JP2005166738A - Electrochemical device and method of manufacturing high molecular multilayer object therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrochemical device wherein a short-circuit is hardly caused by contact between current collectors. <P>SOLUTION: The electrochemical device comprises a power generation element 10 consisting of a first electrode 12, a second electrode 13, and an electrolyte interposed between the electrodes 12 and 13, a pair of current collectors 20 and 21, one of which is in contact with the first electrode 12 and the other in contact with the second electrode 13, which are located face to face with each other with the power generation element 10 put therebetween, and a sealing material 30 which is located between the pair of current collectors 20 and 21 so as to surround the power generation element 10 and seals the pair of current collectors 20 and 21. The sealing material 30 comprises thermoplastic high molecular layers 31 and 33 which are formed on the pair of current collectors 20 and 21 respectively and a crosslinked high molecular layer 32 interposed between the thermoplastic high molecular layers 31 and 33. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrochemical device such as an electric double layer capacitor and a lithium secondary battery.

  Conventionally, electrochemical devices such as electric double layer capacitors and lithium secondary batteries have been widely used in mobile phones, PDAs and the like.

  As such an electrochemical device, a power generation element including a pair of electrodes and an electrolyte sandwiched between them is sandwiched between a pair of current collectors larger than the power generation element, and the peripheral portions of the current collector are thermoplastic polymers. An electrochemical device having a structure sealed with a sealing material made of

  As a sealing material of such an electrochemical device, for example, an ethylene copolymer having a melting point lower than that of the thermoplastic polymer sheet and modified with an unsaturated carboxylic acid or a derivative thereof on both surfaces of the thermoplastic polymer sheet or A thermoplastic laminated sheet obtained by laminating a composition containing this ethylene copolymer is known (see Patent Document 1).

  Further, as sealing materials, thermoplastic polymers such as polyisobutylene-modified polyethylene (see Patent Document 2), modified polypropylene, modified polyethylene (Patent Document 3), and acid-modified polyolefin containing fine particle filler (Patent Document 4) are known. ing.

Further, a method is known in which a portion of a current collector to which a sealing material adheres is chromated (Patent Document 5).
JP 62-133469 A JP-A-2-234344 JP-A-4-121947 JP-A-6-349462 JP-A-2-231257

  However, in the conventional electrochemical device using the thermoplastic sealing material, the thermoplastic polymer may be melted too much at the time of sealing, and the current collectors may contact each other, causing the electrochemical device to short-circuit.

  The present invention has been made in view of the above problems, and an object thereof is to provide an electrochemical device in which short-circuiting due to contact between current collectors is unlikely to occur.

  The electrochemical device of the present invention includes a power generation element having a first electrode and a second electrode, and an electrolyte provided between the electrodes, one in contact with the first electrode and the other in contact with the second electrode, A pair of current collectors that sandwich the power generation element facing each other, and a sealing material that is disposed between the pair of current collectors so as to surround the power generation element and that seals the pair of current collectors Yes. In the present invention, the sealing material includes a thermoplastic polymer layer provided on each of the pair of current collectors, and a crosslinked polymer layer provided between the thermoplastic polymer layers.

  According to the electrochemical device of the present invention, in the sealing material, a cross-linked polymer layer that is hard to melt as compared to these thermoplastic polymer layers is interposed between the pair of thermoplastic polymer layers. For this reason, even when the thermoplastic polymer layer is excessively melted at the time of sealing, the current collectors are hardly brought into contact with each other. Therefore, defects due to short-circuit of the current collector are reduced, and the yield and reliability of the electrochemical device are increased.

  Here, in the present specification and the appended claims, “crosslinked polymer layer” refers to a polymer material in which molecular chains of polymers, oligomers, monomers and the like are crosslinked to form a three-dimensional network structure. Refers to the layer.

  In such an electrochemical device, the crosslinked polymer layer is preferably a material crosslinked by irradiation with ionizing radiation, for example, an electron beam and / or γ-ray. Crosslinking of the polymer by irradiation with ionizing radiation can be performed without adding an electrochemically unstable crosslinking agent. Therefore, the unreacted crosslinking agent remains in the polymer material, and the reliability of the electrochemical device is not impaired.

