is connected to a metal lead A101 having one end electrically connected to the anode and the other end protruding outside the case 105. The cathode is connected to a metal lead C101 having one end electrically connected to the cathode and the other end protruding outside the case 105.
[0015]
The case 106 of the unit cell 102 is also folded about one-half using a single flexible film 107, and the edges 105B of the overlapped inner surfaces are heat-sealed (heat-sealed). The same capacitor element body and electrolyte solution as in the unit cell 101 are accommodated in the case 106. The anode is connected to a metal lead A101 having one end electrically connected to the anode and the other end protruding outside the case 105. The cathode is connected to a metal lead C101 having one end electrically connected to the cathode and the other end protruding outside the case 105.
[0016]
As described above, the thickness d100 of each of the films 104 and 107 is set to 100 μm or less from the viewpoint that the electrochemical capacitor 100 can be disposed in a smaller installation space by making the electrochemical capacitor 100 thinner. When the thickness D100 is set to 400 μm or less, the following problem occurs.
[0017]
That is, in this case, when the sealing portion 104B of the case 105 is bent as in the case described in the above-mentioned Patent Document 1, as shown in FIG. A state in which the space protrudes above (or below) the surface of the partial region 104A that is not heat-sealed, and the dead space R1 that cannot be used for charging / discharging above the partial region 104A (the installation space of the battery in a device to be used) Is formed. A similar dead space is also formed in case 107. Due to this dead space, the electrochemical capacitor 100 has not been able to obtain a sufficient “volume energy density based on the volume of the space to be installed”.
[0018]
Here, the case 105 will be described. When the thickness d100 of the film 104 is set to 100 μm or less and the thickness D100 of the electrochemical capacitor 100 is set to 400 μm or less, the area is larger than the area of the unsealed seal portion 104B. Since the electrode area of the anode and the cathode is generally much larger (for example, 5 times or more), as described above, compared to the dead space formed above and below the seal portion 104B without being bent. The dead space R1 formed by bending the seal portion 104B is larger. This is the same for the case 107.
[0019]
Further, even when the seal portion 104B is not bent, the "space to be installed" is caused by the dead space R2 formed above and below each seal portion between the two unit cells 101 and 102. The reduction in the volume energy density based on the volume of the (installation space) has been a problem. When a large number of unit cells are juxtaposed, the amount of decrease in the "volume energy density based on the volume of the space to be installed" due to the dead space R2 increases.
[0020]
The “volume energy density” of the electrochemical device is originally defined by the ratio of the total output energy to the volume of the capacitor element portion of the electrochemical device or the total volume including the container. In contrast, "volume energy density based on the volume of the space to be installed" is defined as the electrochemical device with respect to the apparent volume determined based on the maximum length, maximum width, and maximum thickness of the electrochemical device. Means the ratio of the total output energy.
[0021]
When an electrochemical device is actually mounted on an electronic device (a portable small electronic device, a power supply system mounted in an electric vehicle or a hybrid vehicle, or the like), the above-mentioned improvement in the original volumetric energy density and the space to be installed are required. It is important to improve the volume energy density based on the volume of the electronic device from the viewpoint of effectively using the limited space in the electronic device while the dead space is sufficiently reduced. In particular, when the thickness of the film constituting the case is 100 μm or less and the thickness of the electrochemical capacitor is 400 μm or less, it is necessary to sufficiently reduce the dead space described above. This is important from the viewpoint of sufficiently obtaining a volume energy density based on
[0022]
The present invention has been made in view of the above-mentioned problems of the related art, and it is easy to reduce the size and weight even in a case where two or more unit cells are connected in series in a state of being juxtaposed. It is another object of the present invention to provide an electrochemical capacitor capable of sufficiently obtaining a volume energy density based on the volume of a space to be installed.
[0023]
[Means for Solving the Problems]
The present inventors have intensively studied to achieve the above object, and as a result, in the case of an electrochemical capacitor having a case formed using a flexible film having a thickness of 100 μm or less, the following conditions are satisfied. The inventor has found that having the configuration is effective from the viewpoint of achieving the above object, and has arrived at the present invention.
