JPS6013292B2 - electric double layer capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric double layer capacitor which improves contact between a current collector of a polarizable electrode and an inert powder, thereby reducing loss value and stabilizing long life.

Conventionally, polarizable electrodes of electric double layer capacitors are prepared by mixing carbon-based powder with a water-dropping polymer, tetrafluoroethylene or copolymer dispersion, or alcohol emulsion as a binder, and applying the mixture to a current collector. There are methods such as press molding, mixing with a sucrose aqueous solution and freezing, and mixing with a fluoro rubber elastomer solution.

In either method, in order to improve adhesion to the current collector, the surface of the current collector is treated by dissolving an oxide film or etching, or by perforation, uneven finishing, or even the use of a net. However, when bending, winding, and assembling polarizable electrodes, the current collector and carbon layer tend to separate or fall off, resulting in an increase in loss value or equivalent series resistance of the capacitor.
Another disadvantage is that electrical characteristics vary greatly during use. In order to eliminate the above-mentioned drawbacks, the present invention has been developed by forming a carbon layer mainly composed of activated carbon on a current collector that is undercoated with a conductive paste made of carbon black with an average particle size of 500 mm or less and an organic binder. An object of the present invention is to provide an electric double layer capacitor with excellent performance by improving the contact state between the current collector of the polarizable electrode and the inert powder by using a polar electrode, thereby reducing loss value and stabilizing a long life. It is.

The details of the present invention will be explained below.

That is, the carbon-based conductive particles have an average particle size of 1 to 1.
A solution containing one or more kinds of carbon blacks such as channel flakes, furnace blacks, thermal blacks, acetylene blacks, and a small amount of organic/winder. This is coated thinly and uniformly on a current collector to a thickness of 0.05 to 0.5 mm, dried, and then an activated carbon layer is formed by a known method to form a polarizable electrode. A separator is interposed between the pair of magnetically divided electrodes to form a wound element, the element is housed in a container, and an electrolytic solution is immersed therein. One type or a mixture of two or more of the various carbon blacks has a layer formed of extremely fine particles that has higher conductivity than activated carbon, and is in close contact with a current collector, so that it can be used as a capacitor with a small loss value. Next, a comparison between an example of the present invention and a conventional reference example will be shown.

Example 1 15% by weight of polyvinyl alcohol having a degree of polymerization of 900 and a degree of saponification of 89 mol % is blended into a furnace black having an average particle size of 116 and thoroughly mixed with 50 oo of warm water to form a paste.

This is placed on a 200 mesh stainless steel net with a thickness of 0.2
Prime the sides evenly and dry at a temperature of 105-110°C. Next, water was added to a mixture of 55 parts of 200 mesh powder activated carbon, 45 parts of furnace black, and 2% by weight of the same polyvinyl alcohol as above, and the mixture was thoroughly mixed to form a paste. After coating and drying at a temperature of 110 qo for 30 minutes, it was heated at a temperature of 15,000 qo for 60 minutes. Use this as a pair of electrodes for 50r
A cabacitor was obtained by winding a thick polypropylene non-woven fabric and storing it in a welder and impregnating it with a picrate/formamide electrolyte. Example 2 15% by weight of polyvinyl alcohol having a degree of polymerization of 900 and a degree of saponification of 89 mol % is blended into a conductive jacket jacket having an average particle size of 10 mm, and thoroughly mixed with 50 oo of warm water to form a paste.

Spread this on a 200 mesh stainless steel net with a thickness of 0.2
Prime the sail evenly and dry at a temperature of 105-110,000 ℃. Next, a mixture of 55 parts of 200 mesh powdered activated carbon, 45 parts of furnace black, and 2% by weight of the same polyvinyl alcohol as above was mixed thoroughly with water to form a paste, which was applied to a thickness of 200 mounds on one side using a barcoder. After drying for 3 minutes at a temperature of 11°C, it was heated for 6 nights at a temperature of 15,000°C. This was used as a pair of electrodes, and was wound and housed in a container with a 50 mm thick polypropylene nonwoven fabric interposed therebetween, and impregnated with a picrate/formamide electrolyte to obtain a capacitor. Example 3 Fine thermal black with an average particle size of 500 mm is mixed with fluoroelastomer and diluted with methyl ethyl ketone to form a paste.

