JPH11154630A - Polar electrode and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve bond strength and contact condition, by laminating a collector on an electrode sheet through a conductive adhesive layer contg. conductive C and binder, so as to penetrate part of this adhesive layer in pores of the electrode sheet at a specified percent age with respect to the depth of the electrode sheet. SOLUTION: An electrode comprises a conductive adhesive layer 13 contg. a conductive adhesive composed of conductive C and binder. This layer can exist in the form of penetration in pores 12 of an electrode sheet 12, using the conductive adhesive dispersed in a dispersant 13A. After removal of the dispersant, anchor effect improves bond strength of a collector 11 to the sheet 12. The penetration percentage of the adhesive layer 13 composed of such conductive adhesive into pores 12a of the sheet 12 is over 15%, pref. over 0.25% and below 30%, pref. 15% of the thickness of the sheet 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizable electrode body having excellent bonding strength between an electrode sheet and a current collector and a small internal resistance, a method of manufacturing the same, and an electric double layer capacitor using the polarizable electrode body. It is about.

[0002]

2. Description of the Related Art Conventional electric double layer capacitors include:
A type in which a separator is interposed between a pair of polarizable electrode bodies, and these are sealed together with an electrolytic solution by a metal case, a sealing plate, and a gasket that insulates them from each other (coin or button type); An electric double layer capacitor unit is formed by overlapping and winding separators, and is housed in a metal case, then impregnated with an electrolyte and sealed (winding type); An electrode laminated body is formed by alternately stacking an electrode thin film and a separator, and a positive electrode lead is connected to a positive electrode end of the electrode, and a negative electrode lead is connected to a negative electrode end of the electrode by caulking. After a capacitor unit is formed and stored in a metal case, there is a type (stack type) in which an electrolytic solution is impregnated into the unit and sealed.

[0003] Here, in the case of an electric double layer capacitor for power use such as an electric vehicle, it is required to have a high energy density and a high output density such that the electric capacity per unit volume is high and the internal resistance is low. You. In order to satisfy such demands, studies have been made to increase the area of the electrode body to increase the facing area of the electrode and to reduce the thickness of the electrode body. Needless to say, the electric double layer capacitor needs to be excellent in mass productivity.

In order to increase the facing area of the electrode body and reduce the thickness of the electrode body, a sheet-like or thin-film electrode body uses a paste-like or ink-like mixture containing an electrode material as a current collector. A method of drying (removing the solvent), rolling, etc. after applying by coating or the like; or preparing an electrode sheet containing an electrode material in advance, superimposing a current collector on the surface of the electrode sheet, and rolling the roll. -It is manufactured by a method of integrating with a wrench or the like.

In such a manufacturing method, in order to reduce the internal resistance of the electric double layer capacitor, it is important to improve the contact integration between the electrode material and the current collector. Here, as the electrode material, carbon powder having good conductivity such as activated carbon and acetylene black is generally used. As shown in FIG. 7, in the electrode material layer or the electrode sheet composed of carbon-based particles (hereinafter, collectively referred to as “electrode material layer 2” when the two are not distinguished from each other), the gap between the particles becomes the pore 3. The porous layer has an uneven surface. Therefore, when a metal foil or a metal sheet having a smooth surface is used as the current collector 1, the interface between the current collector 1 and the electrode material layer 2 is in point contact, and the substantial contact area is reduced. . This not only lowers the bonding strength between the current collector 1 and the electrode material layer 2, but also reduces the air portion (when an electrolyte is injected) between the current collector 1 and the electrode material layer 2. The electric resistance increases due to the increase in the liquid phase portion 4, which causes the electric double layer capacitor characteristics to deteriorate.

In order to ensure a contact area between the current collector and the electrode material layer, there has been proposed an electrode body using a current collector having an uneven surface.