[0024]
That is, the present invention includes a first plate-shaped electrode and a second plate-shaped electrode opposed to each other, and a plate-shaped separator disposed between the first electrode and the second electrode. Two or more capacitor element parts to be
An electrolyte solution;
A case for accommodating two or more capacitor element parts and an electrolyte solution in a sealed state by heat-sealing the edges of the opposing surfaces of the first film and the second film facing each other;
A first lead provided for each capacitor body so that one end is connected to the first electrode and the other end protrudes outside the case;
A second lead provided for each capacitor element so that one end is connected to the second electrode and the other end protrudes outside the case;
Has,
Each capacitor element body is electrically connected to each other in series via a first lead and a second lead,
The case is provided with a partition portion formed by thermally fusing partial regions of the first film and the second film facing each other to prevent contact between two or more capacitor element portions. ,
The thickness d of the first film and the second film and the total thickness D are adjusted so as to simultaneously satisfy the conditions of the following expressions (1) and (2);
An electrochemical capacitor is provided.
d ≦ 100 μm (1)
D ≦ 4d (2)
[0025]
In the electrochemical capacitor of the present invention, since the partition provided in the case as described above is formed by heat-sealing the mutually facing partial regions of the first film and the second film, FIGS. Can significantly reduce the dead space R2 shown in FIG. Therefore, the electrochemical capacitor of the present invention can also easily improve the volume energy density based on the volume of the space to be installed.
[0026]
Further, in the electrochemical capacitor of the present invention, the edges (seal portions) of the inner surfaces of the first film and the second film, which are thermally fused, are not bent. As a result, the dead space R1 shown in FIGS. 10 and 11 can be eliminated. By not bending the edge (seal portion), a dead space is newly generated above and below the edge (seal portion), but is newly generated by adjusting the width of the edge (seal portion). The size of the dead space can be made sufficiently smaller than the dead space R1 shown in FIGS. Therefore, also from this viewpoint, the electrochemical capacitor of the present invention can easily improve the volume energy density based on the volume of the space to be installed.
[0027]
Furthermore, since the electrochemical capacitor of the present invention has a case formed using a flexible film that is lightweight and easily thinned, the shape of the electrochemical capacitor itself can be thin. it can.
[0028]
The electrochemical capacitor of the present invention that satisfies the above configuration conditions can be easily reduced in size and weight and installed even when two or more unit cells are connected in series in a state of juxtaposition. An electrochemical capacitor capable of sufficiently obtaining a volume energy density based on the volume of a space to be provided can be provided.
[0029]
Further, according to the present invention, there is provided a thin film-shaped electrochemical capacitor having a thickness of 400 μm, which can easily obtain an output voltage (for example, 5 V or more) required from a device to be mounted. A capacitor can be provided.
[0030]
Here, in the present invention, the “film” refers to a film having flexibility, capable of being thermally welded between films of the same kind, and capable of being thermally welded to a metal lead. .
[0031]
Further, in the present invention, the thickness d of the first film and the second film is preferably 50 μm or more from the viewpoint of more reliably obtaining sufficient mechanical strength and sealing property of the case. Further, in the present invention, the thickness d of the first film and the second film may be the same or different as long as the thickness satisfies the formula (1).
[0032]
Furthermore, from the viewpoint of more reliably obtaining the electrochemical capacitor of the present invention with sufficient mechanical strength and from the viewpoint of easily manufacturing the electrochemical capacitor, the total thickness D is preferably 200 μm or more.
[0033]
Further, in the electrochemical capacitor of the present invention, from the viewpoint of sufficiently reducing the dead space in which the installation space described above cannot be effectively used, the width of the partition is preferably 0.2 to 2.0 mm. More preferably, it is 0.5 to 1.0 mm.
[0034]
Further, in the electrochemical capacitor of the present invention, from the viewpoint of sufficiently reducing the dead space in the same manner as described above, the width of the heat-sealed edge of each inner surface of the first film and the second film is set to 0.5. To 2.0 mm, more preferably 1.0 to 2.0 mm.
[0035]
Further, the electrochemical capacitor of the present invention has an area of the first film and the second film of 0.09 to 20 cm from the viewpoint of more reliably reducing the size and weight. ² Is preferably 1 to 4 cm ² Is more preferable.
[0036]
Further, in the electrochemical capacitor of the present invention, from the viewpoint of obtaining a sufficient capacitor capacity, in each capacitor element portion, the first electrode and the second electrode each include an electron conductive porous body as a constituent material. Preferably, the separator is made of an insulating porous material, and at least a part of the electrolyte solution is contained in the first electrode, the second electrode, and the inside of the separator.
