JP6222577B2 - Solid electrolytic capacitor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a solid electrolytic capacitor and a method for manufacturing the same.

  Conventionally, a solid electrolyte containing “conductive fine particles containing a conductive polymer compound and a water-soluble polymer compound (hydrophilic polymer compound)” is filled (introduced) in the gap between the anode foil and the cathode foil. A solid electrolytic capacitor is known (for example, see Patent Document 1). In conventional solid electrolytic capacitors, the water-soluble polymer compound has an oxide film repair performance. In a conventional solid electrolytic capacitor, a solid or viscous water-soluble polymer compound is used as such a water-soluble polymer compound (see FIG. 7 of Patent Document 1).

  In the present specification, the “void” includes not only the gap between the anode foil and the separator and the cathode foil and the separator, but also the gap between fibers in the separator. The “void” also includes a gap in an etching pit (concave portion) formed on the surface of the anode foil or the cathode foil by roughening by an etching process.

  According to the conventional solid electrolytic capacitor, since the solid electrolyte containing the water-soluble polymer compound is introduced into the gap between the anode foil and the cathode foil, a defect occurs in the oxide film during the production of the solid electrolytic capacitor. Even so, the water retained by the water-soluble polymer compound can be used for repairing the above-mentioned defective portion, and a solid electrolytic capacitor having a high withstand voltage and low leakage current can be obtained.

  In addition, according to the conventional solid electrolytic capacitor, since the solid electrolyte containing the water-soluble polymer compound is introduced into the gap between the anode foil and the cathode foil, the oxide film is formed when the solid electrolytic capacitor is used for a long time. Even if a defect occurs, the water retained by the water-soluble polymer compound can be used for repairing the defect portion, resulting in a solid electrolytic capacitor having a long life.

  In addition, according to the conventional solid electrolytic capacitor, the water content of the water-soluble polymer compound contained in the solid electrolyte is difficult to change (that is, the water retention ability of the water-soluble polymer compound is increased), so that the solid electrolytic Even when the capacitor is used for a long time, it becomes difficult for water to scatter. In addition, since it is difficult for the water-soluble polymer compound to change its shape due to temperature changes, repeated heating and cooling cycles at normal temperature (when a solid electrolytic capacitor is not used) and high temperature (when a solid electrolytic capacitor is used) are repeated many times. The oxide film is difficult to deteriorate. As a result, even when a solid electrolytic capacitor is used for a long time under harsh conditions, it becomes possible to retain moisture for a long time and also suppress the change in the form of the water-soluble polymer compound for a long time. Therefore, it becomes a solid electrolytic capacitor with a long life.

  As a result, the conventional solid electrolytic capacitor is a solid electrolytic capacitor having a high breakdown voltage, a low leakage current, and a long life.

International Publication No. 2014/050913

  Incidentally, in the technical field of capacitors, there has always been a demand for capacitors that are superior in at least one of long life characteristics, high withstand voltage characteristics, low resistance characteristics, and low temperature characteristics as compared with conventional techniques. There is no exception in the field.

  Therefore, the present invention has been made in view of such circumstances, and provides a solid electrolytic capacitor that is superior to conventional ones in at least one of long life characteristics, high breakdown voltage characteristics, low resistance characteristics, and low temperature characteristics. The purpose is to do. Moreover, it aims at providing the manufacturing method of the solid electrolytic capacitor for manufacturing such a solid electrolytic capacitor.

  The inventors of the present invention have made intensive efforts to achieve the above object, and as a result, the solid or viscous water-soluble polymer compound contained in the solid electrolyte (see FIG. 2B). If a liquid water-soluble polymer compound (see FIG. 2 (a); water-soluble polymer compound 28) is used instead of the molecular compound 27), defects occur in the oxide film of the solid electrolytic capacitor. However, the present inventors have found that the defect portion can be repaired more efficiently than before, and have completed the present invention. The present invention comprises a solid electrolytic capacitor and a method for producing the solid electrolytic capacitor described below.

[1] A solid electrolytic capacitor of the present invention includes an anode foil having an oxide film formed on a surface thereof, a cathode foil, and a separator disposed between the anode foil and the cathode foil. In the gap between the cathode foil and the cathode foil, a particulate solid electrolyte composed of a conductive polymer compound and a liquid water-soluble polymer compound are contained, and the liquid water-soluble polymer compound comprises the solid electrolyte. The ratio of the solid electrolyte in the voids is in the range of 1 vol% to 30 vol%, and the ratio of the liquid water-soluble polymer compound in the voids is 10 vol% to It is characterized by being in the range of 99 vol%.

  According to the solid electrolytic capacitor of the present invention, since a liquid water-soluble polymer compound is introduced into the gap between the anode foil and the cathode foil, it is oxidized when the solid electrolytic capacitor is used for a long time. Even if a defect occurs in the film, the defect portion and the liquid water-soluble polymer compound are more likely to come into contact with each other, so that the defect portion is repaired more efficiently than before. As a result, the solid electrolytic capacitor of the present invention can maintain a normal dielectric film for a longer time than the conventional one, and becomes a solid electrolytic capacitor having longer life characteristics than the conventional one.

  Further, according to the solid electrolytic capacitor of the present invention, since the liquid water-soluble polymer compound is introduced so as to surround the solid electrolyte in the gap between the anode foil and the cathode foil, The dopant (strong acid) which may be liberated or a part thereof is prevented from coming into contact with the fibers of the separator, and the deterioration reaction of the separator due to the dopant can be suppressed. As a result, the solid electrolytic capacitor of the present invention is also a solid electrolytic capacitor having a longer life characteristic than the conventional one from this viewpoint.

  The reason why the ratio of the liquid water-soluble polymer compound in the voids is in the range of 10 vol% to 99 vol% is as follows. That is, when the ratio of the liquid water-soluble polymer compound in the void is less than 10 vol%, the defect portion of the oxide film and the liquid water-soluble polymer compound are difficult to contact with each other. This is because there is a case where it is not efficiently repaired. On the other hand, when the ratio of the liquid water-soluble polymer compound in the gap is larger than 99%, the ratio of the solid electrolyte in the gap is small and the equivalent series resistance (ESR) of the resistance component of the capacitor is large. This is because there is a case. From such a viewpoint, the ratio of the liquid water-soluble polymer compound in the voids is more preferably 20 vol% or more, and further preferably 30 vol% or more. The ratio of the liquid water-soluble polymer compound in the voids is more preferably 96 vol% or less, and still more preferably 90 vol% or less.

  The reason why the ratio of the solid electrolyte in the voids is set within the range of 1 vol% to 30 vol% is as follows. That is, when the proportion of the solid electrolyte in the gap is smaller than 1 vol%, the equivalent series resistance (ESR) of the resistance component of the capacitor is increased. On the other hand, when the ratio of the solid electrolyte in the voids is larger than 30 vol%, the voids are easily clogged with the solid electrolyte in the process of manufacturing the solid electrolytic capacitor, and it is difficult to manufacture the voids. From this point of view, the ratio of the solid electrolyte in the voids is more preferably 1.5 vol% or more, and even more preferably 2 vol% or more. Further, the ratio of the solid electrolyte in the voids is more preferably 25 vol% or less, and further preferably 20 vol% or less.

  In addition, according to the solid electrolytic capacitor of the present invention, since a water-soluble polymer compound is used instead of a general solvent, the water-soluble polymer compound is less likely to permeate through the sealing member. For this reason, the solid electrolytic capacitor of this invention turns into a solid electrolytic capacitor with which the repair effect | action of an oxide film is maintained over a long time.

[2] In the solid electrolytic capacitor of the present invention, it is preferable that an average particle diameter of the particulate solid electrolyte is in a range of 1 nm to 300 nm.

  The reason why the average particle diameter of the solid electrolyte in the form of fine particles is in the range of 1 nm to 300 nm is as follows. That is, when the average particle diameter of the fine particle solid electrolyte is smaller than 1 nm, it may be difficult to produce the fine particle solid electrolyte. On the other hand, when the average particle size of the fine particle solid electrolyte is larger than 300 nm, it may be difficult to introduce the fine particle solid electrolyte into the etching pits (recesses) on the surface of the anode foil. From this point of view, the average particle size of the particulate solid electrolyte is more preferably 2 nm or more, and even more preferably 3 nm or more. Further, the average particle size of the particulate solid electrolyte is more preferably 200 nm or less, and still more preferably 100 nm or less.

