JPS63104415A - Laminated electric double-layer capacitor - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a multilayer electric double layer capacitor.

(Prior Art) Electric double layer capacitors are based on the principle of accumulating charges in an electric double layer formed at the interface between a polarizable electrode with a large specific surface area, such as activated carbon, and an electrolyte.
It is attracting attention because it has a much larger capacitance than other capacitors.

FIG. 1 shows the general structure of a coin-shaped unit cell of an electric double layer capacitor. In FIG. 1, a polarizable electrode 1 mainly composed of activated carbon powder or activated carbon fiber is fixed to a metal case 3 which also serves as an external terminal for one pole by a conductive adhesive layer 5, and a conductive adhesive layer 5 also serves as an external terminal for one pole. A polarizable electrode 2 fixed to a metal case 4 which also serves as the external terminal function of the other pole through a porous separator 6 is disposed opposite to the polarizable electrode 1 through a porous separator 6.

Separator 6 and polarization ('! Electrolyte 1.2 is impregnated with electrolyte and metal cases 3 and 4 are applied via backing material 7) are tightened to 1.+ to obtain unit cell 8.

RA is the main application of such electric double layer capacitors.
As a backup power source for M-I C memory, etc., 5
．． A working voltage of 5V is required, but the withstand voltage of the coin-shaped unit cell is approximately 0.8V when using an aqueous electrolyte, and approximately 1V when using a non-aqueous electrolyte. .8
Since the voltage is ~2.8V, two or more unit cells are usually connected in series.
It is necessary to use 7 pieces stacked together.

When using such coin-shaped unit cells 8 in a stacked manner, a stacked structure as shown in FIG. 9 has conventionally been adopted. In FIG. 9, a cylindrical metal outer case 9 with a bottom is shown.
Three unit cells 8 are stacked in series and housed inside. A cylindrical insulating tube 11 is interposed between the laminate 10 and the side surface of the outer case 9, and a first terminal plate 12 of one electrode having a lead triggering portion is provided on the upper surface of the laminate 10. is arranged, and a second terminal board 14 of the other electrode having a lead triggering part is arranged on the L side of the first terminal board 12 so as to sandwich the insulating plate 13 therebetween. Furthermore, by caulking the upper end 9a of the metal exterior case 9 inward, the laminate 10 is integrally fixed.
In addition, the electrical connection between the metal exterior case and the second end plate 14 is maintained.

(Problems to be Solved by the Invention) However, in the above-mentioned conventional +rJ layer structure,
Unit cell 84fl,'! Between E or laminate 10
The terminal plates 12, 14 and the metal case 9 maintain electrical connection by mechanically abutting each other. Therefore, in such a laminated structure, if a part of the unit cell 8 is even slightly thinner than a predetermined thickness, the abutting portion may become loose, resulting in poor electrical connection. There was a problem with that.

On the other hand, if something thicker than the predetermined thickness is included, excessive pressure will be applied to the unit cell 8 when caulking the upper end 9a of the metal exterior case 9, which will not only cause the unit cell 8 to deform. However, there was a problem in that the sealing performance of the unit cell 8 sometimes deteriorated and the electrolyte leaked out.

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems and provide a highly reliable multilayer electric double layer capacitor that is free from electrical connection failures and electrolyte leakage.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a coin-shaped electric double layer capacitor unit in which an anode and a cathode are housed in a pair of metal cases that also function as external terminals. In a multilayer electric double layer capacitor formed by stacking a plurality of cells in series, a substantially U-shaped metal plate is provided between one unit cell and another unit cell connected in series,
One end of the metal plate is fixed to the anode-side metal case of the one unit cell, and the other end of the metal plate is fixed to the cathode-side metal case of the other unit cell, thereby forming a laminate. The present invention provides a multilayer electric double layer capacitor characterized by the following.

In the present invention, the metal plates used for laminating the unit cells must be able to be fixed to, preferably welded to, the metal case of the unit cells, and have good electrical conductivity, and are preferably made of nickel or SUS 304. .5U
It is made of stainless steel such as S316. The metal plate is preliminarily fixed to the pair of unit cell metal cases (preferably welded) as a rectangular metal plate (although it may be in the shape of a straight line), and has a diameter of about 180 mm.
Since it is formed into a U-shape or U-shape by bending, the thickness is usually 0.05 to 0.5 mm, particularly 0.1 to 0.3 mm.

As a method for fixing the metal plate to the metal case, adhesion using conductive resin is also possible, but more preferably welding, especially electric welding (suboso day welding), laser welding, Alternatively, methods such as plasma welding can also be employed.

