JP2000294460A - Manufacture of electric double layer capacitor electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an electrode which is capable of profitably restraining an active layer from being separated. SOLUTION: An electric double layer capacitor electrode is manufactured through this method which comprises a kneading process where coating material is formed by kneading a main component composed of an active material which is possessed of a large number of fine holes and large in specific surface area, water and organic high-molecular binder, and a coating process where the coating material is applied on a current collector 2 and dried up to serve as an active layer. In this case, when coating material is formed through a kneading process, active material, water and binder are collectively kneaded into coating material when the average molecular weight of binder is smaller than 20,000. When the average molecular weight of binder is larger than 20,000, active material and water are kneaded into a first kneaded material, and then the first kneaded material and binder are kneaded into coating material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing an electrode for an electric double layer capacitor.

[0002]

2. Description of the Related Art In recent years, electric double layer capacitors have been developed. The electric double-layer capacitor physically charges an active material having a large number of pores and a large specific surface area to charge the battery or discharges the charge to discharge the battery. FIGS. 7A and 7B are conceptual diagrams of the electric double layer capacitor.
FIG. 7A shows a state during charging, and FIG. 7B shows a state during discharging. As shown in FIG. 7A, at the time of charging for accumulating electric charges, the anion of the electrolytic solution is attracted to the positive electrode 100 having the pores 100a and the negative electrode 2 having the pores 200a.
At 00, the cations of the electrolyte are attracted. At the time of discharging for discharging the accumulated charges, as shown in FIG.
Anions are desorbed from 00 and cations are desorbed from the negative electrode 200.

An electric double layer capacitor has a large electric capacity and a high stability against repeated charging and discharging, and is being widely used for applications such as a power supply used for vehicles and electric equipment. By the way, in the above-mentioned electric double layer capacitor, activated carbon having pores, an organic polymer-based binder (generally methylcellulose) and water are kneaded as main components in manufacturing the electrodes to be the positive electrode 100 and the negative electrode 200. A kneading step of forming a paste-like or slurry-like coating material is performed. Thereafter, a coating material is coated on the current collector and dried to perform a coating process of forming an active material layer. In this way, an electrode for an electric double-layer capacitor constituted by laminating an active material layer on a current collector is manufactured.

Japanese Patent Publication No. 2507125 discloses that a mixed solution in which activated carbon powder, acetylene black, water and methanol are uniformly dispersed is formed in preparing an electrode for an electric double layer capacitor. A method is disclosed in which a mixed solution in which methylcellulose is dissolved in water is formed, and then both mixed solutions are kneaded and stirred to form a slurry or paste-like coating material. This publication does not focus on the average molecular weight of carboxymethylcellulose as a binder.

[0005]

However, the active material layer applied to the current collector may peel off. When peeling occurs in the active material layer, the performance of the electric double layer capacitor is reduced. In order to suppress the separation of the active material layer, the amount of the binder may be increased. However, since the binder itself has extremely low conductivity, the internal resistance of the electric double layer capacitor increases. Furthermore, the ratio of activated carbon is relatively reduced. Therefore, the performance of the electric double layer capacitor is reduced.

The present invention has been made in view of the above circumstances, and has as its object to provide a method of manufacturing an electrode for an electric double layer capacitor which is advantageous for suppressing the separation of an active material layer.

[0007]

The present inventor has been diligently developing an electrode for an electric double layer capacitor in order to achieve the above object. The present inventor has found that the water containing the organic polymer binder penetrates into the pores of the activated carbon and is adsorbed, so that the amount of the organic polymer binder that can provide the binding force is relatively reduced, and The peel resistance of the material layer is reduced, and if the kneading form of the activated carbon and the binder is changed according to the average molecular weight of the organic polymer binder, it is effective to improve the peel resistance of the active material layer. Was found.