[3] In the solid electrolytic capacitor of the present invention, the liquid water-soluble polymer compound preferably has an oxide film repair performance.

  By adopting such a configuration, as in the case of the conventional solid electrolytic capacitor, a solid electrolytic capacitor having a high withstand voltage, a low leakage current, and a long life is obtained.

[4] In the solid electrolytic capacitor of the present invention, the liquid water-soluble polymer compound is preferably a mixture of two or more water-soluble polymer compounds having different molecular weights.

  By the way, when a water-soluble polymer compound is contained in a solid electrolytic capacitor, it is preferable to use a water-soluble polymer compound having a small molecular weight from the viewpoint of reducing the equivalent series resistance (ESR) at a low temperature. This is because a polymer having a large molecular weight starts to solidify at a low temperature of 10 ° C. or lower, and at that time, the solid electrolyte network is broken to increase the ESR of the solid electrolytic capacitor. In contrast, a water-soluble polymer compound having a low molecular weight has a lower freezing point than a water-soluble polymer compound having a high molecular weight. Therefore, when a solid electrolytic capacitor using a water-soluble polymer compound having a low molecular weight is placed in a low temperature state, The liquid water-soluble polymer compound is difficult to coagulate, and the network of solid electrolytes composed of particulate solid electrolytes is not easily destroyed. Therefore, it is possible to suppress an increase in equivalent series resistance (ESR), and a solid electrolytic capacitor having excellent low temperature characteristics can be obtained.

  However, a water-soluble polymer compound having a small molecular weight has a characteristic that it easily permeates the sealing member. Therefore, when it is used alone, it may be difficult to hold the liquid water-soluble polymer compound for a long period of time. . Considering this, in the present invention, two or more water-soluble polymer compounds having different molecular weights are used. By using a mixture of a water-soluble polymer compound having a low molecular weight and a water-soluble polymer compound having a higher molecular weight than that of the water-soluble polymer compound having a low molecular weight, this reduces the coagulation stress at low temperatures. Thus, the effect of reducing the equivalent series resistance (ESR) at low temperature and the effect that the water-soluble polymer compound hardly permeates through the sealing member can be compatible. As a result, the solid electrolytic capacitor of the present invention is A solid electrolytic capacitor having good low-temperature characteristics and a long lifetime is obtained.

[5] In the solid electrolytic capacitor of the present invention, among the two or more types of water-soluble polymer compounds having different molecular weights, the water-soluble polymer compound having the largest molecular weight has the smallest molecular weight. The molecular weight is preferably 1.2 times or more.

  By setting it as such a structure, the solid electrolytic capacitor of this invention turns into a solid electrolytic capacitor with much more favorable low-temperature characteristics. The reason why the molecular weight of the water-soluble polymer compound having the highest molecular weight is 1.2 times or more the molecular weight of the water-soluble polymer compound having the smallest molecular weight is as follows. That is, when the molecular weight of the water-soluble polymer compound having the largest molecular weight is smaller than 1.2 times the molecular weight of the water-soluble polymer compound having the smallest molecular weight, the freezing point of each water-soluble polymer compound is very narrow. Since it concentrates on the temperature range, the water-soluble polymer compound can easily pass through the sealing member, and has the effect of reducing the equivalent series resistance at low temperature and the effect of suppressing the water-soluble polymer compound from passing through the sealing member. This is because it is difficult to achieve both.

[6] In the solid electrolytic capacitor of the present invention, the ratio of the water-soluble polymer compound having the largest molecular weight among the two or more kinds of polymer compounds having different molecular weights to the liquid water-soluble polymer compound is 20 vol. It is preferable that it exists in the range of% -80 vol%.

  The ratio of the water-soluble polymer compound having the largest molecular weight among the two or more types of water-soluble polymer compounds having different molecular weights relative to the liquid water-soluble polymer compound was set within the range of 20 vol% to 80 vol% as follows. Depending on the reason. That is, when the ratio is smaller than 20 vol%, the ratio of the water-soluble polymer compound having the smallest molecular weight is excessively increased, and the water-soluble polymer compound is likely to permeate the sealing member and scatter to the outside. It is. On the other hand, when the ratio is larger than 80 vol%, the amount of the water-soluble polymer compound having the largest molecular weight increases so that the effect of reducing the equivalent series resistance at low temperatures becomes small.

[7] In the solid electrolytic capacitor of the present invention, the water-soluble polymer compound is preferably a polyalkylene oxide, a water-soluble silicone, a branched polyether, or a derivative thereof.

  Since all of the above water-soluble polymer compounds have many oxygen atoms and high oxidizing power, it is assumed that a defect occurs in the oxide film when the solid electrolytic capacitor is used for a long time by configuring as described above. However, as a result of the high oxidizing power of the water-soluble polymer compound described above being used for repairing the defective portion, the solid electrolytic capacitor of the present invention is a solid electrolytic capacitor with even longer life characteristics. .

[8] In the solid electrolytic capacitor of the present invention, when the water-soluble polymer compound is a polyalkylene oxide, the molecular weight of the water-soluble polymer compound is in the range of 100 to 1000, and the water-soluble polymer When the molecular compound is a water-soluble silicone, a branched polyether, a polyalkylene oxide derivative, a water-soluble silicone derivative or a branched polyether derivative, the molecular weight of the water-soluble polymer compound is in the range of 200 to 3,000. It is preferable that it exists in.

  When the water-soluble polymer compound is polyalkylene oxide, the molecular weight of the water-soluble polymer compound is set within the range of 100 to 1000 for the following reason. That is, when the molecular weight of the water-soluble polymer compound is smaller than 100, the water-soluble polymer compound easily penetrates the sealing member and is scattered outside. On the other hand, when the molecular weight of the water-soluble polymer compound is larger than 1000, the effect of reducing the equivalent series resistance at low temperatures is reduced.

  When the water-soluble polymer compound is a water-soluble silicone, branched polyether, polyalkylene oxide derivative, water-soluble silicone derivative or branched polyether derivative, the molecular weight of the water-soluble polymer compound is in the range of 200 to 3000. The reason is as follows. That is, when the molecular weight of the water-soluble polymer compound is smaller than 200, the water-soluble polymer compound easily penetrates the sealing member and scatters outside. On the other hand, when the molecular weight of the water-soluble polymer compound is larger than 3000, the effect of reducing the equivalent series resistance at low temperature is reduced.

[9] A method for producing a solid electrolytic capacitor according to the present invention includes an anode foil having an oxide film formed on a surface thereof, a cathode foil, and a separator disposed between the anode foil and the cathode foil. In the first step of fabricating the device, and in the gap between the anode foil and the cathode foil, a fine solid electrolyte composed of a conductive polymer compound, the proportion of the solid electrolyte in the gap is 1 vol% to A second step of introducing so as to be within the range of 30 vol%, and a liquid water-soluble polymer compound in the gap between the anode foil and the cathode foil so as to surround the solid electrolyte, and And a third step of introducing the liquid water-soluble polymer compound in the void so as to be in a range of 10 vol% to 99 vol%.

  According to the method for producing a solid electrolytic capacitor of the present invention, the solid electrolytic capacitor of the present invention having the above-described excellent characteristics can be produced.

[10] In the method for producing a solid electrolytic capacitor of the present invention, it is preferable that an average particle diameter of the particulate solid electrolyte is in a range of 1 nm to 300 nm.

  The reason why the average particle diameter of the fine solid electrolyte is in the range of 1 nm to 300 nm is as described above.

[11] In the method for producing a solid electrolytic capacitor of the present invention, in the second step, the void is filled with a solid electrolyte dispersion solution in which the solid electrolyte is dispersed in a solvent by a vacuum impregnation method or a dip impregnation method. Thereafter, it is preferable to introduce the solid electrolyte into the voids by removing the solvent from the voids.

  By setting it as such a method, a predetermined amount of solid electrolyte can be easily introduce | transduced into the very narrow space | gap between anode foil and cathode foil.

[12] In the method for producing a solid electrolytic capacitor of the present invention, in the third step, the void is introduced by filling the void with the liquid water-soluble polymer compound by a vacuum impregnation method or a dip impregnation method. It is preferable.

  By adopting such a method, a predetermined amount of a liquid water-soluble polymer compound can be easily introduced into a very narrow gap between the anode foil and the cathode foil.