  The crosslinked polymer layer is preferably a layer of a material obtained by crosslinking the same thermoplastic polymer as the thermoplastic polymer of the thermoplastic polymer layer.

  According to this, since the structure and properties of the crosslinked polymer layer and the thermoplastic polymer layer are similar, the adhesiveness at the interface between the crosslinked polymer layer and the thermoplastic polymer layer is increased, particularly in the sealing property. An excellent electrochemical device can be obtained. Therefore, intrusion of moisture from the outside, evaporation of the electrolyte solution or the like to the outside is suppressed, and the reliability improvement effect is remarkable.

  In particular, the thermoplastic polymer layer is preferably a polyolefin layer, and the crosslinked polymer layer is preferably a crosslinked polyolefin layer. Polyolefins are characterized by being electrochemically stable and having low moisture permeability. Moreover, since the electrochemical device requires heat resistance at 80 to 100 ° C., the melting temperature of the thermoplastic polymer needs to be higher than this temperature range. At the same time, if the melting temperature of the thermoplastic polymer is 200 ° C. or higher, there is a possibility that the electrolyte solution and the like inside the electrochemical device may be adversely affected by heat conduction during thermal bonding. Therefore, the melting temperature of the thermoplastic polymer is preferably less than 200 ° C. Polyolefin can be preferably used because it can satisfy the above two temperature conditions for the melting temperature.

  The method for producing a polymer multilayer body for an electrochemical device according to the present invention includes: cutting the laminated body in which a crosslinked polymer sheet is provided between thermoplastic polymer sheets along the laminating direction; It includes a cut-out process for obtaining a polymer multilayer body having a similar laminated structure. By using the polymer multilayer body obtained by this production method, the electrochemical device of the present invention can be easily obtained. From such a viewpoint, it is preferable to include a radiation irradiation step of obtaining a crosslinked polymer sheet by irradiating the polymer sheet with ionizing radiation prior to the cutting step.

  According to the present invention, it is possible to provide an electrochemical device in which a short circuit due to contact between current collectors hardly occurs.

Hereinafter, preferred embodiments of an electrochemical device according to the present invention will be described in detail with reference to the drawings. In the following description, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.
(First embodiment)
First, with reference to FIG.1 and FIG.2, the electric double layer capacitor 1 as an electrochemical device of 1st embodiment which concerns on this invention is demonstrated.

  The electric double layer capacitor 1 mainly includes a power generation element 10, a pair of opposing current collectors 20 and 21 that sandwich the power generation element 10 and function as an exterior body, and the power generation element 10 between the current collectors 20 and 21. And a sealing material 30 to be sealed.

  The power generation element 10 includes a first electrode 12 as a positive electrode and a second electrode 13 as a negative electrode facing each other, a separator 14 disposed adjacent to the first electrode 12 and the second electrode 13, An electrode 12, a second electrode 13, and an electrolyte solution (not shown) containing an electrolyte contained in the separator 14.

  The first electrode 12 and the second electrode 13 are electron conductive porous bodies. The constituent material of the first electrode 12 and the second electrode 13 is not particularly limited, and is used as a porous layer constituting a polarizable electrode such as a carbon electrode used in a known electric double layer capacitor. Similar materials can be used. For example, it is obtained by activating treatment of raw coal (for example, petroleum coke produced from a delayed coker using a bottom oil of a fluid catalytic cracking apparatus of heavy petroleum oil or a residual oil of a vacuum distillation apparatus as a raw oil). What has a carbon material (for example, activated carbon) as a main component of a constituent material can be used. Other conditions (types of constituent materials other than carbon materials such as binder and their contents) are not particularly limited. For example, a conductive auxiliary agent (carbon black or the like) for imparting conductivity to the carbon powder or a binder (polytetrafluoroethylene (PTFE) or the like) may be added.