For example, as an electrode body manufactured by the above method, an aluminum net is used as a current collector, and activated carbon powder as an electrode material is dispersed and mixed in a mixed solution of a fluorine-containing polymer and methyl alcohol. Paste
What was applied on the aluminum net (Japanese Unexamined Patent Publication No.
No. 162510); Activated carbon powder and acetylene black were mixed as electrode materials in a mixed solution of water and methanol,
Further, a slurry obtained by adding an aqueous solution of carboxymethyl cellulose is adhered to a current collector composed of a roughened aluminum foil (JP-A-4-162510); activated carbon powder and acetylene as electrode materials A proposal has been made in which a mixture of black and a polytetrafluoroethylene aqueous dispersion and polyvinylpyrrolidone as a binder is adhered to an aluminum expanded metal as a current collector (U.S. Pat. No. 4,327,400). Further, as the electrode body manufactured by the above method, an electrode material sheet in which activated carbon and a conductivity-imparting agent are bound by polytetrafluoroethylene as a binder is produced, and the electrode material sheet and the surface are etched by etching. A thin electrode body has been proposed in which a current collector composed of a metal plate having an opening, such as a roughened metal foil or expanded metal, is overlapped, and a rolling roller is used to enhance the joining integrity (Kimiaki Tokuaki) 54-12620).

[0008]

However, as described above, even if a current collector made of expanded metal or punched metal having an opening is used, The contact area is not yet at a sufficient level, and the joint strength between the electrode material layer and the current collector must be further improved in order to withstand the feed tension and the winding tension during continuous production of electrodes in roll form. Is required. Further, from the viewpoint of high output density, further reduction of the internal resistance, that is, reduction of the air portion interposed between the electrode material layer and the current collector is required.

Here, in the case of a current collector having an opening such as an expanded metal, it is conceivable that the opening is made large so that irregularities on the surface of the electrode sheet can be easily engaged with the opening of the current collector. However, when the opening of the expanded metal or the like is enlarged, the strength of the current collector is reduced, and the unit cross-sectional area of the current collector is reduced. In some cases, the increase in the capacity per unit volume of the electric double layer capacitor may be hindered.

The present invention has been made in view of such circumstances, and an object of the present invention is to improve the bonding strength and the contact state between a current collector and an electrode material in an electrode body to achieve continuous production. An object of the present invention is to provide a polarizable electrode body which is easy and has a high electric capacity and a low internal resistance, a method of manufacturing the same, and an electric double layer capacitor using the polarizable electrode body.

[0011]

According to the present invention, there is provided a polarizable electrode body comprising a current collector and a porous electrode sheet mainly composed of activated carbon laminated on both surfaces of the current collector. And the electrode sheet are laminated via a conductive adhesive layer containing conductive carbon and a binder, and a part of the conductive adhesive layer enters a hole portion of the electrode sheet. And the degree of penetration is 0.15 to 30% with respect to the thickness of the electrode sheet.

The maximum hole diameter of the electrode sheet is 0.5 to 20.
It is preferable that the porosity is 40 to 90%.

The current collector is at least one selected from the group consisting of aluminum, stainless steel, titanium and tantalum.
It is preferable that the kind of metal is formed into any one of a foil shape, a plate shape, and a sheet shape.

The current collector is made of a metal foil, a thin metal plate, or a metal sheet whose surface is formed of a surface having irregularities, and is formed between the current collector and the electrode sheet. It is preferable that a part of the conductive adhesive layer that has entered the concave part of the current collector, and that a part of the convex part of the current collector contact the electrode sheet. Is preferred.

It is preferable that the current collector is a metal foil, a metal sheet, or a metal sheet roughened by etching.

In the conductive adhesive, the conductive carbon is preferably graphite or carbon black, and the conductive carbon preferably has an average particle size of 0.5 to 50 μm. -Is a thermoplastic resin,
It is preferably at least one selected from the group consisting of a cellulose derivative and water glass.

The electric double layer capacitor according to the present invention comprises a plurality of polarizable electrode bodies of the present invention arranged in parallel, a separator interposed between adjacent polarizable electrode bodies, and a space between the polarizable electrode bodies and the separator. Is filled with an electrolytic solution.

In the method for producing a polarizable electrode body of the present invention, a step of applying a conductive adhesive liquid obtained by dispersing a conductive adhesive in a dispersion medium to a surface of an electrode sheet and / or a current collector; Laminating the electrode sheet and the current collector via the formed conductive adhesive liquid layer: and the conductive adhesive liquid layer existing between the superposed electrode sheet and the current collector Removing the dispersion medium from the above.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an embodiment of the polarizable electrode body of the present invention will be described with reference to FIG.

The polarizable electrode body 10 has a structure in which porous electrode sheets 12 mainly composed of activated carbon are laminated on both sides of a current collector 11 via conductive adhesive layers 13. In addition, the conductive adhesive constituting the conductive adhesive layer 13 is applied to the pore portions 12 of the porous electrode sheet 12.
a.