1 is a view for explaining a solid electrolytic capacitor 1 according to Embodiment 1. FIG. FIG. 3 is a diagram for explaining a main part of the solid electrolytic capacitor 1 according to the first embodiment. 3 is a flowchart for explaining a method for manufacturing the solid electrolytic capacitor according to the first embodiment. It is a figure shown in order to demonstrate the manufacturing method of the solid electrolytic capacitor which concerns on Embodiment 1. FIG. It is a figure shown in order to demonstrate the manufacturing method of the solid electrolytic capacitor which concerns on Embodiment 1. FIG. It is a figure shown in order to demonstrate the manufacturing method of the solid electrolytic capacitor which concerns on Embodiment 1. FIG. It is a graph which shows the evaluation result of the item of each sample used for the test example, and a test example. 6 is a graph showing the results of Test Example 1. 6 is a graph showing the results of Test Example 2. 10 is a graph showing the results of Test Example 3. 10 is a graph showing the results of Test Example 4. It is a graph which shows the result of test example 5 (evaluation method 1). It is a graph which shows the result of test example 5 (evaluation method 2).

  Hereinafter, a solid electrolytic capacitor and a method for manufacturing the same according to the present invention will be described based on embodiments shown in the drawings.

[Embodiment 1]
1. Configuration of Solid Electrolytic Capacitor 1 According to Embodiment 1 FIG. 1 is a diagram for explaining a solid electrolytic capacitor 1 according to Embodiment 1. FIG. FIG. 1A is a cross-sectional view of the solid electrolytic capacitor 1 according to the first embodiment, and FIG. 1B is a perspective view of the capacitor element 20.
FIG. 2 is a diagram for explaining a main part of the solid electrolytic capacitor 1 according to the first embodiment. FIG. 2A is a main part sectional view of the solid electrolytic capacitor 1, and FIG. 2B is a main part sectional view of a conventional solid electrolytic capacitor 900 according to a comparative example.

  A solid electrolytic capacitor 1 according to Embodiment 1 is a wound solid electrolytic capacitor, and includes a bottomed cylindrical metal case 10, a capacitor element 20, and a sealing member 40, as shown in FIG. .

  The bottom surface of the metal case 10 has a substantially circular shape, and a valve (not shown) is provided near the center. For this reason, when the internal pressure rises, the valve is broken so that the internal pressure can be released to the outside. The side surface portion of the metal case 10 is erected in a substantially vertical direction from the outer edge of the bottom surface portion. The opening of the metal case 10 is sealed by a sealing member 40, and the two leads 29 and 30 of the capacitor element 20 are drawn out through a through hole provided in the sealing member 40.

  The capacitor element 20 is housed inside the metal case 10 and, as shown in FIGS. 1B and 2A, between the anode foil 21, the cathode foil 23, and the anode foil 21 and the cathode foil 23. And the anode foil 21 and the cathode foil 23 are wound around each other with the separator 25 interposed therebetween.

  The anode foil 21 is formed from a valve metal such as aluminum, tantalum, or niobium. After the surface of the anode foil 21 is roughened by etching, an oxide film 22 is formed by chemical conversion (see FIG. 2A). Similarly to the anode foil 21, the cathode foil 23 is also formed from a valve metal such as aluminum, tantalum, or niobium. The surface of the cathode foil 23 is roughened by an etching process in the same manner as the anode foil 21, and then an oxide film 24 is formed by natural oxidation. The anode foil 21 and the cathode foil 23 are electrically connected to the leads 29 and 30, respectively.

  The width of the separator 25 is larger than the winding width of the anode foil 21 and the cathode foil 23, and the separator 25 is overlapped so as to sandwich the anode foil 21 and the cathode foil 23. The separator 25 is preferably made of cellulose fibers that are chemically compatible with conductive polymer particles or water-soluble polymers, or a synthetic resin such as nylon, PET, or PPS that has excellent heat resistance. Cellulose paper or heat resistant flame retardant paper can be used.

  In the solid electrolytic capacitor 1 according to the first embodiment configured as described above, a solid or viscous body is formed in the gap between the anode foil 21 and the cathode foil 23 as in the case of the conventional solid electrolytic capacitor. The water-soluble polymer compound 27 is not filled (introduced) (see FIG. 2B), but in the gap between the anode foil 21 and the cathode foil 23, fine particles made of a conductive polymer compound are formed. A solid electrolyte 26 and a liquid water-soluble polymer compound 28 are introduced so that the liquid water-soluble polymer compound 28 surrounds the solid electrolyte 26 (see FIG. 2A).

  The ratio of the solid electrolyte 26 in the voids is in the range of 1 vol% to 30 vol%, and the ratio of the liquid water-soluble polymer compound 28 in the voids is in the range of 10 vol% to 99 vol%. Moreover, the average particle diameter of the particulate solid electrolyte is in the range of 1 nm to 300 nm (for example, 20 nm).

  The conductive polymer compound is made of polyethylene dioxythiophene, polythiophene, polypyrrole or polyarinin.

  The solid electrolyte 26 may further include a dopant made of polystyrene sulfonic acid, toluene sulfonic acid, alkylbenzene sulfonic acid, or naphthalene sulfonic acid.

  The water-soluble polymer compound is a polyalkylene oxide, a water-soluble silicone, a branched polyether, or a derivative thereof, for example, polyethylene glycol (PEG). The molecular weight of the water-soluble polymer compound is in the range of 100 to 1000, for example 300.

  The sealing member 40 has high airtightness in order to prevent scattering of the water-soluble polymer material from the inside to the outside and to prevent entry of foreign matter (for example, moisture, chlorine, fine powder, etc.) from the outside to the inside. In addition, it has moderate elasticity to ensure adhesion to the metal case 10 and the leads 29 and 30, and furthermore, these airtightness and elasticity performance can be maintained even in a high temperature state and a low temperature state. It is preferable to select the material. Examples of such materials include rubber materials such as ethylene / propylene / terpolymer (EPT), isobutylene / isoprene rubber (IIR), EPT-IIR blend rubber, silicone rubber, phenol resin, epoxy resin, fluorine resin, and the like. A rubber composite material in which a resin and rubber are bonded together can be suitably used. Among these, isobutylene / isoprene rubber (IIR) having excellent airtightness can be particularly preferably used.

2. Manufacturing Method of Solid Electrolytic Capacitor According to Embodiment 1 The solid electrolytic capacitor 1 according to Embodiment 1 can be manufactured by the following method.
FIG. 3 is a flowchart for explaining the method of manufacturing the solid electrolytic capacitor according to the first embodiment.
4-6 is a figure shown in order to demonstrate the manufacturing method of the solid electrolytic capacitor which concerns on Embodiment 1. FIG. 4 is a diagram for explaining the solid electrolyte introduction process, FIG. 5 is a diagram for explaining the liquid water-soluble polymer compound introduction process, and FIG. 6 is an assembly / sealing process. It is a figure shown in order to demonstrate a process. 4A to FIG. 4D, FIG. 5A to FIG. 5C, and FIG. 6A to FIG. 6C are process diagrams.

  As shown in FIG. 3, the manufacturing method of the solid electrolytic capacitor in Embodiment 1 includes a capacitor element manufacturing step (first step), a chemical conversion treatment step, a solid electrolyte introduction step (second step), and a liquid water solution. The conductive polymer compound introduction step (third step) and the assembly / sealing step are included in this order. Hereinafter, the manufacturing method of the semiconductor device according to the first embodiment will be described along each step.

(1) Capacitor element manufacturing process (first process)
First, an anode foil 21 in which an oxide film 22 is formed by applying a predetermined voltage of 2 to 400 V to a surface of an aluminum foil roughened by a surface-enlarging process, and a cathode foil 23, Then, a capacitor element including a separator 25 disposed between the anode foil 21 and the cathode foil 23 is manufactured (see FIG. 1B). Specifically, an anode foil 21 having an uneven surface and an oxide film 22 formed on the uneven surface and a cathode foil 23 having an uneven surface are overlapped and wound through a separator 25 to form a capacitor element. 20 is produced. At this time, the lead 29 is connected to the anode foil 21, and the lead 30 is connected to the cathode foil 23.

