JP2009021093A - Manufacturing method for battery or capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a battery or a capacitor, using an electrode including activated carbon for a component for electrode active material, in which water existing in an electrode sheet or a separator, or especially, water existing in pores of activated carbon used for the component of the electrode active material can be efficiently eliminated to an extraordinarily low level of concentration in a drying process of the electrode active material before lamination processing or the separator. <P>SOLUTION: A process of eliminating water from the electrode active material by supplying heated drying gas to the electrode active material of an electrode placed in a drying process space for eliminating water from the electrode active material, and a process of eliminating gas including water caused by the above process from the drying process space are repeated a plurality of times. Similar processes as above are carried out for the separator as well. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for efficiently removing water contained in pores of activated carbon, which is a constituent of an electrode active material, in a battery or capacitor manufacturing method using an electrode containing activated carbon as a constituent of an electrode active material. And a method for efficiently removing moisture contained in a separator used together with an electrode active material.

Conventionally, an electrode containing activated carbon as a constituent component of an electrode active material is used for a battery or a capacitor.
For example, in a lithium ion secondary battery, a negative electrode sheet made of a carbon material electrode active material such as activated carbon and a current collector such as a metal foil is used. The cell structure is wound together with a positive electrode sheet made of an electrode active material such as lithium manganate and a current collector such as a metal foil, and the wound body is impregnated with an electrolytic solution. Further, such a cell is sealed in a cylindrical container to form a lithium ion secondary battery.

Moreover, in the electric double layer capacitor, an electrode sheet made of an electrode active material containing activated carbon and a current collector of metal foil is used, and the electrode sheet and the separator are alternately laminated (rolled) to form an electrolyte solution. Has a cell configuration impregnated. Further, such a cell is sealed in a flat container or a cylindrical container to form an electric double layer capacitor.
Furthermore, there is a hybrid type battery using a positive electrode sheet of an electric double layer capacitor and a negative electrode sheet of a lithium ion secondary battery.

  In the manufacture of the battery or capacitor, the electrode sheet and the separator are formed in a sandwich shape in a rectangular shape and in a roll shape in a cylindrical shape, and a lead portion of a current collector (a positive electrode body and a negative electrode body). Is connected to each terminal, and the laminated body (winding body) is accommodated in the container, and then an electrolytic solution is injected from the opening of the container to impregnate the laminated body (winding body) with the electrolytic solution. Many methods have been implemented to seal the container with its tip exposed to the outside.

  In such a lithium ion secondary battery or electric double layer capacitor, an organic electrolytic solution that can obtain a high withstand voltage is generally used as the electrolytic solution. However, charging and discharging are repeated even in the presence of a small amount of moisture. As the electrolyte and water react gradually, a gas such as carbon monoxide and carbon dioxide is generated, resulting in a disadvantage that the withstand voltage is lowered and is likely to be deteriorated. The operation is performed under a dry gas atmosphere, which is dried until the container is sealed.

  Conventionally, in order to efficiently remove moisture, the laminated body (rolled body) is not a laminated body (rolled body) in which the electrode and the separator are stacked in close contact, but the electrode sheet and the separator are separated. Alternatively, it is often carried out by drying under heating and reduced pressure with a gap between the electrode sheet and the separator. However, activated carbon used as a component of the electrode active material has pores and a large specific surface area, and the electrode sheet has a maximum heating temperature. But it usually took more than 10 hours.

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 electrode active material 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 that is generally used as a constituent material of the electrode active material, and a high-frequency current is applied to the electrode. The method of applying to the substrate 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 moisture present in the electrode sheet and the separator, particularly the moisture present in the pores of the activated carbon used as a constituent component of the electrode active material, is efficiently reduced to a very low concentration. It is to provide a method of manufacturing a battery or capacitor that can be removed.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have supplied heated dry gas to heat the electrode active material, desorb moisture from the electrode active material, and gas that has absorbed moisture. By repeatedly performing the treatment for removing water several times, moisture present in the pores of activated carbon generally used as a component of the electrode active material can be efficiently removed to a very low concentration. By performing the same treatment on the separator, it was found that the water present in the separator can be efficiently removed to a very low concentration, and has reached the manufacturing method of the battery or capacitor manufacturing method of the present invention.

