JPS6262449B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to an electric double layer capacitor. This electric double layer capacitor has a characteristic of high capacitance by utilizing an electric double layer formed at the interface between a polarizable electrode and an electrolyte (liquid). For example, as shown in FIG. 1 for a specific example of a disc type (coin type, button type), a separator 3 impregnated with an electrolyte 2 between carbon electrodes 1 made of graphite, activated carbon, some binder of carbon black, etc. was interposed therebetween, and sealed with an adhesive using conductive resins 5, 6 and an insulating ring 4, which served as a current collector and an exterior material. This method is advantageous in the case of electric double layer capacitors that use an aqueous electrolyte because it does not dissolve the conductive resin, but since it is made of synthetic resin, it is susceptible to external pressure and is difficult to connect to the electric circuit. In this case, for connection to external terminals, it was necessary to place a metal plate on the entire surface of the conductive synthetic resins 5 and 6 and fix it under pressure. Therefore, the structure shown in FIG. 1 is only half-finished, and the number of parts required for the finished product increases. Therefore, it is possible to use a metal material instead of the conductive synthetic resins 5 and 6, but in order to make the separator 3 made of metal, select a metal that can withstand the electrolyte used for the separator 3 or an electrolyte that does not corrode the metal. The disadvantage was that it required In other words, synthetic resins are inert to aqueous electrolytes such as dilute sulfuric acid,
This is because metals are easily soluble in organic solvents, but metals usually have the opposite properties. Therefore, an object of the present invention is to provide an electric double layer capacitor which can reduce the number of parts, has a simple structure, has strength and durability, and can be mounted on a printed circuit board without any problems. This invention pays attention to the greatly improved mechanical strength and high electrical conductivity of metal, and replaces the conductive synthetic resins 5 and 6 with a metal lid 12 and a metal case 1.
3 is formed. The metals selected were aluminum, which is a valve metal, and stainless steel, which is a stainless steel. It has been confirmed that aluminum with a high purity of 99.9% or more is desirable, and that stainless steel is preferably 18-8 stainless steel and high chrome stainless steel with a high chromium ratio. However, it has also been found that the electrolyte 10 of the separator 9 causes pitting corrosion in the metal unless the water content is sufficiently reduced.
For example, it was confirmed that in an electrolytic solution consisting of 100 parts of gamma-butyrolactone and 15 parts of tetraethylammonium perchlorate, the water content must be kept below 150 ppm, preferably below 50 ppm. The structure shown in FIG. 2 is the result of the above selection of materials. That is, the separator 9
A metal case 13 is mounted with polarizable electrodes 8 facing each other on both sides of the metal case 13.
The top surface of the polarizable electrode 8 is covered with a metal lid 12, and an insulating sealing body 11 is interposed between the periphery of the metal lid 12 and the opening of the metal case 13. Insulating sealing body 1
1.Cold it on top to make it one piece. Polarizable electrode 8 in the configuration
is made by kneading and pressing activated carbon, graphite, acetylene black with some binder, aluminum,
A stainless steel current collector and activated carbonized carbon fiber cloth were used. As the separator 9, a microporous polypropylene film or Manila hemp paper mixed with glass fiber was used. The electrolytic solution 10 had the above-mentioned composition and the water content was adjusted to 50 ppm or less. Metal cases 12 and 13 are 99.9
% high purity aluminum or stainless steel (SUS304) was used. The sealing body 11 was made of polypropylene, fluorocarbon rubber, IIR rubber, EPT rubber, or the like. An example will be described below. All product dimensions are 25
The diameter is φ (diameter) and the thickness is 1.5 mm. Comparative Example 1 The conductive resins 5 and 6 were made of butyl rubber containing carbon black, the electrolytic solution 2 was made of 30% sulfuric acid, and the separator 3 was made of a 30 μm porous polypropylene film. As a result of actual measurements, the capacitance is 3F, the internal resistance is 0.5Ω, and the withstand voltage is 0.8V. Comparative Example 2 The metal material of the metal case 13 and metal lid 12 is aluminum with a thickness of 0.35 mm, and the electrolyte 10 is 30%
The same sulfuric acid and separator 9 as in 1 above were used. As a result, the metal case 13 was melted and characteristics could not be measured. Example 1 The metal materials 12 and 13 are aluminum with a thickness of 0.35 mm, and the electrolyte 10 is gamma-butyrolactone 100.
Part, tetraethylammonium perchlorate 15
The separator 9 is the same as 1 above. As a result, the capacitance is 2F, the internal resistance is 1Ω, and the withstand voltage is 2V. Example 2 The metal materials 12 and 13 were stainless steel (SUS304) with a thickness of 0.25 mm, and the other parts were the same as in Example 1, and the characteristics were also almost the same. Example 3 In Example 2, the water content of the electrolyte 10 is (1)
250ppm, (2) 150ppm, (3) 50ppm, (4) 10ppm, initial value (before testing) and 2V applied, 70℃-1000
Changes after time (post-test) were compared. The results are shown in the table below.

[Table] As described above, by regulating the water content of the electrolytic solution 10, it has become possible to use metal materials.
However, economical metal materials seem to be limited to high-purity aluminum, which forms a corrosion-resistant oxide film, and stainless steel, which is stainless steel. However, since metal materials can be used as the current collector and electrode plate,
It is possible to make both polarizable electrodes face each other under pressure by itself, and furthermore, it is possible to receive connection terminals in contact with only the local parts of the bipolar plates, or to attach terminals by welding, making it an independent electronic component. Can be done. Also, when connecting in series to increase the withstand voltage, it is sufficient to simply bundle them in a loose stacked structure, which has a great effect.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional example, and FIG. 2 is a sectional view of an embodiment of the present invention. 9... Separator, 10... Electrolyte, 11...
Sealing body, 12...metal lid, 13...metal case.

Claims (1)

[Scope of Claims] 1. A separator impregnated with an electrolyte having an extremely low water content, a polarizable electrode made of a carbon-based electrode material in contact with both sides of the separator, and a combination thereof housed at the bottom. A metal case in electrical contact with one of the polarizable electrodes, a metal lid fitted into the metal case and in electrical contact with the other polarizable electrode, and between the periphery of the metal lid and the opening edge of the metal case. An electric double layer capacitor comprising a sealing body interposed between the metal case and the metal case to insulate each other and integrally caulked with the opening edge of the metal case. 2. The electric double layer capacitor according to claim 1, wherein the electrode material comprises graphite, carbon black, activated carbon, or a combination thereof. 3. Claim 1, wherein the electrode material is carbon fiber cloth or activated carbonized carbon fiber cloth.
The electric double layer capacitor described in . 4. The electric double layer capacitor according to claim 1, 2 or 3, wherein the metal case and the metal lid are made of aluminum or stainless steel.