[0037]
Further, in the electrochemical device of the present invention, as the first film and the second film, the innermost layer made of a synthetic resin that comes into contact with the electrolyte solution, and the metal layer disposed above the innermost layer It is preferable to use a composite packaging film having at least.
[0038]
By arranging the innermost layer made of a synthetic resin, sufficient flexibility of the first film and the second film is ensured, and the seal portion of the first film and the seal portion of the second film are formed. Can sufficiently secure the heat-sealing strength. In addition, by disposing the metal layer, sufficient mechanical strength of the first film and the second film is ensured, and components of the electrolyte solution inside the case escape to the outside of the case, and The flow of air (moisture and oxygen) from inside the case into the inside of the case can be sufficiently prevented. Further, by disposing the innermost layer made of a synthetic resin inside the metal layer, the progress of corrosion of the metal layer due to components of the electrolyte solution inside the case is sufficiently prevented.
[0039]
Thus, an electrochemical device that can sufficiently prevent the occurrence of liquid leakage can be configured more easily and more reliably. Further, it is more preferable to further arrange a layer made of a synthetic resin outside the metal layer from the viewpoint of sufficiently preventing the occurrence of liquid leakage and ensuring sufficient mechanical strength.
[0040]
In the present invention, the “electrolyte solution” may be a gel electrolyte obtained by adding a gelling agent other than a liquid state.
[0041]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the case where the electrochemical capacitor according to the present invention is applied to an electric double layer capacitor will be described in detail with reference to the drawings. In the following description, the same or corresponding parts will be denoted by the same reference characters, without redundant description.
[0042]
FIG. 1 is a front view showing a preferred embodiment of the electrochemical capacitor of the present invention. FIG. 2 is a developed view when the inside of the electrochemical capacitor shown in FIG. 1 is viewed from the normal direction of the surface of the anode of each capacitor body. FIG. 3 is a schematic cross-sectional view showing a main part when the electrochemical capacitor shown in FIG. 1 is cut along the line X1-X1 in FIG. FIG. 4 is a schematic cross-sectional view showing a main part when the electrochemical capacitor shown in FIG. 1 is cut along the line X2-X2 in FIG. FIG. 2 is a schematic cross-sectional view illustrating a main part when the electrochemical capacitor illustrated in FIG. 1 is cut along the line YY in FIG. 1.
[0043]
As shown in FIGS. 1 to 5, the electrochemical capacitor 1 mainly includes two capacitor body parts 60 </ b> A and 60 </ b> B, an electrolyte solution 30, and a case 50 that accommodates these in a sealed state. .
[0044]
The capacitor body 60A is disposed adjacent to the flat anode 10A (first electrode) and the flat cathode 20A (second electrode) facing each other, and between the anode 10A and the cathode 20A. And a flat separator 40A. The capacitor body 60A further includes an anode lead 12A (first lead) having one end electrically connected to the anode 10A and the other end protruding outside the case 50; A cathode lead 22A (a second lead) is provided, one end of which is electrically connected to the cathode 20A and the other end of which is projected outside the case 50.
[0045]
Further, the capacitor element body portion 60B is disposed adjacent to the flat anode 10B (first electrode) and the flat cathode 20B (second electrode) facing each other, and between the anode 10B and the cathode 20B. And a flat separator 40B. Further, the capacitor body 60B includes an anode lead 12B (first lead) having one end electrically connected to the anode 10B and the other end protruding outside the case 50, A cathode lead 22 </ b> B (second lead) is provided, one end of which is electrically connected to the cathode 20 </ b> B and the other end protruding outside the case 50.
[0046]
Further, the anode lead 12A of the capacitor body 60A and the cathode lead 22B of the capacitor body 60B are electrically connected by the metal wire 11. Thus, the two capacitor body portions 60A and 60B are electrically connected in series. As shown in FIGS. 1 and 2, the two capacitor element portions 60A and 60B are juxtaposed on the inner surface of the second film 52 so as to be in a non-contact state with each other.
[0047]
Note that “anode” and “cathode” are determined based on the polarity of the electrochemical capacitor 1 at the time of discharging for convenience of description.
[0048]
The electrochemical capacitor 1 has a configuration described below in order to achieve the above-described object of the present invention.
[0049]
Hereinafter, details of each component of the present embodiment will be described with reference to FIGS.