  That is, the present invention relates to a method for manufacturing a battery or a capacitor using a laminate comprising alternately stacked electrodes containing activated carbon as a constituent of an electrode active material and separators, and the electrode before lamination In the drying process of the active material, a heated drying gas is supplied to the electrode active material of the electrode placed in the drying treatment space to remove moisture from the electrode active material, and a gas containing moisture by the treatment A method for manufacturing a battery or a capacitor is characterized in that the process of removing the water from the dry processing space is repeated a plurality of times.

  The present invention also relates to a method for manufacturing a battery or a capacitor using a laminate comprising an electrode containing activated carbon as a constituent component of an electrode active material and a separator, which are alternately laminated. In the separator drying process, the heated drying gas is supplied to the separator placed in the drying processing space to remove moisture from the separator, and the moisture-containing gas is removed from the drying processing space by the processing. The method of manufacturing a battery or a capacitor is characterized in that the process is repeated a plurality of times.

  According to the battery or capacitor manufacturing method of the present invention, the drying time of the electrode sheet and separator, which has conventionally taken a long time, can be greatly reduced.

  The present invention is applied to a method of manufacturing a lithium ion secondary battery, a hybrid battery, an electric double layer capacitor, or the like using an electrode containing activated carbon as a constituent component of an electrode active material. The present invention is also applied to a rectangular battery, a method for manufacturing a rectangular capacitor, a cylindrical battery, and a method for manufacturing a cylindrical capacitor. In the method for manufacturing a battery or a capacitor according to the present invention, the laminated body includes a wound body.

  The present invention provides a process of removing moisture from the electrode active material by supplying a heated dry gas to the electrode active material of the electrode placed in the drying treatment space in the step of drying the electrode active material before lamination, and In the manufacturing method, the process of removing the gas containing moisture from the process from the drying process space is repeated a plurality of times. In addition, in the drying process of the separator before lamination, the heated drying gas is supplied to the separator placed in the drying processing space, and the moisture is removed from the separator, and the gas containing moisture by the treatment is added to the separator. In this manufacturing method, the process of removing from the drying process space is repeated a plurality of times.

  As shown in FIG. 1, for example, in a lithium ion secondary battery, the battery or capacitor winding body according to the present invention is a current collector such as an active material such as lithium cobaltate, lithium nickelate, or lithium manganate and a metal foil. The positive electrode sheet 1 made of a body and the negative electrode sheet 2 made of a collector such as an active material containing activated carbon as a constituent and a metal foil are alternately laminated via separators 3 made of paper, pulp, plastic, or the like. The lead portion 4 of the positive electrode sheet and the lead portion 5 of the negative electrode sheet are laminated so that they can be connected to the electrode terminals, respectively.

Further, in the electric double layer capacitor, for example, in the electric double layer capacitor, the laminated body of the battery or the capacitor according to the present invention usually has an aluminum foil bonded to an electrode active material containing carbon black or the like in addition to activated carbon. A positive electrode sheet 1 and a negative electrode sheet 2 in which an aluminum foil is similarly bonded to an electrode active material are alternately laminated via a separator made of paper, pulp, plastic, or the like, and a lead portion 4 of the positive electrode sheet. And the lead part 5 of the negative electrode sheet is laminated so that it can be connected to each electrode terminal.
Moreover, the hybrid type battery uses a positive electrode sheet of an electric double layer capacitor and a negative electrode sheet of a lithium ion secondary battery in the above laminate.

  In the present invention, before the wound body or laminate as shown in FIGS. 1 and 2 is laminated, the heated drying gas is supplied to the drying treatment space, and the moisture-containing gas is dried. A drying process of the electrode active material and a drying process of the separator are performed by repeating the removal process from the processing space. For example, an electrode sheet or separator rolled in a roll shape, or an electrode sheet or separator cut into a predetermined size can be dried by the method of the present invention.