That is, if the average molecular weight of the binder is 200,000 or less, it is easy to ensure the peeling resistance of the active material layer with respect to the current collector, and the average molecular weight of the binder is more than 200,000. Also, it has been found that kneading the binder after previously kneading the activated carbon and water to mix them is effective in suppressing the separation of the active material layer. In other words, when the average molecular weight of the organic polymer-based binder is 200,000 or less, activated carbon, water, and the binder are kneaded together to form a coating material. When the average molecular weight of the binder exceeds 200,000, a first kneaded material obtained by kneading activated carbon and water is formed, and then the first kneaded material and the binder are kneaded to form a coating material.

The average molecular weight of the organic polymer binder is 2
The reason why it is effective to suppress the separation of the active material layer when it is less than or equal to 10,000 is not clear, but is presumed as follows. That is, it is presumed that the number of ends of the polymer chains of the binder affects the boundary bonding strength at the boundary between the active material layer and the current collector. It is presumed that the end of the polymer chain constituting the binder functions as a binding action point on the surface of the current collector. Therefore, if the average molecular weight of the binder is reduced to 200,000 or less, although the length of the polymer chains of the binder is relatively short, the number of the polymer chains of the binder relatively increases. Therefore, it is presumed that the number of ends that can contribute as a binding action point of the polymer chain relatively increases, and that the boundary bonding strength at the boundary between the active material layer and the current collector is easily improved.

[0010] Even if the average molecular weight of the binder exceeds 200,000, the kneading of the binder after the active carbon and water are kneaded in advance and the two are blended together improves the peeling resistance of the active material layer. The reason is presumed as follows. That is, when the binder for binding the components constituting the electrode of the electric double layer capacitor, activated carbon and water are kneaded together, water containing the binder easily permeates into the pores of the activated carbon and is adsorbed. Therefore, the binder is reduced. Therefore, if the activated carbon and water are kneaded in advance in a state where the binder does not coexist and the pores of the activated carbon and the water are blended in, the water containing the binder can be suppressed from adsorbing on the activated carbon pores, and the binder is reduced. It can be inferred that the bonding force for bonding the components of the electrode can be secured.

That is, the method of manufacturing an electrode for an electric double layer capacitor according to the present invention comprises kneading an active material having a large specific surface area having a large number of pores, water and an organic polymer binder as main components. A kneading step of forming a coating material,
In a manufacturing method of manufacturing an electrode for an electric double layer capacitor through a coating step of coating a coating material on a current collector and drying to form an active material layer, in forming a coating material in a kneading step, an average molecular weight of a binder When the average molecular weight of the binder exceeds 200,000, the first mixture of the active material, water, and water is kneaded together to form a coating material. A kneading material is formed, and thereafter, the first kneading material and a binder are kneaded to form a coating material.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the method of the present invention, activated carbon is a representative active material having pores. The activated carbon may be in the form of powder, granules, or fibrous,
Therefore, coconut shell activated carbon, wood-based activated carbon, coal-based activated carbon,
A known activated carbon such as an activated carbon made of a resin can be appropriately selected. The specific surface area of the active material such as activated carbon per gram weight can be appropriately selected according to the type of the electric double layer capacitor.
And 3000 ² / g, it is possible in particular to employ the 1500~3000m ² / g. However, it is not limited to these. In this specification, the characteristics of the pores are determined by the BET method (Br
unauer-Emmett-Teller).

As a pore volume having a pore diameter of 1.7 nm to 300 nm, a large pore volume can be adopted. The pore volume having a pore diameter from 1.7 nm to 300 nm is, for example, 0.2 cm ³ / g to 1 c
An active material such as m ³ / g of activated carbon can be employed. In particular, an active material having a pore volume of 0.3 cm ³ / g or more and 0.4 cm ³ / g or more can be employed. it can. The pores of such an active material such as activated carbon have a relatively large size.