[0050]
As described above, the case 50 has the first film 51 and the second film 52 facing each other. Here, as shown in FIG. 2, the first film 51 and the second film 52 in the present embodiment are connected. That is, the case 50 in the present embodiment is formed by bending a rectangular film made of a single composite packaging film at a bending line X3-X3 shown in FIG. (The edge 51B of the first film 51 and the edge 52B of the second film 52 in the drawing) are overlapped and heat-sealed (heat-sealed).
[0051]
The first film 51 and the second film 52 indicate portions of the film having surfaces (F51 and F52) facing each other when a single rectangular film is bent as described above. . Here, in the present specification, the respective edges 51B and 52B of the first film 51 and the second film 52 after being joined are referred to as “seal portions”.
[0052]
This eliminates the need to provide a seal portion for joining the first film 51 and the second film 52 at the portion of the fold line X3-X3, so that the seal portion in the case 50 can be further reduced. As a result, the volume energy density based on the volume of the space where the electrochemical capacitor 1 is to be installed can be further improved.
[0053]
In the case of the present embodiment, as shown in FIGS. 1 and 2, one end of each of the anode lead 12 and the cathode lead 22 connected to the anode 10 is connected to the edge 51B of the first film 51 and the second end. The film 52 is disposed so as to protrude to the outside from a seal portion joined to an edge portion 52B of the film 52.
[0054]
The case 50 is provided with a partition portion 56 for preventing contact between the two capacitor body portions 60A and 60B. And the partition part 56 is formed by heat-sealing the mutually opposing partial regions of the first film 51 and the second film 52. Two internal spaces of the case 50 partitioned by the partition 56 (two internal spaces formed by the non-heat-sealed partial regions 51A and 52A of the first film 51 and the second film 52 and the partition 56). , The capacitor body portions 60A and 60B are accommodated together with the electrolyte solution so as not to contact each other, and each constitutes a unit cell.
[0055]
In the case of the electrochemical capacitor 1, the thickness d of the first film 51 and the second film 52 constituting the case 50 and the total thickness D are expressed by the following equations (1) and (2). It is adjusted to satisfy the conditions at the same time.
d ≦ 100 μm (1)
D ≦ 4d (2)
[0056]
The thickness D (the thickness of the entire electrochemical capacitor 1) is selected from the viewpoint of being able to be installed in a limited narrow installation space in a portable small electronic device and from the viewpoint of more reliably obtaining sufficient mechanical strength. Is preferably from 200 to 400 μm, more preferably from 300 to 400 μm.
[0057]
Further, from the viewpoint of more reliably obtaining sufficient mechanical strength and sealing property of the case 50, the thickness d of the first film 51 and the second film 52 is preferably 50 μm or more. Further, from the viewpoint of sufficiently reducing the dead space in which the installation space cannot be effectively used, the width of the partition portion 56 is preferably 0.2 to 2.0 mm, and more preferably 0.5 to 1.0 mm. .
[0058]
Furthermore, similarly to the above, from the viewpoint of sufficiently reducing the dead space, the widths of the heat-sealed edges 51B and 52B of the inner surfaces of the first film 51 and the second film 52 are 0.5 to 2.0 mm. And more preferably 1.0 to 2.0 mm.
[0059]
In addition, from the viewpoint of more reliably reducing the size and weight, the area of the first film 51 and the second film 52 is 0.09 to 20 cm. ² Is preferably 1 to 4 cm ² Is more preferable.
[0060]
Further, the films constituting the first film 51 and the second film 52 are films having flexibility. Since this film is lightweight and easily formed into a thin film, the shape of the electrochemical capacitor 1 itself can be made thin. Therefore, the original volume energy density can be easily improved, and the volume energy density based on the volume of the space where the electrochemical capacitor 1 is to be installed can be easily improved.
[0061]
The first film 51 and the second film 52 are not particularly limited as long as the film satisfies the condition of the above formula (1) and has flexibility, but ensures sufficient mechanical strength and lightweight of the case. From the outside of the case to the inside of the case and from the viewpoint of effectively preventing the escape of electrolyte components from the inside of the case to the outside of the case, the innermost layer made of a synthetic resin that comes in contact with the electrolyte solution. And a “composite packaging film” having at least a metal layer disposed above the innermost layer.
[0062]
As a composite packaging film that can be used as the first film 51 and the second film 52, for example, a composite packaging film having a configuration shown in FIGS.
[0063]
The composite packaging film 53 shown in FIG. 6 includes a synthetic resin innermost layer 50a that comes into contact with the electrolyte solution on the inner surface F50a and a metal disposed on the other surface (outer surface) of the innermost layer 50a. And a layer 50c. The composite packaging film 54 shown in FIG. 7 has a configuration in which an outermost layer 50b made of a synthetic resin is further disposed on the outer surface of the metal layer 50c of the composite packaging film 53 shown in FIG.
