JP2009021388A - Method of manufacturing electronic double-layer capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an electronic double-layer capacitor which includes the steps of: laminating a plus electrode body, a minus electrode body and a separator; drying the laminate; storing the laminate in a container; injecting an electrolyte into the container; subjecting the laminate to a pressure reduction treatment; and sealing the container stored with the laminate, the manufacturing method for efficiently removing water present in the laminate, especially water present in pores of active carbon etc. used as a composition material for a polarization electrode in the drying step to an extremely low concentration. <P>SOLUTION: When the laminate is dried, processing of heating, pressure-reducing and drying the laminate and processing of supplying dry gas to the laminate are carried out repeatedly a plurality of times. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method of manufacturing 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 electrolyte solution, and removes moisture from a laminate including a positive electrode body, a negative electrode body, and a separator. The present invention relates to an efficient method.

  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 in a dry 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-mentioned problems, the present inventors have repeatedly performed a treatment for drying the laminated body under reduced pressure by heating and a process for supplying a dry gas to the laminated body a plurality of times. It has been found that moisture present in pores such as activated carbon generally used as a constituent material can be efficiently removed to a very low concentration, and has reached the method for producing an electric double layer capacitor of the present invention.

  That is, the present invention includes a step of laminating a positive electrode body, a negative electrode body, and a separator, a step of drying the laminated body, a step of storing the laminated body in a container, a step of injecting an electrolyte into the container, A method for producing an electric double layer capacitor comprising a step of reducing pressure and a step of sealing a container containing the laminate, wherein the laminate is heated and dried under reduced pressure during the step of drying the laminate; And a process for supplying a dry gas to the laminate is repeated a plurality of times.

  According to the method for producing an electric double layer capacitor of the present invention, it is possible to significantly reduce the drying processing time of the multilayer body, which has conventionally taken a long time. In addition, the method of drying after laminating the positive electrode body, the negative electrode body, and the separator is extremely impossible because the surfaces are in close contact with each other. The double-layer capacitor manufacturing method enables drying after stacking. For this reason, it has become possible to perform lamination in a space where moisture has been removed until a very low concentration, such as a glow box, in the presence of air, and the lamination process can be performed very efficiently and easily. it can.

  The present invention includes a step of laminating a positive electrode body, a negative electrode body, and a separator, a step of drying the laminated body, a step of storing the laminated body in a container, a step of injecting an electrolyte into the container, The present invention is applied to a method for manufacturing an electric double layer capacitor including a step of processing and a step of sealing a container containing the laminate. 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.

  In addition, as shown in FIG. 3, the container in the present invention is a flat container 8 for sealing the laminate 7 as described above, and the structure thereof is usually a surface of a metal foil such as an aluminum foil. And coated with a heat-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 addition, also about the inside of a container, before accommodating a laminated body, the process to heat-dry under reduced pressure, the process to heat-dry under reduced pressure, and the process to supply a dry gas are required.

The method for producing an electric double layer capacitor of the present invention is a production method in which, during the step of drying the laminate, the treatment of drying the laminate by heating under reduced pressure and the treatment of supplying a dry gas to the laminate are repeated a plurality of times. It is.
The drying in the present invention is performed after the positive electrode body, the negative electrode body, and the separator are stacked and before being housed in a flat container. When drying is performed before the laminating step, the drying process time can be significantly shortened, but when drying is performed after the laminating step, the laminating operation of the positive electrode body, the negative electrode body, and the separator can be performed very efficiently. Since it can do, the drying after a lamination process is more preferable.

The laminated body in the present invention is usually dried by storing the laminated body in a container that can be heated inside and communicates with a vacuum pump and has a supply port and a discharge port for drying gas.
The pressure condition for drying the heated laminate under reduced pressure is usually 5 KPa (absolute pressure) or less, preferably 1 KPa (absolute pressure) or less, and the temperature condition is usually 100 to 250 ° C., preferably 150 to 220 ° C. In addition, the pressure condition for supplying the dry gas to the laminate is under a higher pressure (about 10 to 200 KPa (absolute pressure)) than the process of heating and drying the laminate, and the temperature condition is usually 100. It is -250 degreeC, Preferably it is 150-220 degreeC.

  Drying of the laminate in the present invention is performed by repeating the heating and vacuum drying process and the drying gas supply process. Each treatment time varies depending on the state of the laminate, treatment conditions, etc., and cannot be unconditionally limited. Usually, each treatment time is 1 to 100 minutes, and each treatment is usually twice or more. Preferably it is performed 3 to 20 times. The time required for the drying is usually 2 to 10 hours. In addition, before the drying which concerns on this invention, the preliminary drying of the constituent material of a laminated body can be performed, and the burden of the drying which concerns on this invention can also be reduced.

  In the present invention, the mechanism by which the drying time of the laminate can be significantly shortened is not clear, but by supplying a heated dry gas after the heating and vacuum drying treatment, the surface of the constituent material of the laminate (particularly It is considered that the inside of the pores of activated carbon or the like used as the polarizable electrode is scavenged by the heated dry gas, and the water present on the surface and inside thereof is efficiently removed. As the dry gas, a gas containing helium, neon, argon, nitrogen, or air as a main component is used. The dry gas is usually used after removing moisture to 100 ppm or less, preferably 10 ppm or less, more preferably 1 ppm or less.

