WO2022210513A1

WO2022210513A1 - Method for manufacturing electrolytic capacitor

Info

Publication number: WO2022210513A1
Application number: PCT/JP2022/014926
Authority: WO
Inventors: 義和平田
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2021-03-31
Filing date: 2022-03-28
Publication date: 2022-10-06
Also published as: JPWO2022210513A1

Abstract

This method for manufacturing an electrolytic capacitor comprises: a first step for preparing an electrode group comprising an anode foil having a porous portion and a dielectric layer covering the surface of the porous portion, a cathode foil, and a separator disposed between the anode foil and the cathode foil; a second step for preparing a processing fluid including a conductive polymer; and a third step for, after controlling the anode foil and the processing fluid to mutually different temperatures, impregnating the electrode group with the processing fluid to form a solid electrolyte layer including the electrically conductive polymer in at least a part of the electrode group.

Description

Manufacturing method of electrolytic capacitor

The present invention relates to a method for manufacturing an electrolytic capacitor.

Capacitors used in electronic devices are required to have a large capacity and a small equivalent series resistance (ESR) value in the high frequency range. Electrolytic capacitors using conductive polymers such as polythiophene are promising as large-capacity, low-ESR capacitors. A capacitor element of an electrolytic capacitor is obtained, for example, by winding an anode foil and a cathode foil through a separator to form an electrode group, and impregnating the electrode group with a treatment liquid containing a conductive polymer.

In Patent Document 1, a film forming process in which a conductive polymer solution is applied to a dielectric layer of a base material for a capacitor and dried to form a conductive polymer film is repeated twice or more, and at least once after the second time. As the conductive polymer solution used in the first film forming process, it is proposed to use a high-viscosity solution having a higher viscosity than the conductive polymer solution used in the first film forming process. The conductive polymer solution described above contains a π-conjugated conductive polymer, a polyanion, and a solvent.

Japanese Patent Application Laid-Open No. 2010-087401

In recent years, there has been a demand for improved performance of electrolytic capacitors.

One aspect of the present invention includes an anode foil having a porous portion and a dielectric layer covering the surface of the porous portion, a cathode foil, and a separator disposed between the anode foil and the cathode foil. a first step of preparing an electrode group; a second step of preparing a treatment liquid containing a conductive polymer; controlling the anode foil and the treatment liquid to different temperatures; and a third step of forming a solid electrolyte layer containing the conductive polymer on at least part of the electrode group by impregnating the electrode group with the solid electrolyte layer.

According to the present invention, the performance of electrolytic capacitors can be improved.

While the novel features of the present invention are set forth in the appended claims, the present invention, both as to construction and content, together with other objects and features of the present invention, will be further developed by the following detailed description in conjunction with the drawings. will be well understood.

1 is a cross-sectional view schematically showing an example of an electrolytic capacitor according to an embodiment of the invention; FIG. FIG. 2 is a partially developed perspective view of the wound body of FIG. 1 ;

An embodiment of an electrolytic capacitor according to the present disclosure will be described below with examples, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values and materials may be exemplified, but other numerical values and materials may be applied as long as the effects of the present disclosure can be obtained. In this specification, the description "numerical value A to numerical value B" includes numerical value A and numerical value B, and can be read as "numerical value A or more and numerical value B or less". In the following description, when lower and upper limits of numerical values relating to specific physical properties, conditions, etc. are exemplified, any of the illustrated lower limits and any of the illustrated upper limits can be arbitrarily combined as long as the lower limit is not greater than or equal to the upper limit. . When a plurality of materials are exemplified, one of them may be selected and used alone, or two or more may be used in combination.

In addition, the present disclosure encompasses a combination of matters described in two or more claims arbitrarily selected from the multiple claims described in the attached claims. In other words, as long as there is no technical contradiction, the matters described in two or more claims arbitrarily selected from the multiple claims described in the attached claims can be combined.

