JP2000173873A - Drive electrolyte solution of electric double layer capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric double-layer capacitor which is enhanced in safety by a method wherein a drive electrolyte solution is prevented from leaking out even when the case is damaged. SOLUTION: At least a gelling agent selected out of polyethylene oxide, polymethyl methacrylate, polyvinyl pyrrolidone, polyacrylonitrile, polyvinylidene fluoride and polyvinylidene chloride is added to a drive electrolyte solution so as to turn it into gel, so that the drive electrolyte solution is prevented from leaking out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolyte for driving an electric double layer capacitor (hereinafter referred to as an electrolyte).

[0002]

2. Description of the Related Art In general, carbon electrodes using carbon powder are widely used for both electrodes of an electric double layer capacitor. As the carbon electrode, polytetrafluoroethylene (PT
It is manufactured by applying an adhesive such as FE) or polyvinylidene fluoride on a metal foil serving as a current collecting electrode, followed by drying. These electrodes are opposed to each other via a separator made of a porous film or paper, and this separator is impregnated with an electrolytic solution and put to practical use.

[0003]

The conventional electrolytic solution has a problem that the internal electrolytic solution leaks when the outer case is damaged.

[0004]

The present invention solves the above-mentioned problems by adding a gelling agent such as polyethylene oxide or polymethyl methacrylate to an electrolytic solution to gel the internal electrolytic solution. To prevent leakage of the electrolyte. That is, in the electrolyte for driving the electric double layer capacitor, polyethylene oxide, polymethyl methacrylate, polyvinylpyrrolidone, polyacrylonitrile,
An electrolytic solution for an electric double layer capacitor, wherein a gelling agent comprising at least one of polyvinylidene fluoride and polyvinylidene chloride is added.

Further, the amount of the gelling agent added is 0.1
An electrolytic solution for an electric double-layer capacitor, characterized in that the amount is 30.0 wt%.

In the above electrolyte, the solute is at least one of tetraethylammonium fluoride and triethylmethylammonium fluoride, and the solvent is propylene carbonate, ethylene carbonate, dimethyl carbonate, ethylmethyl carbonate, tetrahydrofuran, -Methyltetrahydrofuran, at least one of γ-butyrolactone
An electrolytic solution for an electric double layer capacitor characterized by being a seed.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is an electrolytic solution for an electric double layer capacitor to which a gelling agent such as polyethylene oxide and polymethyl methacrylate is added.

[0008]

EXAMPLES (Example) A slurry in which PTFE, activated carbon, and carbon black were kneaded was applied to one side of an aluminum etching foil having a thickness of 20 μm using a roll coater, dried, and then pressed with a 5 ton roll press. A carbon electrode foil was obtained. The carbon electrode foil was cut into a strip having a width of 28 mm by a slitter, and a lead terminal was attached to the aluminum surface by a cold weld method. Thickness 2 which cut this to 30mm width
It was wound with a 5 μm Manila hemp paper with the carbon surfaces facing each other to produce a capacitor element.

As an electrolytic solution, 1 mol / l of tetraethylammonium borofluoride solution in propylene carbonate was added as shown in Table 1.
Was added, and the capacitor element was placed in a pressure cooker filled with an electrolytic solution, and impregnated with the electrolytic solution at 100 ° C. and 2 atm. These are stored in a case and sealed with a sealing plate.
The solution was left to stand in a constant temperature bath at ℃ for 1 hour to gel the electrolyte.
00 electric double layer capacitors were produced. (Comparative Example) In the same manner as in the example, the gelling agents shown in Table 1 were added to prepare 100 electric double layer capacitors. (Conventional Example) A 1 mol / l solution of tetraethylammonium fluoride in propylene carbonate was used as an electrolytic solution without adding a gelling agent. As in the example, the capacitor element was placed in a pressure cooker filled with an electrolytic solution, and impregnated with the electrolytic solution at 100 ° C. and 2 atm. This was housed in a case and sealed with a sealing plate to produce 100 electric double layer capacitors.

[0010]

[Table 1]

Holes were drilled in the back of these products, and the electrolytic solution was shaken off by a centrifugal separator, disassembled, and the element weight before and after centrifugation was measured. The results shown in Table 1 were obtained. In Comparative Example 1a and the conventional example, the electrolytic solution in the separator was reduced by the centrifugal separator. However, in the example, the effect of suppressing the decrease in the electrolytic solution was obtained.

[0012]

[Table 2]

The capacitance and resistance of these products were measured, and Table 2
Was obtained. Although the gelling agent of the present invention interacts between molecules in the electrolyte to promote gelation of the electrolyte, the network structure formed by the interaction of the gelling molecules is larger than the size of the electrolyte ions. Since it is large, the migration of ions is not hindered by the gelation of the electrolytic solution, so that an increase in the specific resistance of the electrolytic solution can be suppressed.

If the amount of the gelling agent to be added is less than 0.1% by weight, the gelation is insufficient and the electrolyte does not have a leakage preventing effect.
If it exceeds 0 wt%, the specific resistance of the electrolytic solution becomes too high.
FIG. 1 shows a characteristic diagram of the amount of polyethylene oxide added and the equivalent series resistance of the product. The addition amount of the gelling agent is 0.1 to
It turns out that 30.0 wt% is preferable. Similar results were obtained with polymethyl methacrylate, polyvinyl pyrrolidone, polyacrylonitrile, polyvinylidene fluoride, and polyvinylidene chloride. Further, similar results were obtained even when a plurality of gelling agents were added.

The electrolyte solution to which the gelling agent is added, other than the electrolyte used in the above embodiment, has a solute of at least one of tetraethylammonium fluoride and triethylmethylammonium fluoride, and the solvent is propylene carbonate. , Ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate,
Diethyl carbonate, methyl acetate, methyl propionate, 1,
At least one of 2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, and γ-butyrolactone may be selected and used.

[0016]

As described above, the electric double layer capacitor in which the gelling agent is added to the electrolytic solution of the present invention prevents the electrolytic solution from leaking at the time of breakage without affecting the capacity and resistance. And can greatly improve the safety of the product.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram of the amount of gelling agent added and the equivalent series resistance of a product.

Claims (3)

[Claims] 1. An electrolytic solution for driving an electric double layer capacitor, comprising: polyethylene oxide, polymethyl methacrylate, polyvinylpyrrolidone, polyacrylonitrile,
An electrolytic solution for driving an electric double layer capacitor, wherein a gelling agent comprising at least one of polyvinylidene fluoride and polyvinylidene chloride is added. 2. The amount of the gelling agent according to claim 1 is:
An electrolytic solution for driving an electric double layer capacitor, wherein the electrolytic solution is 0.1 to 30.0 wt%. 3. The driving electrolyte according to claim 1, wherein
The solute is at least one of tetraethylammonium fluoride and triethylmethylammonium fluoride, and the solvent is propylene carbonate, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl acetate, methyl propionate, -Dimethoxyethane,
Tetrahydrofuran, 2-methyltetrahydrofuran,
An electrolytic solution for driving an electric double layer capacitor, which is at least one of γ-butyrolactone.