JP2000068163A - Manufacture of electric double layer capacitor electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacturing method of an electric double layer capacitor electrode capable of reinforcing the molding of an electrode, preventing the generation of cracks, lowering the diffusion resistance of ions, increasing capacitance at a high current density, and manufacturing a large-sized electrode. SOLUTION: In this manufacturing method of the electric double layer capacitor electrode 2 for using a PVDC resin carbide and forming and molding slurry, the phenol resin of a resol type and fibrous resin whose actual carbon ratio is equal to or less than 30 wt.% are added at the time of forming the slurry, polyethylene glycol or the derivative up to 2,000,000 molecular weight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electric double layer capacitor electrode, and more particularly to a method for manufacturing an electric double layer capacitor electrode to which a binder is added.

[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 capacitance in the farad order can be easily obtained, a semiconductor memory is used instead of a 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.

[0003] Conventionally, in producing electrodes of an electric double layer capacitor, electric sintering has been performed. This method does not require a binder and allows sintering in a short time, but is not suitable for sintering large electrodes. In addition, the obtained electrode has an electrode density of 0.9 to 1.2 g / cc, which is too high, and there are few voids between particles required for the characteristics of the electric double layer capacitor, and the capacitance at a high current density cannot be taken out. There was a problem. Therefore, as a simpler method, a slurry was prepared, poured into a shape, and formed at normal pressure and normal temperature to 90 ° C. Although this method requires the addition of a binder or the like, the density is about 0.7, and effective interparticle voids are formed on the high current density side.

[0004] When molding an electrode, if the size of the electrode is increased or if carbonized powder having a small particle size is used, cracks and cracks occur during molding. It has been proposed to add cellulose fibers to eliminate this. Although the moldability was improved by adding the cellulose fiber, the resistance of the electrode was increased and the capacitance was decreased. Cellulose is a fiber having a residual carbon ratio of 40 to 50% by weight,
In addition, since the carbide does not contribute to the capacitance, the capacitance is decreased when the added amount is increased.

As described above, problems such as cracks and cracks during molding, an increase in resistance, and a decrease in capacitance have been observed with the enlargement of electrodes.

[0006]

SUMMARY OF THE INVENTION The present invention reinforces an electrode compact, prevents cracks and cracks, reduces ion diffusion resistance, increases the capacitance at high current densities, and provides a large electrode. It is an object of the present invention to provide a method for manufacturing an electric double layer capacitor electrode which enables the production of an electrode.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a method for manufacturing an electric double layer capacitor electrode in which a slurry is prepared and molded using a carbide of polyvinylidene chloride resin (hereinafter referred to as "PVDC resin"). When preparing a slurry, an electric double layer capacitor electrode to which polyethylene glycol or a derivative thereof having a molecular weight of up to 2 million, a resole type phenol resin, and a fibrous resin having a residual carbon ratio of 30% by weight or less are added. It is a manufacturing method.

The present invention is also a method for producing an electric double layer capacitor electrode wherein the amount of the polyethylene glycol or a derivative thereof added is 5 to 20% by weight based on the PVDC resin carbide.

Further, the present invention is a method for producing an electric double layer capacitor electrode, wherein the resol type phenol resin is added in an amount of 5 to 10% by weight based on the PVDC resin carbide.

Further, the present invention provides an electric double layer capacitor electrode wherein the amount of the fibrous resin having a residual carbon ratio of 30% by weight or less is 0.5 to 2.5% by weight based on the PVDC resin carbide. It is a manufacturing method.

The present invention is also a method for producing an electric double layer capacitor electrode wherein the fibrous resin is a polyester fiber.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described. The manufacturing method of the electric double layer capacitor electrode of the present invention will be described by way of an example. In this embodiment, 1) a polyester fiber is added to reinforce a molded body, cracks and cracks are prevented, and burned out in a sintering step to form uniform voids throughout the electrode. 2) The voids created by the disappearance of the polyester fibers act as electrolyte paths, lowering the ion diffusion resistance and increasing the capacitance at high current densities. 3) polyester fiber (diameter 5 to 15 μm, length 0.5 to 5 mm, residual carbon ratio 30% by weight or less)
By adding 2.5% by weight, the moldability of the slurry was improved, and a large-sized electrode could be manufactured.

An embodiment will be described. 1) Initial method of carbonizing PVDC resin 2 kg of PVDC resin is packed in a quartz tube, and a thermocouple, an exhaust pipe,
Place a gas injection tube and seal with a rubber stopper. The quartz tube was set in a tube furnace and heated at 180 to 450 ° C. Until the peak temperature, the hydrogen chloride gas discharged in the dehydrochlorination reaction was discharged from the exhaust pipe at its own pressure. During cooling, air flowed at 0.2 to 0.5 L / min from the gas injection pipe to 100 ° C. or less. By the way, the PVDC resin carbide was taken out and pulverized so as to have an average particle size of 8 to 12 μm.

2) Preparation and shaping of slurry A mixed solvent of water: alcohol = (7: 3) was added with a molecular weight of 20
5 to 20% by weight of polyethylene glycol of 0 to 2000 is added to the PVDC resin carbide, and 5 to 10% by weight of a resole type phenol resin is added. After adding 0.5 to 2.5% by weight of a polyester fiber (polyethylene terephthalate fiber, manufactured by Kuraray, trade name "EP101") having a residual rate of 30% by weight or less and 5 to 2.5% by weight, the PVDC resin carbide is added and 2 to 6% by weight. Stirred for hours. Due to the acidic substances contained in the PVDC resin carbide and the acidic groups on the surface, the pH gradually decreases to pH 2 to 4 in 1 to 6 hours at room temperature, and the slurry balances in a good dispersion state. The stirred slurry was poured into a 120 cm square mold, dried as it was in a temperature range from room temperature to 90 ° C for 4 to 24 hours, and molded.