[0064]
The composite packaging film usable as the first film 51 and the second film 52 includes one or more synthetic resin layers including the innermost layer 50a described above, and a metal layer 50c such as a metal foil. Although it is not particularly limited as long as it is a composite packaging material having the above layers, from the viewpoint of more reliably obtaining the same effect as described above, the innermost layer 50a and the innermost layer 50a as in the composite packaging film 54 shown in FIG. An outermost layer 50b made of a synthetic resin disposed on the outer surface side of the case 50 farthest from the inner layer 50a, and at least one disposed between the innermost layer 50a and the outermost layer 50b. More preferably, it is composed of three or more layers having the metal layer 50c.
[0065]
The innermost layer 50a is a layer having flexibility, and its constituent material is capable of exhibiting the above-mentioned flexibility, and is chemically stable (chemical reaction, dissolution) with respect to the electrolyte solution used. , No swelling), and any synthetic resin having chemical stability to oxygen and water (moisture in air), but is not particularly limited, and furthermore, oxygen, water (moisture in air) and Materials having low permeability to components of the electrolyte solution are preferred. Examples thereof include thermoplastic resins such as polyethylene, polypropylene, modified polyethylene acid, modified polypropylene acid, polyethylene ionomer, and polypropylene ionomer.
[0066]
When a layer made of a synthetic resin such as the outermost layer 50b is provided in addition to the innermost layer 50a as in the composite packaging film 54 shown in FIG. Also, the same constituent material as the innermost layer may be used. Further, as the layer made of the synthetic resin, for example, a layer made of an engineering plastic such as polyethylene terephthalate (PET) or polyamide (nylon) may be used.
[0067]
The metal layer 50c is preferably a layer formed of a metal material having corrosion resistance to oxygen, water (moisture in air) and an electrolyte solution. For example, a metal foil made of aluminum, an aluminum alloy, titanium, nickel or the like may be used.
[0068]
Next, the anodes 10A and 10B and the cathodes 20A and 20B will be described. FIG. 8 is a schematic cross-sectional view showing an example of the basic configuration of the anode 10A (or 10B) of the electrochemical capacitor 1 shown in FIG. FIG. 9 is a schematic cross-sectional view showing an example of the basic configuration of the cathode 20A (or 10B) of the electrochemical capacitor shown in FIG. Hereinafter, only the capacitor body 60A will be described, and description of the capacitor body 60B having the same configuration will be omitted.
[0069]
As shown in FIG. 8, the anode 10 </ b> A includes a current collector 16 having a flat plate shape, and a porous layer 18 formed on the current collector 16 and formed of an electron conductive porous body. As shown in FIG. 9, the cathode 20 </ b> A includes a current collector 26 and a porous layer 28 formed on the current collector 26 and formed of an electron-conductive porous material.
[0070]
The current collector 16 and the current collector 26 are not particularly limited as long as they are good conductors capable of sufficiently transferring electric charges to the porous layer 18 and the porous layer 28, and are used in known electric double layer capacitors. Current collectors can be used. For example, the current collector 16 and the current collector 26 include a metal foil such as aluminum.
[0071]
The constituent material of the porous layer 18 and the porous layer 28 is not particularly limited, and those used for the porous layer constituting the polarizable electrode such as a carbon electrode used in a known electric double layer capacitor. The same material as described above can be used. For example, it can be obtained by activating coking coal (for example, petroleum coke produced from delayed coker using bottom oil of fluid catalytic cracking unit of petroleum heavy oil or bottom oil of vacuum distillation unit as starting oil). A carbon material (for example, activated carbon) used as a main component of the constituent material can be used. Other conditions (the types and contents of constituent materials other than the carbon material such as the binder) are not particularly limited. For example, a conductive auxiliary (for example, carbon black) for imparting conductivity to carbon powder and a binder (for example, polytetrafluoroethylene, hereinafter, referred to as PTFE) may be added.
[0072]
The separator 40A disposed between the anode 10A and the cathode 20A is not particularly limited as long as it is formed of an insulating porous material, and a separator used in a known electric double layer capacitor can be used. . For example, as the insulating porous body, a laminated body of a film made of polyethylene, polypropylene or polyolefin, a stretched film of a mixture of the above resins, or at least one constituent material selected from the group consisting of cellulose, polyester and polypropylene And a fiber non-woven fabric.
[0073]
The current collector 28 of the cathode 20A is electrically connected to one end of a cathode lead 22A made of, for example, aluminum, and the other end of the cathode lead 22A extends outside the case 50. On the other hand, the current collector 18 of the anode 10A is also electrically connected to one end of an anode lead conductor 12A made of, for example, copper or nickel, and the other end of the anode lead conductor 12A extends outside the encapsulation bag 14.
[0074]
The electrolyte solution 30 is filled in two internal spaces partitioned by the partition portion 56 of the case 50, and a part thereof is contained inside the two electrochemical capacitor elements 60A and 60B.
[0075]
The electrolyte solution 30 is not particularly limited, and an electrolyte solution used for a known electric double layer capacitor (an aqueous electrolyte solution or an electrolyte solution using an organic solvent) can be used. However, since the electrolytic solution is electrochemically low in decomposition voltage, the withstand voltage of the capacitor is limited to a low level. Therefore, an electrolyte solution using an organic solvent (a non-aqueous electrolyte solution) is preferable.
[0076]
Further, as shown in FIGS. 1 and 2, the portion of the anode lead 12 that contacts the sealing portion of the case 50 including the edge 51 </ b> B of the first film 51 and the edge 52 </ b> B of the second film 52 includes: An insulator 14 is coated to prevent contact between the anode lead 12 and the metal layer 50c in each film. Further, a portion of the cathode lead 22 that contacts the sealing portion of the case 50 including the edge portion 51B of the first film 51 and the edge portion 52B of the second film 52 constitutes the cathode lead 22 and each film. An insulator 24 for preventing contact with the metal layer 50c in the composite packaging film is covered.
[0077]
Although the configuration of the insulator 14 and the insulator 24 is not particularly limited, for example, each of them may be formed of a synthetic resin. Note that the insulator 14 and the insulator 24 may not be disposed as long as the contact of the metal layer 50c in the composite packaging film with each of the anode lead 12 and the cathode lead 22 can be sufficiently prevented.
[0078]
Furthermore, from the viewpoint of being able to be installed even in a limited narrow installation space in a portable small electronic device, a laminated body including the anode 10, the separator 40, and the cathode 20 (from the first electrode, the separator and the second electrode). The thickness of the laminated body (thickness of the capacitor body 60) is preferably 100 to 300 μm, and more preferably 100 to 200 μm.
[0079]
In the case of this electrochemical device 1 (electric double layer capacitor), the capacitance of the capacitor is 1 × 10 ^-3 To 1F, more preferably 0.01 to 0.10F. Thereby, the electrochemical device 1 (electric double layer capacitor) having a large capacity while having a film shape is obtained. These can be used for IC cards, IC tags, etc., making use of their thin characteristics. In addition, applications for toys and the like and applications for portable devices will be expanded.
[0080]
Next, a method for manufacturing the case 50 and the electrochemical capacitor 1 described above will be described.
[0081]
Capacitor element body 60A (a laminate in which anode 10A, separator 40A and cathode 20A are sequentially laminated in this order) and capacitor element body 60B (a laminate in which anode 10B, separator 40B and cathode 20B are sequentially laminated in this order) The production method is not particularly limited, and a known thin film production technique employed for producing a known electrochemical capacitor can be used.
[0082]
When the electrodes serving as the anodes 10A and 10B and the cathodes 20A and 20B are carbon electrodes, for example, a sheet-like electrode can be manufactured using a carbon material such as activated carbon that has been activated by a known method. In this case, for example, a carbon material is pulverized to about 5 to 100 μm to adjust the particle size, and then, for example, a conductive auxiliary (for example, carbon black) for imparting conductivity to the carbon powder and a binder (for example, polytetrafluoroethylene) are used. Fluoroethylene (hereinafter, referred to as PTFE)) is added and kneaded, and the kneaded material is drawn and formed into a sheet.
[0083]
Here, in addition to carbon black, powdered graphite or the like can be used as the conductive auxiliary agent, and as the binder, PVDF, PE, PP, fluororubber, or the like is used in addition to PTFE. be able to.
[0084]
In addition, in order to form a carbon electrode, it is necessary that fine particles obtained by pulverizing a carbon material and carbon black are evenly distributed and knotted with PTFE fiber with almost the same strength. It needs to be done vertically and horizontally.
[0085]
Next, the anode lead conductor 12A and the cathode lead 22A are electrically connected to the anode 10A and the cathode 20A, respectively. The separator 40A is arranged in a state of contact (non-adhesion state) between the anode 10A and the cathode 20A to complete the capacitor body 60A. The anode lead conductor 12B and the cathode lead 22B are electrically connected to the anode 10B and the cathode 20B, respectively. Separator 40B is arranged between anode 10B and cathode 20B in a contact state (non-adhesion state) to complete capacitor element body 60B.
[0086]
Next, an example of a method for manufacturing the case 50 will be described. First, when the first film 51 and the second film 52 are composed of the above-described composite packaging film, a dry lamination method, a wet lamination method, a hot melt lamination method, an extrusion lamination method are used. It is manufactured by using a known manufacturing method such as an application method.
[0087]
For example, a film to be a synthetic resin layer constituting the composite packaging film, and a metal foil made of aluminum or the like are prepared. The metal foil can be prepared, for example, by rolling a metal material.
[0088]
Next, a composite packaging film (multilayer film) is formed by bonding a metal foil via an adhesive onto a film to be a layer made of a synthetic resin so as to preferably have the above-described configuration of a plurality of layers. Is prepared. Then, the composite packaging film is cut into a predetermined size, and one rectangular film is prepared.
[0089]
Next, as described above with reference to FIG. 2, one film is bent, and the sealing portion 51B (the edge portion 51B) of the first film 51 and the sealing portion 52B (the edge portion) of the second film 51 are bent. 52B) is heat-sealed (heat-fused) to a desired seal width under predetermined heating conditions using a sealing machine, for example. At this time, in order to secure an opening for introducing the capacitor body parts 60A and 60B into the case 50, a part where heat sealing is not performed is provided. Thus, the case 50 having the opening is obtained.
[0090]
Then, inside the case 50 having an opening, a capacitor body 60A to which the anode lead conductor 12A and the cathode lead 22A are electrically connected, and the anode lead conductor 12B and the cathode lead 22B are provided. The electrically connected capacitor body 60B is inserted.
[0091]
Next, the case 50 is provided with a partition portion 56 for preventing contact between the capacitor body portions 60A and 60B. The partition part 54 is formed by heat-sealing (thermal fusion) the mutually facing partial regions of the first film 51 and the second film 52 using a sealing machine. At this time, the size, temperature, and pressure applied to the portion to be heat-sealed of the heat-conductive member used for heat sealing so that the width W56 of the obtained partition portion 54 is preferably 0.5 to 1.0 mm, Adjust conditions such as processing time. The pressure applied to the portion to be heat-sealed at this time is 0.5 to 20 kgf / cm. ² It is preferable that The temperature at this time is preferably 175 to 190 ° C. The processing time is preferably 5 to 15 seconds.
[0092]
Then, the electrolyte solution 30 is injected from the opening. Subsequently, the opening of the case 50 is sealed using a sealing machine. Thus, the fabrication of the case 50 and the electrochemical capacitor 1 is completed.
[0093]
As described above, the preferred embodiments of the present invention have been described in detail, but the present invention is not limited to the above embodiments. For example, in the description of the above-described embodiment, a preferred configuration has been mainly described when the present invention is applied to an electric double-layer capacitor, but the electrochemical capacitor of the present invention is not limited to an electric double-layer capacitor. For example, a first plate-shaped electrode and a second plate-shaped electrode facing each other, such as a pseudo capacitor and a redox capacitor, are disposed adjacent to each other between the first electrode and the second electrode. The present invention is applicable to an electric double layer capacitor having a plate-shaped separator and an electrolyte solution and housed in a case formed of a flexible film.
[0094]
Further, in the description of the above embodiment, the case where two capacitor body parts are juxtaposed has been described, but the electrochemical capacitor of the present invention is not limited to this, and three or more capacitor body parts may be further provided. It may be configured to be juxtaposed. Further, in the description of the above-described embodiment, a case has been described in which a unit corresponding to a unit cell having a configuration in which a pair of electrodes and a separator are arranged between the pair of electrodes is juxtaposed as the capacitor body. Depending on the size of the installation space in the device, two or more of the above-described unit cells may be stacked to form one capacitor element body, and two or more of these may be juxtaposed.
