JP2005129913A - Electrochemical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrochemical device in which sealing performance is excellent, and a short circuit between current collectors hardly occurs. <P>SOLUTION: The electrochemical device has a generating element 10 having a pair of electrodes 20, 40 and electrolyte provided between the electrodes 20, 40; a pair of current collectors 70, 70 where one of them contacts to the electrode 20 and the other contacts to the electrode 40, and they are opposed to each other and sandwich the generating element 10; and a sealing member 56 which is disposed between the pair of current collectors 70, 70 and seals the pair of current collectors 70, 70. The sealing member 56 has a cured resin layers 50 formed on the pair of current collectors 70, 70, respectively, and a thermoplastic polymer layer 52 for adhering the cured resin layers 50 to each other. <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).
Japanese Patent Laid-Open No. 62-154469 JP-A-2-234344 JP-A-4-121947 JP-A-6-349462 JP-A-2-250257

  However, in conventional electrochemical devices, the sealing performance of the sealing material is not sufficient, moisture from the atmosphere permeates into the interior and affects the power generation element, and vapor of electrolyte components in the power generation element permeate to the outside. There was a case. When such an event occurs, the voltage of the power generation element may decrease due to self-discharge, or the electrochemical device may swell due to decomposition of moisture that has entered.

  In the conventional method, the thermoplastic polymer may be melted too much at the time of sealing, and the current collectors may come into contact with each other, resulting in a short circuit of the electrochemical device.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrochemical device that has excellent sealing properties and is unlikely to cause a short circuit between current collectors.

  As a result of intensive studies, the present inventors have found that, in conventional electrochemical devices, the sealing property at the interface between the thermoplastic polymer layer and the current collector is particularly insufficient, leading to the present invention. It was.

  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 seals the pair of current collectors, The sealing material includes a cured resin layer formed on each of the pair of current collectors, and a thermoplastic polymer layer that bonds the cured resin layers together.

  According to the electrochemical device of the present invention, a cured resin layer is formed as a sealing material on each current collector, and the adhesive force between such a cured resin layer and the current collector is conventional. It is sufficiently higher than the adhesive force between the thermoplastic polymer layer and the current collector. In addition, these cured resin layers are bonded to each other by a thermoplastic polymer layer as a sealing material, and the adhesive force between the cured resin layer and the thermoplastic polymer layer is also different from that of the conventional thermoplastic polymer layer. It is sufficiently high compared to the adhesive strength with electrical objects. Therefore, at the interface between the sealing material and the current collector, or at the interface between the thermoplastic polymer layer and the cured resin layer, intrusion of moisture from the outside, evaporation of the electrolyte etc. to the outside is suppressed, and the sealing The sealability of the material is sufficiently enhanced.

  In addition, since each of the current collectors has a cured resin layer between the thermoplastic polymer layer and the current collector, when the thermoplastic polymer of the sealing material is melted and heat-sealed, the thermoplastic polymer Even when the metal melts too much, the current collectors do not come into contact with each other to cause a short circuit.

  Moreover, the electrochemical device of the present invention may be configured such that a metal body is contained in the thermoplastic polymer of the sealing material.

  When such a configuration is adopted, the metal body has a lower water permeability than the polymer, and thus the sealing performance of the sealing material is further improved. As a metal body, an aluminum wire or foil is illustrated, for example.

  Further, two thermoplastic polymer layers may be provided, and a metal layer may be provided between these thermoplastic polymer layers. Even in such a configuration, the sealing property of the sealing material can be improved due to the low moisture permeability of the metal layer.

  Here, the cured resin layer is preferably a thermally cured resin layer. A thermosetting resin is low in cost, and a cured resin layer can be formed at a low cost by curing the thermosetting resin.

  The cured resin layer may be a resin layer cured by ultraviolet irradiation.

  Here, the cured resin layer, particularly the thermally cured resin layer, is a resin containing at least one resin selected from the group consisting of an epoxy resin, a urethane resin, a phenol resin, and a furan resin cured by heat or the like. It is preferable. In particular, it is preferable that a resin containing an epoxy resin or a urethane resin is cured by heat or the like.