3) Firing The molded body is sandwiched between carbon plates or the like and fired at 600 to 950 ° C. in a neutral or reducing atmosphere.

4) Characteristics of Sintered Electrode The density of the electrode prepared in the above steps is 0.65 to 0.75.
g / cc, and the sheet resistance of the electrode is 1.0 to
It was 3.0Ω / □. In addition, when the cross section of the electrode was observed with a scanning electron microscope, it was observed that interparticle voids of 5 to 20 μm were distributed throughout the electrode.

5) Comparative Example As Comparative Example 1, PVDC resin carbide was applied at a pressure of 200 k.
The powder was compacted at g / cm ² , and electrically sintered at 850 ° C. to obtain an electrode. As Comparative Example 2, 0.5 to 10% by weight of cellulose fibers was added to a slurry of PVDC resin carbide and phenol resin to improve moldability,
An electrode was obtained by molding at room temperature to 90 ° C. and firing at 850 ° C.

6) Measurement of capacity of sintered electrodes of Examples and Comparative Examples 1 and 2 After grinding the sintered electrodes 2 of Examples and Comparative Examples 1 and 2 to a thickness of 1 mm, the electrodes were ground in water or diluted sulfuric acid. 200 in air after impregnation
Heated at a temperature of 90 ° C. for 90 minutes, immersed again in 35% by weight sulfuric acid, impregnated under reduced pressure for 24 hours, opposed to each other with a 200 μm-thick glass nonwoven fiber separator 1 interposed therebetween, and further placed a Pt plate 3 outside thereof. A current collector plate, and a cell fixed by sandwiching it from outside with a Teflon plate 4 (see FIG. 1)
Was immersed in 35% by weight sulfuric acid, and the capacity at a current density of 0.5 A / cm ² with respect to the electrode projected area was measured. Table 1 shows the measurement results.

[Table 1]

7) Evaluation of Sintered Electrode of Example The electrode of this example has lower diffusion resistance, lower density and higher capacitance than the electrodes of Comparative Examples 1 and 2. This is considered to be due to the following.
In the electrode of this example, a) polyester fiber was added, and the molded article of the large-sized electric double layer electrode was reinforced, and cracks and cracks could be prevented. b) The addition of polyester fibers provided an optimal electrolyte path, reduced ion diffusion resistance and increased capacitance at high current densities. c) polyester fiber (diameter 5 to 15)
(μm, length: 0.5 to 5 mm, residual carbon ratio: 30% by weight or less) by adding 0.5 to 2.5% by weight improves the formability of the slurry and makes it possible to produce large electrodes Was.

[0020]

According to the present invention, the electrode molded body is reinforced, cracks and cracks are prevented, the diffusion resistance of ions is reduced, the capacitance at high current density is increased, and the size of the large electrode is reduced. An electric double layer capacitor electrode that can be manufactured can be manufactured.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method for measuring characteristics of an electric double layer capacitor electrode.

[Explanation of Signs] 1 Separator 2 Electrode 3 Current collector 4 Pt plate

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshikazu Takeda 8 Dosana, Fujisawa City, Kanagawa Prefecture Inside Isuzu Central Research Institute Co., Ltd. (72) Inventor Hideki Shibuya 8 Dosana, Fujisawa City, Kanagawa Prefecture Isuzu Central Research Inc. (72) Inventor Shigeru Murakami 6850 Omachi Omachi, Omachi City, Nagano Prefecture Showa Denko Omachi Plant Co., Ltd. (72) Inventor Tsutomu Masuko 6850 Omachi Omachi Omachi City, Nagano Prefecture Showa Denko Omachi Plant Co., Ltd.

Claims (5)

[Claims] 1. A method of manufacturing an electric double layer capacitor electrode using a PVDC resin carbide to prepare and mold a slurry, wherein, when the slurry is prepared, polyethylene glycol having a molecular weight of up to 2 million or a derivative thereof; A method for producing an electric double layer capacitor electrode, comprising adding a resole type phenol resin and a fibrous resin having a residual carbon ratio of 30% by weight or less. 2. The method according to claim 1, wherein the amount of the polyethylene glycol or a derivative thereof is 5 to 20% by weight based on the weight of the PVDC resin carbide. Manufacturing method of double layer capacitor electrode. 3. The method for manufacturing an electric double layer capacitor electrode according to claim 1, wherein the amount of the resol-type phenol resin is PV
A method for producing an electrode for an electric double layer capacitor, wherein the content is 5 to 10% by weight based on the DC resin carbide. 4. The method for producing an electric double layer capacitor electrode according to claim 1, wherein the amount of the fibrous resin having a residual carbon ratio of 30% by weight or less is:
A method for producing an electric double layer capacitor electrode, wherein the content is 0.5 to 2.5% by weight based on PVDC resin carbide. 5. The method for manufacturing an electric double layer capacitor electrode according to claim 1, wherein the fibrous resin is a polyester fiber. Production method.