  The separator 14 disposed between the first electrode 12 and the second electrode 13 is not particularly limited as long as it is formed of an electrically insulating porous body, and a separator used for a known electric double layer capacitor is used. can do. For example, as the electrically insulating porous body, at least one selected from the group consisting of a laminate of a film made of polyolefin such as polyethylene and polypropylene, a stretched film of a mixture of the above resins, or cellulose, polyester and polypropylene Examples thereof include a fiber nonwoven fabric made of a constituent material.

  Here, in order to suppress a short circuit due to the contact between the first electrode 12 and the second electrode 13, the size of the separator 14 is made larger than the area of the main surface of the electrodes 12, 13, and the end of the separator 14 is connected to the electrode 12. , 13 is preferably projected from the end face. At this time, the end face of the separator 14 is preferably separated from the sealing material 30.

  The electrolyte solution is contained in the holes of the first electrode 12, the second electrode 13, and the separator 14. The electrolyte solution is not particularly limited, and an electrolyte solution (an electrolyte salt aqueous solution or an electrolyte salt solution using an organic solvent) used in a known electric double layer capacitor can be used. However, the aqueous solution of the electrolyte salt is electrochemically low in decomposition voltage, and the withstand voltage of the electric double layer capacitor 1 is limited to be low. Therefore, the electrolyte solution is preferably an electrolyte solution (nonaqueous electrolyte solution) using an organic solvent. .

  In the present embodiment, the electrolyte solution may be a gel electrolyte obtained by adding a gelling agent in addition to the liquid state. Further, instead of the electrolyte solution, a solid electrolyte (a solid polymer electrolyte or an electrolyte made of an ion conductive inorganic material) may be contained.

  The current collectors 20 and 21 are rectangular plate-like conductive materials having an area larger than the areas of the main surfaces of the first electrode 12 and the second electrode 13 of the power generation element 10. These current collectors 20, 21 have a power generation element 10 from above and below such that the lower current collector 21 is in surface contact with the second electrode 13 and the upper current collector 20 is in surface contact with the first electrode 12. Is sandwiched. The material of the current collectors 20 and 21 is not particularly limited as long as it is a good conductor capable of sufficiently transferring charges, and a current collector used in a known electric double layer capacitor can be used.

  As a material for the current collector in the case of a non-aqueous electrolyte, a conductive material rich in corrosion resistance can be used. For example, a metal foil such as aluminum or titanium can be used. The thickness of the metal foil is, for example, about 10 to 100 μm.

  The sealing material 30 is disposed between the pair of current collectors 20 and 21 so as to surround the power generation element 10 and seals between the current collectors 20 and 21. Further, the sealing material 30 has a three-layer structure parallel to the current collectors 20 and 21. Specifically, the sealing material 30 has a three-layer structure of thermoplastic polymer layer 31 / crosslinked polymer layer 32 / thermoplastic polymer layer 33.

  The thermoplastic polymer layer 31 is formed on the lower surface peripheral portion 20 a of the current collector 20, while the thermoplastic polymer layer 33 is formed on the upper surface peripheral portion 21 a of the current collector 21. Moreover, these thermoplastic polymer layers 31 and 33 are firmly bonded on the peripheral portions 20a and 21a of the current collectors 20 and 21 by heat sealing.

  Here, the material of the thermoplastic polymer layers 31 and 33 is not particularly limited as long as it is a thermoplastic polymer material, and examples thereof include fluororesins such as polyolefin, polyester, polyvinylidene fluoride, and copolymers thereof. . In particular, as a material for the thermoplastic polymer layers 31 and 33, polyolefin is preferable from the viewpoints of economy, heat sealability, chemical stability, moisture permeability, and the like. Examples of the polyolefin include polyethylene, polypropylene, acid-modified polyethylene, and copolymers containing these.

  On the other hand, the crosslinked polymer layer 32 is provided between the thermoplastic polymer layer 31 and the thermoplastic polymer layer 33, and the upper and lower surfaces are bonded by the thermoplastic polymer layer 31 and the thermoplastic polymer layer 33. Has been.