  Since these hardened resins, especially heat-cured resins, are particularly firmly bonded to a current collector such as metal, the sealing performance is further improved.

  The thermoplastic polymer layer is made of acid-modified polyolefin, acid-modified polyvinylidene fluoride, polysulfone, polyethersulfone, polyhydantoin, polyetherimide, polyphenylene sulfide, polyetheretherketone, and acid-modified cyclic olefin copolymer. It is preferable that at least one selected from is included.

  These thermoplastic polymers are particularly firmly bonded to a cured resin layer, particularly a thermoset resin layer, and thus exhibit high sealing properties. In particular, the acid-modified polyolefin exhibits a high adhesive force with a cured epoxy resin or urethane resin, in particular, a thermally cured one.

  Moreover, it is preferable to use an acid-modified cyclic olefin copolymer from the viewpoint of reducing the moisture permeability of the thermoplastic polymer itself.

  Further, at least one of the pair of current collectors is preferably formed of aluminum, and a boehmite layer is preferably provided in a region where a cured resin layer, in particular, a thermally cured resin layer is formed.

  As a result, the current collector and the cured resin layer, particularly the thermally cured resin layer, are more firmly bonded.

  Further, three or more current collectors may be provided, and a power generation element and a sealing material may be provided between the current collectors. According to this, in the stacked electrochemical device, the above-described effects are exhibited.

  ADVANTAGE OF THE INVENTION According to this invention, the electrochemical device which is excellent in sealing performance and cannot produce the short circuit between collectors can be provided.

  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 70 and 70 that sandwich the power generation element 10 and functions as an exterior body, and the power generation element 10 between the current collectors 70 and 70. And a sealing material 56 for sealing.

  The power generation element 10 includes a first electrode 40 as a positive electrode and a second electrode 20 as a negative electrode facing each other, a separator 30 disposed adjacent to the first electrode 40 and the second electrode 20, and a first electrode The electrode 40, the second electrode 20, and an electrolyte solution (not shown) containing an electrolyte contained in the separator 30.

  The first electrode 40 and the second electrode 20 are electron conductive porous bodies. It does not specifically limit as a constituent material of the 1st electrode 40 and the 2nd electrode 20, It is used as a porous body layer which comprises polarizable electrodes, such as a carbon electrode used for a well-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 and contents of constituent materials other than carbon materials such as binder) are not particularly limited. For example, a conductive auxiliary agent (carbon black or the like) for imparting conductivity to the carbon powder and, for example, a binder (polytetrafluoroethylene (PTFE) or the like) may be added.

  The separator 30 disposed between the first electrode 40 and the second electrode 20 is not particularly limited as long as it is formed of an electrically insulating porous body, and a separator used in a known electric double layer capacitor is used. can do. For example, as the electrically insulating porous body, at least one structure selected from the group consisting of a laminate of films made of polyethylene, polypropylene or polyolefin, 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 material.

  Here, in order to suppress a short circuit between the first electrode 40 and the second electrode 20, the size of the separator 30 is made larger than the area of the main surface of the electrodes 40, 20, and the end portion of the separator 30 is connected to the electrodes 40, 20. It is preferable to make it protrude from the end surface. At this time, the end face of the separator 30 is preferably separated from the sealing material 56.

  The electrolyte solution is contained in the pores of the first electrode 40, the second electrode 20, and the separator 30. 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 70 are a rectangular plate-like conductive material having an area larger than the areas of the main surfaces of the first electrode 40 and the second electrode 20 of the power generation element 10. These current collectors 70, 70 have the power generation element 10 from above and below such that the lower current collector 70 is in surface contact with the first electrode 40 and the upper current collector 70 is in surface contact with the second electrode 20. Is sandwiched. The material of the current collector 70 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 56 is disposed between the pair of current collectors 70 and 70 so as to surround the power generation element 10 and seals the current collectors 70 and 70. The sealing material 56 has a three-layer structure parallel to the current collector 70. Specifically, the sealing material 56 has a three-layer structure of cured resin layer 50 / thermoplastic polymer layer 52 / cured resin layer 50, for example, thermoset resin layer 50 / thermoplastic polymer layer 52 / heat. It has a three-layer structure of a cured resin layer 50.