(2) Chemical conversion treatment step Next, the capacitor element 20 is converted into a chemical conversion liquid (for example, ammonium adipate, ammonium borate, ammonium phosphate, ammonium glutarate, ammonium azelate, tartaric acid in a chemical conversion bath (not shown). Anode foil 21 is immersed in an aqueous solution of ammonium, ammonium sebacate, ammonium pimelate, ammonium suberate, etc., and a predetermined voltage (for example, 100 V) is applied between the lead 29 on the anode side and the chemical conversion solution for 5 minutes. The oxide film defect part existing at the end of the oxide film and the oxide film defect part that may exist on the surface are repaired (not shown).

(3) Solid electrolyte introduction process (second process)
Next, in the space between the anode foil 21 and the cathode foil 23, the particulate solid electrolyte 26 made of a conductive polymer compound is within the range of 2 vol% to 30 vol% of the solid electrolyte 26 in the space. Introduce as follows. In the solid electrolyte introduction step, after filling the voids with a solid electrolyte dispersion solution in which the solid electrolyte 26 is dispersed in a solvent, the solid electrolyte 26 is introduced into the voids by removing the solvent from the voids.

  Specifically, the solid electrolyte introduction step is performed as follows. That is, as shown in FIG. 4, after the solid electrolyte dispersion solution 62 in which the solid electrolyte 26 is dispersed in a solvent is filled in the solid electrolyte introduction tank 60 (see FIG. 4A), the capacitor is obtained by the immersion impregnation method. The element 20 is immersed in the solid electrolyte dispersion solution 62 (polymer concentration is 2 vol%) (see FIG. 4B). Next, the capacitor element 20 is taken out from the solid electrolyte dispersion solution 62 (see FIG. 4C), and then the capacitor element 20 is heated (see FIG. 4D). This is repeated twice, and the ratio of the solid electrolyte in the voids is 4 vol%. In addition, the solid electrolyte dispersion solution is obtained from a conductive polymer compound (for example, PEDOT polymer) to which a dopant or an emulsifier is added by polymerizing a monomer (for example, EDOT monomer) in a suspended state (radical polymerization or oxidative polymerization). The fine particle solid electrolyte can be prepared, and the fine particle solid electrolyte can be dispersed in a predetermined solvent. The average particle size of the particulate solid electrolyte can be adjusted by appropriately setting the polymerization reaction conditions (for example, the concentration of initiator, monomer, polymerization aid, etc., reaction temperature, reaction solution stirring conditions, etc.). . Moreover, it can also adjust by performing a well-known grinding | pulverization process (for example, stirring crushing process, vibration crushing process, etc.). The particulate solid electrolyte can be subjected to preparative filtration to make the particle diameter uniform.

  In order to make the proportion of the solid electrolyte in the voids larger than 4 vol%, “capacitor element 20 is immersed in solid electrolyte dispersion solution 62, then capacitor element 20 is taken out of solid electrolyte dispersion solution 62; The process of “heating the capacitor element 20” is further repeated several times. The solid electrolyte dispersion solution 62 may be formed by an appropriate method such as increasing the polymer concentration. In order to set the ratio of the solid electrolyte in the voids to 2 vol%, the process is performed only once. Further, in order to make the ratio of the solid electrolyte in the voids smaller than 2 vol%, an appropriate method such as reducing the polymer concentration of the solid electrolyte dispersion solution 62 is performed.

  The introduction amount (volume) of the solid electrolyte is obtained by measuring the weight of the capacitor element in each state (before immersion, after immersion and drying), and converting the weight difference between before and after immersion into the volume using the density of the solid electrolyte. Can be calculated. Therefore, by measuring and calculating in advance the gap (volume) of the capacitor element before immersion, the proportion of the solid electrolyte in the gap can be calculated.

(4) Introduction of liquid water-soluble polymer compound (third step)
Next, the liquid water-soluble polymer compound 28 is surrounded in the space between the anode foil 21 and the cathode foil 23 so as to surround the solid electrolyte 26 and the ratio of the water-soluble polymer compound 28 in the space is It introduce | transduces so that it may become in the range of 10 vol%-99 vol%.

  Specifically, the water-soluble polymer compound filling step is performed as follows. That is, as shown in FIG. 5, after the liquid 72 made of a water-soluble polymer compound is filled in the water-soluble polymer compound filling tank 70 (see FIG. 5A), the capacitor element 20 is obtained by the immersion impregnation method. Is immersed in a liquid 72 made of a water-soluble polymer compound (see FIG. 5B), thereby introducing the liquid water-soluble polymer compound 28 into the voids. Next, the capacitor element 20 is taken out from the liquid 72 made of the water-soluble polymer compound (see FIG. 5C), the excess / deficiency is adjusted, and the amount of liquid water-soluble polymer compound 28 introduced is predetermined. Confirm that the introduction amount (weight) is reached.

  The amount (volume) of the liquid water-soluble polymer compound 28 introduced is determined by measuring the weight of the capacitor element in each state (before immersion and after immersion), and calculating the difference in weight between the liquid water-soluble polymer compound 28 before and after immersion. It can be calculated by converting the volume using the density of the molecular compound. Therefore, by measuring and calculating in advance the gap (volume) of the capacitor element before immersion, the ratio of the liquid water-soluble polymer compound 28 in the gap can be calculated.

(5) Assembly / Sealing Process Finally, the sealing member 40 is attached to the capacitor element 20 (see FIG. 6A), and the capacitor element 20 is inserted into the metal case 10 (see FIG. 6B). The metal case 10 is caulked in the vicinity of the opening end of the metal case 10 (see FIG. 6C). As the sealing member 40, for example, isobutylene / isoprene rubber (IIR) is used. Instead of isobutylene / isoprene rubber (IIR), rubber materials such as ethylene / propylene terpolymer (EPT), EPT-IIR blend rubber, silicone rubber, and resins such as phenol resin (bakelite), epoxy resin, and fluororesin A rubber composite material bonded with rubber can also be used. Thereafter, an aging process is performed by applying a predetermined voltage in a high-temperature atmosphere. Thereby, the solid electrolytic capacitor 1 according to the first embodiment is completed.

3. Effect of Solid Electrolytic Capacitor 1 According to Embodiment 1 and Method for Producing the Same According to solid electrolytic capacitor 1 according to Embodiment 1, a liquid water-soluble polymer is formed in the gap between anode foil 21 and cathode foil 23. Since the compound 28 is introduced, even if the oxide film is deficient when the solid electrolytic capacitor is used for a long time, the deficient portion and the liquid water-soluble polymer compound 28 are more in contact with each other than before. Since it becomes easy, the said defect | deletion location will be repaired more efficiently than before. As a result, the solid electrolytic capacitor 1 according to the first embodiment can maintain a normal dielectric film for a longer time than the conventional one, and becomes a solid electrolytic capacitor having a longer life characteristic than the conventional one.

  Further, according to the solid electrolytic capacitor 1 according to the first embodiment, the liquid water-soluble polymer compound 28 is introduced into the gap between the anode foil 21 and the cathode foil 23 so as to surround the solid electrolyte. Thus, the (strong acid) dopant or a part thereof that may be liberated from the solid electrolyte 26 is inhibited from coming into contact with the fibers of the separator 25, and the deterioration reaction of the separator 25 due to the dopant can be suppressed. As a result, the solid electrolytic capacitor 1 according to the first embodiment is also a solid electrolytic capacitor that is superior in long-life characteristics than the conventional one from this viewpoint.

  The reason why the ratio of the liquid water-soluble polymer compound 28 occupying the voids is within the range of 10 vol% to 99 vol% is as follows. That is, when the proportion of the liquid water-soluble polymer compound 28 occupying the void is smaller than 10 vol%, the deficient portion of the oxide film and the liquid water-soluble polymer compound 28 are difficult to contact, This is because the defective portion may not be efficiently repaired. On the other hand, when the proportion of the liquid water-soluble polymer compound 28 occupying the gap is larger than 99%, the proportion of the solid electrolyte 26 occupying the gap is reduced, and the equivalent series resistance (ESR) of the resistance component of the capacitor is reduced. This is because there is a case where becomes larger. From such a viewpoint, the ratio of the liquid water-soluble polymer compound in the voids is more preferably 20 vol% or more, and further preferably 30 vol% or more. The ratio of the liquid water-soluble polymer compound in the voids is more preferably 96 vol% or less, and still more preferably 90 vol% or less.