A method for manufacturing an electrolytic capacitor according to one embodiment of the present invention includes a first step of preparing an electrode group, a second step of preparing a treatment liquid containing a conductive polymer, and and a third step of forming a solid electrolyte layer containing a polymer. The electrode group includes an anode foil having a porous portion and a dielectric layer covering the surface of the porous portion, a cathode foil, and a separator disposed between the anode foil and the cathode foil.

In the third step, after controlling the anode foil and the treatment liquid to different temperatures, the electrode group is impregnated with the treatment liquid to form a solid electrolyte layer containing a conductive polymer on at least part of the electrode group. In the third step, using the temperature difference between the anode foil and the treatment liquid, the impregnability of the treatment liquid in the porous portion and the separator is adjusted, and the amount of the conductive polymer contained in the porous portion and the separator is adjusted. . As a result, it is possible to improve the performance of the electrolytic capacitor. For example, in the case of step (a-1) described later, the capacitance can be increased, and in the case of step (a-2) described later, the ESR can be reduced.

By providing a temperature difference between the anode foil and the treatment liquid, it is possible to cause a local concentration difference in the treatment liquid impregnated in the electrode group, and to bias the amount of conductive polymer adhered inside the electrode group. Specifically, when the temperature of the anode foil is higher than the temperature of the treatment liquid, the concentration of the treatment liquid in the vicinity of the porous portion of the anode foil increases, increasing the filling amount of the conductive polymer in the porous portion. can be done. Further, when the temperature of the treatment liquid is higher than the temperature of the anode foil, the concentration of the treatment liquid in the vicinity of the separator increases, and the filling amount of the conductive polymer in the separator can be increased.

The third step includes a step (a) of controlling the anode foil and the treatment liquid to different temperatures, and a step (b) of impregnating the electrode group with the treatment liquid after step (a) to form a solid electrolyte layer. and including. In step (b), the electrode assembly may be impregnated with the treatment liquid and then dried.

The step (a) may include the step (a-1) of making the temperature of the anode foil higher than the temperature of the treatment liquid. In this case, the porous portion of the anode foil can be impregnated with a large amount of the treatment liquid (conductive polymer), and the dielectric layer can be sufficiently coated with the conductive polymer to increase the capacitance. .

In step (a-1), for example, the temperature of the anode foil may be higher than the temperature of the treatment liquid by a temperature difference in the range of 50°C or more and 100°C or less. For example, the temperature of the anode foil may be 80° C. or higher and 120° C. or lower, and the temperature of the treatment liquid may be 20° C. or higher and 30° C. or lower. Step (a-1) is performed, for example, by heating the anode foil and/or cooling the treatment liquid.

Step (a) may include step (a-2) of making the temperature of the treatment liquid higher than the temperature of the anode foil. In this case, the separator can be impregnated with a large amount of treatment liquid (conductive polymer), and many conductive paths are formed with the conductive polymer between the anode foil and the cathode foil to reduce the ESR. can be done.

In step (a-2), for example, the temperature of the treatment liquid may be higher than the temperature of the anode foil by a temperature difference in the range of 50°C or more and 100°C or less. For example, the temperature of the anode foil may be −20° C. or higher and 0° C. or lower, and the temperature of the treatment liquid may be 30° C. or higher and 60° C. or lower. Step (a-2) is performed, for example, by cooling the anode foil and/or heating the treatment liquid.

The heating or cooling of the anode foil may be performed by heating or cooling the electrode group. The anode foil has high thermal conductivity and is easy to control the heating (cooling) temperature. On the other hand, separators have low thermal conductivity and are less susceptible to heating (cooling). Therefore, even by heating (cooling) the electrode group, the impregnability of the porous portion and the separator with the treatment liquid can be adjusted using the temperature difference between the anode foil and the treatment liquid.

The above steps (a) and (b) may be performed once or multiple times. When step (a) is performed multiple times, the temperature of the anode foil and/or the treatment liquid may be changed during the multiple times of step (a). When step (b) is performed multiple times, drying may be performed each time the electrode group is impregnated with the treatment liquid.

