JPH09251926A - Electric double layer capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electric double layer capacitor which has metal-made collecting electrodes made by forming main blocks of collecting electrode integrated with tabs and which has a low resistance loss of the collecting electrodes at charging/discharging and is enough to allow a large currents to flow, hence suited to high capacitance capacitors. SOLUTION: A metal-made collecting electrode 11As has a mesh-like main body 11Aa having many small holes and sheet-like tab which has no small hole and is formed with the main body in a unit. The main body 11Aa and tab 11Ab are formed in one body from an expanding-machined Al foil and tab leading direction is approximately perpendicular to the expanding direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic capacity 1000 to be used as a power source for electric bicycles, electric tools, etc.
The present invention relates to a large-capacity laminated electric double layer capacitor of about 10,000 F, and more particularly to an electric double layer capacitor having an improved collector electrode structure.

[0002]

2. Description of the Related Art A large-capacity electric double layer capacitor that can be used as a power source for temporarily supplying a large amount of energy has recently adopted a laminated structure instead of the original wound structure. That is, a wound-type electric double-layer capacitor has a strip-shaped separator sandwiched between a strip-shaped positive electrode and a strip-shaped negative electrode, and these are wound in a paste form, and the wound body is housed in a metal cylindrical case. In this case, the electrolytic solution is impregnated, and the cylindrical shape has a low mounting efficiency in the power supply device.

Therefore, a laminated electric double layer capacitor is proposed in which rectangular positive electrodes and negative electrodes are alternately laminated with a separator interposed therebetween, and the electrode laminate is housed in a rectangular outer case. ing. FIG. 9 is a diagram schematically showing the basic structure of a conventional laminated electric double layer capacitor.

As shown in FIG. 9, a positive electrode 50 has a conductive metal collector electrode 5 for a positive electrode, which is formed by integrally molding a rectangular collector electrode body 51a and a narrow tab 51b.
1 and polarizable electrodes 52a and 52b for accumulating positive charges located on both sides thereof. The tab 51b is for electrical connection with the positive electrode external terminal 72. Similarly, the negative electrode 60 includes a collector electrode body 61 a and a tab 61.
It is composed of a conductive negative metal collector electrode 61 formed by integrally molding b and polarizable electrodes 62a and 62b for accumulating negative charges on both sides thereof. The positive electrode 50 and the negative electrode 60 are alternately laminated, for example, 50 each with a separator 71 interposed therebetween.
The collector electrode bodies 51a and 61a, the polarizable electrode 52a,
52b, 62a, 62b and the separator 71 generally have the same shape and a rectangular shape with the same size.

Then, the electrode laminated body in which the electrodes 50 and 60 are superposed is provided with two fastening plates (not shown) on both sides in order to bring the collector main body of each electrode 50 and 60 into close contact with the polarizable electrode. It is stored in a rectangular outer case (not shown) in a state in which it is arranged on the outermost part and a tightening belt is wound around the outermost part and tightened in the stacking direction. Next, a predetermined electrolytic solution is impregnated, and each positive electrode tab 51b is connected to a positive electrode external terminal 72 fixed to a case upper lid (not shown).
Similarly, each tab 61b for the negative electrode is connected to the negative electrode external terminal 73, and thereafter, the case upper lid is attached to the opening of the case so as to be hermetically sealed.

The polarizable electrode has a thickness of 0.1 to 10.
It is about 2.0 mm and is made of activated carbon for accumulating charges. Then, the metal collecting electrodes 51, 61
Has a thickness of about 5 to 300 μm, such as aluminum net foil, aluminum punching foil made by punching metal like aluminum foil, aluminum expanded foil made by expanding aluminum foil, etc. A metal-like metal foil with a large number of small holes is used, and the current collector body and the tab are integrally formed by die-cutting such a metal-like metal foil. Is. The reason why such a mesh-shaped material is used is to allow the electrolytic solution to soak into the polarizable electrode efficiently (to fill the micropores of the activated carbon with the electrolytic solution or replace it with the electrolytic solution).

An organic electrolytic solution is used as the electrolytic solution, and a representative example thereof is a propylene carbonate solution containing a special salt. The separator 71 is made of a porous material having ion permeability and electric insulation, and for example, polypropylene fiber nonwoven fabric is used.