The electrode sheet 12 is obtained by appropriately mixing carbon black, polytetrafluoroethylene powder or the like with activated carbon as a carbon electrode material, and rolling the mixture obtained by adding ethanol, oil or the like to the mixture. It is a porous sheet. That is, the gaps between the activated carbon particles become the holes 12a, forming a porous sheet. The “sheet” referred to in the present specification is a concept that also includes a film.

As the activated carbon used as a raw material of the electrode sheet 12, activated carbon generally used as a carbon electrode can be used. Specifically, non-carbonized materials such as charcoal, coconut charcoal, brown coal, and sawdust are used. Activated by a gas such as water vapor or carbon dioxide, or activated by a chemical such as zinc chloride can be used, and the properties thereof may be powdery or granular. Is also good. As described above, since the specific surface area of the activated carbon is remarkably increased by the activation, an electrode having a large electric capacity per unit volume can be formed.

The maximum pore size of the electrode sheet 12 (maximum pore size) is preferably 0.5 to 20 μm. When the maximum pore diameter is less than 0.5 μm, the conductive adhesive hardly enters the pore portion 12 a of the electrode sheet 12,
If it is larger than m, the conductive adhesive penetrates deep into the holes 12 a of the electrode sheet 12, and the conductive adhesive hardly remains at the contact interface between the current collector 11 and the electrode sheet 12.
This is because the inside of the pores of the activated carbon is covered with the conductive adhesive, and the performance of the capacitor is reduced.
In addition, the maximum pore diameter referred to in the present specification is ASTM-E-128.
Refers to the pore size measured by the bubble point in ethanol according to -61.

The porosity of the electrode sheet 12 is preferably 4
0-90%, more preferably 60-80%.
You. If the porosity is less than 40%, the conductive adhesive layer 13
The conductive adhesive constituting the electrode sheet 12 has pores 12a.
Since the amount that can enter the conductive adhesive layer 13 decreases,
The joint strength can be sufficiently improved by the
Because you can't. On the other hand, if it is larger than 90%,
If the amount of conductive adhesive is insufficient, conductive adhesive may enter.
Holes 12a that do not exist are present, and the bonding strength is reduced.
This is because the improvement effect becomes insufficient. Also with the current collector 11
Air layer between (If electrolyte is used, electrolyte is injected
To form a liquid phase)
This is because the resistance is lowered. Reverse
If the amount of the conductive adhesive is sufficient, the electrode sheet 12
The conductive adhesive penetrates deep into the holes 12a,
Most of the pores of the activated carbon forming the sheet 12 are conductive
The specific surface area of the activated carbon
And the performance of the capacitor decreases.
Because Here, the porosity (%) referred to in this specification
Is the pore volume relative to the volume (V) of the entire electrode sheet 12
(V₀ ) Ratio [(V ₀ / V) × 100]
Value. The pore volume is the true density of the electrode sheet 12.
(Ρ) and the weight (W) of the electrode sheet 12
The volume (W / ρ) of the solid portion of the electrode sheet 12 is determined by the volume of the entire film.
It is obtained from the following equation of subtracting from the product V. V₀ = V- (W / ρ)

The porosity and the maximum pore diameter of the electrode sheet 12 can be adjusted by the type of activated carbon as a constituent material of the electrode sheet 12, the amount of binder, the roll pressure at the time of preparing the electrode sheet, and the like.

The conductive adhesive constituting the conductive adhesive layer 13 is made of conductive carbon and a binder. The conductive adhesive layer 13 can exist in a form of entering the holes 12a of the electrode sheet 12 by using the conductive adhesive liquid dispersed in the dispersion medium, and after removing the dispersion medium, by an anchor effect, The joining strength between the current collector 11 and the electrode sheet 12 can be improved. In addition, the conductive adhesive layer 13
Due to the unevenness of the surface of the electrode sheet 12, the air gap exists at the contact interface with the current collector 11 so as to fill the gap (air section). As a result, the volume of the air section interposed at the contact interface decreases. Thus, a decrease in the internal resistance of the polarizable electrode body 10 can be prevented.