Step (a) may include step (a-1) and step (a-2). That is, the third step includes a 3A step and a 3B step. In the 3A step, after the temperature of the anode foil is made higher than the temperature of the treatment liquid, the electrode group is impregnated with the treatment liquid. In the step, after the temperature of the treatment liquid is made higher than the temperature of the anode foil, the electrode group may be impregnated with the treatment liquid. The order of the 3A step and the 3B step is not limited.

In the 3A step, the electrode group may be impregnated with the treatment liquid after the temperature of the anode foil is made higher than the temperature of the treatment liquid by a temperature difference in the range of 50°C or more and 100°C or less. In the 3B step, the electrode group may be impregnated with the treatment liquid after the temperature of the treatment liquid is raised higher than the temperature of the anode foil by a temperature difference in the range of 50° C. or more and 100° C. or less.

In the 3rd step, it is preferable to perform the 3B step after the 3A step. In this case, it is easy to reduce the ESR while increasing the capacitance. The treatment liquid can diffuse through the separator into the porous portion of the anode foil. It is better to first perform the 3A step of impregnating the porous portion with a large amount of the treatment liquid and then perform the 3B step of impregnating the separator with a large amount of the treatment liquid so that the treatment liquid can be efficiently applied to the porous portion and the separator. can be impregnated.

In the second step, as treatment liquids, a treatment liquid A and a treatment liquid B containing a component different from the treatment liquid A are prepared, in the 3A step, the electrode group is impregnated with the treatment liquid A, and in the 3B step, , the treatment liquid B may be impregnated into the electrode group. The treatment liquid A may contain a component capable of repairing defects in the dielectric layer or a component capable of suppressing an increase in leakage current caused by defects in the dielectric layer.

The treatment liquid A may contain a conductive polymer A, and the treatment liquid B may contain a conductive polymer B having a higher conductivity than the conductive polymer A. The 3B step allows the separator to contain a large amount of the conductive polymer B having a high conductivity, thereby reducing the ESR. Conductive polymer B, which has a high conductivity, tends to cause an increase in leakage current. Contact of the polymer B to the porous portion can be restricted, and an increase in leakage current can be suppressed.

The conductivity of the conductive polymer A is, for example, 10 S/cm or more and 200 S/cm or less. The conductivity of the conductive polymer B is, for example, 300 S/cm or more and 500 S/cm or less.

The conductivity of the conductive polymer in the treatment liquid is measured by applying the treatment liquid on the substrate and drying it to form a conductive polymer film (for example, a thickness of 10 μm to 30 μm) and measuring the conductivity of the film. It is required by Loresta GX and PSP probes manufactured by Nitto Seiko Analyticc Co., Ltd. can be used as conductivity measuring devices.

(First step)
In the first step, an electrode group is prepared. The electrode group includes an anode foil having a porous portion and a dielectric layer covering the surface of the porous portion, a cathode foil, and a separator disposed between the anode foil and the cathode foil.

In the first step, an electrode group may be obtained by disposing a separator between the anode foil and the cathode foil. In the case of a wound-type capacitor, an electrode group (wound body) may be formed by winding an anode foil and a cathode foil with a separator interposed between the anode foil and the cathode foil. In the case of a laminated capacitor, the anode foil and the cathode foil may be folded in a zigzag manner with a separator interposed between the anode foil and the cathode foil to form an electrode group (laminate).

(anode foil)
The anode foil has a porous portion and a dielectric layer covering the surface of the porous portion. At least part of the dielectric layer of the anode foil is in contact with the conductive polymer (solid electrolyte layer). The porous portion is formed, for example, by roughening the surface of the metal foil by etching or the like. The dielectric layer is obtained by forming an oxide film on the roughened surface of the metal foil by chemical conversion treatment or the like.