  The crosslinked polymer layer 32 is a layer of a crosslinked polymer material in which molecular chains such as polymers, oligomers, and monomers are bonded together by crosslinking to form a three-dimensional network structure. Such a crosslinked polymer material can be obtained by a known method such as crosslinking by reacting molecular chains or crosslinking between molecular chains using a crosslinking agent.

  Here, as a crosslinking method, for example, a material containing a molecular chain is irradiated with an electron beam, an ultraviolet ray, a γ-ray, an X-ray, the raw material containing a molecular chain is heated, and a material containing a molecular chain is crosslinked Adding an agent can be used, and furthermore, these methods can be appropriately combined.

  Examples of the crosslinked polymer include crosslinked polymers obtained by irradiating a raw material containing molecular chains with ionizing radiation such as X-rays, electron beams, and γ rays. For example, a crosslinked polymer can be obtained by crosslinking a thermoplastic polymer such as polyolefin by irradiating with ionizing radiation. Specifically, a crosslinked polyolefin, a crosslinked fluororesin, etc. can be illustrated. Such crosslinking by irradiation with ionizing radiation can be performed without adding an electrochemically unstable crosslinking agent to the raw material containing the molecular chain. Therefore, the unreacted crosslinking agent does not remain in the crosslinked polymer and the reliability of the electrochemical device is not impaired.

Here, it is preferable to use an electron beam and / or a gamma ray as the ionizing radiation from the viewpoint of the ability of the ionizing radiation to penetrate the substance. As irradiation conditions for electron beam irradiation, the irradiation dose is preferably 20 to 300 kGy. This irradiation dose range does not necessarily have to be satisfied by a single irradiation. That is, it is only necessary that the total irradiation dose by a plurality of irradiations is within the above range. When the irradiation dose falls below the above range, there is a tendency that a sufficient crosslinking effect cannot be obtained in the polymer. In addition, when the irradiation dose exceeds the above range, the degradation reaction of the molecule proceeds more than the crosslinking reaction in the polymer, and the polymer tends to be fragile. The accelerating voltage is selected in a range that is high enough not to attenuate in the thickness direction of the polymer and low enough not to deteriorate the polymer. The acceleration voltage is set in consideration of absorption by the window of the electron beam light source, but it is desirable to set the acceleration voltage to about 150 kV when directly irradiating the polymer material.
When ionizing radiation is γ-rays, γ-rays have a high transmission amount due to high energy and are not easily influenced by the external environment, so that there is little in-plane variation in dose, so that a more uniform crosslinked structure polymer can be obtained. The irradiation dose of γ rays is desirably in the same range as in the case of electron beams.

  Moreover, from the viewpoint of electrochemical stability, moisture permeability, melt viscosity and the like, a crosslinked polyolefin is preferable as a crosslinked polymer crosslinked by ionizing radiation. Examples of the cross-linked polyolefin include cross-linked acid-modified polyethylene, cross-linked polypropylene, and copolymers containing these.

  Moreover, as a crosslinked polymer, for example, a cured product of a thermosetting resin that is crosslinked by heating a raw material containing molecular chains or a cross-linked polymer by irradiating ultraviolet rays to a raw material containing molecular chains. The cured product of the ultraviolet curable resin, specifically, the cured epoxy resin, the cured urethane resin, the cured phenol resin, the cured acrylic resin, the cured melamine resin, and the cured furan resin. Etc. can be illustrated.

  When the thermosetting resin or the ultraviolet curable resin is crosslinked, it is preferable that the thermosetting resin or the ultraviolet curable resin contains a crosslinking agent (curing agent). The cross-linking agent is not particularly limited as long as it can cross-link molecular chains when heated or irradiated with ultraviolet rays. For example, sulfur compounds, organic peroxides, polyhydric phenol resins, polyhydric amino resins , Polyvalent halogen compounds, polyvalent amine compounds, polyvalent azo compounds, polyvalent isocyanate compounds, polyvalent silyl isocyanate compounds, polyvalent epoxy compounds, silane compounds, titanate compounds, polyvalent carboxylic acid compounds And acid anhydrides.