  The reason why the ratio of the solid electrolyte 26 in the voids is set within the range of 1 vol% to 30 vol% is as follows. That is, when the proportion of the solid electrolyte 26 in the gap is smaller than 1 vol%, the equivalent series resistance (ESR) of the resistance component of the capacitor may increase. On the other hand, when the proportion of the solid electrolyte 26 occupying the gap is larger than 30 vol%, in the process of manufacturing the solid electrolytic capacitor, the gap is easily clogged with the solid electrolyte 26 and is difficult to manufacture. From this point of view, the ratio of the solid electrolyte in the voids is more preferably 1.5 vol% or more, and even more preferably 2 vol% or more. Further, the ratio of the solid electrolyte in the voids is more preferably 25 vol% or less, and further preferably 20 vol% or less.

  Further, according to the solid electrolytic capacitor 1 according to the first embodiment, since a water-soluble polymer compound is used instead of a general solvent, the water-soluble polymer compound is difficult to permeate through the sealing member 40 to the outside. . For this reason, the solid electrolytic capacitor 1 according to Embodiment 1 is a solid electrolytic capacitor in which the repair action of the oxide film is maintained for a long time.

  Further, according to the solid electrolytic capacitor 1 according to the first embodiment, since the average particle diameter of the particulate solid electrolyte 26 is in the range of 1 nm to 300 nm, it becomes easy to produce the particulate solid electrolyte. In addition, it becomes easy to introduce a fine solid electrolyte into etching pits (concave portions) on the surface of the anode foil.

  Further, according to the solid electrolytic capacitor 1 according to the first embodiment, the liquid water-soluble polymer compound 28 has an oxide film repairing performance, so that the breakdown voltage is high as in the case of the conventional solid electrolytic capacitor, and A solid electrolytic capacitor having a low leakage current and a long life is obtained.

  In addition, according to the solid electrolytic capacitor 1 according to Embodiment 1, the water-soluble polymer compound is polyalkylene oxide, water-soluble silicone, branched polyether, or a derivative thereof, and any of the water-soluble polymer compounds described above. Since it has a large amount of oxygen atoms and high oxidizing power, the above-described water-soluble polymer compound can be formed by the above-described configuration even if a defect occurs in the oxide film when the solid electrolytic capacitor is used for a long time. As a result of being able to use the high oxidizing power possessed for the repair of the above-mentioned defective portion, the solid electrolytic capacitor 1 according to Embodiment 1 becomes a solid electrolytic capacitor with further excellent long-life characteristics.

  When the water-soluble polymer compound is polyalkylene oxide, the molecular weight of the water-soluble polymer compound 28 is set within the range of 100 to 1000 for the following reason. That is, when the molecular weight of the water-soluble polymer compound 28 is smaller than 100, the water-soluble polymer compound easily penetrates the sealing member 40 and is scattered outside. On the other hand, when the molecular weight of the water-soluble polymer compound 28 is larger than 1000, the effect of reducing the equivalent series resistance at low temperatures is reduced.

  When the water-soluble polymer compound 28 is a water-soluble silicone, a branched polyether, a polyalkylene oxide derivative, a water-soluble silicone derivative or a branched polyether derivative, the molecular weight of the water-soluble polymer compound is in the range of 200 to 3,000. The reason is as follows. That is, when the molecular weight of the water-soluble polymer compound is smaller than 200, the water-soluble polymer compound easily penetrates the sealing member 40 and is scattered outside. On the other hand, when the molecular weight of the water-soluble polymer compound is larger than 3000, the effect of reducing the equivalent series resistance at low temperature is reduced.

  According to the method for manufacturing a solid electrolytic capacitor according to the first embodiment, the solid electrolytic capacitor 1 according to the first embodiment having the excellent features described above can be manufactured.

  Further, according to the method for manufacturing the solid electrolytic capacitor according to the first embodiment, in the second step, the solid electrolyte dispersion solution 62 in which the solid electrolyte 26 is dispersed in the solvent is filled in the gap by the immersion impregnation method. Since the solid electrolyte 26 is introduced into the gaps by removing the solvent, the predetermined amount of the solid electrolyte 26 can be easily introduced into the extremely narrow gap between the anode foil 21 and the cathode foil 23.

  Further, according to the method for manufacturing the solid electrolytic capacitor according to the first embodiment, in the third step, the voids are filled with the liquid water-soluble polymer compound 28 by the immersion impregnation method. A predetermined amount of the liquid water-soluble polymer compound 28 can be easily introduced into a very narrow gap between the two.

[Embodiment 2]
The solid electrolytic capacitor (not shown) according to the second embodiment has basically the same configuration as that of the solid electrolytic capacitor 1 according to the first embodiment, but the configuration of a liquid water-soluble polymer compound is the embodiment. 1 is different from that of the solid electrolytic capacitor 1 according to FIG. That is, in the solid electrolytic capacitor according to Embodiment 2, the liquid water-soluble polymer compound is a mixture of two or more types of water-soluble polymer compounds having different molecular weights. Specifically, the liquid water-soluble polymer compound is composed of PEG having a molecular weight of 100 and PEG having a molecular weight of 600.

  In the solid electrolytic capacitor according to Embodiment 2, the water-soluble polymer compound having the largest molecular weight (PEG having a molecular weight of 600) is selected from two types of water-soluble polymer compounds having different molecular weights (PEG having a molecular weight of 100 and PEG having a molecular weight of 600). ) Is 6 times the molecular weight 100 of the water-soluble polymer compound having the smallest molecular weight (PEG having a molecular weight of 100). The ratio of PEG having a molecular weight of 600 to the liquid water-soluble polymer compound is in the range of 20 vol% to 80 vol%, for example, 50 vol%.

  As described above, the solid electrolytic capacitor according to the second embodiment is different from the solid electrolytic capacitor 1 according to the first embodiment in the configuration of the liquid water-soluble polymer compound, but the solid electrolytic capacitor 1 according to the first embodiment. As in the case of, the gap between the anode foil and the cathode foil is filled with a liquid water-soluble polymer compound. Even if it occurs, the defect portion and the liquid water-soluble polymer compound are more likely to come into contact with each other, so that the defect portion is repaired more efficiently than before. As a result, the solid electrolytic capacitor according to the second embodiment can maintain a normal dielectric film for a longer time than the conventional one, and becomes a solid electrolytic capacitor having a longer life characteristic than the conventional one.

  Further, according to the solid electrolytic capacitor according to the second embodiment, the liquid water-soluble polymer compound is a mixture of two or more types of water-soluble polymer compounds having different molecular weights, so that the equivalent series resistance can be lowered. It is possible to achieve both the effect and the effect that the water-soluble polymer compound hardly permeates through the sealing member, and as a result, the solid electrolytic capacitor according to Embodiment 2 has good low-temperature characteristics and has a long life. It becomes a long solid electrolytic capacitor.

  In addition, according to the solid electrolytic capacitor according to the second embodiment, the water-soluble polymer compound having the largest molecular weight among the two or more types of water-soluble polymer compounds having different molecular weights is the water-soluble polymer having the smallest molecular weight. Since the molecular weight of the compound is 1.2 times or more, the solid electrolytic capacitor according to Embodiment 2 is a solid electrolytic capacitor with even better low-temperature characteristics. The reason why the molecular weight of the water-soluble polymer compound having the highest molecular weight is 1.2 times or more the molecular weight of the water-soluble polymer compound having the smallest molecular weight is as follows. That is, when the molecular weight of the water-soluble polymer compound having the largest molecular weight is smaller than 1.2 times the molecular weight of the water-soluble polymer compound having the smallest molecular weight, the freezing point of each water-soluble polymer compound is very narrow. Since it concentrates on the temperature range, the water-soluble polymer compound can easily pass through the sealing member, and has the effect of reducing the equivalent series resistance at low temperature and the effect of suppressing the water-soluble polymer compound from passing through the sealing member. This is because it is difficult to achieve both.

  The ratio of the water-soluble polymer compound having the largest molecular weight among the two or more types of water-soluble polymer compounds having different molecular weights relative to the liquid water-soluble polymer compound was set within the range of 20 vol% to 80 vol% as follows. Depending on the reason. That is, when the ratio is smaller than 20 vol%, the ratio of the water-soluble polymer compound having the smallest molecular weight is excessively increased, and the water-soluble polymer compound is likely to permeate the sealing member and scatter to the outside. It is. On the other hand, when the ratio is larger than 80 vol%, the amount of the water-soluble polymer compound having the largest molecular weight increases so that the effect of reducing the equivalent series resistance at low temperatures becomes small.