The type of metal that constitutes the metal foil is not particularly limited. Examples of metals constituting the metal foil include metals with valve action, such as aluminum, tantalum, niobium, and titanium, and alloys of metals with valve action, in view of the ease with which the dielectric layer can be formed. . A preferred example is aluminum and aluminum alloys.

(cathode foil)
A metal foil can be used for the cathode foil. The kind of metal that constitutes the metal foil is not particularly limited. As the metal foil, those exemplified for the anode foil can be used. A metal (dissimilar metal) different from the metal forming the metal foil or a non-metal coating may be provided on the surface of the metal foil. Examples of dissimilar metals and non-metals include metals such as titanium and non-metals such as carbon.

A metal foil whose surface has been roughened by etching or the like may be used as the cathode foil. That is, the cathode foil may have a porous portion on its surface. A chemical conversion film may be provided on the roughened surface of the metal foil. In this case, in the third step, the electrode group may be impregnated with the treatment liquid after the cathode foil and the treatment liquid are controlled to different temperatures. By heating or cooling the electrode group, the anode foil as well as the cathode foil may be controlled to a temperature different from that of the treatment liquid. Thereby, the impregnation property of the treatment liquid into the porous portion of the cathode portion may be adjusted.

(separator)
For the separator, for example, a nonwoven fabric containing fibers of cellulose, polyethylene terephthalate, vinylon, polyamide (for example, aliphatic polyamide, aromatic polyamide such as aramid), or the like is used.

(Second step)
In the second step, a treatment liquid containing a conductive polymer is prepared. A dispersion (or solution) of a conductive polymer is used as the treatment liquid. Water is usually used as a dispersion medium (or solvent) for the treatment liquid. The treatment liquid may contain a dopant together with the conductive polymer, and may further contain components other than the conductive polymer and the dopant.

The treatment liquid can be obtained, for example, by oxidative polymerization of a conductive polymer precursor in a dispersion medium (or solvent), and the dispersion medium (or solvent) may contain a dopant. Examples of conductive polymer precursors include monomers constituting the conductive polymer and/or oligomers in which several monomers are linked. The conductivity of the conductive polymer can be adjusted by, for example, the polymerization conditions of the conductive polymer precursor (for example, the type of the conductive polymer precursor, the oxidizing agent, or the catalyst), the type of the dopant, and the like. can.

Examples of conductive polymers include polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, and derivatives thereof. Such derivatives include polymers having polypyrrole, polythiophene, polyfuran, polyaniline, and polyacetylene as basic skeletons. For example, derivatives of polythiophene include poly(3,4-ethylenedioxythiophene) and the like. These conductive polymers may be used alone or in combination. Also, the conductive polymer may be a copolymer of two or more monomers. The weight average molecular weight of the conductive polymer is not particularly limited, and may be in the range of 1,000 to 100,000, for example. A preferred example of a conductive polymer is poly(3,4-ethylenedioxythiophene) (PEDOT).

Examples of dopants include polyvinylsulfonic acid, polystyrenesulfonic acid, polyallylsulfonic acid, polyacrylsulfonic acid, polymethacrylsulfonic acid, poly(2-acrylamido-2-methylpropanesulfonic acid), polyisoprenesulfonic acid, polyacrylic including acids. These may be used alone or in combination of two or more. These may be added in the form of salts. The dopant may be present in the electrolyte in the form of an anion in which cations (eg, protons) are dissociated from at least some of the acidic groups. A preferred example of a dopant is polystyrene sulfonic acid (PSS).

The weight average molecular weight of the dopant is not particularly limited. From the viewpoint of facilitating formation of a homogeneous solid electrolyte layer, the dopant may have a weight average molecular weight in the range of 1,000 to 100,000.

The conductive polymer may be a dopant-doped conductive polymer, such as poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonic acid (hereinafter also referred to as PEDOT/PSS). There may be.

The concentration of the conductive polymer (eg, PEDOT/PSS) in the treatment liquid is, for example, 1% by mass or more and 3% by mass or less. When the concentration of the conductive polymer in the treatment liquid is within the above range, the viscosity of the treatment liquid at 20° C. is, for example, 10 mPa·s or more and 60 mPa·s or less.

