JPH10163075A - Electrochemical device and electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrochemical device in which the number of materials is reduced for cost reduction and necessity of an insertion work for a separator is eliminated, and an electrode used for the electrochemical device. SOLUTION: Electric insulating ion conductive layers 7 and 7 having a thickness of 25-50μm are provided on ion absorbing/emitting layers 5 and 6 of one surface of each electrode 1, 2 (left surfaces of the electrodes 1 and 2 in Fig,. 1), respectively. As the electric insulation ion conducting layer 7, a porous solid- state film, wherein a plurality of pores are, in a wet method or a dry method or a mechanical method, made on a synthetic resin film such as polypropylene(PP), polyethylene(PE), etc., or a solid-state film in which such ceramics fine powder as magnesium oxide is applied and film-formed with, for example, PVdF as a binder, or a solid electrolyte having high ion conductivity and no electronic conductivity, is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intermediate device between a capacitor and a battery, and more particularly to an electrochemical device that retains electric charge by absorbing ions and an electrode used in the electrochemical device.

[0002]

2. Description of the Related Art FIG. 3 shows an intermediate device between a capacitor which emits a weak current for a long time (or a predetermined voltage is applied for a long time) and a battery which emits a larger current for a shorter time. FIG. 3 is a schematic view showing a configuration of a main part of a conventional electrochemical device, in which a thickness direction is enlarged. Electrodes 11 and 12 are
Grids 13 and 14 each having a thickness of about 20 μm and made of strip-shaped aluminum foil or copper foil are arranged so as to face each other, and leads 18 and 19 are connected to both grids 13 and 14, respectively. On both sides of both grids 13 and 14, carbon and polyvinylidene fluoride (PVdF) as a binder are provided.
Is applied to a thickness of 30 to 200 μm,
Ion absorbing / releasing layers 15, 15, 16, 16 for absorbing / releasing ions are formed. One of both electrodes 11, 12 (electrode 11 in FIG. 2)
On both sides, electrically insulating separators 17, 17 such as a strip of paper or non-woven fabric having a thickness of 25 to 50 μm are arranged.

The electrodes 11 and 12 and the separators 17 and 17 are spirally wound and inserted into a bottomed cylindrical case. In the case, for example, trimethylalkylammonium boron tetrafluoride, propylene carbonate (PC) or An electrolyte such as ethylene carbonate (EC) is injected to impregnate the electrolyte into the separator, and the case is sealed with a lid.

In such an electrochemical device, an electrode
When an appropriate voltage is applied to 11, 12, separators 17, 17
Anions and cations in the electrolyte impregnated into the electrodes are polarized to the corresponding electrodes 11 and 12, and the ion-absorbing layer 1
It is occluded at 5,15,16,16. As a result, electric charges are accumulated in the electrochemical device, and a potential difference is formed between the electrodes 11 and 12. Then, the electrochemical device releases the accumulated charges to the outside from the leads 18 and 19 through the grids 13 and 14 by releasing the anions and cations stored in the ion absorbing and releasing layers 15, 15, 16 and 16. .

[0005]

However, in the conventional electrochemical device, a separator must be interposed between the electrodes in order to prevent a short circuit between the opposed electrodes. However, there was a problem that the cost was high. Further, it takes time and effort to interpose the separator, and when a defect occurs in the interposition of the separator, there is a possibility that an internal short circuit may occur.

The present invention has been made in view of such circumstances, and has as its object to reduce the number of materials by forming an electrically insulating ion-conductive layer on an ion absorbing / releasing layer provided on a grid. Accordingly, it is an object of the present invention to provide an electrochemical device capable of reducing cost and eliminating the need for an interposition work of a separator, and an electrode used for the electrochemical device.

[0007]

According to a first aspect of the present invention, there is provided an electrochemical device comprising: a plurality of electrodes provided with an ion absorbing / releasing layer for absorbing / releasing ions on one or both sides of a plate-like grid; An electrochemical device that arranges layers so as to face each other, interposes an electrolyte between the electrodes, and stores charges by absorbing ions polarized by application of a voltage to the electrolyte in the ion absorbing / releasing layer of the corresponding electrode. Wherein an electrically insulating ion-conductive layer is formed on one or both of an ion-absorbing layer provided on one surface of the grid and / or an ion-absorbing layer provided on both surfaces of the grid.

According to a second aspect of the present invention, in the electrochemical device according to the first aspect, the electrically insulating ion-conductive layer is formed by forming a plurality of holes in an electrically insulating solid film.