  The upper cured resin layer 50 is formed on the lower surface peripheral portion 70 a of the upper current collector 70, and the lower cured resin layer 50 is formed on the upper surface peripheral portion 70 a of the lower current collector 70. Has been.

  These cured resin layers 50 are formed by applying a thermosetting resin or an ultraviolet curable resin on the peripheral edge portion 70 a of the current collector 70 and curing it by heating or ultraviolet irradiation. It is firmly bonded on the peripheral edge 70a.

  Here, the material of the cured resin layer 50 is an electrically insulating polymer formed by polymerizing and curing a monomer or oligomer by heating or ultraviolet irradiation. The cured resin layer 50 may be a resin layer obtained by curing a resin layer containing a monomer or oligomer by polymerization or the like, and may be, for example, a resin cured by electron beam irradiation or the like.

  The material of the cured resin layer 50 is preferably formed by curing a resin containing at least one resin selected from the group consisting of an epoxy resin, a urethane resin, a phenol resin, and a furan resin. Such a resin adheres very strongly to the current collector by curing.

  On the other hand, the thermoplastic polymer layer 52 bonds the upper cured resin layer 50 and the lower cured resin layer 50 together. The material of the thermoplastic polymer layer 52 is not particularly limited as long as it is a polymer having thermoplasticity, but is not limited to acid-modified polyolefin, acid-modified polyvinylidene fluoride, polysulfone, polyethersulfone, polyhydantoin, polyetherimide. In particular, a polymer containing at least one selected from the group consisting of polyphenylene sulfide, polyether ether ketone, and acid-modified cyclic olefin copolymer can be used particularly suitably.

  Examples of the acid-modified polyolefin include polyethylene, polypropylene, 4-methylpentene, copolymers of these polymers and acrylic, and those obtained by grafting maleic anhydride onto these polymers.

  In particular, when the cured resin is a cured product of epoxy or urethane resin, it is preferable to use acid-modified polyolefin as the material of the thermoplastic polymer layer 52 because the adhesiveness to the cured resin layer is high.

  Further, from the viewpoint of reducing the moisture permeability of the thermoplastic polymer layer 52 itself, it is preferable to use an acid-modified cyclic olefin copolymer as the material of the thermoplastic polymer layer 52.

  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 70 shown in FIG. The current collector 70 can be formed, for example, by cutting a conductive metal foil such as aluminum into a rectangular shape having a predetermined size.

  Subsequently, by applying a curable resin such as a thermosetting resin with a predetermined width on the peripheral edge portion 70a along the four sides on the surface of each current collector 70, and curing the curable resin by heat treatment or the like. Then, a cured resin layer 50 formed in a frame shape is obtained.

  Next, a thermoplastic polymer film is prepared and cut into a frame shape corresponding to the above-described cured resin layer 50 to obtain a thermoplastic polymer frame film 52a.

  Next, the sheet-like first electrode 40 and the second electrode 20 are respectively formed in the central portion of the surface on which the cured resin layer 50 is formed on each current collector 70. The formation method of these 1st electrodes 40 and the 2nd electrode 20 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 40 and the second electrode 20 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 to each of the current collectors 70 and 70 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.

  Next, the separator 30 is prepared. The separator 30 can be formed by cutting a porous insulating material such as paper into a predetermined size.

  Subsequently, the electrolyte solution is dropped onto the first electrode 40 formed on one current collector 70, and the electrolyte is also dropped onto the second electrode 20 formed on the other current collector 70.