(Third step)
In the third step, after the anode foil and the treatment liquid are controlled to different temperatures, the electrode group is impregnated with the treatment liquid to form a solid electrolyte layer containing a conductive polymer on at least part of the electrode group. A capacitor element is thus obtained. The impregnation with the treatment liquid may be performed by immersing the electrode group in the treatment liquid, or by dripping the treatment liquid onto the electrode group. The impregnation with the treatment liquid may be performed under an atmospheric pressure atmosphere or under a reduced pressure atmosphere. After being impregnated with the treatment liquid, the electrode group containing the treatment liquid may be dried. Drying may be performed by heating (eg, 120° C. to 200° C.).

In the third step, the electrode group is impregnated with the treatment liquid a plurality of times, at least one of which impregnates the electrode group with the treatment liquid after controlling the anode foil and the treatment liquid to different temperatures. It may be a step of causing

(Other processes)
The method for manufacturing an electrolytic capacitor may include a step of impregnating the capacitor element with a liquid component. The method for manufacturing an electrolytic capacitor may include a step of sealing a bottomed case in which the capacitor element is accommodated.

(liquid component)
The liquid component may be an electrolytic solution or a non-aqueous solvent. The liquid component has a role of protecting the conductive polymer. Moreover, the inclusion of the liquid component can improve the contact between the conductive polymer and the dielectric layer, and can also improve the repairability of defects in the dielectric layer. The electrolytic solution can function as an electrolyte together with the conductive polymer.

The non-aqueous solvent may be an organic solvent or an ionic liquid. Examples of non-aqueous solvents include polyhydric alcohols such as ethylene glycol and propylene glycol, cyclic sulfones such as sulfolane (SL), lactones such as γ-butyrolactone (GBL), N-methylacetamide, N,N- Amides such as dimethylformamide and N-methyl-2-pyrrolidone, esters such as methyl acetate, carbonate compounds such as propylene carbonate, ethers such as 1,4-dioxane, ketones such as methyl ethyl ketone, and formaldehyde. . The non-aqueous solvent may be used singly or in combination of two or more.

The liquid component may contain an acid component and a base component. Examples of acid components include maleic acid, phthalic acid, benzoic acid, pyromellitic acid, resorcinic acid, and the like. Examples of base components include 1,2,4-trimethylimidazoline, 1,2-dimethyl-1,4,5,6-tetrahydropyrimidine, 1-methylimidazole, and the like.

The electrolyte contains a non-aqueous solvent and a solute (eg, organic salt) dissolved therein. Examples of the non-aqueous solvent that constitutes the electrolytic solution include the examples of the non-aqueous solvent described above. Examples of solutes include inorganic salts and organic salts. An organic salt is a salt in which at least one of the anion and cation contains an organic substance. Examples of organic salts include trimethylamine maleate, ethyldimethylamine phthalate, mono-1,2,3,4-tetramethylimidazolinium phthalate, mono-1,3-dimethyl-2-ethylimidazolinium phthalate, and the like. is included.

In order to suppress dedoping of the dopant, the pH of the liquid component may be less than 7 or 5 or less.

Here, FIG. 1 is a cross-sectional view schematically showing an example of an electrolytic capacitor according to an embodiment of the invention. FIG. 2 is a partially unfolded perspective view of the wound body of FIG.

The electrolytic capacitor 200 includes a wound body 100 (electrode group). The wound body 100 is constructed by winding the anode foil 10 and the cathode foil 20 with the separator 30 interposed therebetween. The wound body 100 contains a conductive polymer (not shown).

One ends of the

lead tabs

50A and 50B are connected to the anode foil 10 and the cathode foil 20, respectively, and the wound body 100 is formed by winding the

lead tabs

50A and 50B.

Lead wires

60A and 60B are connected to the other ends of

lead tabs

50A and 50B, respectively.