The conductive carbon used in the conductive adhesive is graphite exhibiting high electrical conductivity due to the presence of delocalized π electrons; several layers of graphite carbon microcrystals form a turbostratic structure. Carbon black as a spherical aggregate that has been obtained; pyrolytic graphite obtained by thermally decomposing hydrocarbons such as methane, propane, and acetylene in the gas phase and depositing them in a thin film state on a blackboard serving as a substrate can be used. . Of these,
Graphite and carbon black are preferably used. As carbon black, acetylene black having a high structure and excellent electrical conductivity is preferably used.

The average particle size of such conductive carbon is 0.1.
It is preferably from 5 to 50 μm. Average particle size is 50μ
If it is larger than m, most of the conductive carbon particles cannot enter the pores 12a of the electrode sheet 12, so that not only an increase in bonding strength due to the anchor effect cannot be expected,
This is because it is difficult to achieve the penetration required to reduce the internal resistance. When the thickness is less than 0.5 μm, most of the conductive carbon particles can enter deep into the pores 12 a of the electrode sheet 12, so that the conductive carbon hardly remains at the interface between the current collector 11 and the electrode sheet 12. This is because the bonding strength cannot be improved. In addition, the conductive carbon is the electrode sheet 1
2, the pores of the activated carbon forming the electrode sheet 12 are covered with the conductive carbon, and as a result, the specific surface area of the activated carbon decreases, that is, the activity decreases. This is because the capacitor performance is reduced.

The binder used for the conductive adhesive is water glass; cellulose derivatives such as sodium salt or ammonium salt of carboxymethyl cellulose; polyvinyl alcohol, polyvinyl butyral, polyvinyl acetate, polybis (polybutene). And the like.

The degree to which the conductive adhesive layer 13 composed of the conductive adhesive having the above configuration enters the hole portion 12a of the electrode sheet 12 (the degree of entry) depends on the electrode sheet 1
0.15% or more, preferably 0.25
% Or more and 30% or less, preferably 15% or less.
If the electrode sheet 12 can penetrate only to a depth of less than 0.15% with respect to the thickness of the electrode sheet 12, no improvement in bonding strength due to the anchor effect can be obtained.
This is because an air layer may intervene between the conductive adhesive layer 2 and the conductive adhesive layer 13 and cause an increase in internal resistance. On the other hand, when the electrode sheet 12 has penetrated to a depth of more than 30% with respect to the thickness of the electrode sheet 12, the bonding strength is improved, but the inside of the pores of the activated carbon constituting the electrode sheet is electrically conductive adhesive. Is too high, the specific surface area of the activated carbon decreases, and the activity decreases, and as a result, the capacitance decreases.

The degree of penetration (%) referred to in the present specification means that the electrode sheet can be obtained by cutting an arbitrary portion of the polarizable electrode body 10 in the thickness direction with a cutter and observing the cross section with an electron microscope. Of the average distance (t) between the tip of the conductive adhesive layer 13 on the side of the electrode sheet 12 and the tip of the electrode sheet 12 on the side of the conductive adhesive layer 13 relative to the average thickness (T) of the sample 12 [(t / T) × 100]. The degree of penetration of the conductive adhesive layer 13 into the hole portion 12a of the electrode sheet 12 is determined by the maximum hole diameter of the electrode sheet 12, the amount of the conductive adhesive, the pressure applied when the electrode sheet 12 and the current collector 11 are laminated, and the like. Can be adjusted as appropriate.

The current collector 11 is preferably made of a metal such as aluminum, stainless steel, titanium, and tantalum. These metals may be in any shape of foil, plate, or sheet. In the polarizable electrode of the present invention, a metal foil having a flat surface, a thin metal plate, a metal sheet, or the like can be used as the current collector. As shown in FIG. 1, the current collector 11 and the electrode sheet are used. The gap existing at the interface is filled with the conductive adhesive 13 for the point contact with the electrode 12 so that the air layer can be less intervened, and the conductive adhesive 13 can further enter the holes 12 a of the electrode sheet 12. Thereby, it is possible to improve the joining strength by the anchor effect.

A more preferable current collector 11 is a metal foil, a thin metal plate, or a metal sheet which is roughened so as to have irregularities on the surface. Examples of the method of surface roughening include sand blasting and etching. In particular, a method of chemical etching using a chemical agent is suitable for the anchor effect of the adhesive because pores and irregularities formed on the current collector surface are suitable. It is preferable because it is.