  Subsequently, as shown in FIG. 3B, the separator 30 is stacked on the first electrode 40, and the electrolyte solution is also dropped on the separator 30. Then, the thermoplastic polymer frame-like film 52 a is placed facing the corresponding position on the cured resin layer 50 formed in a frame shape on the current collector 70.

  Next, the first electrode 40 is formed on the other current collector 70 such that the second electrode 20 faces the separator 30 and the cured resin layer 50 is in contact with the thermoplastic polymer frame film 52a. The laminated body 70 is laminated.

  After that, while drawing a vacuum in the vacuum vessel, the heater 98 having a shape corresponding to the shape of the peripheral portion 70a of the current collector 70 is pressed against the current collector 70 from above and heated to form a frame shape of the thermoplastic polymer. The film 52a is melted and the upper and lower cured resin layers 50 are bonded and sealed to obtain the electric double layer capacitor 1 shown in FIG.

  Instead of forming the first electrode 20 and the second electrode 40 by applying a paste on the current collector 70, a sheet-like electrode may be formed and laminated on the current collector 70.

  According to such an electric double layer capacitor, the cured resin layers 50 and 50 such as a thermally cured resin layer are formed on the peripheral edge portions 70a of the current collectors 70 and 70, respectively. The adhesive force between the resin layer 50 and the current collector 70 is sufficiently higher than the adhesive force between the conventional thermoplastic polymer layer and the current collector 70. In addition, these cured resin layers 50 and 50 are bonded to each other by the thermoplastic polymer layer 52, and the adhesive force between the cured resin layer 50 such as the thermally cured resin layer and the thermoplastic polymer layer 52 is also conventionally known. The adhesive strength between the thermoplastic polymer layer and the current collector 70 is sufficiently high. Therefore, at the interface between the sealing material 56 and the current collector 70, or at the interface between the thermoplastic polymer layer 52 and the cured resin layer 50, moisture intrusion from the outside, evaporation of the electrolyte solution or the like to the outside, etc. The sealing property of the sealing material 56 is sufficiently enhanced.

  Further, since the cured polymer layer 52 such as a thermally cured resin layer is provided between the thermoplastic polymer layer 52 and each current collector 70, the thermoplastic polymer layer 52 of the sealing material 56 is provided. In the case of melting and heat-sealing, even when the thermoplastic polymer layer 52 is excessively melted, the current collectors 70 and 70 are not brought into contact with each other and short-circuited. In addition, it may replace with heat sealing and may seal by ultrasonic welding.

  Therefore, the electric double layer capacitor 1 according to the present embodiment has excellent sealing performance and is less likely to cause a short circuit between the current collectors. Therefore, the reliability is extremely high.

(Second embodiment)
Then, with reference to FIG. 4, the electric double layer capacitor 2 as an electrochemical device which concerns on 2nd embodiment is demonstrated. The electric double layer capacitor 2 according to this embodiment is different from the electric double layer capacitor 1 of the first embodiment in that boehmite is used as a current collector 70 on a surface in contact with a hardened resin layer 50 such as a heat hardened resin layer. The aluminum foil in which the layers 72 are formed is used.

  The boehmite layer 72 has an AlO (OH) structure. Since the boehmite layer 72 adheres extremely firmly to the cured resin layer 50 such as a heat-cured resin layer, the sealing performance is further improved.

  In addition, the boehmite layer 72 has a peripheral portion of the aluminum foil as the current collector 70 in pure water at 80 to 100 ° C., preferably 95 to 100 ° C., for 5 to 120 minutes, preferably 20 to 60 minutes. It can be formed by dipping or contacting with heated steam at 90 to 130 ° C. for 5 to 60 minutes. The film thickness of the boehmite layer 72 thus obtained is preferably 0.1 to 5 μm.

(Third embodiment)
Then, with reference to FIG.5 and FIG.6, the electric double layer capacitor 3 as an electrochemical device which concerns on 3rd embodiment is demonstrated.