  Further, in the present invention, the wound or laminated body as described above is sealed in a container, and the constituent material is usually a metal foil such as an aluminum foil whose surface is covered with a heat-meltable plastic film. Is. In the production of a battery or capacitor, it is necessary to dry the container, and this container is also supplied with a heated dry gas to heat the container before storing the wound body or laminated body, and moisture from the container. It is also possible to repeat the treatment for removing the water and the treatment for removing the gas containing moisture a plurality of times for drying.

The electrode active material in the present invention is usually dried with a vacuum pump (vacuum pump), a container having a supply port and a discharge port for a dry gas, a drying processing space such as a processing chamber, only an electrode sheet, only a separator. Alternatively, the electrode sheet and the separator are housed in a state where they are not in close contact with each other.
The supply of the heated drying gas to the drying processing space is usually performed in a state where the drying processing space and the vacuum pump are shut off. Further, the removal of the gas containing moisture from the drying processing space is usually performed in a state where the drying processing space and the vacuum pump are in communication.

Although it does not restrict | limit especially as pressure conditions at the time of supplying dry gas, Usually, 50-1000 KPa (absolute pressure), Preferably under pressure (110-1000 KPa (absolute pressure)) higher than a normal pressure Done. Moreover, as temperature conditions of a dry gas, it is 100-300 degreeC normally, Preferably it is 150-250 degreeC.
The pressure condition for removing the dry gas is usually a pressure lower than the pressure for supplying the dry gas, preferably 10 KPa (absolute pressure) or less, more preferably 1 KPa (absolute pressure) or less. Yes, a vacuum pump is used.

  The electrode active material in the present invention is dried by repeating the heated drying gas supply process and the gas removal process as described above. Each treatment time varies depending on the state of the electrode active material, treatment conditions, etc., and cannot be generally limited. However, each treatment time is usually 1 to 100 minutes, and each treatment is usually twice or more. It is preferably performed 3 to 20 times. The time required for the drying is usually 1 to 10 hours.

  In the present invention, the mechanism by which the drying time of the electrode active material can be significantly shortened is not clear, but when heated dry gas is supplied to heat the electrode active material, the pores of the activated carbon that is the electrode active material After the moisture contained in is desorbed from the activated carbon and moves into the gas and the gas that has absorbed the moisture is removed, the moisture in the pores of the activated carbon is reduced by repeating the supply and removal of the heated dry gas again. It is considered to be removed efficiently. 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 above-described drying step is completed and a laminated body or a wound body is formed, these are stored in a container that has been subjected to a drying process, and the production of a battery or a capacitor is continued.
The stacked body or the wound body is stored in the container so that the electrode terminal of the laminated body or the wound body is 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 electrode active material is removed, and the laminate or the wound body can be efficiently impregnated with the electrolytic solution. Also, 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 electrode active material. You can also. After the laminated body or the wound body is depressurized, the container is sealed by pressing, for example, two heated heat-seal bars with the container interposed therebetween, and a battery or a capacitor is obtained. 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.

(Drying of electrode active material and separator)
A 100 mm square positive electrode sheet, negative electrode sheet, and paper separator (30 sheets in total) with an aluminum foil bonded to an electrode active material made of a mixture of activated carbon, carbon black, etc., at a temperature of 25 ° C. and a humidity of 60% After being left for 24 hours in a test chamber filled with air, the sample was stored in a 600 cc drying container having a supply port and a discharge port for drying gas in a state where they were not in close contact with each other.

  Next, dry nitrogen gas having a moisture content of 1 ppm or less and a temperature of 200 ° C. was supplied under pressure (150 to 200 KPa (absolute pressure)) at 3000 cc / min for 25 minutes. Subsequently, the drying container was decompressed for 5 minutes under a pressure condition of 10 KPa (absolute pressure) or less to remove nitrogen gas. Furthermore, the process of supplying the heated dry nitrogen gas and the process of removing the nitrogen gas are repeated 9 times (total 10 times, total processing time: 5 hours) to dry the electrode active material and the separator. finished.