FIG. 2 shows a polarizable electrode using a current collector whose surface is roughened so as to have irregularities. In the polarizable electrode body 10 ′, not only the part of the conductive adhesive constituting the conductive adhesive layer 13 enters the holes 12 a of the electrode sheet 12, but also the concave portions of the current collector 11 ′. 11'a, and the joint strength between the two can be improved.
In this case, the conductive adhesive that has entered the concave portion 11'a eliminates air existing in the concave portion, prevents an increase in electric resistance due to the interposition of the electrolytic solution when the capacitor is used, and prevents the current collector 11 'from being electrically conductive. It can also contribute to improving the bonding strength between the adhesive layer 13 and the electrode sheet 12.

When a current collector 11 'having a roughened surface having irregularities is used, the polarizer having a structure as shown in FIG. 3 is used depending on the amount of the conductive adhesive and the pressure applied during lamination. An electrode body 10 ″ can also be obtained. That is, as a whole of the polarizable electrode body 10 ″, the conductive adhesive layer 13 is interposed between the current collector 11 ′ and the electrode sheet 12. The portion 11 ′ b is in contact with the projection of the electrode sheet 12. In such a case, the internal resistance can be further reduced. That is, as a conductive path, a path (indicated by an arrow A in FIG. 3) that conducts from the current collector 11 ′ to the electrode sheet 12 via the conductive adhesive layer 13, and a path directly from the current collector 11 ′ to the electrode sheet 12. Thus, two types of paths are formed, namely, a path that is conducted to the path (indicated by an arrow B in FIG. 3). Since the path B has a lower electrical resistance than the path A, the formation of the two types of conductive paths A and B in this way can further reduce the internal resistance and increase the electric power output. A multilayer capacitor can be provided.

The polarizable electrode having the above configuration can be manufactured by the following method.

First, a conductive adhesive liquid prepared by dispersing a conductive adhesive in a dispersion medium is prepared. Here, as a dispersion medium for preparing the conductive adhesive liquid, water, a lower alcohol or the like is used, and the concentration of the conductive carbon is 20 to 30% by weight.
It is preferable to prepare so that Specifically, a conductive adhesive liquid having a composition as shown in Table 1 is preferably used. It is preferable to appropriately select these and use them at a concentration of 1 to 30 times.

[0038]

[Table 1]

The prepared conductive adhesive solution is applied to at least one surface of the electrode sheet and the current collector. The coating may be applied to either one of the electrode sheet and the current collector, or may be applied to both. However, a more preferable method is a method of applying to the bonding surface of the current collector. Since the surface of the electrode sheet is actually an aggregate of powder and the surface has irregularities throughout,
When the conductive adhesive liquid is applied to the electrode sheet side,
The conductive adhesive liquid penetrates into the pores of the electrode sheet, and the penetration rate of the conductive adhesive into the pores of the electrode sheet depends on the penetration degree suitable for improving the bonding strength and reducing the internal resistance. It is because it exceeds. Further, even in consideration of mass productivity, it is preferable to apply to a current collector having a higher strength than an electrode sheet.

The coating amount of the conductive adhesive solution is 2 to 2 in terms of the conductive adhesive amount (total amount of conductive carbon and binder).
It is preferably about 15 g / m ² , more preferably 3 to 10 g / m ^2.
g / m ² . Although depending on the pressure at the time of lamination in the next step, generally, the larger the amount of coating, the larger the thickness of the conductive adhesive layer to be formed. When used, a polarizable electrode body as shown in FIG. 2 is obtained.

Next, the polarizable electrode material sheet and the current collector are overlapped via the applied conductive adhesive liquid to form a laminate. There are various methods of laminating,
Although they may be simply superimposed, it is preferable to compress them by passing them between rolls or the like so as to securely bond the lamination interfaces. In the case where a roughened metal foil is used as the current collector, by appropriately controlling the application amount of the conductive adhesive and the lamination pressure, as shown in FIG.
It is possible to obtain a polarizable electrode body in which the projections of the current collector and the projections of the metal sheet are in contact with each other.

Next, the dispersion medium is removed from the conductive adhesive liquid layer of the obtained laminate. Although various removal methods are conceivable, a method of removing the dispersion medium using hot air drying is preferably employed. The temperature of the hot air may be selected at a temperature near the boiling point of the dispersion medium. By removing the dispersion medium by drying or the like, it becomes a conductive adhesive composed of a binder and conductive carbon, and plays a role of bonding the current collector and the electrode sheet.

