JP2007227519A - Manufacturing method of electric double layer capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an electric double layer capacitor with which moisture existing in a laminated body, especially moisture existing in a pore of an activated carbon used as a composition material of a polarizable electrode, can efficiently be removed to very low concentration in the manufacturing method of the electric double layer capacitor for storing the laminated body formed of a positive electrode body, a negative electrode body and a separator in a vessel, pouring electrolytic solution into the vessel and impregnating it in the laminated body, and sealing the vessel in a state where a tip of a terminal of the positive electrode body and that of the negative electrode body are exposed outside. <P>SOLUTION: The laminated body or the composition material is impregnated in organic solution before electrolytic solution is impregnated in the laminated body. Treatment for discharging water included in solution with organic solution is performed. A process is included for removing moisture from the laminated body or the composition material. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method of manufacturing an electric double layer capacitor in which electricity is accumulated in an electric double layer that is an interface between a polarizable electrode such as activated carbon and an electrolyte solution, and a laminate comprising a positive electrode body, a negative electrode body, and a separator, or a constituent material thereof The present invention relates to a method for efficiently removing moisture.

  In recent years, an electric double layer capacitor that accumulates electricity in an electric double layer that is an interface between a polarizable electrode such as activated carbon and an electrolytic solution has been put into practical use as a power storage medium. As a general configuration of an electric double layer capacitor, an electric sheet having a configuration in which a current collector such as a metal foil and a polarizable electrode such as activated carbon and separators are alternately laminated and impregnated with an electrolytic solution. A multilayer capacitor cell is formed, and the electric double layer capacitor cell is sealed in a container to form an electric double layer capacitor.

  In addition, an electric double layer capacitor is manufactured by forming a laminated body of an electrode sheet and a separator in a sandwich shape in a square electric double layer capacitor and in a roll shape in a cylindrical electric double layer capacitor. After connecting the lead portions of the (positive electrode body and negative electrode body) to each terminal and storing the laminate in a container, the electrolyte solution is injected from the opening of the container to impregnate the laminate with the electrolyte solution. Many methods for sealing containers with their tips exposed to the outside have been implemented.

  In such an electric double layer capacitor, an organic electrolytic solution capable of obtaining a high withstand voltage is generally used as the electrolytic solution. However, when charging and discharging are repeated even in the presence of a small amount of water, the electrolytic solution gradually Since water reacts and the gas such as carbon monoxide and carbon dioxide is generated and the withstand voltage is lowered and deteriorates easily, the laminate and the container are sufficiently dried before injecting the electrolytic solution, Subsequent operations are performed under an inert gas atmosphere until the container is sealed.

  Conventionally, the laminate is dried by heating under reduced pressure in order to remove moisture until the content becomes extremely low. However, the laminate uses a polarizable electrode having pores such as activated carbon and a large specific surface area, the laminate has a configuration in which the polarizable electrode and the separator are closely adhered, and the separator Usually, since the thing made from a cellulose is used, since the upper limit of the heating temperature in the case of drying is about 150-200 degreeC etc., even if it uses a vacuum dryer, drying of a laminated body is usually 10 hours. It took more than that.

Under such circumstances, conventionally, as a method of removing moisture in the container and maintaining a high withstand voltage over a long period of time, for example, a method of including a moisture adsorbent in the polarizable electrode and the separator, a desiccant in the container There have been proposed a method of adding water, a method of applying a high-frequency current to the electrode before impregnating the electrolytic solution, and removing moisture.
Japanese Patent Laid-Open No. 10-144570 Japanese Patent Laid-Open No. 10-321483 JP-A-11-54378 JP 2000-182910 A

However, the method using a moisture adsorbent or a desiccant is difficult to remove moisture present in the pores of activated carbon or the like generally used as a constituent material of a polarizable electrode. The method of applying to the electrode also required a long-time application process in order to remove moisture to an extremely low concentration.
Therefore, the problem to be solved by the present invention is that the electric water that can efficiently remove moisture present in the laminate, particularly moisture present in pores such as activated carbon used as a polarizable electrode, to a very low concentration. It is to provide a method for manufacturing a multilayer capacitor.