(Measurement of moisture content)
The dried positive electrode sheet and negative electrode sheet were alternately laminated through the dried separator, and the lead part of the positive electrode sheet and the lead part of the negative electrode sheet were bonded to the electrode terminals by welding to produce a laminate. . The laminating operation during this period was performed in a dry nitrogen gas atmosphere.
In addition, a square flat container having a side of 150 mm and having an aluminum foil whose surface was 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 12 ppm.

(Drying of electrode active material and separator)
The same positive electrode sheet, negative electrode sheet, and paper separator (30 sheets in total) as in Example 1 were left in a test chamber filled with air at a temperature of 25 ° C. and a humidity of 60% for 24 hours. They were stored in a similar drying container having a capacity of 600 cc so that they were not in close contact with each other.
Next, an electrode active material and a separator were obtained in the same manner as in Example 1 except that the treatment for supplying heated dry nitrogen gas and the treatment for removing nitrogen gas were performed a total of six times (total treatment time: 3 hours). Dried.

(Measurement of moisture content)
After a laminate was produced in the same manner as in Example 1, this was inserted into a flat container, 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 wound body was decompressed. During this period, the electrode terminals were energized and subjected to 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 water content was 28 ppm.

[Comparative Example 1]
(Drying of electrode active material and separator)
The same positive electrode sheet, negative electrode sheet, and paper separators as in Example 1 (30 sheets in total) were allowed to stand in a test chamber filled with air at a temperature of 25 ° C. and a humidity of 60% for 24 hours, and then the inside could be heated. It was stored in a drying container having a capacity of 600 cc communicating with the vacuum pump in a state where they were not in close contact with each other.
Next, the temperature of the drying container was raised to 200 ° C. and the pressure was reduced, and the electrode active material and the separator were dried under heating and reduced pressure at 200 ° C. and 5 KPa (absolute pressure) for 18 hours.

(Measurement of moisture content)
After a laminate was manufactured in the same manner as in Example 1, this was inserted into a flat container, 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 wound body 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 battery of this invention or a capacitor can shorten the drying time of an electrode sheet and a separator significantly.

The perspective view which shows an example of the winding body in this invention The perspective view which shows an example of the laminated body in this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode sheet 2 Negative electrode sheet 3 Separator 4 Positive electrode sheet lead part 5 Negative electrode sheet lead part

Claims (7)

  A method for producing a battery or a capacitor using a laminate comprising alternately laminated activated carbon as an electrode active material component and a separator, wherein the electrode active material is dried before lamination. In the process, the heated dry gas is supplied to the electrode active material of the electrode placed in the dry treatment space, the moisture is removed from the electrode active material, and the gas containing moisture by the treatment is supplied to the dry treatment space. A process for producing a battery or a capacitor, wherein the process of removing from the battery is repeated a plurality of times.   A method for producing a battery or a capacitor using a laminate comprising an electrode containing activated carbon as a constituent component of an electrode active material and a separator, which are alternately laminated, and in the step of drying the separator before lamination, Supplying the heated dry gas to the separator placed in the drying treatment space, removing the moisture from the separator, and removing the moisture-containing gas from the drying treatment multiple times. A method for producing a battery or a capacitor, characterized by comprising:   The battery or capacitor manufacturing method according to claim 1 or 2, wherein the heated drying gas is supplied to the drying processing space in a state where the drying processing space and the decompression pump are shut off.   The method for manufacturing a battery or capacitor according to claim 1 or 2, wherein the removal of the moisture-containing gas from the drying processing space is performed in a state where the drying processing space and the decompression pump are in communication.   The method for manufacturing a battery or a capacitor according to claim 1 or 2, wherein the dry gas has a temperature of 100 to 300 ° C.   The method for manufacturing a battery or a capacitor according to claim 1, wherein the dry gas has a moisture content of 100 ppm or less.   The method for manufacturing a battery or a capacitor according to claim 1, wherein the dry gas is helium, neon, argon, nitrogen, or air.

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