In this manner, a polarizable electrode body (see FIGS. 1 to 3) in which an electrode sheet is laminated and integrated on both sides of the current collector via the conductive adhesive layer is manufactured. You.
2 and 3 illustrate only one side of the current collector.

The polarizable electrode body having the above-described structure has a high bonding strength between the current collector and the electrode sheet. Therefore, a long polarizable electrode body is prepared, wound and stored in a roll. It can be transported, and is excellent in the manufacture, storage and transportability and durability of polarizable electrode bodies. Moreover, in the polarizable electrode body, the amount of air interposed between the current collector and the electrode sheet can be reduced as compared with the related art, so that the internal resistance is small.

In the electric double layer capacitor of the present invention, a plurality of combinations (see FIG. 4) in which the polarizable electrode bodies 10 and the separators 15 shown in FIG. And an electrolyte solution is filled between them. As the separator 15, a separator conventionally used for an electric double layer capacitor can be used. Specifically, a porous sheet made of polytetrafluoroethylene, polyethylene, polypropylene, or the like is made hydrophilic; Porous sheet and the like.

In FIG. 4, reference numeral 9 denotes a current collecting terminal attached to the current collector, and a current collecting lead is attached to the current collecting terminal 9. Although the electric double layer capacitor element shown in FIG. 4 is an example using the polarizable electrode body 10, the polarizable electrode body 1
The same configuration can be made using any of 0 ′ and 10 ″. Further, the plurality of polarizable electrode bodies arranged in parallel may be all the same type, or different types of polarizable electrode bodies may be arranged in parallel.

Further, of the plurality of polarizable electrode bodies arranged in parallel, as for the polarizable electrode body provided at the end, as shown in FIG. 5, an electrode sheet is laminated only on one side of the current collector. A polarized electrode body can be used.

Since the electric double layer capacitor of the present invention uses the polarizable electrode body of the present invention having a small internal resistance, it can exhibit a small size, a high electric capacity and a high output density.

[0049]

The present invention will be described below in more detail with reference to examples.

Example 1 Activated carbon powder (specific surface area 2200
Ethanol was added to a mixture consisting of 85% by weight, 7% by weight of Ketjen black, and 8% by weight of polytetrafluoroethylene, and kneaded with a mixture comprising 85% by weight of m ² / g and an average particle size of 7 μm.
By rolling, width 10 cm, thickness 0.8 mm, porosity 6
A 6% long electrode sheet having a maximum pore diameter of 18 μm was obtained. As the current collector, a high-purity aluminum foil having a thickness of 50 microns and a width of 15 cm was used. As the conductive adhesive, a conductive adhesive liquid in which natural graphite (average particle diameter: 3 μm) as conductive carbon and carboxymethylcellulose Na salt as binder are dispersed in a dispersion medium is prepared and manufactured. Was served. The prepared conductive adhesive liquid contains 30% by weight of conductive carbon, 8% by weight of binder, 60% by weight of water, and 2% by weight of ammonia.
% By weight.

A conductive adhesive solution was applied to both sides of the current collector with a coating roll such that 4 cm or more was left at one end in the width direction of the current collector. The amount of the conductive adhesive liquid applied is 20 g / m ^2.
(7 g / m ² when converted to the amount of conductive adhesive corresponding to the total amount of conductive carbon and binder). After the application, the above-mentioned long electrode sheet was overlaid on the application portion (both sides) of the current collector, and then passed through a compression roll to obtain a laminated sheet in which the contact interfaces were securely bonded to each other. Thereafter, the laminated sheet was passed through a continuous hot-air dryer set at a drying temperature of 110 ° C. to remove the dispersion medium from the conductive adhesive liquid layer, thereby obtaining a long polarizable electrode body. The passing speed in the dryer is a speed at which the dryer enters the dryer for 3 minutes.

