JPS6014500B2 - electric double layer capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric double layer capacitor having an improved electrolyte and a longer life.

In general, ammonium salts and alkali metal salts such as lower carboxylic acids, perchloric acid, phosphoric acid, nitric acid, and sulfuric acid, which have large ionization constants, are often used as solutes in electrolytes used in electric double layer capacitors, and water or non-alkali metal salts are often used as solvents. Aqueous organic solvents are often used.

This non-aqueous organic solvent also requires a certain amount of moisture to obtain ionic conductivity, and contains moisture adsorbed by the activated carbon and other moisture caused by the constituent materials. These reduce the decomposition voltage of the electrolyte, causing destruction of the electric double layer, increase in leakage current, generation of hydrogen gas, and dissolution of the current collector metal, thereby significantly shortening the life of the electric double layer capacitor. Among these, hydrogen gas, which is the main component of the gas generated on the cathode side and one of the components on the anode side, has the disadvantage that it is large in amount and tends to cause destruction of the outer container and reduction deterioration of the electrolyte. In order to eliminate the above-mentioned drawbacks, the present invention absorbs hydrogen gas for a long time by impregnating it with an electrolyte containing 0.05 to 3% by weight of ortho-nitrophenol or para-nitrophenol as a hydrogen gas absorbent. The purpose of this invention is to provide an electric double layer capacitor with stable characteristics and a long service life.

The details of the present invention will be explained below.

In other words, the present invention uses activated carbon or carbon black as a binder (
binder) and press-molding it on the current collector, or mix a sucrose aqueous solution and activated carbon and apply it to the current collector and bind it, or mix activated carbon and tetrafluoroethylene dispersion or alcohol emulsion. A pair of splittable electrodes and a separator formed by mixing and forming a rubber into a bag electric body by rolling and heat-adhering it, or by mixing and phosphorizing carbonyl nickel powder and activated carbon powder and winding them together. Alternatively, 0.0% orthonitrophenol or paranitrophenol may be added to the electrolyte that is impregnated into the stacked capacitor elements.
It is added in an amount of 0.05 to 3% by weight. In general, nitrophenols are more active than nitrobenzene due to the influence of the OH group, and especially o-nitrophenol and p-nitrophenyl, which have N02 groups in the ortho (10) and para (1P) positions, are easy to replace with strings. It has the property of converting into ami/phenol corresponding to . O-nitrophenol or p-contains aqueous and non-aqueous electrolytes containing organic or inorganic acid salts such as lower carboxylic acids with large ionization constants, perchloric acid, phosphoric acid, nitric acid, ammonium salts such as sulfuric acid, and alkali metal salts.
When nitrophenol is added, almost no hydrogen gas is generated from both electrodes even if a voltage higher than the normal separation voltage (0.8 to 1.6 V, DC) of these electrolytes is applied.
Stainless steel plates were used for both the anode and cathode, and the electrodes were 0.5
A voltage of 10 V, DC was applied to the molar ammonium maleate-methylformamide electrolyte (temperature 25°C), and P
・Table 1 shows a comparison of hydrogen gas generation with and without the addition of nitrophenol. Table 1Table 1
(continued) As is clear from Table 1, when o-nitrophenol or p-nitrophenol is added to the electrolyte, no hydrogen gas is generated from both electrodes.

Next, comparisons will be made between examples of the present invention and conventional comparative examples and reference examples.

Example 1 A 20% polyvinyl alcohol aqueous solution was mixed with activated carbon powder of 325 mesh or more in an amount of 2% by weight based on the activated carbon powder, and this was applied to a current collector and baked by heating to obtain a polarizable electrode.

This is wound as a pair of electrodes through a separator made of manifold paper. This wound element was coated with 3% by weight of p.
A capacitor was obtained by mixing an electrolyte containing nitrophenol. Example 2 A capacitor was obtained by impregnating the same wound element as in Example 1 with an electrolyte prepared by adding 1% by weight of p-nitrophenol to a 50% solution of 0.5 mol ammonium maleate-methylformamide.