The electrochemical device according to a third aspect of the present invention is the electrochemical device according to the first aspect, wherein the electrically insulating ion-conductive layer is formed using a solid electrolyte.

An electrode according to a fourth aspect of the present invention is provided in the electrochemical device according to any one of the first to third aspects.

According to the first and fourth aspects of the present invention, a plurality of electrodes having an ion absorbing / releasing layer for absorbing / releasing ions on one or both sides of a plate-like grid are provided so that the ion absorbing / releasing layers face each other. And an electrolyte is interposed between the electrodes, and charges are retained by storing ions polarized by application of a voltage to the electrolyte in the ion absorbing / releasing layer of the corresponding electrode, but provided on one surface of this grid. An electrically insulating ion-conductive layer is formed on one or both of the ion-absorbing / releasing layer and the ion-adsorbing / releasing layer provided on both sides of the grid. The electrically insulating ion-conductive layer insulates between the opposing electrodes without hindering the movement of ions to the corresponding electrodes when a voltage is applied.

[0012] This makes it possible to wind two electrodes disposed opposite to each other and to stack a plurality of electrodes without interposing a separator between the electrodes. Therefore, the work of interposing the separator is unnecessary, and the insulation failure due to the trouble of the work of interposing the separator does not occur. Further, since the separator is not required, the number of materials is small. Furthermore,
The formation of the electrically insulating ion conductive layer can be easily performed by, for example, applying an electrically insulating ion conductive material on the ion absorbing / releasing layer. Since the costs required for management and transportation are not required, manufacturing costs can be reduced. Further, when an electrically insulating ion-conductive layer is formed on both of the ion-absorbing and releasing layers provided on both sides of the grid of the electrode, the electrode opposed thereto may be provided with only the ion-absorbing and releasing layer. The cost can be further reduced.

In the second and fourth inventions, for example, a plurality of holes are formed in an electrically insulating solid film such as polypropylene or polyethylene by a wet method or a dry method to form an electrically insulating ion-conductive layer. Form. In such an electrically insulating ion-conductive layer, the solid film insulates the electrodes facing each other and allows ions to pass through a plurality of holes formed in the solid film.

In the third and fourth aspects of the present invention, the electrically insulating ion-conductive layer is formed of a solid electrolyte having high ionic conductivity but little electron conductivity. As a result, the opposed electrodes are insulated from each other without hindering the polarization of ions and without interposing a separator.

[0015]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is an exploded perspective view showing the configuration of the electrochemical device according to the present invention. FIG.
FIG. 2 is a schematic view showing a configuration of a main part of the electrochemical device shown in FIG. 1, in which a thickness direction is emphasized. Electrodes 1 and 2 of the electrochemical device are provided with grids 3 and 4 made of aluminum foil or copper foil having a thickness of about 20 μm. The two grids 3 and 4 are arranged so as to face each other, and leads 8 and 9 are connected to the grids 3 and 4, respectively. A mixture of carbon and PVdF as a binder is applied to both surfaces of both grids 3 and 4 to a thickness of 30 to 200 μm, and ion absorbing / releasing layers 5, 5 and 6 for absorbing and releasing ions. 6 are formed. On the ion absorbing / releasing layers 5 and 6 on one surface of the electrodes 1 and 2 (the left surfaces of the electrodes 1 and 2 in FIG. 1), electrically insulating ion conductive layers 7 and 7 having a thickness of 25 to 50 μm are provided respectively. It is.

As the electrically insulating ion conductive layer 7, a synthetic resin film such as polypropylene (PP) and polyethylene (PE), or a solid film formed by applying and forming a ceramic fine powder such as magnesium oxide, for example, using PVdF as a binder. A porous solid membrane in which a plurality of pores are opened by a wet method or a dry method or mechanically so that the porosity is approximately 60 to 90% can be used. Also,
Instead of a porous solid membrane, while having a high ionic conductivity, such as an organic solid electrolyte such as a polymer containing a polyethylene oxide derivative and a polymer containing an ion dissociating group, or an inorganic solid electrolyte such as LiSrO ₃ and LiBaO ₃ , A solid electrolyte having no electronic conductivity can also be used. When an inorganic solid electrolyte is used, a slurry is applied to the ion absorbing / releasing layer, dried, and then fired to form an electrically insulating ion conductive layer on the ion absorbing / releasing layer. Further, a plurality of pores may be opened in the solid electrolyte to improve ionic conductivity.