The long sheet-like polarizable electrode body is
Punched into a square cm shape to form a rectangular polarizable electrode body,
A current collector terminal of 2 cm × 4 cm was attached to the current collector portion of each polarizable electrode body. Then, a combination of a polarizable electrode body and a separator as shown in FIG. 4 was produced, and 13 units of the total of this combination were juxtaposed as shown in FIG. In this state, after vacuum drying at 200 ° C. for 3 hours, it was stored in an aluminum case 20. And
A current collecting lead 23 was attached to each current collecting terminal, a positive electrode terminal and a negative electrode terminal were further attached to the current collecting lead, and a 1 molar concentration of propylene carbonate solution of tetraethylammonium tetrafluoroborate was injected as an electrolyte 22. Then, the upper cover 21 was attached and the case 20 was sealed to produce a rectangular electric double layer capacitor.

Further, the 10 cm square polarizable electrode body prepared above was cut at an arbitrary position in the thickness direction, and the cut surface was observed under a microscope to determine the penetration of the conductive adhesive.

Example 2 The composition of the conductive adhesive solution was changed to 30% by weight of acetylene black (average particle size: 40 μm), 8% by weight of carboxymethyl cellulose sodium salt, 60% by weight of water, and 2% by weight of ammonia. A rectangular electric double layer capacitor was produced in the same manner as in Example 1 except that the penetration of the conductive adhesive of the polarizable electrode body was determined.

Examples 3 and 4: Using an aluminum foil roughened by etching as a current collector (Example 3)
Except that the aluminum foil roughened by etching was used for the current collector and the coating amount in terms of the conductive adhesive was changed to 3.5 g / m ² (Example 4), A rectangular electric double layer capacitor was prepared, and the penetration of the conductive adhesive of the polarizable electrode body was determined.

Comparative Example 1: The composition of the conductive adhesive solution was 30% by weight of natural graphite (particle size: 80 μm), 8% by weight of carboxymethyl cellulose sodium salt, 60% by weight of water, and 2% by weight of ammonia.
A rectangular electric double layer capacitor was manufactured in the same manner as in Example 1 except that the weight% was changed.

Further, when a cut surface obtained by cutting an arbitrary portion of the fabricated polarizable electrode body in the thickness direction was observed with a microscope, it was found that the conductive carbon (natural graphite) had a large particle diameter, so that the pores of the electrode sheet were often used. Could not enter.

Comparative Example 2 A rectangular electric double layer capacitor was prepared in the same manner as in Example 1 except that the electrode sheet was changed to an electrode sheet having a width of 10 cm, a thickness of 0.8 mm, a porosity of 66%, and a maximum pore diameter of 30 μm. And the degree of penetration of the conductive adhesive of the polarizable electrode body was determined.

Comparative Example 3 A high-purity aluminum foil having a roughened metal foil surface was used as a current collector, and the electrode sheets were directly laminated on both surfaces without a conductive adhesive therebetween. A rectangular electric double layer capacitor was produced in the same manner as in Example 1 except that a laminated sheet formed by roll rolling was used.

Comparative Example 4: SW (short width) is 1.0 mm, L
W (long width) is 2.0 mm and St (strand width) is 0.2 mm.
A high-purity aluminum expanded metal having a thickness of 23 mm and t (original plate thickness) of 80 microns is used as a current collector.
A rectangular electric double layer capacitor was produced in the same manner as in Example 1 except that a laminated sheet formed by roll rolling so that electrode sheets were laminated was used.

With respect to the electric double layer capacitors produced in Examples 1 to 4 and Comparative Examples 1 to 4, the capacitance and the internal resistance were measured. Table 2 shows the results.

[0062]

[Table 2]

As can be seen from Table 2, the electric double layer capacitor using the polarizable electrode body of the present invention in which the degree of penetration of the conductive adhesive is within a predetermined range is smaller than the electric double layer capacitor of the comparative example. Resistance was small. In particular, in Example 4 in which the surface was roughened and the amount of the conductive adhesive applied was reduced, the internal resistance was reduced. This is because the conductive adhesive layer is thin enough to allow the protrusions of the current collector and the protrusions of the electrode sheet to come into direct contact.

On the other hand, a polarizable electrode body without a conductive adhesive layer (Comparative Examples 3 and 4) and a polarizable electrode body without a conductive adhesive entering pores of an electrode sheet (Comparative Example 1) ), An electric double layer capacitor using a polarizable electrode body (Comparative Example 2) in which the degree of penetration of the conductive adhesive is too large and the conductive adhesive is considered to be not much left at the interface between the current collector and the electrode sheet. Has increased internal resistance. In any case, it is considered that the liquid space interposed at the contact interface between the current collector and the electrode sheet was increased. Further, in Comparative Example 2, since the conductive adhesive penetrated deep into the pores of the electrode sheet, many of the pores of the activated carbon constituting the electrode sheet were covered with the conductive adhesive. It is considered that the electric capacity has decreased.