  The solid electrolytic capacitor according to the second embodiment has the same configuration as that of the solid electrolytic capacitor 1 according to the first embodiment except for the configuration of the liquid water-soluble polymer compound, and thus the solid electrolytic capacitor according to the first embodiment. It has a corresponding effect among the effects of the electrolytic capacitor 1.

[Test example]
The following Test Examples 1 to 5 are test examples showing that the solid electrolytic capacitor of the present invention is a solid electrolytic capacitor excellent in long life characteristics, equivalent series resistance (ESR) characteristics, and low temperature characteristics.

  FIG. 7 is a chart showing the specifications of each sample used in the test examples and the evaluation results of the test examples. 7A is a chart showing the specifications of the sample used in Test Example 1 and the evaluation results of Test Example 1. FIG. 7B is the table showing the specifications of the sample used in Test Example 2 and the test example. 7 is a chart showing the evaluation results of Test Example 3, and FIG. 7C is a chart showing the evaluation results of Test Example 3. FIG. It is a graph which shows the evaluation result of the item of used sample, and the test example 4. FIG.

<Test Example 1>
Test Example 1 is a test example for confirming that the solid electrolytic capacitor of the present invention is a solid electrolytic capacitor having longer life characteristics than the solid electrolytic capacitor of the comparative example from the viewpoint of equivalent series resistance (ESR). It is.

1. Sample Preparation (1) Sample 1 (Example)
A solid electrolytic capacitor similar to the solid electrolytic capacitor 1 according to Embodiment 1 was produced and used as Sample 1. However, polyethylenedioxythiophene (PEDOT) was used as the conductive polymer compound. Moreover, what further contains the dopant which consists of polystyrene sulfonic acids was used as a solid electrolyte. In addition, polyethylene glycol (PEG 300) having a molecular weight of 300 was used as the liquid water-soluble polymer compound.
(2) Sample 2 (comparative example)
A solid electrolytic capacitor same as the solid electrolytic capacitor according to Sample 1 except that a solvent (γ-butyrolactone) is introduced instead of PEG300 in the gap between the anode foil and the cathode foil is prepared. 2 (comparative example).
(3) Sample 3 (comparative example)
The same solid electrolytic capacitor as the solid electrolytic capacitor according to Sample 1 is manufactured except that an electrolytic solution using γ-butyrolactone as a solvent is introduced in the gap between the anode foil and the cathode foil instead of PEG300. Sample 3 (comparative example).
(4) Sample 4 (comparative example)
A solid electrolytic capacitor, which is the same as the solid electrolytic capacitor according to Sample 1 except that a solvent (ethylene glycol) is introduced instead of PEG 300 in the gap between the anode foil and the cathode foil, is prepared. (Comparative example).
(5) Sample 5 (comparative example)
A solid electrolytic capacitor same as the solid electrolytic capacitor according to Sample 1 except that an electrolytic solution using ethylene glycol as a solvent is introduced in the gap between the anode foil and the cathode foil instead of PEG300 is prepared. Sample 5 (comparative example).

2. Evaluation Method Each sample (samples 1 to 5) was placed in a constant temperature and humidity chamber at 25 ° C., and a predetermined alternating voltage (100 kHz) was applied to each sample to measure an equivalent series resistance (ESR). The measurement was performed every 500 hours for 4000 hours. As a result, an evaluation of “◯” is given when the ESR when 4000 hours have elapsed from the start of measurement is 1.5 times or less of the initial value, and the ESR when 4000 hours have elapsed from the start of the measurement is 1. If the value is greater than 5 times and less than 5 times, an evaluation of “△” is given, and if the ESR after 4000 hours from the start of measurement is greater than 5 times the initial value, an evaluation of “x” is given. Gave.

3. Evaluation Results FIG. 8 is a graph showing the results of Test Example 1.
As can be seen from the graph of FIG. 8, in Sample 1 (Example), the ESR hardly changes from the initial value even after 4000 hours have elapsed from the start of measurement, and the ESR when 4000 hours have elapsed from the start of measurement is the initial value. Since it was 1.5 times or less of the value, an evaluation of “◯” was given (see FIG. 7A).

  In Sample 2 (Comparative Example) and Sample 3 (Comparative Example), both ESRs started to increase after about 3000 hours from the start of measurement, and both ESRs reached about 12 mΩ after 4000 hours from the start of measurement. Since the ESR when 4000 hours passed from the start of measurement was larger than 1.5 times the initial value and 5 times or less, an evaluation of “Δ” was given (see FIG. 7A).

In sample 4 (comparative example), ESR started to increase after about 1500 hours from the start of measurement, and after 3000 hours from the start of measurement, ESR reached about 15 mΩ and continued to increase. Since it is considered that the ESR when 4000 hours have elapsed from the initial value is larger than five times the initial value, an evaluation of “x” was given (see FIG. 7A).
In sample 5 (comparative example), ESR started increasing from the start of measurement, and after 1000 hours from the start of measurement, ESR reached about 19 mΩ and continued to increase. Since the ESR is considered to be larger than 5 times the initial value, an evaluation of “x” was given (see FIG. 7A).

  From this, it was confirmed that the solid electrolytic capacitor of the present invention (solid electrolytic capacitor according to Sample 1) was a solid electrolytic capacitor having excellent long-life characteristics from the viewpoint of equivalent series resistance (ESR).

<Test Example 2>
Test Example 2 is a test example for confirming that the solid electrolytic capacitor of the present invention is a solid electrolytic capacitor having a longer life characteristic than the solid electrolytic capacitor of the comparative example from the viewpoint of weight change.
1. Preparation of Sample A solid electrolytic capacitor having the same configuration as the solid electrolytic capacitor according to Sample 1 was produced and used as Sample 6 (Example). Moreover, the solid electrolytic capacitor which has the same structure as the solid electrolytic capacitor which concerns on the samples 2-5 was produced, and it was set as the samples 7-10 (comparative example).

2. Evaluation Method Each sample (samples 6 to 10) was placed in a constant temperature and humidity chamber at 25 ° C., and then the weight when these were left indoors was measured. The weight was measured using an electronic balance every 500 hours for 4000 hours. As a result, an evaluation of “◯” was given when the weight change from the initial value after 4000 hours from the start of measurement was 100 mg or less, and an evaluation of “x” was given when the weight change was larger than 100 mg. .

3. Evaluation Results FIG. 9 is a graph showing the results of Test Example 2.
As can be seen from the graph of FIG. 9, the weight change was about 140 mg in Sample 7 (Comparative Example), and the weight change was about 130 mg in Sample 8 (Comparative Example). Therefore, since both the weight changes exceeded 100 mg, both were given an evaluation of “x” (see FIG. 7B).

  On the other hand, in sample 6 (Example), the weight change is about 25 mg, in sample 9 (Comparative Example), the weight change is about 50 mg, and in Sample 10 (Comparative Example), Since the change in weight was about 65 mg, and thus the change in weight was 100 mg or less, all were evaluated as “◯” (see FIG. 7B). This means that a liquid water-soluble polymer compound, ethylene glycol, and an electrolytic solution using ethylene glycol as a solvent hardly permeate the outside through the sealing member.

  From this, it was confirmed that the solid electrolytic capacitors according to Samples 6, 7, and 10 are solid electrolytic capacitors having excellent long life characteristics from the viewpoint of weight change.

  From the results of Test Example 1 and Test Example 2, it was confirmed that the solid electrolytic capacitor of the present invention was a solid electrolytic capacitor with excellent long-life characteristics from the viewpoint of equivalent series resistance (ESR) and weight change. .

<Test Example 3>
Test Example 3 is a test example for confirming that the solid electrolytic capacitor of the present invention is a capacitor having excellent low-resistance characteristics (equivalent series resistance (ESR) characteristics) like the electrolytic capacitor.
1. Sample Preparation (1) Sample 11 (Example)
A solid electrolytic capacitor having the same configuration as that of the solid electrolytic capacitor according to Sample 1 was produced and used as Sample 11 (Example).

(2) Sample 12 (comparative example)
The same capacitor as the solid electrolytic capacitor according to the sample 11 except that the solid electrolyte is not introduced into the gap between the anode foil and the cathode foil and the electrolyte is introduced instead of PEG300 ( An electrolytic capacitor) was produced and used as Sample 12 (Comparative Example).