  Further, as the material of the crosslinked polymer layer 32, it is preferable to use a material obtained by crosslinking the same thermoplastic polymer material as the thermoplastic polymer layers 31 and 32. In this case, since the structures and properties of the crosslinked polymer layer 32 and the thermoplastic polymer layer 31 are similar, the adhesion between the crosslinked polymer layer 32 and the thermoplastic polymer layers 31 and 33 is increased, and the sealing material 30 is further increased. Can improve the sealing performance. Crosslinking of the thermoplastic polymer can be easily performed by using electromagnetic radiation, particularly electron beam.

  Specifically, the material of the thermoplastic polymer layers 31 and 33 may be a polyolefin, and the material of the crosslinked polymer layer 32 may be a crosslinked polyolefin obtained by crosslinking the same polyolefin as the polyolefin of the thermoplastic polymer layers 31 and 33. Particularly preferred. Polyolefins are characterized by being electrochemically stable and having low moisture permeability. Moreover, since the electrochemical device requires heat resistance at 80 to 100 ° C., the melting temperature of the thermoplastic polymer needs to be higher than this temperature range. At the same time, if the melting temperature of the thermoplastic polymer is 200 ° C. or higher, there is a possibility that the electrolyte solution and the like inside the electrochemical device may be adversely affected by heat conduction during thermal bonding. Therefore, the melting temperature of the thermoplastic polymer is preferably less than 200 ° C. Polyolefin can be preferably used because it can satisfy the above two temperature conditions for the melting temperature.

  Next, an example of a method for manufacturing the electric double layer capacitor 1 described above will be described with reference to FIGS. 3 (a) and 3 (b).

  First, a pair of current collectors 20 and 21 shown in FIG. These current collectors 20 and 21 can be formed, for example, by cutting a conductive metal foil such as aluminum into a rectangular shape having a predetermined size.

  Next, the sheet-like first electrode 12 and the second electrode 13 are respectively formed in the central portion of the main surface of each of the current collectors 20 and 21. The formation method of these 1st electrode 12 and the 2nd electrode 13 is not specifically limited, The well-known thin film manufacturing technique employ | adopted for manufacture of the well-known electric double layer capacitor 1 can be used.

  For example, when the first electrode 12 and the second electrode 13 are carbon electrodes (polarizable electrodes), a sheet-like electrode can be produced using a carbon material such as activated carbon that has been activated by a known method. Specifically, for example, after pulverizing the carbon material to about 5 to 100 μm and adjusting the particle size, for example, a conductive auxiliary agent (carbon black or the like) for imparting conductivity to the carbon powder, for example, a binder, For example, an organic solvent such as MIBK may be added and kneaded to obtain a paste, and this paste may be applied onto each of the current collectors 20 and 21 and dried. Application can be performed by metal mask printing, a doctor blade method, a roll press method, or the like.

  Here, as the conductive auxiliary agent, in addition to carbon black, powdered graphite and the like can be used, and as the binder, in addition to polytetrafluoroethylene, polyvinylidene fluoride, fluororubber and the like are used. can do.

  Instead of forming the first electrode 12 and the second electrode 13 by applying a paste on the current collectors 20 and 21, sheet-like electrodes are formed and laminated on the current collectors 20 and 21. May be.

  Next, the separator 14 is prepared. The separator 14 can be formed by cutting a porous insulating material such as paper into a predetermined size. The area of the main surface of the separator 14 is larger than that of the first electrode 12 and the second electrode 13.

  Then, the frame-shaped sealing material 30 as a polymeric multilayer body for electrochemical devices is prepared. First, two rectangular thermoplastic polymer sheets (thermoplastic polymer sheets) having the same size as the current collectors 20 and 21 and a rectangular crosslinked polymer sheet having the same size as the current collectors 20 and 21 (crosslinking height) (Molecular sheet) 1 sheet is prepared, and after the cross-linked polymer sheet is sandwiched between the thermoplastic polymer sheets by thermocompression bonding and these three sheets are integrated, the first electrode 12 and the second electrode 13 are supported. The center part is cut out to obtain a frame-shaped sealing material 30 (cutout process). The structure of the sealing material 30 is thermoplastic polymer layer 31 / crosslinked polymer layer 32 / thermoplastic polymer layer 33.

  In addition, the crosslinked polymer sheet used at this process is a sheet | seat formed from the above crosslinked polymers, and can be manufactured by a well-known method. For example, the thermoplastic polymer layers 31 and 33 have a thickness of about 5 to 200 μm, and the crosslinked polymer layer 32 has a thickness of about 10 to 200 μm.

  Subsequently, the electrolyte solution is dropped on the second electrode 13 formed on one current collector 21, and the electrolyte solution is also dropped on the first electrode 12 formed on the other current collector 20.

  Subsequently, as shown in FIG. 3B, a separator 14 is laminated on the second electrode 13, and the electrolyte solution is dropped on the separator 14. Then, the frame-shaped sealing material 30 is placed on the peripheral edge 21 a of the current collector 21.

  Next, the other current collector 20 is placed on the current collector 21 so that the first electrode 12 faces the separator 14 and the peripheral portion 20a of the current collector 20 is in contact with the frame-shaped sealing material 30. Laminate.

  Then, while drawing the vacuum in the vacuum vessel, the frame-shaped heater 98 corresponding to the shape of the peripheral portion 20a of the current collector 20 is pressed against the current collector 20 from above to heat the sealing material 30, thereby forming the frame shape. The thermoplastic polymer layers 31 and 33 of the sealing material 30 are melted and bonded to the peripheral edge portion 20a of the current collector 20 and the peripheral edge portion 21a of the current collector 21, respectively, and sealed, and the electric double layer capacitor shown in FIG. Get one.

  At this time, the temperature of the heater 98 is controlled to a temperature at which the thermoplastic polymer layers 31 and 33 of the sealing material 30 are melted and the crosslinked polymer layer 32 is not melted. The manufacturing process of the electric double layer capacitor 1 according to this embodiment is completed through the above processes.

  According to such an electric double layer capacitor 1, the sealing material 30 includes the thermoplastic polymer layers 31 and 33 provided on the pair of current collectors 20 and 21, respectively, and the thermoplastic polymer layers 31 and A cross-linked polymer layer 32 provided between 33 is provided. For this reason, even when the thermoplastic polymer layers 31 and 33 are excessively melted when the current collectors 20 and 21 are sealed, the thermoplastic polymer layers 31 and 33 are interposed between the thermoplastic polymer layers 31 and 33. In contrast, the cross-linked polymer layer 32 is less likely to be melted as compared with the above. Accordingly, the cross-linked polymer layer 32 becomes an obstacle and makes it difficult for the current collectors 20 and 21 to contact each other.

  Thereby, since the electrical double layer capacitor 1 of this embodiment does not easily cause a short circuit between the current collectors 20 and 21, the yield and reliability can be extremely increased. In addition, instead of sealing by heat (heat sealing), sealing may be performed by ultrasonic welding. In this case as well, the same actions and effects as described above are produced.

  The preferred embodiment of the present invention has been described in detail above, but the present invention is not limited to the above embodiment.

  For example, in the above-described embodiment, a configuration suitable for the case where the present invention is applied to an electric double layer capacitor has been described. However, the present invention is not limited to an electric double layer capacitor. For example, a pseudo capacitor or a redox capacitor is used. It is applicable to other electrochemical capacitors.

  Furthermore, in the description of the above embodiment, a configuration suitable when the present invention is applied to an electrochemical capacitor (particularly an electric double layer capacitor) has been described. However, the present invention is not limited to this, and lithium ions The present invention can also be applied to various secondary batteries including secondary batteries. In this case, the porous layer that becomes the first electrode (positive electrode) 12 contains an electrode active material that can be used for the positive electrode of a secondary battery such as a lithium ion secondary battery. Moreover, the porous body layer used as the 2nd electrode (negative electrode) 13 contains the electrode active material which can be used for the negative electrodes of secondary batteries, such as a lithium ion secondary battery. In this case, it is preferable to use aluminum, titanium or the like for the current collector in contact with the first electrode 12 from the viewpoint of corrosion resistance, and the current collector in contact with the second electrode 13 has a viewpoint of not forming an alloy with lithium. Therefore, it is preferable to use copper, nickel or the like.