[0065]

The polarizable electrode body of the present invention has excellent bonding strength between the current collector and the electrode sheet, so that it can be manufactured as a long sheet, and is excellent in mass productivity and storage and transportability. In addition, since there is little air interposed at the contact interface between the current collector and the electrode sheet, the internal resistance is small.

Therefore, the electric double layer capacitor using the polarizable electrode body of the present invention is a high performance electric double layer capacitor which is excellent in productivity, small in size, high in electric capacity and high in output density.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a polarizable electrode body of the present invention.

FIG. 2 is a schematic view showing a configuration of one side of a polarizable electrode body according to claim 4;

FIG. 3 is a schematic view showing a configuration of one side of a polarizable electrode body according to claim 5;

FIG. 4 is a diagram showing a configuration in which a polarizable electrode body of the present invention and a separator are combined.

FIG. 5 is a diagram showing a state in which a plurality of electric double layer capacitor elements are arranged in parallel.

FIG. 6 is a schematic diagram showing a configuration of an electric double layer capacitor according to one embodiment of the present invention.

FIG. 7 is a schematic view showing a configuration of a conventional polarizable electrode body.

[Explanation of symbols]

 10, 10 ', 10' 'Polarized electrode body 11, 11' Current collector 12 Electrode sheet 12a Void 13 Conductive adhesive layer 15 Separator

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yuichi Okada 1-42-5 Akatsutsumi, Setagaya-ku, Tokyo Inside Japango Tex Co., Ltd.

Claims (12)

[Claims] 1. A polarizable electrode body in which a porous electrode sheet mainly composed of activated carbon is laminated on both sides of a current collector, wherein the current collector and the electrode sheet contain conductive carbon and a binder. Laminated via a conductive adhesive layer containing, a part of the conductive adhesive layer has penetrated into the pores of the electrode sheet, and the degree of penetration is relative to the thickness of the electrode sheet. 0.15 to 30%. 2. The electrode sheet according to claim 1, wherein said electrode sheet has a maximum pore diameter of 0.5 to 2.
The polarizable electrode body according to claim 1, which has a thickness of 0 µm. 3. The electrode sheet has a porosity of 40 to 90.
% Of the polarizable electrode body according to claim 1. 4. The current collector comprises at least one selected from the group consisting of aluminum, stainless steel, titanium and tantalum.
The polarizable electrode body according to any one of claims 1 to 3, wherein the seed metal is formed in any one of a foil shape, a plate shape, and a sheet shape. 5. The current collector is made of a metal foil, a metal thin plate, or a metal sheet whose surface is formed of a surface having irregularities, and is provided between the current collector and the electrode sheet. The polarizable electrode body according to any one of claims 1 to 4, wherein a part of the formed conductive adhesive layer enters a concave portion of the current collector. 6. The polarizable electrode body according to claim 5, wherein a part of the projection of the current collector is in contact with the electrode sheet. 7. The polarizable electrode body according to claim 5, wherein the current collector is a metal foil, a metal sheet, or a metal sheet roughened by etching. 8. The polarizable electrode body according to claim 1, wherein said conductive carbon is graphite or carbon black. 9. The conductive carbon has an average particle size of 0.5 to 5
The polarizable electrode body according to any one of claims 1 to 8, which has a thickness of 0 µm. 10. The polarizable electrode according to claim 1, wherein the binder is at least one selected from the group consisting of a thermoplastic resin, a cellulose derivative, and water glass. 11. A polarizable electrode body according to claim 1, wherein a plurality of polarizable electrode bodies are arranged in parallel, a separator is interposed between adjacent polarizable electrode bodies, and an electrolytic solution is provided between the polarizable electrode body and the separator. An electric double layer capacitor characterized by being filled with a liquid. 12. A step of applying a conductive adhesive liquid obtained by dispersing a conductive adhesive in a dispersion medium to a surface of an electrode sheet and / or a current collector; Interposing the electrode sheet and the current collector through:
And removing the dispersion medium from the conductive adhesive liquid layer existing between the superposed electrode sheet and the current collector;
A method for producing a polarizable electrode body, comprising: