JPH07111936B2 - Multilayer Electric Double Layer Capacitor - Google Patents

Description

The present invention relates to a laminated electric double layer capacitor.

(Prior Art) An electric double layer capacitor is based on the principle of accumulating electric charges in an electric double layer formed at an interface between a polarizable electrode having a large surface area such as activated carbon and an electrolytic solution. It is attracting attention because it can obtain a much larger capacitance than a capacitor.

FIG. 3 shows a general structure of a coin type unit cell of a conventional electric double layer capacitor. In FIG. 3, a polarizable electrode 19 whose main component is activated carbon powder or activated carbon fibers is fixed to a metal case 21 by a conductive adhesive layer 20, and similarly fixed to a metal case 22 by a conductive adhesive layer 20 '. Polarizable electrode 23 is a porous separator
It is arranged to face the polarizable electrode 19 via 24.
The separator 24 and the polarizable electrodes 19 and 23 are impregnated with the electrolytic solution, and the metal cases 21 and 22 are caulked and sealed via the packing 25 to obtain a unit cell 26.

RAM, which is the main application of such electric double layer capacitors
-As an IC memory backup power supply, a working voltage of 5.5 V is required, whereas the withstand voltage of the coil-type unit cell is about 0.8 V when an aqueous electrolyte is used, and a non-aqueous solvent-based When an electrolytic solution is used, the voltage is about 1.8 V to 2.8 V, so it is usually necessary to stack 2 to 7 unit cells in series.

Conventionally, when two Snit cells having a withstand voltage of 2.8 V using a non-aqueous solvent-based electrolytic solution are laminated in series and used, a laminated structure as shown in FIG. 4 is adopted. In FIG. 4, two unit cells 26 are stacked in series and housed in a metallic outer case 27 having a bottomed cylindrical shape. A cylindrical insulating tube 29 is provided between the side surface of the laminate 28 and the inner surface of the outer case 27.
The first terminal plate 30 of the electrode on one side having the lead pull-up portion is arranged on the upper surface of the laminated body 28, and the insulating plate 31 is sandwiched on the upper surface of the first terminal plate 30. As described above, the second terminal plate 32 of the electrode on the other side having the lead pulling portion is arranged. Furthermore, the upper end of the metal outer case 27
By crimping 27a inward, the laminated body 28 is fixed in the outer case 27, and the electrical connection between the metal outer case 27 and the second terminal plate 32 is maintained.

(Problems to be Solved by the Invention) However, in such a conventional laminated electric double layer capacitor, after the metal case is sealed by caulking to assemble the unit cell as described above, the unit cell is further assembled. Since two cells must be stacked in series and integrated by caulking the metal outer case by attaching a terminal board or the like, the number of manufacturing steps is large and the work is complicated. .

An object of the present invention is to solve the above problems and to obtain a laminated electric double layer capacitor in which the manufacturing cost is reduced by simplifying the manufacturing process.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides an electric electrode formed at an interface between a pair of polarizable electrodes and a non-aqueous solvent-based electrolytic solution that are opposed to each other with a separator interposed therebetween. In a laminated type electric double layer capacitor in which two capacitor elements of an electric double layer capacitor using multiple layers are laminated in series, the inner surface is in contact with the anode side of one of the capacitor elements and is made of metal that also serves as an external connection terminal and an outer case. First electrode plate, a metal third electrode plate whose inner surface is in contact with the cathode side of the other capacitor element and also serves as an external connection terminal and an outer case, and both surfaces are the cathode side and the other side of the one capacitor element, respectively. A second electrode plate disposed in the middle of the first electrode plate and the third electrode plate so as to come into contact with the anode side of the capacitor element, and the circumference of the first, second and third electrode plates. The present invention provides a laminated electric double layer capacitor characterized in that its ends are integrally crimped and sealed via an electric insulating material.

Of the electrode plates used in the present invention, either the first electrode plate or the third electrode plate polarized to the plus side and the second electrode plate are required to have electrochemical corrosion resistance. As a material for forming the electrode plate, SUS316
In addition to highly corrosion-resistant stainless steels such as L and SUS447J1, aluminum, aluminum clad materials, and valve action metals such as titanium, zirconium, and tantalum are preferably used. On the other hand, the material forming the first electrode plate or the third electrode plate polarized to the minus side is not particularly limited, but general-purpose stainless steel such as SUS304, nickel, etc. can be used.

As the electric insulating material used in the present invention, various plastic materials can be used, but from the viewpoint of solvent resistance to the electrolytic solution and sealing property, packing made of polypropylene, polyethylene or the like is preferably used.

The material of the polarizable electrode used in the present invention is not particularly limited, but it is preferable to use activated carbon or activated fiber which is electrochemically inactive to the electrolytic solution and has a large specific surface area.

In particular, an electrode in which a binder such as polytetrafluoroethylene (PTFE) is added to activated carbon to form a roll-formed sheet, and if necessary, stretching treatment is performed, the capacity per unit volume, strength and long-term reliability It is excellently used and is therefore preferably used.

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

The electrolytic solution used in the present invention is not particularly limited, and is usually used for electric double layer capacitors, that is, a non-aqueous solvent system in which an electrochemically stable solute (electrolyte) is dissolved in a polar organic solvent. An electrolytic solution is used as appropriate. As the solvent of the electrolytic solution, propylene carbonate, 1
-Butylene carbonate, γ-butyrolactone, acetonitrile, dimethylformamide, 1,2-dimethoxyethane, sulfolane, nitromethane and the like are preferably used.

Examples of the solute of the electrolytic solution include perchloric acid, hexafluorophosphoric acid, tetrafluoroboric acid, alkali metal salts such as perfluoroalkylsulfonic acid, tetraalkylammonium salt, tetraalkylphosphonium salt, and the like. 0.1 to 3.0 M / solute in the solvent, preferably 0.
An electrolytic solution dissolved at a concentration of 5 to 1.5 M / is preferably used.

(Operation) In the present invention, two capacitor elements are housed in a state in which they are connected in series in a single metal outer case, caulked once, and a sealing operation is performed to obtain a conventional laminated structure as shown in FIG. A self-supporting capacitor having a function equivalent to that of the electric double layer capacitor of the type is obtained.

Therefore, the production process can be greatly simplified as compared with the conventional product, the productivity can be remarkably improved, and the production cost can be reduced.

(Example) Hereinafter, the Example of this invention is described based on drawing.

1 and 2 are views showing an embodiment of a laminated electric double layer capacitor according to the present invention.

First, the configuration will be described. In FIG. 1, reference numeral 1 denotes a first electrode plate made of stainless steel, which has a peripheral end portion 1a having an L-shaped cross section and also serves as an external connection terminal and an exterior case. A polarizable electrode 2 is fixed to the inner surface of the plate 1 via a conductive adhesive layer 3. Reference numeral 12 is a third electrode plate made of stainless steel which has a peripheral end portion 12a having a U-shaped cross section and also serves as an external connection terminal and an outer case,
The polarizable electrode 11 is fixed to the inner surface of the third electrode plate 12 via a conductive adhesive layer 13. A disk-shaped second electrode plate 6 having a peripheral end portion 6a is arranged between the first electrode plate 1 and the third electrode plate 12, and polarizable electrodes are provided on both surfaces of the second electrode plate 6, respectively. 5 and 8 are fixed to each other via conductive adhesive layers 7 and 9. Polarizing electrodes 2 and 5 and polarizable electrodes 8 and 11
Are arranged so as to face each other with separators 4 and 10 made of polypropylene fiber non-woven fabric, respectively, to form capacitor elements A and B. Each of the polarizable electrodes 2, 5, 8 and 11 is obtained by kneading activated carbon powder and 10% by weight of polytetrafluoroethylene, forming a sheet, stretching and punching into a disc shape. The peripheral edge 1a of the first electrode plate 1 and the peripheral edge 6a of the second electrode plate 6 are made of polypropylene packing.
14 is insulated, the peripheral end 12a of the third electrode plate 12 is insulated from the peripheral ends 1a and 6a by the polypropylene packing 15, and the peripheral end 12a is caulked inward so that the first, second and The three-electrode plate includes two capacitor elements and is integrally caulked and sealed.

If external connection terminals are required, the terminal plates 16 and 18 can be connected to the first electrode plate 1 and the third electrode plate 12, respectively, as shown in FIG. In addition, the terminal tube 16 has an insulating tube 17 to prevent short circuit.
Is installed.

Next, the operation and effect will be described. As shown in FIG. 1, the laminated electric double-layer capacitor according to the present invention having the above-mentioned structure has the capacitor element A and the capacitor element B laminated in series via the second electrode plate 6 and externally. Since the plate is made of metal and has the functions of a connection terminal and an outer case, and is integrated by caulking and sealing so as to be covered by the first electrode plate 1 and the third electrode plate 12, there is no difference from the process of assembling the unit cell. Depending on the number, a self-supporting laminated electric double layer capacitor having the same function as the conventional laminated product as shown in FIG. 4 can be manufactured at low cost.

(Effects of the Invention) As described above, according to the present invention, it is possible to obtain a low-cost laminated electric double layer capacitor with a simplified manufacturing process.

[Brief description of drawings]

1 and 2 are sectional views showing an embodiment of the laminated electric double layer capacitor according to the present invention, and FIG. 3 is a partial sectional view showing the structure of a unit cell of a general electric double layer capacitor, FIG. FIG. 1 is a sectional view showing a conventional laminated electric double layer capacitor. 1 ... First electrode plate, 1a, 6a, 12a ... Peripheral end portion, 2, 5, 8, 11 ... Polarizable electrode, 3, 7, 9, 13 ... Conductive adhesive layer, 4, 10 ... … Separator, 6 …… Second electrode plate, 12 …… Third electrode plate, 14,15 …… Packing (electrically insulating material), 16,18 …… Terminal plate, 17 …… Insulation tube, A, B …… Capacitor element.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Bibliographic references Sho 50-18930 (JP, U)

Claims (1)

[Claims] 1. Two capacitor elements of an electric double layer capacitor, which utilize an electric double layer formed at an interface between a pair of polarizable electrodes and a non-aqueous solvent-based electrolytic solution which are opposed to each other via a separator, are laminated in series. In the laminated electric double-layer capacitor, the first metal member whose inner surface abuts on the anode side of one of the capacitor elements and which also serves as an external connection terminal and an outer case.
A third metal plate whose inner surface is in contact with the cathode side of the other capacitor element and also serves as an external connection terminal and an outer case
An electrode plate, and a second electrode plate arranged between the first electrode plate and the third electrode plate so that both surfaces contact the cathode side of the one capacitor element and the anode side of the other capacitor element, respectively. , The first, second and third
A laminated electric double-layer capacitor, characterized in that the peripheral edges of the electrode plates are integrally caulked and sealed with an electric insulating material interposed therebetween.