2. Evaluation Method Each sample (sample 11 and sample 12) was placed in a constant temperature and humidity chamber at 25 ° C., and ESR was measured while applying a predetermined alternating voltage to each sample and changing the frequency. When the ESR is 1Ω or less in the entire range of 0.1 kHz to 1000 kHz, an evaluation of “◯” is given, and when the ESR is larger than 1Ω in at least a part of the range of 0.1 kHz to 1000 kHz, “× Was given a rating.

3. Evaluation Results FIG. 10 is a graph showing the results of Test Example 3.
As can be seen from FIG. 10, both sample 11 (Example) and sample 12 (Comparative Example) were evaluated as “◯” because ESR was 1Ω or less in the entire range from 0.1 kHz to 1000 kHz. (See FIG. 7C.)
From this, it was confirmed that the solid electrolytic capacitor according to Sample 11 (Example) was a capacitor having a low ESR, similar to the capacitor (electrolytic capacitor) according to Sample 12 (Comparative Example).

  Therefore, it was confirmed that the solid electrolytic capacitor of the present invention is a capacitor having a low resistance characteristic (equivalent series resistance (ESR) characteristic) as well as the electrolytic capacitor. From Test Example 3, in the frequency band of 0.3 kHz or more, the solid electrolytic capacitor of the present invention is a capacitor that is more excellent in low resistance characteristics (equivalent series resistance (ESR) characteristics) than the electrolytic capacitor. I was able to confirm that.

<Test Example 4>
Test Example 4 is a test example for confirming that the solid electrolytic capacitor of the present invention is a solid electrolytic capacitor having superior low-temperature characteristics than the solid electrolytic capacitor according to the comparative example.
1. Sample Preparation (1) Sample 13 (Example)
A solid electrolytic capacitor having the same configuration as that of the solid electrolytic capacitor according to Sample 1 was produced as Sample 13 (Example). However, the proportion of the solid electrolyte in the voids was 4 vol%. In order to set the ratio of the solid electrolyte in the voids to 4 vol%, the process of “immersing the capacitor element in the solid electrolyte dispersion, then taking out the capacitor element, and then heat-treating the capacitor element” is performed twice. carry out.
(2) Sample 14 (Example)
A solid electrolytic capacitor having the same configuration as that of the solid electrolytic capacitor according to Sample 1 was produced and used as Sample 14 (Example). However, the ratio of the solid electrolyte in the voids was 2 vol%. In order to set the ratio of the solid electrolyte in the voids to 2 vol%, the above-described process is performed once.

(3) Sample 15 (comparative example)
Instead of introducing PEG300 into the gap between the anode foil and the cathode foil, a configuration other than the introduction of the electrolytic solution is the same as the solid electrolytic capacitor according to the sample 13 (so-called hybrid capacitor). Sample 15 (comparative example) was obtained.

2. Evaluation Method Each sample (samples 13 to 15) was placed in a thermo-hygrostat, and a predetermined alternating voltage (10 kHz) was applied to each sample to change the temperature, and the ESR was measured. As a result, when the ESR is 0.3Ω or less over the entire temperature range from −60 ° C. to 0 ° C. (hereinafter referred to as evaluation criteria), an evaluation of “◯” is given, and the temperature range from −60 ° C. to 0 ° C. An evaluation of “x” was given when the ESR exceeded 0.3Ω in at least a part of the samples.

3. Evaluation Results FIG. 11 is a graph showing the results of Test Example 4.
As can be seen from the graph of FIG. 11, in the sample 15 (comparative example), when the temperature is changed from 0 ° C. in a lower temperature direction, the ESR rapidly increases, and at −25 ° C., the ESR is about 0. It has reached 28Ω and continues to increase. Therefore, since it is considered that the evaluation standard is not satisfied, an evaluation of “x” is given (see FIG. 7D).
On the other hand, in the sample 14 (example), the ESR is in the range of about 0.19Ω to 0.21Ω over the entire temperature range from −60 ° C. to 0 ° C., and in the sample 13 (example), The ESR was about 0.03Ω over the entire temperature range from −60 ° C. to 0 ° C. Therefore, both of the evaluation criteria were evaluated as “◯” (see FIG. 7D).
Note that Sample 14 (Example) and Sample 15 (Comparative Example) both have good ESR at 3 mΩ or less in the high temperature range, but in the low temperature range, Sample 15 (Comparative Example). While the ESR increases rapidly, the ESR of the sample 14 (Example) does not increase rapidly. Therefore, it can be said that Sample 14 (Example) has better low-temperature characteristics than Sample 15 (Comparative Example).

  From the above, it was confirmed that the solid electrolytic capacitor of the present invention was a solid electrolytic capacitor having superior low-temperature characteristics as compared with the solid electrolytic capacitor of the comparative example. This is considered to be due to the following reason. That is, in Sample 15 (Comparative Example), it is considered that the current flow that was carried by the electrolyte because the electrolyte was solidified at a low temperature, whereas in Samples 13 and 14 (Example), This is presumably because the liquid water-soluble polymer compound does not solidify at a low temperature, so that the network of solid electrolytes is not easily destroyed.

<Test Example 5>
Test Example 5 shows that “a solid electrolytic capacitor according to Embodiment 2 (a solid electrolytic capacitor in which a liquid water-soluble polymer compound is a mixture of two or more water-soluble polymer compounds having different molecular weights) has low-temperature characteristics. This is a test example for confirming that “a solid electrolytic capacitor having excellent lifespan characteristics from the viewpoint of weight change”.

1. Sample Preparation (1) Sample 16 (PEG100 + PEG600)
A solid electrolytic capacitor having the same configuration as that of the solid electrolytic capacitor according to the second embodiment was produced and used as sample 16 (PEG100 + PEG600).
(2) Sample 17 (PEG100)
A solid electrolytic capacitor having the same structure as the solid electrolytic capacitor according to Sample 1 except that PEG having a molecular weight of 100 was used as the liquid water-soluble polymer compound was prepared as Sample 17 (PEG 100).
(3) Sample 18 (PEG600)
A solid electrolytic capacitor having the same structure as the solid electrolytic capacitor according to Sample 1 except that PEG having a molecular weight of 600 was used as the liquid water-soluble polymer compound was prepared as Sample 18 (PEG 600).
(4) Sample 19 (solid electrolytic capacitor)
Instead of introducing a particulate solid electrolyte into the gap between the anode foil and the cathode foil, a layered conductive polymer solid electrolyte formed by chemical oxidation polymerization in the gap between the anode foil and the cathode foil is used. A capacitor having the same configuration as that of the solid electrolytic capacitor according to Embodiment 1 except that it was introduced was produced as Sample 19 (solid electrolytic capacitor).

2. Evaluation method (1) Evaluation method 1
Each sample (samples 16 to 19) was placed in a thermostatic chamber, and a predetermined alternating voltage (100 kHz) was applied to each sample to measure the ESR while changing the temperature. The measured ESR was plotted on a graph with temperature on the horizontal axis and ESR on the vertical axis, and the low temperature characteristics were evaluated from the shape of the obtained curve and ESR.

(2) Evaluation method 2
Each sample (samples 16 to 18) was placed in a constant temperature and humidity chamber at 25 ° C., and then the samples were left indoors, and the weight was measured after 200 hours, 500 hours and 730 hours. The weight was measured using an electronic balance.

3. Evaluation result (1) Evaluation result 1 (Evaluation result by evaluation method 1)
FIG. 12 is a graph showing the results of Test Example 5 (Evaluation Method 1).
As can be seen from the graph of FIG. 12, in sample 16 (PEG100 + PEG600), the ESR decreased gently until 0 ° C., showed a minimum value of 110 mΩ at 0 ° C., and then gradually increased below 0 ° C. And became 160 mΩ at −40 ° C. In Sample 17 (PEG100), ESR decreased gently until 0 ° C, showed a minimum value of 110 mΩ at 0 ° C, and then gradually increased below 0 ° C to 145 mΩ at -40 ° C. It was. In Sample 18 (PEG 600), ESR gently decreased until 40 ° C., ESR increased moderately at 20 ° C. or lower, showed a maximum value of 350 mΩ at −10 ° C., and then decreased to −10 ° C. or lower. Gradually decreased to 220 mΩ at −40 ° C. In sample 19 (solid electrolytic capacitor), the ESR decreased gently until 20 ° C., showed a minimum value of 110 mΩ at 0 ° C., and almost no change in ESR was observed below 0 ° C.

