JPH1197314A - Double electric layer capacitor and electrode and manufacture therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an IR drop, by making an electrode to have a low resis tance and to increase a capacitance during a high electric current density, by adding noble metal having a sulfuric acid resistance and a catalytic property to carbide made of polyvinylidene chloride (PVDC), and by forming an electrode for a double electric layer capacitor by the carbide. SOLUTION: An electrode for a double electric layer capacitor is formed by adding noble metal having a sulfuric acid resistance and a catalytic property to carbide made of PVDC resin, and by using the carbide. The double electric layer capacitor can be formed by the electrode building in the capacitor. The double electric layer capacitor is preferably formed by powder of PVDC resin being carbonize at 180 deg.C to 600 deg.C, by the noble metal having a sulfuric acid resistance and a catalytic property being added to the generated carbide and being nobled, and after that by being sintered at 600 deg.C to 950 deg.C. Preferable samples of the noble metal having a sulfuric acid resistance and a catalytic property to be added to the carbide is Pt, Pd or Rh and the adding volume is preferable 0.01 to 30 weight %.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric double layer capacitor, an electrode and a method for manufacturing the same.

[0002]

2. Description of the Related Art An electric double layer capacitor is a capacitor utilizing an electrostatic solution of an activated carbon powder and an electrolytic solution impregnated in an activated carbon powder. The withstand voltage and the maximum operating temperature depend on the decomposition voltage and temperature of the electrolytic solution, and the rated voltage is as low as several volts. However, since the Farad order capacitance can be easily obtained, the semiconductor memory is used instead of the battery. It has been widely used for low current density applications such as backup of (D-RAM), and has recently been studied for use in applications having higher current densities, for example, in place of in-vehicle lead-acid batteries. ing.

Heretofore, as an electrode for an electric double layer capacitor, a material obtained by mixing a binder with activated carbon and sintering or a material subjected to an activation treatment (impurity removal treatment by oxidation) after sintering has been used. However, the use of these electrodes has caused the following problems. a) Activated carbon has a low density because it has many macropores and a high pore volume ratio. b) Although the specific surface area is large, the distribution of the pore diameter is wide, so that there are few effective pores acting as electrodes for electric double layer capacitors. c) sintering at a relatively high temperature to promote sintering,
There are few effective pores acting as electrodes for electric double layer capacitors. d) When sintering at a low temperature (850 ° C. or lower), graphitization does not proceed, so there is no intergranular sintering strength and the resistance value is high.

[0004] To solve these problems, PVDC
It has been proposed to use (polyvinylidene chloride) resin carbide (see JP-A-7-249551).
The use of PVDC resin (or vinylidene chloride-based copolymer) carbide has advantages over other activated carbons because of the following. PVDC resins have two dehydrochlorination reaction temperatures. The first point is the dehydrochlorination reaction in the self-molecular chain at 180 ° C to 250 ° C, and the second point is the dehydrochlorination reaction between the molecular chains at 450 ° C to 550 ° C. I have. The pores formed by the dehydrochlorination reaction at the first point are 3
It is called a micropore of 6 ° or less, and when it is used as an electrode for an electric double layer capacitor, it works effectively as an interface with an electrolytic solution. For this reason, activation treatment as an electrode is unnecessary. In addition, sintering can proceed at a relatively low temperature while maintaining effective micropores by the dehydrochlorination reaction at the second point. For this reason, generation of mesopores or macropores having a large diameter, which is unnecessary for the electrode for an electric double layer capacitor, can be suppressed. For this reason, PVD
C resin carbide has a smaller specific surface area than activated carbon,
Since the sintering density is higher than that of activated carbon, the capacity per volume is large.

However, the PVDC resin carbide has the following problems. a) It is difficult to mold because it is binderless. b) Ohmic resistance is high because graphite does not advance during sintering at low temperature (850 ° C. or lower). Therefore, at a high current density, the IR drop is large and the capacity cannot be taken out. c) The PVDC resin carbide can be sintered at a high density, but has a high diffusion resistance due to few voids and macropores between particles.

[0006]

SUMMARY OF THE INVENTION The present invention provides a high power density electric double layer capacitor with reduced electrode resistance, reduced IR drop, and increased capacitance, especially at high current densities. That is.

[0007]

SUMMARY OF THE INVENTION The present invention relates to an electrode for an electric double layer capacitor comprising a PVDC resin carbide.
It is an electrode for an electric double layer capacitor having a sulfuric acid resistant and catalytic noble metal.

