JPS6322050B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an electric double layer capacitor that is inexpensive and uses carbon paint as a conductive material for the polarizable electrodes and counter electrode current collectors of molded elements and for series connections between elements. A capacitor having a desired withstand voltage is obtained.

In electric double layer capacitors, electrochemically stable,
It is necessary to use a material with a low ionization tendency (in other words, a high electron affinity), and alloys with precious metals such as gold and platinum or chromium have been used. In addition, since the current collectors are formed on the polarizable electrodes and the counter electrode by vapor deposition or sputtering, material costs and manufacturing man-hours are major problems.

Furthermore, since these materials are expensive, it is desirable to use them as thinly as possible and in small quantities; however, if they are too thin, especially when connected in series, there is a risk that they will become a common electrolyte between adjacent cells and cause self-discharge.

The present invention uses gold, which is expensive in terms of material cost,
By using an inexpensive, easy-to-work, and electrochemically stable carbon paint that does not use platinum and does not require vapor deposition or sputtering to form a current collector on the polarizable electrode and counter electrode, It is an object of the present invention to provide an electric double layer capacitor that eliminates the conventional drawbacks, and the details of the present invention will be described below.

Figures 1 to 3 show configuration examples of the electric double layer capacitor of the present invention. Figure 1 shows the configuration of the elements, Figure 2 shows the stacked configuration, and Figure 3 shows the configuration of the elements stacked in series. Shows the connected configuration.

First, the solid electrolytes used in the electric double layer capacitor of the present invention include cuprous halides and alkali halides (the alkali ions are Rb ⁺ , K ⁺ , NH ₄ ⁺ , N(CH ₃ ) ₄ ⁺ ) as raw material, 1/5 of Cu ⁺ ions are Rb ⁺ , K ⁺ ,
Mix the mixture in a predetermined ratio so that it is replaced with a cation selected from NH ₄ ⁺ and N(CH ₃ ) ₄ ⁺ , mold it into a tablet, and then place it in a degassed container and heat it at 200°C.
The material prepared by heating for 17 hours was used.

In Figure 1, 1 is the counter electrode, which is made by press-molding a mixture of this and a solid electrolyte with a Cu ₂ S/Cu mixing ratio of 40/60 to 20/80 through a 60-mesh Cu net. It is. The addition ratio of solid electrolyte is 10 to 20%. 2 is a current collector for this counter electrode 1, which is formed on the counter electrode 1 using carbon paint.

3 is a press-molded solid electrolyte, and 4 is a polarizable electrode, which is a mixed molded product with solid electrolyte 3 containing 10 wt % of activated carbon. 5 is a current collector of this polarizable electrode 4;
It is formed on the polarizable electrode 4 using carbon paint.

Here, the element breakdown voltage of a single cell is 0.6V, and a predetermined breakdown voltage can be obtained by series connection.

Next, the configuration of the stacking method will be described. In FIG. 2, reference numeral 6 denotes an element, and a plurality of elements are stacked on top of each other. Contact between the elements 6 and between the elements 6 and the metal case 7 is achieved by pressure contact through carbon paint. Leads 8 and 9 are attached by welding, soldering, etc. to the metal case 7 and the 60-mesh Cu net of the counter electrode 1 of the terminal element 6, respectively. Reference numeral 10 indicates packing rubber, and reference numeral 11 indicates an insulating resin plate. The open end of the metal case 7 is curled inward, and the elements 6 are pressed together by the packing rubber 10 and the resin plate 11.

Next, an example of a configuration in which the devices are connected in series laterally will be described. In FIGS. 3a and 3b, 6 is an element as in FIG. 2, and the element group is formed by bonding the metal foil lead 12 onto the current collectors 2 and 5 of the element 6 with carbon paint and connecting them. It is inserted between thermoplastic resin films 13 and the periphery is sealed by thermal welding. Reference numeral 14 designates a terminal in which a portion of the resin film 13 is cut out to expose a portion of the lead 12 to the outside.

With the configuration shown in Figure 2, it is possible to obtain the features of being strong and compact.
With the configurations shown in FIGS. 3a and 3b, it can be made thin.

Next, the effect of the present invention was demonstrated using 0.1 g of a mixture of 10 wt% activated carbon and a solid electrolyte as a polarizable electrode.
0.2g of solid electrolyte, Cu ₂ S/Cu = 40/6 as counter electrode
Using 0.2g of 0, mold it into a cylindrical shape of 10mmφ,
As a current collector for the counter electrode and polarizable electrode, a carbon paint called Aquadac #580 (trade name of Acheson Co., USA) is applied and solidified with hot and cold air to create an element with a withstand voltage of 0.6 V and a capacity of 3 F.
It is needless to mention the cost comparison between gold, platinum, chromium, their alloys, and carbon paint; carbon paint is cheaper.

As an example of electrical characteristics, the results of comparing the frequency dependence of element impedance are shown in Figure 4. B shows an element using a current collector according to the present invention.

As is clear from FIG. 4, there is no difference between the conventional element and the element according to the present invention, and it can be seen that they have the same level of performance. In addition, the following effects can be considered when comparing the use of carbon paint with the conventional method.

(1) Shortening the time required for device manufacturing.

(2) Improved workability (man-hours and processes for vacuum deposition and sputtering are not required).

(3) In the stacking method, the binding strength between each element is strong, and since the elements are in a liquid state, the contact area is large, which is advantageous for reducing the contact resistance between the elements.

(4) Since the coefficient of thermal expansion is smaller than that of metals, it is advantageous against sudden temperature changes. Further, it is possible to prevent a common electrolyte from forming between adjacent cells, and self-discharge can be made negligibly small.

As described above, by using carbon paint as a conductive material for the current collector and the series connection between elements according to the present invention, it is possible to provide an electric double layer capacitor that is inexpensive and requires fewer manufacturing steps.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of an element of an electric double layer capacitor according to the present invention, FIG. 2 is a cross-sectional view showing an example of the structure when the elements are stacked, and FIGS. 3 a and b are the same elements. A cross-sectional view and a plan view showing an example of the structure when connected in series horizontally, No. 4
The figure shows the frequency dependence of element impedance, and shows a conventional current collector element formed on a polarizable electrode or counter electrode by vapor-depositing gold, platinum, chromium, or an alloy thereof, and a current collector element formed on a polarizable electrode or counter electrode using carbon paint according to the present invention. FIG. 6 is a diagram showing a comparison of characteristics with an element formed above. 1... Counter electrode, 2, 5... Current collector, 3... Solid electrolyte, 4... Polarizable electrode, 6... Element.

Claims (1)

[Claims] 1 A polarizable electrode made of a molded mixture of activated carbon and a solid electrolyte and a counter electrode made of a molded mixture of Cu ₂ S, Cu, and a solid electrolyte are integrally molded so as to face each other with a solid electrolyte layer in between. constitute the element,
An electric double layer capacitor characterized in that carbon paint is used as a conductive material for a polarizable electrode and a current collector of a counter electrode of the element and a series connection between the elements.