This is placed on a 200 mesh stainless steel net with a thickness of 0.2
Prime the legs evenly and dry at a temperature of 105-110 qo. Next, 55 parts of 200 mesh powdered activated carbon, 45 parts of furnace plaque, degree of polymerization 90, degree of saponification 89 mol%
Add water to a mixture of 2% by weight of polyvinyl alcohol and mix thoroughly to form a paste. Apply the paste to a thickness of 200 mm on one side using a barcoder, dry for 30 minutes at a temperature of 110 mm, and then apply a paste at a temperature of 15 mm to 60 mm. Heat for a minute. This was used as a pair of electrodes, and was wound up and housed in a container with a polypropylene nonwoven fabric having a thickness of 50 mm interposed therebetween, and was impregnated with a picrate/formamide electrolyte to obtain a capacitor. Reference example 4200
55 parts of mesh powder activated carbon, 45 parts of Furnace Flak
Water was added to a mixture of 2% by weight of polypynyl alcohol with a degree of polymerization of 90Q and a degree of saponification of 89 mol%, mixed thoroughly to form a paste, which was applied to a thickness of 200mm on one side using a barcoder at a temperature of 110:00. After drying for 3 minutes,
Heat at 0 temperature for 6 minutes.

This was used as a pair of electrodes, and a 50 mm thick polypropylene nonwoven fabric was interposed between the electrodes, which were wound up and housed in a container, and a picrate/formamide electrolyte solution was mixed therein to obtain a capacitor. A comparison of the electrical characteristics of the electric double layer capacitors obtained in Examples 1 to 3 and Reference Example 4 is shown in FIGS. 1 to 3.

Figure 1 shows the high temperature load test (temperature 70qo, 1.5V.DC
Figure 2 shows the change in equivalent series resistance in the high temperature load test, and Figure 3 shows the change in leakage current in the high temperature load test.Curves 1 to 3 are examples of each example. 1 to 3, curve 4 shows the characteristics of Reference Example 4. Examples 1 to 3 have good adhesion between the current collector and the carbon layer, and changes in characteristics due to high-temperature load tests are extremely small compared to Reference Example 4. Since there is no direct contact with the liquid, there is no dissolution of the current collector and the leakage current can be suppressed to a low level.As detailed above, according to the present invention, carbon black with an average particle size of 500 mm or less and an organic/window By using a polarizable electrode in which a carbon layer mainly composed of activated carbon is formed on a current collector that is undercoated with a conductive paste consisting of Therefore, it is possible to provide an electric double layer capacitor that has excellent performance in terms of reduction in energy consumption and long life stabilization.

[Brief explanation of the drawing]

The figures show a comparison of the characteristics of the embodiment of the present invention and a conventional reference example in a high-temperature load test. Figure 1 is a curve diagram showing the rate of change in capacitance, and Figure 2 shows the change in equivalent series resistance. FIG. 3 is a curve diagram showing changes in leakage current. Hina Figure 2 Figure 3

Claims (1)

[Claims] 1. A current collector undercoated with a conductive paste made of carbon black with an average particle size of 500 mμ or less and an organic binder, and a carbon layer mainly composed of activated carbon formed on the current collector. An electric double layer capacitor comprising a polar electrode and a separator interposed between the pair of polarizable electrodes, the electric double layer capacitor being formed by winding the pair of polarizable electrodes and the separator. 2. The electric double layer capacitor according to claim 1, wherein the carbon black is a channel black, a furnace black, a thermal black or an acetylene black.