Example 3 0.05% by weight of 1M ammonium maleate-methylformamide solution was added to the same wound element as in Example 1 above.
A capacitor was obtained by mixing an electrolyte to which p-nitrophenol was added.

Example 4 A wound element similar to that of Example 1 above was coated with 2% by weight of O.
A capacitor was obtained by mixing an electrolyte containing nitrophenol.

Example 5 0.05% by weight of 1M ammonium maleate-methylformamide solution was added to the same wound element as in Example 1 above.
A capacitor was obtained by mixing an electrolyte to which o-nitrophenol was added.

Example 6 A wound element similar to that of Example 1 above was coated with 1% by weight of O.
A capacitor was obtained by impregnating it with an electrolyte to which nitrophenol was added.

Example 7 A wound element similar to that of Example 1 above was coated with 3% by weight of O.
A capacitor was obtained by impregnation with an electrolyte to which nito-phenol was added.

Comparative Example 8 A wound element similar to that of Example 1 above was coated with 4% by weight of P in a 1M ammonium maleate-methylformamide solution.
A capacitor was obtained by impregnating it with an electrolyte containing nitrophenol.

Comparative Example 9 In the same winding as in Example 1 above, 1 mol of ammonium maleate-methylformamide solution was added to 0.0 round weight%.
A capacitor was obtained by impregnating it with an electrolyte to which o-nitrophenol was added.

Comparative Example 10 A wound element similar to that of Example 1 above was coated with 4% by weight of O.
A capacitor was obtained by impregnating it with an electrolyte containing nitrophenol.

Comparative Example 11 A wound element of the same type as in Example 1 was added with 0.0 phantom weight % in 1 mol ammonium maleate-methylformamide solution.
A capacitor was obtained by impregnating it with an electrolyte to which p-nitrophenol was added.

Reference Example 12 A capacitor was obtained by impregnating the same wound element as in Example 1 with an electrolyte of 1 mol ammonium maleate-methylformamide solution.

These Examples 1 to 7, Comparative Examples 8 to 11 and Reference Example 1
Table 2 shows the operation status of the check valve in a test in which the rated voltage was applied to the capacitor No. 2 at a temperature of 80 pm.

Table 2 From Table 2, it can be seen that the valve operation frequency of the capacitors of Examples 1 to 4 in which the electrolyte containing 0.05 to 3% by weight of nitrophenol was mixed was all zero, and the hydrogen gas absorption effect and long life effect were remarkable. is clear.

In addition, when we disassembled and investigated the capacitor in which the valve operated, we found perforation and cracks in the carbon layer, and it was found that good results were obtained in terms of the physical effects of generated gas and the influence on leakage current. Note that if the amount of nitrophenol added is less than 0.05% by weight, the hydrogen gas absorption effect will not be obtained much;
If the amount exceeds % by weight, the pH of the electrolyte will decrease, the specific resistance will change, the viscosity will change, solutes will precipitate, and a sufficient effect will not be obtained. As detailed above, according to the present invention, a capacitor element consisting of a pair of polarizable electrodes mainly made of carbon and a separator interposed therebetween is coated with 0.00% ortho-nitrophenol or para-nitrophenol as a hydrogen gas absorbent.
By impregnating the capacitor with an electrolyte added in an amount of 0.5 to 3% by weight, it is possible to provide an electric double layer capacitor that absorbs hydrogen gas, has a long service life, and has stable characteristics.

Claims (1)

[Claims] 1. 0.00.0 of orthonitrophenol or paranitrophenol is applied to a capacitor element consisting of a pair of polarizable electrodes mainly made of carbon and a separator interposed between them.
An electric double layer capacitor characterized in that it is impregnated with an electrolyte added in an amount of 5 to 3% by weight.