The organic polymer binder is for binding the active material, and at least one of methyl cellulose, carboxymethyl cellulose, ethyl cellulose, carboxyethyl cellulose and the like can be employed, but methyl cellulose is a typical one. is there. The coating material serving as the active material layer has, as its main components, an active material having pores and capable of accumulating electric charge and having a large specific surface area, and a binder binding these. Further, it is also preferable to mix a conductive material in the coating material in order to increase the conductivity in the active material layer. Carbon black, metal powder, or the like can be used as the conductive material.

The mixing ratio of the active material such as activated carbon is 70 to 90 parts by weight, and the binder is 5 to 15 parts.
The ratio by weight of the conductive material is 5 to 15 parts by weight. However, it is not limited to this mixing ratio. It is preferable that the binder be reduced as much as possible in order to reduce the internal resistance of the electric double layer capacitor if the peeling resistance can be ensured with the compounding ratio in the coating material.

In the method of the present invention, the coating material can be in the form of a slurry or a paste. In the method of the present invention, an active material layer is formed by applying a coating material to the surface of the current collector and drying the same. The coating material may be applied to one side of the current collector, or may be applied to both sides of the current collector. Printing can be employed as the application method, and known application methods such as a doctor blade method, a screen printing method, and a spin coating method can be employed.

The electrode manufactured as described above may be housed in a roll-wound state in a case of an electric double layer capacitor, or may be cut into a predetermined length and applied in a large number to form an electric double layer capacitor. May be accommodated in the case. The electrode manufactured as described above may be used as a positive electrode or a negative electrode in an electric double layer capacitor.

In the electric double layer capacitor according to the present invention, an electrolytic solution in which an electrolyte is dissolved in a solvent can be used. The solvent is not particularly limited, and a known solvent can be used, and propylene carbonate, ethylene carbonate, tetrahydrofuran, dimethoxyethane, and the like can be used. The electrolyte is not particularly limited, and a known electrolyte can be used, and examples thereof include a salt of a cation and an anion. Examples of the electrolyte include LiBF ₄ , LiPF ₆ , LiClO ₄ , (C
_{2 H 5) 4 NBF 4,} (CH 3) 4 NBF 4, CH 3 (C 2 H 5)
₃ NBF _{4 and the} like.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be specifically described below with reference to Embodiments 1 and 2. Embodiment 1 Embodiment 1 is intended for a case where the average molecular weight of cellulose as a binder is relatively large. FIG. 1 is a flowchart showing the manufacturing process. As can be understood from FIG.
The pre-kneaded material and the second pre-kneaded material were separately formed. That is, the first pre-kneaded material was formed into a paste by pre-kneading activated carbon functioning as an active material and water in a vacuum atmosphere. The second pre-kneaded material was formed into a paste by pre-kneading carbon black, water, and methyl cellulose functioning as a binder in a vacuum atmosphere.

The average molecular weight of the binder, methylcellulose, was about 300,000 as measured by GPC.
GPC means gel-permeation chromatography. When a polymer solution is flowed through a column packed with fine swollen gel particles, GPC starts from a high molecular weight section and gradually decreases. The molecular weight is measured by using the performance of the molecular weight fraction flowing out. The average molecular weight was determined from the GPC results based on a known standard sample.

Table 1 shows the mixing ratio of the first pre-kneaded material and the second pre-kneaded material. As shown in Table 1, the first pre-kneading material did not contain methyl cellulose as a binder, and the activated carbon was 24 g and the water was 72 g by weight.
Activated carbon was not contained in the second pre-kneading material 2, and carbon black was 3 g, methyl cellulose was 3 g, and water was 75 g in weight.

[0022]

[Table 1] In performing the above-described kneading, a planetary ball mill is used as a kneading machine, and a menor pot is used as a storage pot (volume: 5).
00cc), and a menor ball (diameter: 10 mm) was used.

Next, the first pre-kneaded material and the second pre-kneaded material were fully kneaded in a vacuum atmosphere to form a paste-like coating material. Table 2 shows the kneading time and the degree of vacuum during kneading.

[0024]

[Table 2] The coating material after the main kneading was subjected to a defoaming treatment. The defoaming treatment was performed by stirring with a propeller for 15 minutes in a vacuum atmosphere of -70 cmHg.

Thereafter, the paste-like coating material formed as described above was applied to the surface of the current collector (aluminum foil) by a doctor blade method so as to have a coating thickness of about 100 μm. Thereafter, drying was performed at a target temperature of 140 ° C. for 10 minutes, whereby an active material layer was formed on the current collector. FIG. 2 shows a manufacturing facility 1 for applying an application material formed as described above to obtain an active material layer. As shown in FIG. 2, the manufacturing equipment 1 includes an unwinding roller 3 that continuously unwinds the current collector 2,
A coating device 5 for coating and applying the coating material 4 thereon; and a drying furnace 6 for drying the coating material 4 on the current collector 2 to form an active material layer 8.
A winding roller 7 for winding the current collector 2 on which the active material layers 8 are stacked; and guide rollers 7a to 7e for guiding the current collector 2.
And

Fine irregularities are formed on the surface of the current collector 2 by etching to improve the bonding property of the active material layer 8. The surface roughness of the fine irregularities is about 2-3 μm. According to the manufacturing equipment 1 described above, the coating material 4 is coated by the coating device 5 on the current collector 2 moving in the direction of the arrow X1. The coating material 4 is dried by the drying furnace 6 to form the active material layer 8. FIG. 3 shows a cross section of the electrode manufactured as described above. As shown in FIG. 3, an active material layer 8 is laminated on the current collector 2.

In the first embodiment, as described above, the average molecular weight of the binder methyl cellulose is about 300,000. When methyl cellulose having a large average molecular weight is used, activated carbon and water are preliminarily kneaded to make the first mixture.
A pre-kneaded material (containing no vitander) was formed, and a second pre-kneaded material (containing no activated carbon) was formed by pre-kneading methyl cellulose, carbon black, and water.

Thereafter, the first pre-kneaded material and the second pre-kneaded material were fully kneaded, so that activated carbon and methylcellulose were united to form a coating material 4. That is, in the form 1, the activated carbon was brought into contact with water after the activated carbon was brought into contact with water to allow the two to blend in. If the coating material 4 formed by contacting the activated carbon with methylcellulose after the activated carbon and water are contacted as described above is used, the peeling resistance of the active material layer 8 applied on the current collector 2 is improved. Could be improved.

The reason why the peel resistance of the active material layer 8 is improved is presumed as follows. That is, when methyl cellulose, which is a binder for binding the components constituting the electrode of the electric double layer capacitor, activated carbon and water are kneaded together, water containing methyl cellulose penetrates into the pores of the activated carbon. Due to the adsorption, the amount of methyl cellulose that can function as a binder is reduced. Therefore, as in Embodiment 1, if activated carbon and water are previously kneaded in a state where methylcellulose does not coexist, and the pores of the activated carbon are blended with water, water containing methylcellulose penetrates into the activated carbon pores and is adsorbed. It can be inferred that the reduction in the amount of methylcellulose that can function as a binder can be suppressed, and the binding force of the components of the electrode can be secured.

The present inventor examined the peeling resistance of the active material layer 8 by attaching the adhesive tape to the active material layer 8 on the current collector 2 and then peeling the adhesive tape. In the active material layer 8 according to the embodiment 1, the test evaluation was ○, and no or almost no peeling of the active material layer 8 was observed.
A similar peel test was performed on Comparative Example 1. In Comparative Example 1, the same methylcellulose (average molecular weight: about 300,000) as in Embodiment 1 was kneaded together in a state where activated carbon, methylcellulose, carbon black, and water coexisted to form a paste-like coating material. . In the active material layer formed of the coating material according to Comparative Example 1, the test evaluation was x,
It peeled off from the interface between the current collector aluminum foil and the electrode, and no active material layer remained on the aluminum foil.

The activated carbon used in the embodiment 1 has a specific surface area of about 2600 m ³ / g. nm to 300 nm
The volume of the pore size up to about 0.71 cm ³ / g.
On the other hand, general activated carbon conventionally used has a specific surface area of about 2000 m ³ / g, and is 1.7 nm to 300 n.
The pore size volume up to m was about 0.2 cm ³ / g.
Thus, the activated carbon used in Embodiment 1 has a large pore volume as compared with conventional activated carbon while maintaining a large specific surface area. In such activated carbon, it is easy to secure the mobility of the electrolyte ions in the pores while securing the amount of electrolyte ions adsorbed on the activated carbon. In particular, it is easy to secure the mobility of electrolyte ions at low temperatures. Therefore, it is possible to contribute to securing the performance of the electric double layer capacitor at a low temperature.

In the case of such an activated carbon having a large pore volume, although having the above-mentioned advantages, the size of the pore itself is large, so that unlike the conventional activated carbon having a small pore size, methylcellulose is used. It is presumed that the water contained easily permeates into the pores, and the loss of methylcellulose that can function as a binder is greater than that of other activated carbons. Therefore, if the activated carbon and water are preliminarily kneaded in a state where methylcellulose does not coexist as in the form 1, and the pores of the activated carbon and water are blended in advance, it is possible to suppress the penetration of methylcellulose into the pores of the activated carbon, It is presumed that the amount of methylcellulose that can function as a binder can be secured, and the binding of the electrode constituent components is secured.

In the first embodiment, after the paste-like coating material 4 is prepared, the paste-like coating material 4 is not immediately applied to the current collector 2 but is left for about one week.
Was applied to the current collector 2, peeling of the active material layer 8 was observed. That is, if the paste-like coating material 4 according to the first embodiment is left without being applied to the current collector 2, it tends to deteriorate with time. The reason for the deterioration with time is presumed to be that the water containing the methyl cellulose as a binder gradually penetrates into the pores of the activated carbon while the coating material 4 is left, so that the methyl cellulose component functioning as a binder decreases. You. Therefore, it is preferable to apply the paste-like coating material 4 according to the first aspect to the current collector 2 within a short time after kneading. Therefore, it is preferable that the coating material 4 according to the first aspect is applied to the current collector 2 within 6 hours, preferably within 2 hours.

(Embodiment 2) Next, Embodiment 2 will be described. Form 2
Is for when the average molecular weight of the binder is relatively small.
In Form 2, the average molecular weight of methyl cellulose as a binder was about 100,000 as measured by GPC.
The activated carbon used in Embodiment 2 was of the same type as that used in Embodiment 1.

First, in the form 2, the activated carbon, carbon black, methylcellulose and water are kneaded all together in a vacuum atmosphere to form a paste-like coating material 4b.
(FIG. 4 shows a state where the coating material 4b is applied to the current collector 2).
Was formed. The mixing ratio according to the embodiment 2 was such that activated carbon was 24 g, carbon black was 3 g, methyl cellulose was 3 g, and water was 100 g by weight. The kneading time is 60 minutes,
The test was performed in a vacuum atmosphere of -70 cmHg. The kneading conditions were the same as in the first embodiment. That is, a planetary ball mill is used as a kneading machine, and a menor pot (500c) is used as a storage pot.
c), as the ball to be used, a ball made of Menor
m) was used.

The coating material 4b after kneading was subjected to a defoaming treatment. The defoaming treatment is performed at −70 as in the case of the first embodiment.
The stirring was performed with a propeller for 15 minutes in a vacuum atmosphere of cmHg. Then, as in the case of the first embodiment, as can be understood from FIG. 4, the paste-like coating material 4b formed as described above is applied to the surface of the current collector 2 by a doctor blade method so that the coating thickness becomes about 100 μm. Applied.
Thereafter, drying was performed at a target temperature of 140 ° C. for 10 minutes, whereby an active material layer 8 b was formed on the current collector 2. Fine irregularities are formed on the surface of the current collector 2 by an etching process to enhance the bonding property of the active material layer 8b. The surface roughness of the fine irregularities is about 2-3 μm.

As described above, according to the embodiment 2 in which methyl cellulose having a small average molecular weight of 100,000 or less is used as a binder, the length of the polymer chain of methyl cellulose is shortened, and the entangling property of the polymer chain is reduced. Although the crack resistance of the active material layer 8b on the current collector 2 was slightly reduced, the peel resistance of the active material layer 8b from the current collector 2 could be improved.

In other words, the present inventors examined the peeling resistance of the active material layer 8b by attaching the adhesive tape to the active material layer 8b on the current collector 2 and then peeling the adhesive tape. However, although damage occurs in the active material layer, the active material layer does not peel off from the interface of the aluminum foil, and the active material layer 8b according to mode 2
Was evaluated as, and the peeling resistance of the active material layer 8b was good.

After the paste-like coating material 4b manufactured as described above is left for one week, the coating material 4b is applied to the current collector 8 and dried. The present inventor examined the state of peeling of the active material layer by peeling off the adhesive tape after bonding. Also in this case, the test evaluation for the active material layer was ○, and no peeling of the active material layer was observed. That is, according to the form 2, in which methyl cellulose having an average molecular weight as small as about 100,000 is used as a binder and simultaneously kneaded with activated carbon or the like,
The problem of deterioration with time in the paste-like coating material 4b can be improved.

The reason why the separation resistance of the active material layer 8b is improved in the embodiment 2 is presumed as follows. That is, the active material layer 8
It is presumed that the boundary bonding strength at the boundary between b and the current collector 2 affects the number of polymer chain ends more than the binder polymer chain itself. This is because it is presumed that the ends of the polymer chains constituting the methylcellulose serve as the binding action points on the surface of the current collector 2. In Embodiment 2, the average molecular weight of methyl cellulose as a binder is 100,000 or less, which is lower than that in Embodiment 1. When the average molecular weight of the binder methylcellulose is thus low, as can be understood from FIG. 5, the polymer chains of the binder are relatively short, but the number of polymer chains of methylcellulose relatively increases. Therefore, the number of ends considered to be able to contribute as the binding action point of the polymer chain relatively increases. Therefore, it is presumed that the boundary bonding strength at the boundary between the active material layer 8b and the current collector 2 is improved, and the peeling resistance of the active material layer 8b is improved.

(Application Example) FIG. 6 shows a conceptual diagram of an application example.
Reference numeral 20 denotes a current collector for a positive electrode, 21 denotes a current collector for a negative electrode, 22 denotes a positive electrode, 23 denotes a negative electrode, 24 denotes a separator for separating the positive electrode 22 and the negative electrode 23, 25 denotes an electrolytic solution containing an electrolyte, and 26 denotes these. Is a case in which is stored in a sealed state. A large number of the positive electrodes 23 and the negative electrodes 23 are laminated, and are in close contact with each other via the separator 24.

The electric double layer capacitor according to the present invention is, of course, not limited to the structure and form shown in FIG. (Supplementary Note) The following technical ideas can be understood from the above description. -Additional notes: a kneading step of forming a coating material by kneading an active material having a large specific surface area having a large number of pores, water and an organic polymer binder as main components, and forming the coating material into a current collector. In the manufacturing method of manufacturing an electrode for an electric double layer capacitor through a coating step of coating and drying to form an active material layer, in forming the coating material in the kneading step, the average molecular weight of the binder is 200,000. A method for producing an electrode for an electric double layer capacitor, which is set as follows, wherein an active material, water and a binder are kneaded together to form the coating material. According to such a manufacturing method, loss of the binder is small. Further, since the active material, water, and the binder are simultaneously kneaded, it is advantageous in improving the productivity.

(Supplementary note) The method for producing an electrode for an electric double layer capacitor, wherein the binder has an average molecular weight of 150,000 or less or 100,000 or less. -Additional notes: a kneading step of forming a coating material by kneading an active material having a large specific surface area having a large number of pores, water and an organic polymer binder as main components, and forming the coating material into a current collector. In the manufacturing method of manufacturing an electrode for an electric double layer capacitor through a coating step of coating and drying to form an active material layer, an average molecular weight of the binder is 200,000 in forming the coating material in the kneading step. And forming a first kneaded material obtained by kneading an active material and water, and then kneading the first kneaded material and the binder to form the coating material. Of manufacturing an electrode for an electric double layer capacitor.

Additional Items: In the additional items, the pores of the active material have a specific surface area of 1500 m ² / g or more;
The pore volume having a pore size of up 300nm from 1.7nm, 0.2cm ³ / g~1cm ³ /g(0.3cm
³ / g or more, 0.4 cm ³ / g or more). Since such activated carbon has a large pore volume, it has an advantage of easily securing the mobility of electrolyte ions at a low temperature, but water containing a binder easily penetrates into the pores, and there is a problem that the binder is reduced. However, if the binder is post-kneaded after the active material and water are previously kneaded and blended together as described in the supplementary items, it is advantageous in suppressing the loss of the binder.

Additional notes: a kneading step of forming a coating material by kneading an active material having a large specific surface area having a large number of pores, water and an organic polymer binder as main components, In a manufacturing method of manufacturing an electrode for an electric double layer capacitor through a coating step of coating and drying an active material layer on a current collector, in forming the coating material in the kneading step, the average molecular weight of the binder Is set to 200,000 or less. This is advantageous for ensuring the peel resistance of the active material layer.

[0046]

According to the method of manufacturing an electrode for an electric double layer capacitor according to the present invention, the average molecular weight of the organic polymer-based binder used is adjusted to 20%.
If it is less than 10,000, the active material, water and binder are kneaded together to form a coating material. When the average molecular weight of the binder exceeds 200,000, a first kneading material in which the active material and water are kneaded is formed, and then the first kneading material and the binder are kneaded to form a coating material.

When the active material layer is formed by applying the coating material thus formed, the peeling resistance of the active material layer can be improved. This is advantageous for improving the performance of the electric double layer capacitor.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a blending process of activated carbon, cellulose, carbon black, and water according to a first embodiment.

FIG. 2 is a configuration diagram schematically showing a manufacturing facility.

FIG. 3 is a cross-sectional view schematically showing an electrode for an electric double layer capacitor according to the first embodiment.

FIG. 4 is a cross-sectional view schematically showing an electrode for an electric double layer capacitor according to a second embodiment.

FIG. 5 is a cross-sectional view schematically illustrating a state in which an end of a polymer chain constituting a binder of an active material layer acts as a binding action point to a current collector according to the second embodiment.

FIG. 6 is a cross-sectional view schematically illustrating the concept of an electric double layer capacitor according to an application example.

FIG. 7 is a conceptual diagram of an electric double layer capacitor, in which (A)
Indicates the time of charging, and (B) indicates the time of discharging.

[Explanation of symbols]

In the figure, 1 is a manufacturing facility, 2 is a current collector, 4 is a coating material, and 8 is an active material layer.

Claims (1)

[Claims] 1. A kneading step of kneading an active material having a large specific surface area having a large number of pores, water and an organic polymer binder as main components to form a coating material, and collecting the coating material. A manufacturing method of manufacturing an electrode for an electric double layer capacitor through a coating step of coating and drying the body to form an active material layer. In forming the coating material in the kneading step, the average molecular weight of the binder is 200,000. In the following cases, the active material, water, and the binder are kneaded together to form the coating material. When the average molecular weight of the binder exceeds 200,000, a first kneaded material in which the active material and water are kneaded is formed. And
Thereafter, the first kneading material and the binder are kneaded to form the coating material, the method for manufacturing an electrode for an electric double layer capacitor.