  As a result of intensive studies to solve the above-described problems, the present inventors impregnated a laminate or a constituent material thereof in an organic solution, and performed a treatment for discharging water contained in the laminate together with the organic solution. It has been found that moisture present in pores such as activated carbon generally used as a constituent material of an electrode can be efficiently removed to a very low concentration, and has reached the manufacturing method of the electric double layer capacitor of the present invention. .

  That is, in the present invention, a laminate composed of a positive electrode body, a negative electrode body, and a separator is housed in a container, an electrolyte is injected into the container and the laminate is impregnated, and then the container is attached to the tip of the terminal of the positive electrode body and A method of manufacturing an electric double layer capacitor in which the tip of a negative electrode terminal is exposed to the outside, and the laminate or its constituent material is impregnated with an organic solution before the laminate is impregnated with an electrolyte. And a method for producing an electric double layer capacitor comprising a step of removing moisture from the laminate or a constituent material thereof.

  When the impregnation treatment of the organic solution in the manufacturing method of the electric double layer capacitor of the present invention is applied before or immediately after the assembly of the laminated body, the moisture adhering in the pores such as activated carbon used as the polarizable electrode is removed. Since it is washed away with the organic solution, the drying process time of the laminate, which has conventionally taken a long time, can be greatly shortened. In addition, when the impregnation treatment of the organic solution in the method for manufacturing the electric double layer capacitor of the invention is applied between the container storage of the multilayer body and the injection of the electrolytic solution, the moisture remaining in the pores is further reduced. Can be removed.

  In the present invention, a laminated body composed of a positive electrode body, a negative electrode body, and a separator is housed in a container, an electrolyte is injected into the container and the laminated body is impregnated, and then the tip of the terminal of the positive electrode body and the terminal of the negative electrode body The method is applied to a method of manufacturing an electric double layer capacitor that is sealed with its tip exposed to the outside. The present invention is also applied to a method for manufacturing a square electric double layer capacitor and a method for manufacturing a cylindrical electric double layer capacitor. Hereinafter, a square electric double layer capacitor will be described in detail as an example, but the present invention is not limited thereto.

  As shown in FIG. 1, the laminate in the present invention is usually a positive electrode body 1 in which an aluminum foil is bonded to a polarizable electrode made of a mixture containing activated carbon, carbon black, and the like. Are laminated alternately with separators made of paper, pulp, plastic or the like, and the lead part 3 of the positive electrode body and the lead part 4 of the negative electrode body are respectively connected to the electrode terminals. In order to be able to be connected, about 10 to 100 sheets in total are laminated so as to form a square or rectangular laminated body having a side of about 50 to 200 mm. In addition to the laminate as shown in FIG. 1, the laminate in the present invention is a diagram in which the lead portion 3 of the positive electrode body and the positive electrode terminal 5 are bonded, and the lead portion 4 of the negative electrode body and the negative electrode terminal 6 are bonded. A laminate as shown in FIG.

  Further, as shown in FIG. 3, the container in the present invention is a container 8 for sealing the laminate 7 as described above, and its constituent material is usually a surface of a metal foil such as an aluminum foil. It is coated with a meltable plastic film. When storing the laminate as described above, two sheets of a metal foil having a square or rectangular shape coated with a heat-meltable plastic film in advance are stacked, and an opening for storing the laminate is provided. The removed peripheral part is heated and pressed to form a bag.

In the method for producing an electric double layer capacitor of the present invention, before impregnating the laminate with an electrolyte, the laminate or the constituent material thereof (particularly activated carbon used as a polarizable electrode) is impregnated in an organic solution, It is a manufacturing method for performing a treatment (impregnation treatment) for discharging water contained in these together with an organic solution. In the impregnation treatment, the container (particularly the inside) may be impregnated with the laminate or the constituent material thereof.
In the present invention, the impregnation treatment with the organic solution may be performed before the laminate is impregnated with the electrolytic solution. However, it is preferable to assemble the laminate so that the organic solution can be easily impregnated, and the laminate is laminated in terms of workability. It is preferable to carry out between the body container storage and the electrolyte injection.