A winding stop tape 40 is arranged on the outer surface of the cathode foil 20 located in the outermost layer of the wound body 100 , and the ends of the cathode foil 20 are fixed by the winding stop tape 40 . When the anode foil 10 is prepared by cutting from a large-sized foil, the rolled body 100 may be further subjected to a chemical conversion treatment in order to provide a dielectric layer on the cut surface.

The wound body 100 is housed in the bottomed case 211 so that the

lead wires

60A and 60B are located on the opening side of the bottomed case 211. As the material of the bottomed case 211, metals such as aluminum, stainless steel, copper, iron, and brass, or alloys thereof can be used.

A sealing member 212 is placed in the opening of the bottomed case 211 in which the wound body 100 is accommodated, and the opening end of the bottomed case 211 is crimped to the sealing member 212 for curling, and the seat plate 213 is attached to the curled portion. By arranging them, the wound body 100 is sealed in the bottomed case 211 .

The sealing member 212 is formed so that the

lead wires

60A and 60B pass therethrough. The sealing member 212 may be an insulating material, preferably an elastic material. Among them, highly heat-resistant silicone rubber, fluororubber, butyl rubber, isoprene rubber and the like are preferable.

[Example]
EXAMPLES The present invention will be described in more detail below based on examples, but the present invention is not limited to the examples.

<<Example 1>>
A wound electrolytic capacitor (diameter Φ: 10 mm×length L: 12 mm) was produced by the following procedure.

(Preparation of anode foil)
An Al foil (thickness: 100 μm) whose surface was roughened by etching was subjected to a chemical conversion treatment. Specifically, the Al foil was anodized at 150 V in an ammonium adipate aqueous solution (2% concentration). Thus, a dielectric layer was formed on the surface of the Al foil to obtain an anode foil.

(Preparation of cathode foil)
An Al foil (thickness: 50 μm) whose surface was roughened by etching was subjected to a chemical conversion treatment. Specifically, the Al foil was anodized at 3V in an ammonium adipate aqueous solution (2% concentration). Thus, a dielectric layer was formed on the surface of the Al foil to obtain a cathode foil.

(Production of wound body)
An anode lead tab and a cathode lead tab to which lead wires were connected were connected to the prepared anode foil and cathode foil, respectively. Then, the anode foil and the cathode foil were wound with a separator sandwiched therebetween, and the outer surfaces were fixed with a winding stop tape. Thus, a wound body (diameter 8.5 mm, height 7.0 mm) was produced as an electrode group. A non-woven fabric of aramid fibers (thickness: 40 μm) was used as the separator.

(Preparation of treatment liquid containing conductive polymer)
The following treatment liquid A was prepared as a treatment liquid containing a conductive polymer. PEDOT/PSS means PEDOT doped with PSS.

Treatment liquid A: aqueous dispersion of PEDOT/PSS (conductivity 100 S/cm) (concentration 2% by mass)

(Formation of solid electrolyte layer)
The step of impregnating the treatment liquid containing the conductive polymer was performed once. Specifically, the temperatures of the wound body and the treatment liquid A were adjusted to the temperatures shown in Table 1, respectively. The temperature of the anode foil was set to 120°C by heating the wound body to 120°C. Next, about 200 mg of treatment liquid A was dropped onto the wound body using a dispenser, and then the wound body impregnated with treatment liquid A was left for 5 minutes under a reduced pressure atmosphere (-90 kPa). Next, the wound body impregnated with the treatment liquid A was dried at 150° C. for 30 minutes under atmospheric pressure. In this manner, a solid electrolyte layer containing a conductive polymer was formed in the wound body to obtain a capacitor element.

(capacitor sealing)
A sealing member and a seat plate were placed in the opening of the bottomed case to seal the capacitor element. Thus, the electrolytic capacitor X1 was completed. After that, an aging treatment was performed at 140° C. for 1 hour while applying a rated voltage.

<<Comparative example 1>>
In the step of forming the solid electrolyte layer, impregnation of the wound body with the treatment liquid was carried out at room temperature. That is, when impregnating the wound body with the treatment liquid, the temperatures of the wound body and the treatment liquid were each set to 25°C. An electrolytic capacitor Y1 was fabricated in the same manner as in Example 1 except for the above.

The following evaluation 1 was performed for the electrolytic capacitor X1 of Example 1 and the electrolytic capacitor Y1 of Comparative Example 1.

[Evaluation 1]
Under the environment of 20° C., the initial capacitance (μF) at a frequency of 120 Hz was measured using an LCR meter for four-terminal measurement. Table 1 shows the evaluation results.

In the electrolytic capacitor X1, a large amount of conductive polymer was contained in the porous portion of the anode foil, and a higher capacitance than the electrolytic capacitor Y1 was obtained.

<<Example 2>>
In the step of forming the solid electrolyte layer, the wound body and the treatment liquid A were adjusted to temperatures shown in Table 2, respectively. By cooling the wound body to -10°C, the temperature of the anode foil was set to -10°C. An electrolytic capacitor X2 was produced in the same manner as in Example 1 except for the above.

The following evaluation 2 was performed for the electrolytic capacitor X2 of Example 2 and the electrolytic capacitor Y1 of Comparative Example 1.

[Evaluation 2]
Initial ESR (mΩ) was measured at a frequency of 100 kHz in an environment of 20° C. using a 4-terminal LCR meter. Table 2 shows the evaluation results.

In the electrolytic capacitor X2, the separator contained a large amount of conductive polymer, and an ESR lower than that of the electrolytic capacitor Y1 was obtained.

<<Example 3>>
In the step of preparing the treatment liquid containing the conductive polymer, the following treatment liquid A and treatment liquid B were prepared.

Treatment liquid B: aqueous dispersion of PEDOT/PSS (conductivity 400 S/cm) (concentration 2% by mass)

In the process of forming the solid electrolyte layer, the impregnation process of the treatment liquid containing the conductive polymer was performed twice. Specifically, the following 3A process and 3B process were performed in this order.

(3rd A step)
The temperatures of the wound body and the treatment liquid A were adjusted to the temperatures shown in Table 3, respectively. Next, about 200 mg of treatment liquid A was dropped onto the wound body using a dispenser, and then the wound body impregnated with treatment liquid A was left for 5 minutes under a reduced pressure atmosphere (-90 kPa). Next, the wound body impregnated with the treatment liquid A was dried at 150° C. for 30 minutes under atmospheric pressure.

(3B step)
Next, the wound body and the treatment liquid B were adjusted to the temperatures shown in Table 3, respectively. Next, using a dispenser, about 200 mg of the treatment liquid B was dropped onto the wound body, and then the wound body impregnated with the treatment liquid B was left for 5 minutes under a reduced pressure atmosphere (-90 kPa). Next, the wound body impregnated with the treatment liquid B was dried at 150° C. for 30 minutes under an atmospheric pressure atmosphere.

An electrolytic capacitor X3 was produced in the same manner as in Example 1 except for the above.

<<Comparative Example 2>>
In the process of forming the solid electrolyte layer (process 3A and process 3B), the wound body was impregnated with the treatment liquid under a room temperature environment. That is, in the 3A process and the 3B process, the temperatures of the wound body and the treatment liquid were each set to 25°C. Except for the above, an electrolytic capacitor Y2 was produced in the same manner as in Example 3.

The following evaluation 3 was performed for the electrolytic capacitor X3 of Example 3 and the electrolytic capacitor Y2 of Comparative Example 2.

[Evaluation 3]
The initial capacitance (μF) and initial ESR (mΩ) were obtained in the same manner as in Evaluation 1 and Evaluation 2 above. The leakage current (LC) was obtained by measuring the current value (μA) when the rated voltage was applied for 1 minute under the environment of 20°C. Table 3 shows the evaluation results.

With the electrolytic capacitor X3, a higher capacitance and a lower ESR were obtained than with the electrolytic capacitor Y2. In the electrolytic capacitor X3 manufactured by performing the 3A step and the 3B step in this order, it was possible to reduce the LC while reducing the ESR as compared with the electrolytic capacitor Y2.

The electrolytic capacitor obtained by the electrolytic capacitor manufacturing method according to the present invention can be used for applications requiring high performance.

Although the present invention has been described in terms of its presently preferred embodiments, such disclosure should not be construed as limiting. Various alterations and modifications will no doubt become apparent to those skilled in the art to which the invention pertains after reading the above disclosure. Therefore, the appended claims are to be interpreted as covering all variations and modifications without departing from the true spirit and scope of the invention.

10: anode foil, 20: cathode foil, 30: separator, 40: winding stop tape, 50A, 50B: lead tab, 60A, 60B: lead wire, 100: wound body, 200: electrolytic capacitor, 211: bottomed case, 212: sealing member, 213: seat plate

Claims

Preparing an electrode group comprising: an anode foil having a porous portion and a dielectric layer covering the surface of the porous portion; a cathode foil; and a separator disposed between the anode foil and the cathode foil. 1 step;
a second step of preparing a treatment liquid containing a conductive polymer;
After controlling the anode foil and the treatment liquid to different temperatures, the electrode group is impregnated with the treatment liquid to form a solid electrolyte layer containing the conductive polymer on at least a part of the electrode group. 3 steps;
A method of manufacturing an electrolytic capacitor, comprising:
The method of manufacturing an electrolytic capacitor according to claim 1, wherein in the third step, the temperature of the anode foil is made higher than the temperature of the treatment liquid, and then the electrode group is impregnated with the treatment liquid.
3. The method according to claim 2, wherein in the third step, the electrode assembly is impregnated with the treatment liquid after raising the temperature of the anode foil to a temperature higher than the temperature of the treatment liquid by 50° C. or more and 100° C. or less. A method for manufacturing an electrolytic capacitor.
The method of manufacturing an electrolytic capacitor according to claim 1, wherein in the third step, the electrode group is impregnated with the treatment liquid after the temperature of the treatment liquid is made higher than the temperature of the anode foil.
5. The method according to claim 4, wherein in the third step, the electrode group is impregnated with the treatment liquid after the temperature of the treatment liquid is raised to be higher than the temperature of the anode foil by 50° C. or more and 100° C. or less. A method for manufacturing an electrolytic capacitor.
The third step includes a 3A step and a 3B step,
In the 3A step, after the temperature of the anode foil is made higher than the temperature of the treatment liquid, the electrode group is impregnated with the treatment liquid,
2. The method of manufacturing an electrolytic capacitor according to claim 1, wherein, in said 3B step, said electrode group is impregnated with said treatment liquid after making the temperature of said treatment liquid higher than the temperature of said anode foil.
7. The method according to claim 6, wherein in the 3A step, the electrode group is impregnated with the treatment liquid after the temperature of the anode foil is raised higher than the temperature of the treatment liquid by 50° C. or more and 100° C. or less. A method for manufacturing an electrolytic capacitor.
8. The method according to claim 6 or 7, wherein, in the 3B step, the electrode group is impregnated with the treatment liquid after making the temperature of the treatment liquid higher than the temperature of the anode foil in a range of 50° C. or more and 100° C. or less. A method for manufacturing the electrolytic capacitor described.
The method for manufacturing an electrolytic capacitor according to any one of claims 6 to 8, wherein in the third step, the 3B step is performed after the 3A step.
In the second step, as the treatment liquid, a treatment liquid A and a treatment liquid B containing a component different from the treatment liquid A are prepared;
In the 3A step, the electrode group is impregnated with the treatment liquid A,
10. The method for manufacturing an electrolytic capacitor according to claim 6, wherein in the 3B step, the electrode group is impregnated with the treatment liquid B.