In the present invention, the noble metal may be Pt, P
An electrode for an electric double layer capacitor, which is one or more of d and Rh.

The present invention is the electrode for an electric double layer capacitor, wherein the amount of the noble metal added is 0.01 to 30 wt%.

Further, the present invention is an electrode for an electric double layer capacitor, wherein the electrolyte is sulfuric acid.

The present invention also relates to an electric double layer capacitor provided with an electrode made of a PVDC resin carbide, wherein the electrode is a sulfuric acid resistant and catalytic noble metal containing noble metal.

Further, the present invention relates to a method for preparing a PVDC resin powder by adding
This is a method for producing an electrode for an electric double layer capacitor which is carbonized at 80 to 600 ° C., added with a sulfuric acid resistant and catalytic noble metal, molded, and sintered at 600 to 950 ° C.

Further, the present invention is a method for producing an electrode for an electric double layer capacitor, wherein the noble metal is attached to a PVDC resin powder by electroless plating.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described. An example of the method for manufacturing an electrode for an electric double layer capacitor according to the present invention will be described.

First, a first embodiment will be described. The PVDC resin is heated at 180 to 600 ° C. to cause a dehydrochlorination reaction and carbonization,
It is pulverized and sieved with a vibration milling machine to obtain carbonized powder having a particle size of 22 μm or less. Next, 100 g of the carbonized powder was boiled with 35 wt% sulfuric acid, filtered while washing with water, and then filtered.
The solution was added to 500 cc of a solution of stannous chloride dissolved in 4% by weight of dilute hydrochloric acid to a concentration of 5% by weight and stirred for 5 to 30 minutes. In this step, Sn is supported on the carbonized powder. afterwards,
After repeating filtration and washing three times, the resultant was immersed in 500 cc of a solution of palladium chloride dissolved in 0.5 wt% diluted hydrochloric acid to a concentration of 0.05 wt%, and stirred for 5 to 30 minutes. In this step, the Sn supported on the carbonized powder in the previous step becomes Pd
And Pd is carried on the carbonized powder. Thereafter, filtration and washing were further repeated five times to remove unsupported metals and ions. Then, it dried at 120 degreeC for 4 hours. The dried carbonized powder is packed in a 25 mm square carbon mold and 20 to 40
While molding at a pressure of 0 kg / cm ² , current sintering was performed until the temperature reached 850 ° C. to obtain an electrode.

Next, a second embodiment will be described. The PVDC resin is heated at 180 to 600 ° C. to cause a dehydrochlorination reaction and carbonization,
It is pulverized and sieved with a vibration milling machine to obtain carbonized powder having a particle size of 22 μm or less. Next, 100 g of the carbonized powder was boiled with 35 wt% sulfuric acid, filtered while washing with water, then immersed in a solution of palladium chloride in 0.75 wt% diluted hydrochloric acid, and stirred for 30 minutes. In this electroless plating step, Pd was deposited on the carbonized powder. Thereafter, filtration and water washing were further repeated five times to remove unsupported metals and ions. Then, it dried at 120 degreeC for 4 hours. 25 dried carbonized powders
mm carbon mold, 20 ~ 400kg / cm
^The electrode was obtained by current sintering until the temperature reached 850 ° C. while molding at a pressure of ² .

Embodiment 3 will be described. 18 PVDC resin
The mixture is heated at 0 to 600 ° C. to cause a dehydrochlorination reaction and carbonized, crushed and sieved by a vibration milling machine to obtain a carbonized powder having a particle size of 22 μm or less. Next, 100 g of the carbonized powder was boiled with 35 wt% sulfuric acid, filtered after washing with water, and then immersed in a solution of platinum chloride dissolved in 0.75 wt% diluted hydrochloric acid at 65 ° C.
For 60 minutes. In this electroless plating step, Pt was deposited on the carbonized powder. Thereafter, filtration and water washing were further repeated five times to remove unsupported metals and ions. Then 1
Dry at 20 ° C. for 4 hours. Dry carbonized powder 25mm □
And sintering with current until the temperature reached 850 ° C. while molding at a pressure of ^{20 to} 400 kg / cm ² to obtain an electrode.