  As the organic solution used in the present invention, an organic solution having a boiling temperature of about 40 ° C. to 140 ° C. is usually used. Examples of these organic solutions include ethers such as propyl ether, methyl butyl ether, ethyl propyl ether, ethyl butyl ether, trimethylene oxide, tetrahydrofuran, and tetrahydropyran, alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, and butyl alcohol, acetone, Ketones such as ethyl methyl ketone, iso-propyl methyl ketone and iso-butyl methyl ketone, amines such as propylamine, butylamine, diethylamine, dipropylamine and triethylamine, esters such as ethyl acetate, propyl acetate and butyl acetate, hexane and heptane , Hydrocarbons such as octane, nonane, decane, cyclohexane, cycloheptane, cyclooctane, cyclononane, and cyclodecane. Moreover, the organic solution containing 2 or more types of these can also be used.

  In the present invention, an organic solution containing the same component as the component contained in the electrolytic solution and an organic solution having the same component as the electrolytic solution can be used. Regardless of which organic solution is used, these are organic solutions from which moisture has been removed to a low concentration, and are usually removed to 100 ppm or less, preferably 50 ppm or less, more preferably 10 ppm or less. Organic solution. Examples of the method for removing water contained in the organic solution include a method using a desiccant such as calcium chloride, silica gel, synthetic zeolite, or a pervaporation membrane containing dimethylsiloxane, a dialysis membrane, or the like.

  In the present invention, the impregnation treatment with an organic solution can be performed twice or more. For example, ethers, alcohols, ketones, amines, esters, or hydrocarbons are used for the first impregnation treatment, and an organic solution having the same components as the electrolytic solution is used for the second impregnation treatment. Can be used. In addition, when performing the impregnation treatment a plurality of times, the impregnation treatment can be efficiently performed by performing the decompression treatment between the respective impregnation treatments.

  In the present invention, the impregnation method of the organic solution in the laminate or the constituent material thereof is not particularly limited. However, when the impregnation treatment is performed before or immediately after the assembly of the laminate, for example, in an inert gas atmosphere. It is carried out by putting the organic solution in a container for impregnation treatment and immersing the laminate or its constituent material in the container. When impregnation is performed between container storage of the laminate and injection of the electrolyte, for example, a thin tube for supplying an organic solvent and a thin tube for discharging are inserted from the opening of the container, and an organic solvent supply port is inserted. In addition, the organic solution is circulated through a circulation path communicating with the organic solvent outlet, and at least one portion of the circulation path is removed while removing moisture mixed in the organic solution using a pervaporation membrane or the like. At that time, the electrode terminal can be energized to perform electrolytic purification.

  The temperature of the organic solution during the impregnation treatment is usually room temperature or a temperature in the vicinity thereof (about 0 to 100 ° C.), but the upper limit is a temperature not exceeding the boiling point of the organic solution. Further, the pressure of the organic solution is usually normal pressure or a pressure in the vicinity thereof (90 to 110 KPa), but the organic solution can be easily activated by operating under a pressure of about 110 to 1000 KPa (absolute pressure). It is preferable in that it can penetrate into the pores. In addition, during the impregnation treatment, vibration such as ultrasonic vibration can be imparted to the laminate, the constituent material thereof, or the organic solution. When the impregnation treatment is performed before or immediately after assembling the laminate, after the impregnation treatment, the laminate or its constituent material is taken out from the organic solution in a gas atmosphere having a very low moisture content such as an inert gas, and subsequently. And dried.

  In the present invention, after the impregnation treatment with the organic solution and the storage of the laminate in the container are completed, the electrolytic solution is injected from the opening of the container, and then the inside of the container is decompressed, and the laminate is decompressed. . By this decompression treatment, the gas adsorbed on the polarizable electrode such as activated carbon is removed, and the laminate can be efficiently impregnated with the electrolytic solution. In addition, if necessary, between the injection of the electrolyte and the sealing of the container, the electrode terminal is energized and subjected to electrolytic purification in order to electrolyze and remove moisture and functional groups contained in the polarizable electrode. You can also. After the laminate is depressurized, the container is sealed by pressing, for example, two heated heat-seal bars with the container sandwiched therebetween, and an electric double layer capacitor configured as shown in FIG. 3 is obtained. It is done. In the present invention, the process from injection of the electrolytic solution to sealing of the container is performed in a dry inert gas atmosphere.

  EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited by these.

  A positive electrode body, a negative electrode body, and a paper separator made by bonding aluminum foil to a polarizable electrode made of a mixture of activated carbon, carbon black, PTFE, and the like, and a lead portion of the positive electrode body and a lead portion of the negative electrode body are respectively electrode terminals. In total, 30 sheets were stacked so that they could be connected to each other to obtain a square laminate (thickness 15 mm) having a side of 100 mm as shown in FIG. Next, the lead portion of the positive electrode body and the lead portion of the negative electrode body were respectively bonded to the electrode terminals by welding to produce a laminate as shown in FIG. Note that, at the tip of the lower end portion (the portion opposite to the electrode terminal) of the laminate, the constituent material of the laminate was opened in a fan shape when viewed from the side so that the organic solution could be efficiently impregnated.

  The laminated body is immersed in dehydrated tetrahydrofuran filled in a processing vessel with the tip of the lower end opened in a fan shape when viewed from the side under a nitrogen atmosphere, and ultrasonic vibration is applied to tetrahydrofuran. Then, the laminate was impregnated with an organic solution for 10 minutes. Thereafter, the laminate was taken out from tetrahydrofuran and further dried under reduced pressure at 160 ° C. for 1 hour using a vacuum dryer. Conventionally, drying is performed under reduced pressure at 160 ° C. for 10 hours or more.

  A square flat container with a side of 150 mm made of aluminum foil whose surface is coated with a polyethylene film is immersed in a treatment container filled with dehydrated tetrahydrofuran in a nitrogen atmosphere, and ultrasonic waves are added to tetrahydrofuran. The container was impregnated with an organic solution for 10 minutes while applying vibration. Thereafter, the container was taken out from tetrahydrofuran and further dried under reduced pressure at 80 ° C. for 1 hour using a vacuum dryer.

After the laminate and the flat container were cooled to room temperature under a nitrogen atmosphere, the laminate was inserted into the container. Next, 90 ml of an electrolytic solution in which an ammonium salt or the like was dispersed in a propylene carbonate solvent was poured into the container. After the injection of the electrolytic solution was completed, the inside of the container was decompressed with a vacuum pump for 30 minutes, and the laminate was decompressed. During this period, the electrode terminal was energized to perform electrolytic purification. Thereafter, the opening of the container was heated and pressurized at 150 ° C. from the outside to seal the container and obtain an electric double layer capacitor.
As a result of measuring the capacitance and the internal resistance at 25 ° C. and 2.7 V charge of this electric double layer capacitor, it was 1520F and 3.1 mΩ, respectively, and it was confirmed that the performance was excellent. Moreover, as a result of measuring the electrostatic capacity and the internal resistance again after repeating the charging for 1 hour and the discharging for 30 minutes 20 times, both were values of the difference within 1%, and deterioration could not be confirmed.

  A positive electrode body, a negative electrode body, and a paper separator made by bonding aluminum foil to a polarizable electrode made of a mixture of activated carbon, carbon black, PTFE, and the like, and a lead portion of the positive electrode body and a lead portion of the negative electrode body are respectively electrode terminals. In total, 30 sheets were stacked so that they could be connected to each other to obtain a square laminate (thickness 15 mm) having a side of 100 mm as shown in FIG. Next, the lead portion of the positive electrode body and the lead portion of the negative electrode body were respectively bonded to the electrode terminals by welding to produce a laminate as shown in FIG. This laminate was dried under reduced pressure at 160 ° C. for 1 hour using a vacuum dryer.