[0008]

However, in the above-mentioned conventional electric double layer capacitor, as a metal collector electrode, a metal mesh foil having a large number of small holes is punched out to form a collector electrode body. A tab-integral type that is integrally formed with a tab is used, and a tab that is band-shaped and has a smaller width and a smaller cross-sectional area than the collector main body is also mesh-shaped. However, there is a problem that the resistance loss is large in the vicinity of the tab where the current is concentrated (the current density is high) in the collector electrode body, and the output is reduced.

The present invention has been made to solve the above-mentioned problems, and by improving the structure of the tab-integrated metal collector electrode, the resistance loss in the metal collector electrode during charge and discharge is small and large. An object of the present invention is to provide an electric double layer capacitor suitable for a large-capacity capacitor capable of passing an electric current.

[0010]

In order to achieve the above-mentioned object, a positive electrode comprising a metal collector electrode for a positive electrode and a polarizable electrode for accumulating a positive charge, a metal collector electrode for a negative electrode and a negative charge. Electricity that accumulates electric charges in an electric double layer formed at the interface between the electrolytic solution and the polarizable electrode by alternately stacking a negative electrode composed of a polarizable electrode for storage with a separator interposed therebetween. The following measures are taken in the double layer capacitor.

According to a first aspect of the present invention, the metal collector electrode is formed by integrally molding a collector electrode body and a tab for drawing out from the collector electrode body and connecting to an external terminal. The electric double layer capacitor is characterized in that it has a mesh shape with small holes and the tab has a sheet shape without small holes. In a second aspect based on the first aspect, the collector electrode body is configured to change the degree of small hole distribution so that the resistance value in the vicinity of the tab is smaller than the resistance value in the remaining portion. It is an electric double layer capacitor characterized in that

In a third aspect of the present invention, the metal collector electrode is formed by integrally molding a collector electrode body and a tab for drawing out from the collector electrode body and connecting to an external terminal, and the tab has no small hole. The electric double layer is formed in a sheet shape, and the collector main body has a sheet shape in the vicinity of the tab like the tab, and the remaining portion has a mesh shape in which a large number of small holes are formed. It is a capacitor.

In a fourth aspect of the present invention, the metal collector electrode is formed by integrally molding a metal material in which a collector electrode body and a tab for drawing out from the collector electrode body and connecting to an external terminal are expanded. Further, the electric double layer capacitor is characterized in that the tab pull-out direction and the expanding direction are substantially perpendicular to each other.

In the electric double layer capacitor according to the first aspect of the present invention configured as described above, the metal collector electrode has a mesh-like shape in which a large number of small holes are formed in order to efficiently impregnate the polarizable electrode with the electrolytic solution. The integrated collector body and the tabs that are sheet-shaped without small holes to reduce the resistance value are integrally molded.Therefore, compared with the conventional electric double layer capacitors having mesh-shaped tabs, The resistance loss at the tab during discharge is small. A metal-made collecting electrode having such a structure is, for example, a press with a blade having a die-cutting surface having a collecting electrode body-corresponding portion having a large number of small hole-forming protrusions and a smooth tab-corresponding portion. The metal foil is die-cut by a machine to be integrally formed.

Here, in the electric double layer capacitor according to the first aspect of the invention, in the mesh-shaped collector electrode body, the current is concentrated and the current density increases as it approaches the tab during charging / discharging, and the resistance loss in the vicinity of the tab occurs. large. Therefore, there is room for improvement in reducing the resistance value in the vicinity of the tab of the collector electrode body.

In order to improve this point, in the electric double layer capacitor according to the second aspect of the present invention, the resistance value in the vicinity of the tab where the current is most concentrated in the collector body of the metal collector electrode is the resistance value in the remaining portion. Since the hole diameter of each small hole in the vicinity of the tab is made smaller than the hole diameter of each small hole in the region other than the vicinity of the tab, the small hole distribution degree is changed so that Compared with the electric double layer capacitor of the first invention, the resistance value in the vicinity of the tab of the collecting electrode body can be made smaller, and the resistance loss in the collecting electrode body can be made smaller.

Further, in the electric double layer capacitor according to the third aspect of the present invention configured as described above, the tabs of the metal collector electrodes are sheet-shaped without small holes, and the collector electrode body is sheet-shaped like the tabs in the vicinity of the tabs. Since the remaining portion is a mesh having a large number of small holes, the resistance value at the current concentration portion (near the tab) of the collector electrode body is smaller than that of the electric double layer capacitor of the first invention. It is possible to reduce the resistance loss in the collector main body.

In the electric double layer capacitor according to the fourth aspect of the present invention, the metal collector electrode is formed by integrally molding the collector electrode body and the tab from an expanded metal material such as aluminum expanded foil, and As shown in FIG. 8, the tab pulling direction and the expanding direction (material stretching direction) are substantially perpendicular to each other.
Compared with the case where the tab drawing direction and the expanding direction are the same, the resistance value is small because the current (electrons) flow path in the metal collector electrode is short.

[0019]

1 is a front view schematically showing an example of a metal collector electrode according to a fourth invention.

As shown in the figure, this metal collector electrode 11
A is, in this example, an expanded thickness of 50 μm.
m of aluminum foil (JIS: 1N30) is die-cut by a press machine with a blade to form a rectangular collector electrode body 1
1Aa and a tab 11Ab having a narrow width and a strip shape are integrally formed.

Further, as shown in FIG. 1, the metal collector electrode 11A is integrally formed so that the tab drawing direction and the expanding direction are substantially perpendicular to each other. This allows
This metal collector electrode 11A has a tab pull-out direction and an expand direction as shown in FIG.
The current (electrons) flow path in the metal collector electrode is short and the resistance value is small. The dimensions of this metal collector electrode 11A are, for example, collector electrode body 11Aa: width 50 mm, length 100 mm, tab 11Ab: width 15 mm, length 100.
mm.

FIG. 2 is a perspective view showing an example of the whole structure of a laminated type electric double layer capacitor having the metal collector electrode shown in FIG. 1 with a part cut away.

As shown in the figure, the positive electrode 10 has a tab 11
The metal collector electrode 11A for the positive electrode having Ab and the polarizable electrodes 12a, 1 for accumulating positive charges located on both sides thereof.
2b. Similarly, the negative electrode 20 is composed of a negative electrode metal collector electrode 21A having the same structure as the metal collector electrode 11A, and negative charge storage polarizable electrodes 22a and 22b located on both sides thereof. There is. The positive electrode 10 and the negative electrode 20 are stacked alternately and alternately with a separator 31 interposed therebetween. In the electrodes 10 and 20 arranged on the outermost side, the polarizable electrodes are arranged only on the inner side, not on both sides.

In this example, metal collector electrodes 11A and 21A
Collector electrode body, polarizable electrodes 12a, 12b, 22a, 2
2b and the separator 31 are rectangular in shape and size. And in this example, the polarizable electrodes 12a, 1
2b, 22a and 22b, each having a thickness of about 0.5 mm, are kneaded with activated carbon powder for accumulating charges, carbon black for improving electric conductivity, and PTFE (polytetrafluoroethylene) as a binder. Is used as a sheet (made into a flat plate), and a polypropylene fiber nonwoven fabric having a thickness of about 25 μm is used as the separator 31.

Then, the electrode laminated body in which the electrodes 10 and 20 are superposed on each other is provided with fastening plates 32 on the outermost sides of both sides in order to bring the metal collecting electrode of each electrode 10 and 20 into close contact with the polarizable electrode. It is placed in a rectangular outer case 34 in a state where it is placed and fastened in the stacking direction by winding a fastening belt 33 around it. Next, a predetermined electrolytic solution is impregnated, and each tab 11Ab of each metal collector electrode 11A is connected to the positive electrode external terminal 35 fixed to the case upper lid 34a by snapping or the like. At this time, since each metal collector electrode 11A is formed by integrally forming the collector electrode body 11Aa and the tab 11Ab, the connection work between the collector electrode and the tab, which is conventionally performed, becomes unnecessary. Similarly, the tab (not shown) of each metal collector electrode 21A is connected to the negative electrode external terminal 36. After that, the case upper lid 34a is attached to the opening of the case 34 so as to be hermetically sealed.

As described above, in the electric double layer capacitor provided with the metal collector electrode in which the collector electrode body and the tab are integrally molded from the expanded metal material, the electric double layer capacitor according to the present invention has a conventional structure. The resistance value of the metal collector electrodes 11A, 21A can be made smaller, and the resistance loss in the metal collector electrodes 11A, 21A can be made smaller than that of the above.

FIG. 3 is a front view schematically showing an example of the metal collector electrode according to the first invention.

As shown in the figure, this metal collector electrode 11
In this example, B has a thickness of 50 with a blade press having a die-cutting surface having a collector electrode body corresponding portion having a large number of small hole forming protrusions and a tab corresponding portion having a smooth surface.
By punching out an aluminum foil (JIS: 1N30) of μm, a collector electrode body 11Ba having a large number of small holes and having a mesh shape, and a tab 11 having a sheet shape without small holes.
It is formed integrally with Bb. As a result, the resistance loss in the tab 11Bb at the time of charging / discharging can be reduced as compared with the conventional electric double layer capacitor having the mesh tab.

FIG. 4 is a front view schematically showing an example of the metal collector electrode according to the second invention, and FIG. 5 is a front view schematically showing another example thereof.

The metal collector electrode 11C shown in FIG. 4 is that the collector electrode body 11Ca in the form of a mesh and the tab 11Cb in the form of a sheet are integrally formed, as shown in FIG.
Although it has the same structure as that of the metal collector electrode 11B, the collector electrode body 11Ca is different in this example in that the size of the small holes is changed in two steps while keeping the number of small holes per unit area constant. By adopting the small hole distribution pattern, the resistance value near the tab where the current is most concentrated becomes smaller than the resistance value in the remaining portions. In this metal collector electrode 11C, for example, a small hole forming projection is shown in FIG.
It can be manufactured by die-cutting the aluminum foil with a blade press having a die-cutting surface having a collector electrode body-corresponding portion and a smoothed tab-corresponding portion formed in the distribution pattern shown in FIG. .

Further, the metal collector electrode 11D shown in FIG.
In this example, the number of small holes per unit area is set to be constant in order to further reduce resistance loss and heat generation due to current concentration that increases as the collector electrode body 11Da approaches the tab 11Db from the periphery of the collector electrode body. By using a small hole distribution pattern in which the size of the small holes is changed in three steps, the resistance value near the tab where the current is concentrated becomes smaller than the resistance value in the remaining portions. . Thereby, in the electric double layer capacitor having the metal collector electrode 11C of FIG. 4 or the metal collector electrode 11D of FIG.
The resistance value in the current concentration portion (near the tab) of the collector electrode body can be made smaller than that of the first invention described above, and the resistance loss in the collector electrode body can be made smaller.

In the example shown in FIGS. 4 and 5,
In order to reduce the resistance value of the collector electrode body toward the tab, the number of small holes per unit area was kept constant and the size of each small hole was changed in multiple steps. Alternatively, the size of the small holes may be fixed and the number of small holes per unit area may be changed, or both the size of the small holes and the number of small holes per unit area may be changed. You may

FIG. 6 is a front view schematically showing an example of a metal collector electrode according to the third invention, and FIG. 7 is a front view schematically showing another example thereof.

As shown in FIG. 6, this metal collector electrode 11
E is formed by integrally molding a collector electrode body 11Ea and a tab 11Eb by stamping out an aluminum foil. The tab 11Eb has a sheet shape without small holes. Then, the portion along the two sides close to the tab 11Eb is formed into a sheet shape, and the remaining portion is formed into a mesh shape so that the resistance value near the tab where the current is most concentrated in the collector main body 11Ea becomes small. . This collector electrode 11E has, for example, a die-cut surface having a small-hole forming protrusion and a collector-electrode body-corresponding portion in which an L-shaped smooth surface is formed in the pattern shown in FIG. 6 and a smoothed tab-corresponding portion. It can be manufactured by punching the aluminum foil with the bladed press machine.

Further, the metal collector electrode 11F of the example shown in FIG.
The tab 11Fb is in the form of a sheet having no small holes, and the collector electrode body 11Fa is connected to the tab 11Fb in order to further alleviate heat generation due to current concentration that increases as the tab body 11Fb approaches the tab 11Fb from the periphery of the collector electrode body. The tree-like portion is formed into a sheet shape, and the remaining portion is formed into a mesh shape so that the resistance value in the vicinity of the tab where the current is most concentrated in the collector electrode body 11Fa is reduced. As a result, in the electric double layer capacitor having the metal collector electrode 11E of FIG. 6 or the metal collector electrode 11F of FIG. 7, the current concentration portion (near the tab) of the collector electrode body is different from that of the first invention described above. 2), the resistance value in the collector electrode body can be further reduced.