  In the present embodiment, in order to form a layer corresponding to the thermoplastic polymer layer 52 of the first embodiment, as shown in the cross-sectional view of FIG. A material obtained by thermocompression bonding an acid-modified polypropylene film as a plastic polymer layer is used. The diameter of the aluminum wire 53 is, for example, 50 μm to 100 μm. And as shown in FIG. 6, the sealing material 56 is comprised by providing this between the cured resin layers 50 and 50, such as a thermosetting resin layer.

  According to the electric double layer capacitor 3 of this embodiment, since the aluminum wire (metal body) 53 having a moisture permeability smaller than that of the polymer is provided in the thermoplastic polymer layer 54, the sealing property of the sealing material 56 is improved. It is extremely high.

  In addition, as a metal body, iron, copper, nickel, stainless steel, etc. other than aluminum can be applied. Further, the cross-sectional shape of the metal body may be, for example, a rectangular cross section other than a circular shape.

  Moreover, in order to improve the sealing performance of a sealing material like the electrochemical device of this embodiment, the following forms can also be taken. In other words, two thermoplastic polymer layers 52 referred to in the first embodiment are provided, and a metal layer is disposed between these thermoplastic polymer layers 52 and 52. Even in such a configuration, the sealing property of the sealing material can be improved due to the low moisture permeability of the metal layer.

  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, the configuration suitable for the case where the present invention is applied to an electric double layer capacitor has been described. However, the electrochemical device of the present invention is not limited to an electric double layer capacitor. It is applicable to electrochemical capacitors such as capacitors and redox capacitors.

  Furthermore, in the description of the above embodiment, a configuration suitable for the case where the present invention is applied to an electrochemical capacitor (particularly an electric double layer capacitor) has been described. However, the electrochemical device of the present invention is not limited to this. The present invention is also applicable to various secondary batteries including a lithium ion secondary battery. In this case, the porous body layer that becomes the electrode 40 (positive electrode) contains an electrode active material that can be used for the positive electrode of a secondary battery such as a lithium ion secondary battery. In addition, the porous layer serving as the electrode 20 (negative electrode) contains an electrode active material that can be used for the negative electrode of a secondary battery 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 positive electrode 40 from the viewpoint of corrosion resistance. From the viewpoint of not forming an alloy with lithium in the current collector in contact with the negative electrode 20, copper, It is preferable to use 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. In addition, in FIG. 7, the constituent material of the electric double layer capacitor in each Example and a comparative example is shown. In the table of FIG. 7, the first layer of the sealing material is a layer located on one side of the pair of current collectors, the third layer is a layer located on the other current collector side, and the second layer The layer is a layer provided between the first layer and the third layer.

  First, a pair of current collectors on which a thermoset resin layer and electrodes were formed was prepared.

  As the current collector, an aluminum foil (thickness 20 μm) cut into a predetermined rectangular shape was used. Then, a urethane-modified epoxy resin (manufactured by Nippon Paint Co., Ltd., Olga Select 30NC Primer P-2) was spray-applied with a width of 2 mm along the four peripheral edges of one surface on the current collector. Then, the current collector coated with the urethane-modified epoxy resin was heat-treated at 150 ° C. for 20 minutes and thermally cured to form a frame-shaped thermally cured resin layer.

  Subsequently, an electrode was formed on the current collector. Specifically, 9% by weight of fluororubber (manufactured by DuPont, VitonVGF), 86% by weight of activated carbon (FR25 manufactured by Kuraray Co., Ltd.), 5% by weight of carbon black (manufactured by Denki Kagaku Kogyo), The mixture was mixed with methyl isobutyl ketone to form a paste, which was applied to the central portion on the surface side where the thermoset resin in the current collector was formed by a metal mask method, and dried to obtain an electrode. Here, no paste was applied to the thermally cured resin part.

  Subsequently, a frame-shaped thermoplastic polymer film was prepared. As the thermoplastic polymer, an acid-modified polypropylene film (thickness 50 μm, manufactured by Mitsui Chemicals, Admer QE060) was used. Specifically, the acid-modified polypropylene film was cut into a frame shape corresponding to the above-described frame-shaped thermoset resin layer to form a frame-shaped thermoplastic polymer film.