[0095]
【The invention's effect】
As described above, according to the present invention, even in a case where two or more unit cells are connected in series in a state of being juxtaposed, miniaturization and weight reduction are easy, and they should be installed. An electrochemical capacitor capable of sufficiently obtaining a volume energy density based on the volume of a space can be provided. In particular, according to the present invention, a thin film-shaped electrochemical capacitor (for example, an electrochemical capacitor having a thickness of 200 to 400 μm) can be provided.
[Brief description of the drawings]
FIG. 1 is a front view showing a preferred embodiment of an electrochemical capacitor according to the present invention.
FIG. 2 is a developed view when the inside of the electrochemical capacitor shown in FIG. 1 is viewed from the normal direction of the surface of the anode of each capacitor body.
FIG. 3 is a schematic cross-sectional view showing a main part when the electrochemical capacitor shown in FIG. 1 is cut along the line X1-X1 in FIG.
4 is a schematic cross-sectional view showing a main part when the electrochemical capacitor shown in FIG. 1 is cut along the line X2-X2 in FIG.
FIG. 5 is a schematic cross-sectional view showing a main part when the electrochemical capacitor shown in FIG. 1 is cut along the line YY in FIG.
6 is a schematic cross-sectional view showing an example of a basic configuration of a film serving as a constituent material of the case of the electrochemical capacitor shown in FIG.
FIG. 7 is a schematic cross-sectional view showing another example of the basic structure of a film as a constituent material of the case of the electrochemical capacitor shown in FIG.
8 is a schematic sectional view showing an example of a basic configuration of an anode of the electrochemical capacitor shown in FIG.
9 is a schematic cross-sectional view showing an example of a basic configuration of a cathode of the electrochemical capacitor shown in FIG.
FIG. 10 is a front view showing a conventional electrochemical capacitor adopting a configuration in which two or more unit cells are connected in series in a state of juxtaposition.
11 is a schematic cross-sectional view when the electrochemical capacitor 100 shown in FIG. 10 is cut along the line X100-X100 in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Electrochemical capacitor, 10A, 10B ... Anode, 11 ... Metal wire, 12A, 12B ... Anode lead wire, 14A, 14B ... Insulator, 20A, 20B ... Cathode, 22A, 20B ... Cathode lead wire, 24A, 24B: Insulator, 30: Electrolyte solution, 40A, 40B: Separator, 50: Case, 51: First film, 51B: Edge (seal), 52: Second film, 56: Partition, 60A, 60B: Capacitor element part.

Claims (6)

Two or more configured to include a first plate-shaped electrode and a second plate-shaped electrode facing each other, and a plate-shaped separator disposed between the first electrode and the second electrode. A capacitor body part of
An electrolyte solution;
A case for accommodating the two or more capacitor element portions and the electrolyte solution in a hermetically sealed state by thermally fusing the edges of the opposing surfaces of the first film and the second film opposing each other;
A first lead provided for each of the capacitor elements such that one end is connected to the first electrode and the other end protrudes outside the case;
A second lead provided for each of the capacitor body portions such that one end is connected to the second electrode and the other end protrudes outside the case;
Has,
The capacitor element portions are electrically connected to each other in series via the first lead and the second lead,
The case has a partition portion formed by heat-sealing the mutually facing partial regions of the first film and the second film to prevent contact between the two or more capacitor element portions. Is provided,
The thickness d of the first film and the second film and the total thickness D are adjusted so as to simultaneously satisfy the conditions of the following expressions (1) and (2);
An electrochemical capacitor, characterized in that:
d ≦ 100 μm (1)
D ≦ 4d (2) The electrochemical capacitor according to claim 1, wherein the width of the partition is 0.2 to 2.0 mm. 3. The electrochemical capacitor according to claim 1, wherein a width of a heat-sealed edge of each inner surface of the first film and the second film is 0.5 to 2.0 mm. 4. . 4. The electrochemical capacitor according to claim 1, wherein the first film and the second film have an area of 0.09 to ²⁰ cm ^{2. 5} . In each of the capacitor element portions, the first electrode and the second electrode each include an electron conductive porous body as a constituent material, the separator is made of an insulating porous body, and the electrolyte solution is The electrochemical device according to any one of claims 1 to 4, wherein at least a part thereof is contained in the first electrode, the second electrode, and the inside of the separator. Capacitors. The film is formed from a composite packaging film having at least an innermost layer made of a synthetic resin that comes into contact with the electrolyte solution, and a metal layer disposed above the innermost layer. The electrochemical capacitor according to claim 1.

Images