[0036]

As described above, according to the first to fourth inventions of the present application, it is possible to reduce the resistance loss in the metal collector electrode during charging and discharging, as compared with the conventional electric double layer capacitor. It is possible to realize an electric double layer capacitor suitable for a large-capacity capacitor that can carry current.

[Brief description of drawings]

FIG. 1 is a front view schematically showing an example of a metal collector electrode according to a fourth invention.

FIG. 2 is a perspective view showing an example of the whole constitution of a laminated type electric double layer capacitor according to a fourth invention having the metal collector electrode shown in FIG.

FIG. 3 is a front view schematically showing an example of a metal collector electrode according to the first invention.

FIG. 4 is a front view schematically showing an example of a metal collector electrode according to the second invention.

FIG. 5 is a front view schematically showing another example of the metal collector electrode according to the second invention.

FIG. 6 is a front view schematically showing an example of a metal collector electrode according to the third invention.

FIG. 7 is a front view schematically showing another example of the metal collector electrode according to the third invention.

FIG. 8 is a front view schematically showing a metal collector electrode for comparison.

FIG. 9 is a diagram schematically showing a basic configuration of a conventional laminated electric double layer capacitor.

[Explanation of symbols]

10 ... Positive electrode 11A-11F ... Metal collector electrode 11Aa
~ 11 Fa ... collector electrode body 11 Ab ~ 11 Fb ... tab
12a, 12b, 22a, 22b ... Polarizable electrode 20 ... Negative electrode 21A ... Metal collector electrode 31 ... Separator 32 ... Tightening plate 33 ... Tightening belt 3
4 ... Square outer case 34a ... Case upper lid 35 ... Positive electrode external terminal 36 ... Negative electrode external terminal

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsushi Mitsui, 2 Daidai-cho, Kanagawa-ku, Yokohama-shi, Kanagawa 5 Power Systems Co., Ltd. (72) Masaaki Yamagishi 2-5 Taidai, Kanagawa-ku, Yokohama-shi, Kanagawa In stock company power system

Claims (4)

[Claims] 1. A separator comprising a positive electrode composed of a metal collector electrode for a positive electrode and a polarizable electrode for positive charge storage, and a negative electrode composed of a metal collector electrode for a negative electrode and a polarizable electrode for negative charge storage. In the electric double layer capacitor utilizing the accumulation of electric charges in the electric double layer formed at the interface between the electrolytic solution and the polarizable electrode, the metal collecting electrode is The electrode main body and a tab for drawing out from the collector electrode main body and connecting to an external terminal are integrally formed, and the collector electrode main body is in a mesh shape having a large number of small holes, and the tab is a small hole. An electric double layer capacitor, which is characterized by having no sheet shape. 2. The electric double layer capacitor according to claim 1, wherein the collector electrode body has a small hole distribution degree such that a resistance value in the vicinity of the tab is smaller than a resistance value in the remaining portion. An electric double layer capacitor characterized by being changed. 3. A separator comprising a positive electrode composed of a metal collector electrode for a positive electrode and a polarizable electrode for positive charge storage, and a negative electrode composed of a metal collector electrode for a negative electrode and a polarizable electrode for negative charge storage. In the electric double layer capacitor utilizing the accumulation of electric charges in the electric double layer formed at the interface between the electrolytic solution and the polarizable electrode, the metal collecting electrode is The electrode body and a tab for pulling out from the current collecting electrode body and connecting to an external terminal are integrally formed, and the tab is a sheet without small holes. An electric double layer capacitor, characterized in that it is in the form of a sheet, and the remaining portion is in the form of a mesh having a large number of small holes. 4. A separator comprising a positive electrode composed of a metal collector electrode for a positive electrode and a polarizable electrode for positive charge storage, and a negative electrode composed of a metal collector electrode for a negative electrode and a polarizable electrode for negative charge storage. In the electric double layer capacitor utilizing the accumulation of electric charges in the electric double layer formed at the interface between the electrolytic solution and the polarizable electrode, the metal collecting electrode is The electrode body and the tab for pulling out from the collecting electrode body and connecting to the external terminal are integrally formed from an expanded metal material, and the tab withdrawing direction and the expanding direction are substantially perpendicular to each other. An electric double layer capacitor characterized by being a thing.