  Furthermore, a separator was prepared. This separator was formed by cutting paper having a thickness of 50 μm (manufactured by Nippon Advanced Paper Co., Ltd.) into a shape larger than the area of the main surface of the electrode and smaller than the inside of the thermoset resin frame.

  Subsequently, a current collector, a frame-shaped thermoplastic film, and a separator were laminated.

  Specifically, first, an appropriate amount of the electrolyte solution was dropped on the electrode of one of the current collectors, a separator was stacked on the electrode, and an appropriate amount of the 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 1.6 mol / L was used. Subsequently, a frame-shaped thermoplastic film was superposed on the thermosetting resin of one current collector.

  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 thermosetting resin layer of the other current collector was overlapped with the frame-shaped thermoplastic film.

  Subsequently, under a vacuum atmosphere, the heater corresponding to the frame shape of the thermoplastic film is pressed from the outer surface of the upper current collector, the thermoplastic film is melted and the thermosetting resin layers are bonded to each other and sealed Thus, the electric double layer capacitor was completed. Here, ten such electric double layer capacitors were obtained.

(Example 2)
An electric double layer capacitor of Example 2 was obtained in the same manner as in Example 1 except that an aluminum foil having a boehmite layer formed on the surface of the aluminum foil on which the heat-cured resin layer was formed was used as the current collector.

(Examples 3 to 7)
Examples 3 to 7 were carried out in the same manner as in Example 1 except that acid-modified polyvinylidene fluoride, polysulfone, polyethersulfone, polyhydantoin and polyetherimide were used in place of acid-modified polypropylene as the thermoplastic polymer. The electric double layer capacitor was obtained.

(Examples 8 and 9)
Electric double layer capacitors of Examples 8 and 9 were obtained in the same manner as in Example 1 except that acid-modified cyclic olefin copolymer was used as the thermoplastic polymer. The cyclic olefin copolymer has a characteristic that moisture permeability is small (moisture is difficult to permeate) compared to polypropylene and polyethylene. The acid modification was carried out by putting a cyclic olefin copolymer, maleic anhydride and an organic peroxide in a twin screw extruder.

  In Example 8, an acid-modified cyclic olefin copolymer obtained by grafting Topas of Ticona GmbH with maleic anhydride was used.

  In Example 9, an acid-modified cyclic olefin copolymer obtained by grafting Mitsui Chemicals's appel with maleic anhydride was used.

(Example 10)
Example 10 corresponds to the third embodiment. In this example, a urethane-modified epoxy resin was applied to an aluminum foil as in Example 1, but no acid-modified polypropylene film cut into a frame shape was prepared. Instead, as shown in FIG. 5, an aluminum wire having a diameter of 50 μm and an acid-modified polypropylene film that was thermocompression-bonded, more specifically, a thermocompressor using an extruder were prepared. Then, as shown in FIG. 6, this was provided between urethane-modified epoxy resins, and an electric double layer capacitor was produced in the same manner as in Example 1.

(Example 11)
In Example 11, an ultraviolet curable epoxy resin (manufactured by Three Bond) was used as the first layer and the third layer in place of the urethane-modified epoxy resin (manufactured by Nippon Paint, Olga Select 30NC Primer P-2). After the resin coating, ultraviolet rays were irradiated 9900mJ / cm ^2. Otherwise, an electric double layer capacitor was produced in the same manner as in Example 1.

(Example 12)
In Example 12, instead of the urethane-modified epoxy resin (Nippon Paint, Olga Select 30NC Primer P-2) as the first layer and the third layer, a urethane-modified epoxy resin (
Mitsui Chemicals, product number: 802-30CX) was used. Curing was performed at 260 ° C. for 30 seconds. Otherwise, an electric double layer capacitor was produced in the same manner as in Example 1.