In the present invention, after the step of laminating the positive electrode body, the negative electrode body, and the separator, and the step of drying the laminated body, the step of storing the laminated body in a container, the step of injecting an electrolyte into the container, A step of reducing the pressure and a step of sealing the container containing the laminate are performed.
The stack is stored in the container so that the electrode terminals of the stack are on the opening side of the container. Next, an 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 gas atmosphere.

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

(Production of laminate)
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, etc., and a positive electrode body lead portion and a negative electrode body lead portion are connected to electrode terminals, respectively. In total, 30 sheets were laminated 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. Since the lamination work during this time was performed in the air (25 ° C., humidity 60%), it could be efficiently performed in less than half the time compared to the lamination work in the glow box.

(Drying the laminate)
Next, this laminated body was accommodated in a drying container having a capacity of 400 cc, which can be heated inside, communicated with a vacuum pump, and has a supply port and a discharge port for a dry gas. Then, while raising the temperature of the container for drying to 200 degreeC, it pressure-reduced and it heat-depressurized and dried for 20 minutes on the conditions of 200 degreeC and 2-8 KPa (absolute pressure). Next, dry nitrogen gas at 200 ° C. was supplied for 20 minutes under the condition of 2000 cc / min. Furthermore, the process of drying by heating under reduced pressure and the process of supplying dry nitrogen gas to the laminate were repeated 5 times (total 6 times, total treatment time: 4 hours) to complete the step of drying the laminate. Note that the pressure in the second and subsequent heating and drying processes was 2 KPa or less.

(Measurement of moisture content)
A square flat container having a side of 150 mm and having an aluminum foil whose surface is covered with a film containing polypropylene as a base material was dried under reduced pressure at 50 ° C. for 15 hours using a vacuum dryer. This flat container had an opening on one side. Next, in a dry nitrogen gas atmosphere, the laminate was inserted into a flat container so that the electrode terminal was on the opening (bonding part) side of the container, and then ammonium salt or the like was dispersed in the propylene carbonate solvent. 120 ml of electrolyte was poured into the container. Subsequently, 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, when the container is sealed, an electric double layer capacitor can be obtained. Before that, the electrolytic solution was sampled and the water content of the electrolytic solution was measured. As a result, the water content was 9 ppm.

(Drying the laminate)
In the same manner as in Example 1, a laminate as shown in FIG. The laminating operation during this time was performed in air (25 ° C., humidity 60%) in the same manner as in Example 1.
Next, the laminate was prepared in the same manner as in Example 1 except that the laminate was heated and dried under reduced pressure and the dry nitrogen gas was supplied to the laminate three times in total (total treatment time: 2 hours). Dried.

(Measurement of moisture content)
The laminate was inserted into a flat container dried under reduced pressure in the same manner as in Example 1, and 120 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. Subsequently, 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 electrolytic solution was sampled in the same manner as in Example 1, and the moisture content of the electrolytic solution was measured. As a result, the moisture content was 25 ppm.

[Comparative Example 1]
(Drying the laminate)
In the same manner as in Example 1, a laminate as shown in FIG. The laminating operation during this time was performed in air (25 ° C., humidity 60%) in the same manner as in Example 1.
Next, this laminated body was accommodated in a drying container having a capacity of 400 cc similar to that in Example 1, which was heatable inside, communicated with a vacuum pump, and had a drying gas supply port and a discharge port. Subsequently, the temperature of the drying container was raised to 200 ° C. and reduced in pressure, and dried under reduced pressure by heating for 18 hours under the conditions of 200 ° C. and 8 KPa (absolute pressure) or less.

(Measurement of moisture content)
The laminate was inserted into a flat container dried under reduced pressure in the same manner as in Example 1, and 120 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. Subsequently, 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 electrolytic solution was sampled in the same manner as in Example 1, and the moisture content of the electrolytic solution was measured. As a result, the moisture content was 60 ppm.

  As mentioned above, it turned out that the manufacturing method of the electric double layer capacitor of this invention can shorten the drying time of a laminated body significantly.

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 (4)

  A step of laminating a positive electrode body, a negative electrode body, and a separator, a step of drying the laminate, a step of storing the laminate in a container, a step of injecting an electrolyte into the container, a step of subjecting the laminate to reduced pressure, And a method of manufacturing an electric double layer capacitor including the step of sealing the container containing the laminate, wherein the laminate is heated and dried under reduced pressure during the step of drying the laminate, and the laminate A method of manufacturing an electric double layer capacitor, wherein the process of supplying a dry gas is repeated a plurality of times.   2. The electricity according to claim 1, wherein the step of drying the laminated body is performed by housing the laminated body in a container that is internally heatable, communicates with a vacuum pump, and has a supply port and a discharge port for a dry gas. A manufacturing method of a double layer capacitor.   The method for producing an electric double layer capacitor according to claim 1, wherein the process of supplying the dry gas to the multilayer body is performed under a higher pressure than the process of drying the multilayer body under reduced pressure by heating and at a temperature of 100 to 250 ° C.   The method for producing an electric double layer capacitor according to claim 1, wherein the dry gas is helium, neon, argon, nitrogen, or air.

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