  Further, a square flat container having a side of 150 mm and having an aluminum foil whose surface was coated with a polyethylene film as a base material was dried under reduced pressure at 80 ° C. for 15 hours using a vacuum dryer. The flat container has an opening on one side. After the laminate and the flat container were cooled to room temperature under a nitrogen atmosphere, the laminate was inserted into the flat container so that the electrode terminals were on the opening (bonding portion) side of the container. In addition, a thin tube for supplying the organic solvent and a thin tube for discharging were inserted from the opening of the container.

90 ml of an electrolytic solution as an organic solvent was poured into the container and the laminate was impregnated for 10 minutes, and the electrode terminals were energized for electrolytic purification. Next, the electrolytic solution was discharged, and the inside of the container was depressurized with a vacuum pump for 5 minutes. Subsequently, nitrogen was supplied into the flat container, and the injection and discharge of the organic solvent and the decompression in the container were repeated 10 times. Finally, the inside of the container was decompressed with a vacuum pump for 30 minutes, and the laminate was decompressed. Thereafter, the opening of the container was heated and pressurized at 150 ° C. from the outside to seal the container and obtain an electric double layer capacitor.
As a result of measuring the electrostatic capacity and the internal resistance at 25 ° C. and 2.7 V charge of this electric double layer capacitor, they were 1490 F and 3.0 mΩ, respectively, and it was confirmed that the performance was excellent. Moreover, as a result of measuring the electrostatic capacity and the internal resistance again after repeating the charging for 1 hour and the discharging for 30 minutes 20 times, both were values of the difference within 1%, and deterioration could not be confirmed.

  As described above, it was found that the electric double layer capacitor of the present invention can greatly shorten the drying time of the multilayer body or its constituent materials.

The perspective view which shows an example of the laminated body in this invention The perspective view which shows an example of laminated bodies other than FIG. 1 in this invention. Configuration diagram showing an example of an electric double layer capacitor in the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode body 2 Negative electrode body 3 Lead part of positive electrode body 4 Lead part of negative electrode body 5 Positive electrode terminal 6 Negative electrode terminal 7 Laminated body 8 Container

Claims (10)

  A laminated body composed of a positive electrode body, a negative electrode body, and a separator is housed in a container, and an electrolyte is injected into the container to impregnate the laminated body, and then the container is connected to the tip of the terminal of the positive electrode body and the terminal of the negative electrode body. A method of manufacturing an electric double layer capacitor that is sealed with a tip exposed to the outside, wherein the laminate or its constituent material is impregnated with an organic solution before the laminate is impregnated with an electrolytic solution, Or the manufacturing method of the electrical double layer capacitor characterized by including the process of removing a water | moisture content from the constituent material.   The method for producing an electric double layer capacitor according to claim 1, wherein the impregnation treatment with an organic solution is performed before assembly of the multilayer body.   The method for producing an electric double layer capacitor according to claim 1, wherein the impregnation treatment with the organic solution is performed between container storage of the laminate and injection of the electrolytic solution.   The impregnation treatment with the organic solution distributes the organic solution in a circulation path communicating with the organic solvent supply port and the organic solvent discharge port of the container, and removes water mixed in the organic solution in at least one place of the circulation path. The manufacturing method of the electric double layer capacitor of Claim 3 to perform.   The method for producing an electric double layer capacitor according to claim 1, wherein the impregnation treatment with the organic solution is performed a plurality of times, and the decompression treatment is performed between the impregnation treatments.   The method for producing an electric double layer capacitor according to claim 1, wherein the impregnation treatment with the organic solution is performed while applying vibration to the laminate, the constituent material thereof, or the organic solution.   The method for producing an electric double layer capacitor according to claim 1, wherein the organic solution is one or more selected from ethers, alcohols, ketones, amines, esters, and hydrocarbons.   The method for producing an electric double layer capacitor according to claim 1, wherein the organic solution is a solution containing the same component as the component contained in the electrolytic solution.   The method for producing an electric double layer capacitor according to claim 1, wherein the organic solution is an electrolytic solution. The method for producing an electric double layer capacitor according to claim 1, wherein the content of water contained in the organic solution is 100 ppm or less.

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