Next, based on an Example, the effect of this invention is demonstrated more concretely.
(Example 1)
The electric double layer capacitor having the same configuration as the electric double layer capacitor 1 shown in FIGS.

  First, a pair of current collectors having electrodes was prepared. As the current collector, an aluminum foil (thickness 20 μm) cut into a predetermined rectangular shape was adopted, and electrodes were formed on these current collectors. Specifically, 9% by weight of fluorine rubber (DuPont, VitonVGF), 86% by weight of activated carbon (FR25, Kuraray Co., Ltd.), 5% by weight of carbon black (manufactured by Denki Kagaku), a predetermined amount of methyl The mixture was mixed with isobutyl ketone to form a paste, applied to the center of the main surface of the current collector by a metal mask method, and dried to obtain an electrode.

  Next, a separator was prepared. This separator was formed by cutting out paper having a thickness of 31 μm (manufactured by Nippon Kogyo Paper) larger than the area of the main surface of the electrode.

  Subsequently, a frame-shaped sealing material having a three-layer structure was prepared. First, three uncrosslinked acid-modified high-density polyethylene sheets (thickness 31 μm) having the same planar shape as the current collector are prepared as thermoplastic polymer sheets, and one of them is irradiated with an electron beam for crosslinking. Then, a cross-linked acid-modified high-density polyethylene sheet as a cross-linked polymer sheet was obtained (radiation irradiation step). Here, the acceleration voltage of the electron beam was 200 kV, and the absorbed dose of the electron beam was 100 kGy. Then, a crosslinked acid-modified high-density polyethylene sheet as a crosslinked polymer sheet is sandwiched between uncrosslinked acid-modified high-density polyethylene sheets, and these are integrated by thermocompression bonding. A three-layer structure of crosslinked acid-modified high-density polyethylene layer / uncrosslinked acid-modified high-density polyethylene layer was formed. Then, the part corresponding to the electrode in a 3 layer sheet | seat was cut out, and it was set as the frame-shaped sealing material as a polymeric multilayer body for electrochemical devices (cutting process).

  Subsequently, a frame-shaped sealing material was placed on the surface of the current collector on which the electrode was formed so as to surround the electrode, and was thermocompression bonded at 130 ° C. to temporarily fix the sealing material. Subsequently, an appropriate amount of electrolyte solution was dropped on one electrode of the current collector, a separator was laminated on the electrode, and an appropriate amount of electrolyte solution was dropped on the separator. As the electrolyte solution, a solution in which triethylmethylammonium tetrafluoroborate was dissolved in propylene carbonate at a concentration of 1.4 mol / L was used.

  Subsequently, an appropriate amount of the electrolyte solution was also dropped on the electrode of the other current collector. Then, the other current collector was superposed on one current collector. At this time, the electrode of the other current collector was in contact with the separator, and the peripheral portion of the other current collector was overlapped with the frame-shaped sealing material.

  Subsequently, in a vacuum atmosphere, a frame-shaped heater corresponding to the sealing material is pressed from the outer surface of the upper current collector to melt the non-crosslinked acid-modified high-density polyethylene layer of the sealing material between the current collectors. The electric double layer capacitor was completed by sealing. Here, the temperature of the heater was controlled so that the temperature of the sealing material was 160 ° C. Moreover, ten such electric double layer capacitors were obtained.

  When the resistance of these electric double layer capacitors was measured, there was no short circuit.

(Example 2)
In Example 2, the electric double layer capacitor of Example 2 was used in the same manner as in Example 1 except that γ-rays were used as the ionizing radiation, and the uncrosslinked acid-modified high-density polyethylene sheet was crosslinked at an irradiation dose of 80 kGy. Got.

(Example 3)
In Example 3, instead of the crosslinked acid-modified high-density polyethylene layer, a urethane-modified epoxy resin (manufactured by Nippon Paint, Olga Select 30NC Primer P-2), which is a thermosetting resin, is heat-treated at 150 ° C. for 20 minutes. An electric double layer capacitor of Example 3 was obtained in the same manner as in Example 1 except that a cured product (thickness: 100 μm) was used.