The above-mentioned laminate may be provided with external metal terminals for connection to equipment to be used by fixing, preferably by welding, to the metal cases at both ends of the laminate in the stacking direction.

In order to achieve the object of the present invention, it is more preferable to integrally fix the laminate as it is or the laminate with the external metal 9;i; by a resin mold or a heat-shrinkable tube. preferable. By doing so, even if the electrolyte should leak out of the cell, it can almost completely prevent it from dissipating to the outside. As the resin used in this case, epoxy resin, polyacrylonitrile resin, silicone resin, etc. are preferably selected.

The material of the polarizable electrode of the unit cell used in the present invention is not particularly limited, but it is preferable to use activated carbon powder or activated carbon fiber that is electrochemically inert to the electrolyte and has a large specific surface area.

In particular, activated carbon powder contains polytetrafluoroethylene (PT).
The electrode is made by adding a binder such as FE), roll-forming it into a sheet, and subjecting it to stretching treatment as necessary.
It is preferably used because it has excellent capacity per unit volume, strength, and long-term reliability.

As the separator used in the present invention, a usual separator for electric double layer capacitors, such as a separator made of polypropylene fiber nonwoven fabric or glass fiber mixed paper nonwoven fabric, can be used.

The electrolytic solution used in the present invention is not particularly limited, and may be one commonly used for electric double layer condensers, and an electrochemically stable solute (electrolyte) dissolved in a polar organic solvent. used as appropriate.

As a solvent for the electrolytic solution, propylene carbonate, butylene carbonate 1-3β-butyrolactone, γ-butyrolactone, acetonitrile, dimethylbormamide, 1
, 2-dimethoxyethane, sulfolane, nitromethane, etc. are preferably used.

Examples of solutes in the electrolytic solution include alkali metal salts, tetraalkylammonium salts, and tetraalkylphosphonium salts such as perchloric acid, hexafluorinated phosphoric acid, tetrafluorinated boric acid, and perfluoroalkylsulfonic acid. of solute in the above solvent at a concentration of 0.1 to 3. OM/7! , preferably an electrolytic solution dissolved at a concentration of 0.5 to 1.5 M/β is suitably used.

(Example) Embodiments of the present invention will be described below based on the drawings.

Figure 2.3 shows the laminated electric double layer capacitor of the present invention.
It is a figure showing one example of this. In Figure 2(b), 1
Reference numeral 6 denotes a laminate formed by stacking two unit cells in series, with a U-shaped metal plate 15 between the anode side metal case of one unit cell A and the cathode side metal case of the other unit cell B. is interposed. The metal plate 15 is shown in FIG. 2(a).
As shown in FIG.
The other end 15b is welded to the anode side metal case of one unit cell A, the other end 15b is welded to the cathode side metal case of another unit cell B, and the metal plate 15 is bent 180° with the metal plate 15 inside (Fig. 2). A laminate 16 shown in b) is constructed.

Further, in FIG. 3(b), 17 is a laminate formed by stacking three unit cells in series, unit cells A,
Between cell B and unit cells B and C, U-shaped metal plates 15 are provided alternately. As shown in FIG. 3(a), the metal plate 15 is
5a is welded to the anode side metal case of unit cell B, and the other end 15b is welded to the cathode side metal case of unit cell C. Unit cells A and B are The laminate 17 shown in FIG. 3(b) is constructed by welding and bending 180° with the metal plate 15 inside in the same manner as shown in FIG. 3(a). When the number of stacked unit cells is four or more, a stacked body can be obtained in the same manner. According to this embodiment, there is no need to mechanically press and stack the metal cases of the unit cells together by caulking the exterior metal cases as in the past, so the number of parts and assembly steps are reduced, and electrical connection is possible. A highly reliable multilayer electric double layer capacitor free from defects and leakage of electrolyte can be obtained.

FIG. 4.5 shows another embodiment of the multilayer electric double layer capacitor according to the present invention. This embodiment is characterized in that external metal terminals 18 to 21 for connection to devices in use are provided in the metal cases at both ends of the stack in the stacking direction. FIG. 4 shows a laminate 16 in which external metal terminals 18 and 19 are provided horizontally to the surface of the metal case of the unit cell, and FIG. External metal terminals 20 and 21 are shown in a direction perpendicular to the plane. The shape and mounting direction of such external metal terminals can be changed as appropriate depending on the usage pattern of the capacitor. Note that the external terminal 20 in FIG. 5 is covered with an insulating tube 22 to prevent short-circuiting.

