JPH02281608A - Electrical double layer capacitor - Google Patents

Abstract

PURPOSE:To lessen the contact resistance between the particles of activated carbon and to reduce an ESR by a method wherein powder activated carbon which is used for forming carbon paste electrodes is heat-treated and a graphite whisker is grown on the surfaces of the particles of the activated carbon. CONSTITUTION:Non-conductive gaskets 4 are formed of an unvulcanized non-conductive rubber sheet, these gaskets 4 are respectively fixed by pressure on current collecting materials 2 consisting of an unvulcanized conductive rubber sheet to form recessed parts and carbon paste electrodes 3a obtainable by mixing activated carbon, which is obtainable by growing a graphite whisker on the surfaces of the particles of powder activated carbon by heat-treating in an inert gas-containing atmosphere, and a sulfuric acid are filled in the formed recessed parts. After a pair of these filled sheets are combined into one through a porous separator 5 of polypropyrene make, the combined material is left to stand in an atmosphere of temperatures of 125+ or -<5> deg.C under a pressure of 4kg/cm<2> and the sheets are vulcanized and adhered. Then, after 8 sheets of these basic cells 1a are laminated in series and are formed as a laminated material 6, the laminated material 6 is housed in a metal sheathed case 8, an insulating case 7 with electrode plates 9 arranged on the laminated material 6 is made to cover on the laminated material 6, a mechanical pressure is applied to the laminated material 6 through the plates 9 and the case 7 and as this state is held, the upper end of the case 8 is sealed by caulking.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electric double layer capacitor, and particularly to a carbon paste electrode for an electric double layer capacitor.

[Conventional technology]

Conventionally, the element 1b of this type of electric double layer capacitor (hereinafter referred to as basic cell) is electrically insulating as shown in FIG.
A pair of carbon paste electrodes 3b made of powdered activated carbon, an electrolyte solution, etc., with an ion-permeable porous separator 5 in between, a current collector 2 made of conductive rubber, etc. placed on the outside thereof, and a pair of current collectors. A non-conductive gasket 4 made of insulating rubber or the like was arranged between the bodies to airtightly seal the porous separator 5 and the carbon paste electrode 3b from the side.

Furthermore, as shown in FIG. 5, the electric double layer contemp is constructed by casing the basic cell 1bf according to the working voltage: a laminate 6 in which the required number of cells are laminated, and an insulating case 7 to prevent short circuit with the metal exterior case 8. Then, the electrode 1 is connected via the electrode plate 9.
It has a structure that extracts 0.

Electric double layer capacitors are made of
In order to reduce the contact resistance between the carbon paste electrode and the current collector, etc., 1 to 50Ic from above and below is applied to the stacked body 6 of the basic cell lb.
While a pressure of 9/- is applied and maintained, the open end of the metal exterior case 8 is bent inward and caulked to stabilize the properties.

[Problem to be solved by the invention]

The above-mentioned conventional electric double layer capacitor has a large contact resistance between activated carbon particles, and therefore the equal series resistance (hereinafter referred to as E8R) of the electric double layer capacitor is large. Therefore, when discharging with a large current after charging, the ESR of the electric double layer capacitor causes a significant voltage drop.

An object of the present invention is to provide an electric double layer capacitor in which the contact resistance between activated carbon particles can be reduced and, as a result, the equivalent series resistance (ESR) is reduced.

[Means to solve the problem]

The electric double layer capacitor of the present invention is an electric double layer capacitor having a carbon paste electrode made of a mixture of powdered activated carbon and an electrolyte solution, in which the powdered activated carbon used for the carbon paste electrode is heat treated to grow graphite whiskers on the particle surface. It is characterized by the fact that it is

〔Example〕

Next, one embodiment of the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view of a basic cell according to an embodiment of the present invention.

As shown in FIG. 1, an unvulcanized non-conductive rubber sheet with a float of 0.5 is concentrically punched out with an inner diameter of 6.0 and an outer diameter of ILO to form a non-conductive gasket 4.