Embodiment 4 will be described. 18 PVDC resin
The mixture is heated at 0 to 600 ° C. to cause a dehydrochlorination reaction and carbonized, crushed and sieved by a vibration milling machine to obtain a carbonized powder having a particle size of 22 μm or less. Next, 100 g of the carbonized powder was boiled with 35 wt% sulfuric acid, filtered while washing with water, and immersed in a solution in which rhodium chloride was dissolved in 0.75 wt% diluted hydrochloric acid.
Stirred for 0 minutes. In this electroless plating process, P
h precipitated. Thereafter, filtration and water washing were further repeated five times to remove unsupported metals and ions. Then, 12
Dry at 0 ° C. for 4 hours. The dried carbonized powder was packed in a 25 mm square carbon mold, and was sintered by current conduction until the temperature reached 850 ° C. while being molded at a pressure of ^{20 to} 400 kg / cm ² to obtain an electrode.

A comparative example will be described. 180 PVDC resin
The mixture is heated at ~ 600 ° C to cause a dehydrochlorination reaction and carbonization, and then pulverized and sieved by a vibration milling machine to obtain a carbonized powder having a particle size of 22μ or less. Next, the carbonized powder was packed in a 25 mm square carbon mold, and while being formed at a pressure of ^{20 to} 400 kg / cm ² , current was sintered until the temperature reached 850 ° C. to obtain an electrode.

The electrodes obtained in Examples 1 to 4 and Comparative Example were polished to a thickness of 1 mm, and the sheet resistance was measured by a four-terminal four-needle method. Next, the electrode was immersed in 35% by weight sulfuric acid, and impregnated under reduced pressure for 24 hours. The electrode 2 was opposed to the non-woven fiber separator 1 having a thickness of 200 μm with a separator 1 therebetween.
A t-plate was arranged to form a current collector plate 3, which was then sandwiched and fixed from the outside with a fixed plate 4 made of Teflon to produce a cell (see FIG. 1). This cell was immersed in 35% by weight sulfuric acid to give a current density of 0.02 A / cm ^{2 with} respect to the electrode projected area.
And the capacity at 0.2 A / cm ² were measured. Table 1 shows the measurement results.

[Table 1]

As shown in Table 1, prior to sintering in Examples 1 to 4, sulfuric acid-resistant and catalytic noble metals, Pt, Pd, and Rh were supported on carbonized powder and then sintered. The sheet resistance has decreased and the capacity has increased. The reason for the increase in capacity is that, due to the catalytic action of the added noble metal, the charge is stored by the adsorption and desorption reaction of hydrogen or oxygen ions in water during charging of the electric double layer capacitor, and the redox capacity is added. . The increase in capacitance on the high current density side is due to the decrease in loss due to resistance due to a decrease in sheet resistance and the appearance of the added redox capacitance described above.

The amount of the noble metal added is 0.01 to 30 wt%
It is preferable that If it is less than 0.01 wt%, the resistance of the electrode cannot be reduced, and the capacity cannot be increased. Also, if it exceeds 30 wt%, PVDC
The amount of resin carbide is reduced, and the function as an electric double layer capacitor is reduced.

[0023]

According to the present invention, the resistance of the electrode is reduced and the IR
The drop can be reduced, and the capacitance at a high current density can be increased, and an electric double layer capacitor with a high output density can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method for measuring characteristics of an electrode manufactured by a manufacturing method according to an embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Separator 2 Electrode 3 Current collector 4 Fixing plate

Claims (7)

[Claims] 1. An electrode for an electric double layer capacitor comprising a PVDC resin carbide, wherein the electrode has a sulfuric acid resistant and catalytic noble metal. 2. The electrode for an electric double layer capacitor according to claim 1, wherein the noble metal is at least one of Pt, Pd, and Rh. 3. The electrode for an electric double layer capacitor according to claim 1, wherein the amount of the noble metal added is 0.01 to 30 wt%. 4. The electrode for an electric double layer capacitor according to claim 1, wherein the electrolyte is sulfuric acid. 5. An electric double layer capacitor provided with an electrode made of a PVDC resin carbide, wherein said electrode has a sulfuric acid-resistant and catalytic noble metal. 6. An electric double layer wherein PVDC resin powder is carbonized at 180 to 600 ° C., a sulfuric acid-resistant and catalytic noble metal is added, molded, and then sintered at 600 to 950 ° C. Manufacturing method for capacitor electrodes. 7. The method for manufacturing an electrode for an electric double layer capacitor according to claim 5, wherein the noble metal is attached to the PVDC resin powder by electroless plating.