The electrodes 1 and 2 are spirally wound and inserted into a cylindrical case 20 having a bottom. When a porous solid film is used as the electrically insulating ion-conductive layers 7, 7, an electrolyte such as PC or EC containing tetraethylammonium boron tetrafluoride is injected into the case, and the electrolyte is discharged. Impregnating the electrically insulating ionic conductive layers 7, 7;
On the other hand, when an organic solid electrolyte is used as the electrically insulating ion-conductive layers 7, 7, the opening of the case 20 is sealed with the lid 22 provided with the positive electrode terminal 23 without injecting the electrolytic solution.

When an inorganic solid electrolyte is used as the electrically insulating ion-conductive layer, the inorganic solid electrolyte is not flexible, so that the electrodes cannot be wound, and a plurality of plate-like electrodes are stacked. In this case, each of the odd-numbered electrodes is connected by a current collector, and each of the even-numbered electrodes is connected by another current collector. Then, leads are connected to both current collectors.

As described above, since the work of interposing the separator is unnecessary, the working efficiency is high. Further, since the number of materials of the electrochemical device is small, the cost is low and material management is easy.

In such an electrochemical device, when an appropriate voltage is applied from the leads 8 and 9 to the electrodes 1 and 2,
The anions and cations in the electrically insulating ion-conductive layers 7, 7 correspond to the ion absorbing / releasing layers 5, 5, 5 of the corresponding electrodes 1, 2.
Occluded in 6,6. As a result, a potential difference is formed between the two electrodes 1 and 2, and charges are accumulated in the electrochemical device.
Then, the electrochemical device includes the ion absorbing / releasing layers 5, 5, 6, 6
By releasing anions and cations occluded in the leads 8, the accumulated charges are transferred to the leads 8,
Release from 9 to the outside.

The electrodes 1 and 2 shown in FIG. 1 are provided with the electrically insulating and ion-conductive layers 7 and 7 on the ion absorbing and releasing layers 5 and 6 on one surface of the electrodes 1 and 2, respectively. The present invention is not limited to this, and an electrically insulating ion conductive layer may be provided on the ion absorbing / releasing layer on both surfaces of the electrode. In this case, an electrode provided only with an ion absorbing / releasing layer can be used as an electrode arranged opposite to an electrode provided with an electrically insulating ion conductive layer on both surfaces, and cost can be reduced. .

[0022]

As described in detail above, the first, second and fourth
According to the present invention, two electrodes arranged opposite to each other can be wound and a plurality of electrodes can be stacked without interposing a separator between the opposed electrodes. Therefore, the assembling of the electrochemical device is facilitated, and the assembling efficiency is improved. Further, the cost can be reduced because the number of materials is small. On the other hand, when an electrically insulating ion-conductive layer is formed on both of the ion-absorbing and releasing layers provided on both sides of the grid of the electrode, the electrode opposed thereto may be provided with only the ion-absorbing and releasing layer. The cost can be further reduced.

In the third and fourth aspects of the present invention, since the electrically insulating ion-conductive layer is formed by the solid electrolyte, the present invention has excellent effects such as eliminating the need for an electrolytic solution and improving the assembly efficiency. Play.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a configuration of an electrochemical device according to the present invention.

FIG. 2 is a schematic diagram showing a configuration of a main part of the electrochemical device shown in FIG.

FIG. 3 is a schematic diagram showing a configuration of a main part of a conventional electrochemical device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electrode 2 electrode 3 grid 4 grid 5 ion absorbing / releasing layer 6 ion absorbing / releasing layer 7 electrically insulating ion conductive layer 8 lead 9 lead

Claims (4)

[Claims] 1. A plurality of electrodes each having an ion absorbing / releasing layer for absorbing / releasing ions on one or both sides of a plate-like grid are arranged so that the ion absorbing / releasing layers face each other, and between each electrode. In an electrochemical device that retains electric charge by interposing an electrolyte and storing ions polarized by application of a voltage to the electrolyte in an ion absorbing / releasing layer of a corresponding electrode, an ion absorbing / releasing layer provided on one surface of the grid, Alternatively, an electrochemical device characterized in that an electrically insulating ion conductive layer is formed on one or both of the ion absorbing / releasing layers provided on both surfaces of the grid. 2. The electrochemical device according to claim 1, wherein the electrically insulating ion-conductive layer has a plurality of holes formed in an electrically insulating solid film. 3. The electrochemical device according to claim 1, wherein the electrically insulating ion-conductive layer is formed using a solid electrolyte. 4. An electrode provided in the electrochemical device according to claim 1.