(Example 13)
In Example 13, a block urethane-modified epoxy resin (Mitsui Chemicals, product number 830) was used in place of the urethane-modified epoxy resin (Nippon Paint, Olga Select 30NC primer P-2). Curing was performed at 260 ° C. for 30 seconds. Otherwise, an electric double layer capacitor was produced in the same manner as in Example 1.

(Comparative Example 1)
In Comparative Example 1, the electric double layer capacitor of Comparative Example 1 was prepared in the same manner as in Example 1 except that only the acid-modified polypropylene as the thermoplastic polymer layer was sealed without forming the thermoset resin layer. Obtained.

  Then, these electric double layer capacitors were charged to 2.5 V, and kept in a thermostatic bath at 60 ° C. and a relative humidity of 90% for 20 days for an acceleration test. Thereafter, the voltage of the electric double layer capacitor was measured. The result is shown in FIG.

  With respect to the electric double layer capacitors of Examples 1 to 13, no short circuit occurred, and the voltage after the acceleration test was 2.35 V or more. A sufficiently high voltage after the acceleration test indicates that the sealing property of the sealing material of the electric double layer capacitor is sufficiently high.

  Moreover, in Example 10 in which the aluminum wire was provided in the acid-modified polypropylene, the voltage after the acceleration test was a relatively high value among the examples, and improvement in reliability was recognized. This is considered to be due to the fact that aluminum has a lower water permeability than a polymer.

  On the other hand, in the electric double layer capacitor of Comparative Example 1, a short circuit between the electrodes occurred with a high probability, and the voltage after the acceleration test was considerably low. A low voltage after the acceleration test indicates that the sealing performance is poor.

FIG. 1 is a cross-sectional view of the electric double layer capacitor according to the first embodiment. 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. FIG. 4 is a cross-sectional view of the electric double layer capacitor according to the second embodiment. FIG. 5 is a cross-sectional view showing a part of the sealing material used in the electric double layer capacitor according to the third embodiment. FIG. 6 is a cross-sectional view of the electric double layer capacitor according to the third embodiment. FIG. 7 is a table showing the sealing materials, current collectors, number of shorts generated, and voltage after the acceleration test of the electric double layer capacitors of Examples 1 to 13 and Comparative Example 1.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 2, 3 ... Electric double layer capacitor (electrochemical device), 10 ... Electric power generation element, 20 ... Second electrode, 40 ... First electrode, 50 ... Hardened resin layer, 52 ... Thermoplastic polymer layer, 53 ... Aluminum wire (metal body), 56 ... sealing material, 70 ... current collector, 70a ... peripheral portion.

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 sealing material is an electrochemical device including a cured resin layer formed on the pair of current collectors, and a thermoplastic polymer layer that bonds the cured resin layers to each other.   The electrochemical device according to claim 1, wherein a metal body is contained in the thermoplastic polymer layer of the sealing material.   The electrochemical device according to claim 1, wherein two thermoplastic polymer layers are provided, and a metal layer is disposed between each of the thermoplastic polymer layers.   The electrochemical device according to claim 1, wherein the cured resin layer is a thermally cured resin layer.   The electrochemical device according to claim 1, wherein the cured resin layer is a resin layer cured by ultraviolet irradiation.   The electrochemical device according to claim 4 or 5, wherein the cured resin layer is obtained by curing at least one resin selected from the group consisting of an epoxy resin, a urethane resin, a phenol resin, and a furan resin.   The thermoplastic polymer layer is composed of acid-modified polyolefin, acid-modified polyvinylidene fluoride, polysulfone, polyethersulfone, polyhydantoin, polyetherimide, polyphenylene sulfide, polyetheretherketone, and acid-modified cyclic olefin copolymer. The electrochemical device according to any one of claims 1 to 6, comprising at least one selected.   The electricity according to any one of claims 1 to 7, wherein at least one of the pair of current collectors is formed of aluminum, and a boehmite layer is provided in a region where the cured resin layer is formed. Chemical device.

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