6 to 8 show still another embodiment of the multilayer electric double layer capacitor according to the present invention.

These embodiments are characterized in that the unit cell stack is integrally fixed by a fixing means. FIG. 6 shows external metal terminals 18 and 19 on the laminate 16.
Fig. 7 shows a laminate 17 with external metal terminals 20, 21 attached and fixed by molding with resin 23, and a heat-shrinkable tube 24.
The immobilized one is shown. When molded with resin 23, the external metal terminals 18 and 19 are also firmly fixed in the resin 23, which increases the strength of the terminals 18 and 19 and prevents liquid leakage from the unit cell and moisture from outside. Intrusion is prevented. Fixation using the heat-shrinkable tube 24 is extremely easy.

In addition, as shown in FIG.
In the case where the external metal terminals 20 and 21 are molded with resin 23 while stored inside, the external metal terminals 20 and 21 are firmly fixed in the resin 23, and the mounting strength is further improved.

By using the resin mold 23 in combination with the heat-shrinkable tube 24, stable immobilization can be achieved relatively easily.

The electric double-layer condenser unit cell used in the present invention is a non-solvent type with a withstand voltage of 1.8μ, and the electrolyte is 0.5M/0.5M of tetraethylammonium tetrafluoroborate in propylene carbonate. j! As a polarizable electrode, use a solution dissolved at a concentration of 2.
500=/g of activated carbon powder was mixed with a 10% by weight tetrafluoroethylene dispersion as a binder, and a sheet (diameter: 113 nm, thickness: 2.0 mm) was used.

Using the unit cell described above, 1,000 pieces of each of the product according to the present invention shown in FIG. 8 and the conventional product shown in FIG. I compared the numbers.

As a result, 18 connection failures and 13 liquid leakage failures occurred in the conventional product, whereas no connection failures or liquid leakage failures were observed in the product according to the present invention.

(Effects of the Invention) As explained above, according to the present invention, a highly reliable multilayer electric double layer capacitor without electrical connection defects or leakage of electrolyte can be obtained, and in addition, the number of laminated parts is reduced and the number of assembly steps is reduced. Since there are also fewer parts, costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing the structure of a unit cell of an electric double layer capacitor, and FIG. 2.3 shows an embodiment of the multilayer electric double layer capacitor according to the present invention. Figure 2 (a
) and (b) show the structure of the two-piece laminate, and Fig. 3 (a
) and (b) show the structure of the three-piece laminate. FIG. 4.5 shows another embodiment of the multilayer electric double layer capacitor according to the present invention, and FIG. 4 shows the structure of a two-layer stack. Fifth
The figure shows the structure of the three-layered product, and FIGS. 6 to 8 are cross-sectional views showing still other embodiments of the multilayer electric double layer capacitor according to the present invention. In FIG. 6, the fixing means is a resin mold. In FIG. 7, the fixing means is a heat-shrinkable tube, and in FIG. 8, the fixing means is a resin mold in the outer case. FIG. 9 shows a conventional multilayer electric double layer capacitor. 15... Metal plate, 15a... One end, 15b... Other end, 16, 17... Laminate, 18, 19.20.21 ...External metal terminal, 2
2... Insulating tube, 23... Resin, 24... Heat shrinkable tube, 25... Exterior case, A, B, C... ...unit cell.

Claims (6)

[Claims] (1) In a multilayer electric double layer capacitor formed by stacking a plurality of coin-type electric double layer capacitor unit cells in series, each unit has an anode and a cathode housed in a pair of metal cases that also serve as external terminals. A substantially U-shaped metal plate is provided between the cell and another unit cell connected in series, one end of this metal plate is fixed to the anode side metal case of the one unit cell, and the metal plate is fixed to the anode side metal case of the one unit cell. A multilayer electric double layer capacitor, characterized in that the other end of the plate is fixed to the cathode side metal case of the other unit cell to form a multilayer body. (2) The multilayer electric double layer capacitor according to claim 1, wherein external metal terminals are fixed to metal cases at both ends in the stacking direction of the multilayer body. (3) The multilayer electric double layer capacitor according to claim 1 or 2, wherein the laminate is integrally fixed by a fixing means. (4) The multilayer electric double layer capacitor according to claim 3, wherein the fixing means covers the multilayer body with a resin mold. (5) The laminated electric double layer capacitor according to claim 3, wherein the fixing means covers the laminated body with a heat-shrinkable tube. (6) The multilayer electric double layer capacitor according to claim 3, wherein the fixing means comprises providing an outer case to the laminate and performing resin molding in the outer case.