Example 4
In Example 4, in place of the cross-linked acid-modified high-density polyethylene layer, Example 1 and Example 1 were used except that an ultraviolet curable epoxy resin (manufactured by ThreeBond) was cured by irradiating ultraviolet rays at 9900 mJ / cm ^2. Similarly, an electric double layer capacitor of Example 4 was obtained.

(Example 5)
In Example 5, instead of the cross-linked acid-modified high-density polyethylene layer, a thermosetting resin urethane-modified epoxy resin (Mitsui Chemicals, product number: 802-30CX) was heat-treated at 260 ° C. for 30 seconds for thermosetting. An electric double layer capacitor of Example 5 was obtained in the same manner as Example 1 except that the prepared one was used.

(Example 6)
In Example 6, instead of the cross-linked acid-modified high-density polyethylene layer, a block urethane-modified epoxy resin (manufactured by Mitsui Chemicals, product number 830), which is a thermosetting resin, was heat-cured by heat treatment at 260 ° C. for 30 seconds. An electric double layer capacitor of Example 6 was obtained in the same manner as in Example 1 except that those were used.

(Comparative Example 1)
In Comparative Example 1, ten electric double layer capacitors were obtained in the same manner as in Example 1 except that a single-layer acid-modified high-density polyethylene film (thickness: 131 μm) was used as the sealing material.

  And when the resistance of the electric double layer capacitors of Examples 1 to 6 was measured, there was no short circuit. On the other hand, when the resistance of the electric double layer capacitor of Comparative Example 1 was measured, there were 5 out of 10 objects.

FIG. 1 is a cross-sectional view of an electric double layer capacitor according to an embodiment of the present invention. FIG. 2 is a top view of the electric double layer capacitor of FIG. FIGS. 3A and 3B are cross-sectional views illustrating a method for manufacturing the electric double layer capacitor of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electric double layer capacitor (electrochemical device), 10 ... Electric power generation element, 12 ... First electrode, 13 ... Second electrode, 20, 21 ... Current collector, 20a, 21a ... Peripheral part, 32 ... Crosslinked polymer layer 31, 33 ... thermoplastic polymer layer, 30 ... sealing material.

Claims (8)

A power generation element having a first electrode and a second electrode, and an electrolyte provided between the electrodes;
A pair of current collectors, one of which is in contact with the first electrode and the other of which is in contact with the second electrode, and sandwiching the power generation element opposite to each other;
A sealant disposed between the pair of current collectors so as to surround the power generation element, and sealing the pair of current collectors,
The said sealing material is an electrochemical device which has the thermoplastic polymer layer each provided on the said pair of electrical power collector, and the bridge | crosslinking polymer layer provided between the said thermoplastic polymer layers.   The electrochemical device according to claim 1, wherein the crosslinked polymer layer is a material crosslinked by irradiation with ionizing radiation.   The electrochemical device according to claim 1 or 2, wherein the ionizing radiation is an electron beam and / or a gamma ray.   The electrochemical device according to claim 2 or 3, wherein an irradiation dose of the ionizing radiation is 20 to 300 kGy.   The electrochemical device according to any one of claims 1 to 4, wherein the crosslinked polymer layer is a layer of a material obtained by crosslinking the same thermoplastic polymer as the thermoplastic polymer of the thermoplastic polymer layer. .   The electrochemical device according to claim 5, wherein the thermoplastic polymer layer is a polyolefin layer, and the crosslinked polymer layer is a crosslinked polyolefin layer.   A cutting step of obtaining a polymer multilayer body having a laminated structure similar to that of the laminate body by cutting out a laminate body provided with a crosslinked polymer sheet between thermoplastic polymer sheets along the lamination direction. A process for producing a polymer multilayer for electrochemical devices. The polymer multilayer body for electrochemical devices according to claim 7, further comprising a radiation irradiation step of obtaining the crosslinked polymer sheet by irradiating the polymer sheet with ionizing radiation prior to the cutting step. Manufacturing method.

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