Next, an unvulcanized conductive rubber sheet is punched out with a diameter of 11.0111 mm to form a current collector 2, and the above-mentioned non-conductive gasket 4 is placed and crimped concentrically on the current collector 2 to form a recess. .

In this recess, heat the temperature at 2,800°C or higher at 30°C in an inert gas atmosphere.
Carbon paste electrode 3a made of a mixture of activated carbon with an average particle size of 3.0 μm and 30% by weight sulfuric acid, in which graphite whiskers are grown on the surface of powdered activated carbon by heat treatment for minutes.
A carbon paste-filled sheet is obtained by filling the carbon paste.

Next, the pair of paste-filled sheets are made of polypropylene with a thickness of 2 mm in the direction in which the carbon paste electrodes 3a face each other.
5 μm, diameter 8. After combining the two concentrically arranged through a porous separator 5 of Qmx, apply pressure of 4#/car in the vertical direction, and while maintaining this pressure, 125
It was left in an atmosphere at a temperature of 5°C for 3 hours, and the parts of the present invention were bonded by vulcanization between the unvulcanized non-conductive gaskets and between the unvulcanized non-conductive gasket and the unvulcanized current collector. A basic cell 1a of the example was obtained.

Next, as shown in FIG. 2, the basic cell 1a of one embodiment of the present invention is
After stacking eight sheets in series to form a laminate 6, the laminate 6 is housed in a metal exterior case 8, and the laminate 6 is covered with an insulating case 7 in which an electrode plate 9 is arranged. Laminated body 6 via insulation case 7
While maintaining this state, the upper end of the outer case 8 is caulked and sealed, and the operating voltage is set to 5.
■An electric double layer capacitor was obtained.

Figure 3 shows a conventional electric double layer capacitor consisting of a basic cell 1b and an electric double layer capacitor according to an embodiment of the present invention using powdered activated carbon on which graphite whiskers are grown.
0 ESR average values are shown.

The horizontal axis is the level, and the vertical axis is the ESR of the electric double layer capacitor. The ESR of electric double layer capacitors using powdered activated carbon on which graphite whiskers are grown is about 1/1 that of conventional ones.
We were able to realize an electric double layer capacitor with a lower EAR than the conventional one.

Further, as shown in Table 1, the electric double layer capacitor of the present invention has the same characteristics as the conventional capacitor except for EAR.

〔Effect of the invention〕

As explained above, the present invention has the effect of lowering the ESR of an electric double layer capacitor by using powdered activated carbon in which digraphite whiskers have grown through heat treatment for a carbon paste electrode.

As described above, the graphite electrode of the present invention has great industrial value.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a basic cell of an electric double layer capacitor to which powdered activated carbon on which graphite whiskers are grown is applied according to an embodiment of the present invention, and Fig. 2 is a cross-sectional view of a basic cell of an electric double layer capacitor made of the basic cell of the present invention. The vertical cross-sectional view and FIG. 3 are graphs showing the relationship between the electric double layer capacitor obtained in the present invention and the E8R of a conventional electric double layer capacitor.
Figure 4 is a vertical cross-sectional view of a basic cell of a conventional electric double layer capacitor, and Figure 5 is a vertical cross-sectional view of an electric double layer capacitor consisting of a conventional basic cell. be. 1a... Basic cell of the present invention, 1b... Conventional basic cell, 2... Current collector, 3a... Carphone paste electrode of the present invention, 3b... Conventional carphone paste electrode t pole, 4... non-conductive gasket, 5... porous separator, 6... laminate, 7... insulating case, 8...
...Metal exterior case, 9... Electrode plate, 10... Electrode. To the agent, patent attorney Susumu Uchihara ES ((1) Figure 3 Figure 4 Figure 5 kL: Mizure ≦ WR Rushiru

Claims (1)

[Claims] An electric double layer capacitor having a carbon paste electrode made of a mixture of powdered activated carbon and an electrolyte solution, characterized in that the powdered activated carbon used in the carbon paste electrode is heat-treated to grow graphite whiskers on the particle surface. Electric double layer capacitor.