  A polymer having a high molecular weight solidifies at a low temperature, and at that time, the network of the solid electrolyte is broken to increase the ESR of the solid electrolytic capacitor. Therefore, as can be seen from the graph of FIG. 12, the ESR of Sample 18 (PEG 600) is higher than that of Sample 17 (PEG 100) and Sample 19 (solid electrolytic capacitor by chemical oxidative polymerization) at low temperatures. Surprisingly, however, sample 16 (PEG100 + PEG600) has an ESR comparable to that of sample 17 (PEG100) at low temperatures despite the use of a water-soluble polymer compound containing a high molecular weight polymer (PEG600). Is shown.

  From this, it can be confirmed from Evaluation Result 1 (Evaluation Result by Evaluation Method 1) that the solid electrolytic capacitors according to Samples 16, 17 and 19 are solid electrolytic capacitors having excellent low-temperature characteristics.

(2) Evaluation result 2 (Evaluation result by evaluation method 2)
FIG. 13 is a graph showing the results of Test Example 5 (Evaluation Method 2).
As can be seen from the graph of FIG. 13, in sample 16 (PEG100 + PEG600), the change in weight is about −1.7 mg, and in sample 17 (PEG100), the change in weight is about −2.7 mg. In (PEG600), the weight change was about -1.1 mg. This means that a solid electrolytic capacitor (sample 16) using a mixture of two or more water-soluble polymer compounds having different molecular weights is not as solid as a solid electrolytic capacitor (PEG 600) using a water-soluble polymer compound having a large molecular weight. Although there is no water-soluble polymer compound (PEG100) using a water-soluble polymer compound having a small molecular weight, the water-soluble polymer compound is less likely to permeate the sealing member and scatter to the outside. It turned out to be an excellent solid electrolytic capacitor.

  As described above, from the results of Test Example 5, the solid electrolytic capacitor according to Sample 16 (the solid electrolytic capacitor according to Embodiment 2 of the solid electrolytic capacitor of the present invention (a mixture of two or more water-soluble polymer compounds having different molecular weights) was obtained. The solid electrolytic capacitor used)) was confirmed to be a solid electrolytic capacitor having excellent low-temperature characteristics and excellent long-life characteristics from the viewpoint of weight change.

  As described above, the solid electrolytic capacitor and the method for manufacturing the same according to the present invention have been described based on the above embodiments, but the present invention is not limited to this and can be implemented without departing from the gist thereof. For example, the following modifications are possible.

(1) In each of the above-described embodiments, PEG is used as the water-soluble polymer compound, but the present invention is not limited to this. Water-soluble polymer compounds other than PEG (for example, water-soluble silicone and branched polyether) may be used.

(2) In Embodiment 2 described above, water-soluble polymer compounds of the same type (PEG) were used as the two types of water-soluble polymer compounds having different molecular weights, but the present invention is not limited to this. Absent. Different types of water-soluble polymer compounds (for example, PEG and water-soluble silicone, PEG and branched polyether, water-soluble silicone and branched polyether, etc.) may be used.

(3) In Embodiment 2 described above, the water-soluble polymer compound is a mixture composed of two types of polymer compounds having different molecular weights, but the present invention is not limited to this. The water-soluble polymer compound is composed of three or more types of water-soluble polymer compounds having different molecular weights (for example, PEG, water-soluble silicone, branched polyether, PEG having a molecular weight of 100, PEG having a molecular weight of 600, and water-soluble silicone). It may be a mixed mixture.

(4) In each embodiment described above, in the second step, the solid electrolyte is introduced into the gap between the anode foil and the cathode foil by the immersion impregnation method, but the present invention is not limited to this. . A solid electrolyte may be introduced into the gap between the anode foil and the cathode foil by a vacuum impregnation method.

(5) In each of the above-described embodiments, the third step was introduced by filling the gap between the anode foil and the cathode foil with a liquid water-soluble polymer compound by the immersion impregnation method. The invention is not limited to this. You may introduce | transduce by filling the space between anode foil and cathode foil with a liquid water-soluble polymer compound by the vacuum impregnation method.

(6) In each of the above embodiments, a solid electrolyte not containing a water-soluble polymer compound is used as the solid electrolyte, but the present invention is not limited to this. As the solid electrolyte, a solid electrolyte containing a water-soluble polymer compound may be used.

(7) In the above-described Test Examples 1 to 4, the solid electrolytic capacitor of the present invention was evaluated using a solid electrolytic capacitor using PEG (PEG 300) having a molecular weight of 300, but the present invention is not limited to this. It is not something. Similar evaluation results can be obtained using a solid electrolytic capacitor using a PEG having a molecular weight of 100 to 600 (PEG 100 to PEG 600).

(8) In each of the embodiments described above, the solid electrolytic capacitor of the present invention has been described using a wound solid electrolytic capacitor. However, the present invention is not limited to this. The present invention is also applicable to a multilayer type other solid electrolytic capacitor.

DESCRIPTION OF SYMBOLS 1 ... Solid electrolytic capacitor, 10 ... Metal case, 20 ... Capacitor element, 21 ... Anode foil, 22, 24 ... Oxide film, 23 ... Cathode foil, 25 ... Separator, 26 ... Solid electrolyte, 27 ... (Solid or viscous body) Water-soluble polymer compound, 28 ... liquid water-soluble polymer compound, 29, 30 ... lead, 40 ... sealing member, 60 ... solid electrolyte introduction tank, 62 ... solid electrolyte introduction solution, 70 ... liquid Water-soluble polymer compound introduction tank, 72 ... Liquid composed of water-soluble polymer compound

Claims (9)

An anode foil having an oxide film formed on the surface;
A cathode foil;
A separator disposed between the anode foil and the cathode foil,
In the gap between the anode foil and the cathode foil, a particulate solid electrolyte made of a conductive polymer compound and a liquid water-soluble polymer compound having an oxide film repairing performance are contained in the liquid water solution. A conductive polymer compound is introduced so as to surround the solid electrolyte,
Ratio of the solid electrolyte occupying the gap is in the range of 1vol% ~30vol%, the proportion of the liquid water-soluble polymer compound occupied in the air gap, Ri near the range of 10vol% ~99vol% ,
The solid electrolytic capacitor, wherein the liquid water-soluble polymer compound is a mixture of two or more types of polyethylene glycol having different molecular weights . The solid electrolytic capacitor according to claim 1,
The solid electrolytic capacitor, wherein an average particle diameter of the particulate solid electrolyte is in a range of 1 nm to 300 nm. The solid electrolytic capacitor according to claim 1 or 2 ,
Wherein among the molecular weight of two or more kinds of polyethylene glycol having a molecular weight of molecular weight is largest polyethylene glycol, the solid electrolytic capacitor, wherein the molecular weight is at least 1.2 times the smallest of the polyethylene glycol molecular weight. The solid electrolytic capacitor according to any one of claims 1 to 3 ,
The ratio of polyethylene glycol having the highest molecular weight among the two or more types of polyethylene glycol having different molecular weights to the liquid water-soluble polymer compound is in the range of 20 vol% to 80 vol%. Capacitor. In the solid electrolytic capacitor according to any one of claims 1 to 4 ,
The molecular weight of the polyethylene glycol is a solid electrolytic capacitor, characterized in that in the range of 100 to 1000. A first step of producing a capacitor element comprising an anode foil having an oxide film formed on a surface thereof, a cathode foil, and a separator disposed between the anode foil and the cathode foil;
In the space between the anode foil and the cathode foil, a particulate solid electrolyte made of a conductive polymer compound is used so that the proportion of the solid electrolyte in the space is in the range of 1 vol% to 30 vol%. A second step to be introduced;
In the gap between the anode foil and the cathode foil, a liquid water-soluble polymer compound having an oxide film repairing performance surrounds the solid electrolyte and occupies the liquid water-soluble water-soluble polymer compound. look including a third step of introducing as the proportion of the polymer compound is within a range of 10vol% ~99vol% in this order,
The method for producing a solid electrolytic capacitor, wherein the liquid water-soluble polymer compound is a mixture of two or more types of polyethylene glycol having different molecular weights . In the manufacturing method of the solid electrolytic capacitor of Claim 6 ,
The method for producing a solid electrolytic capacitor, wherein an average particle size of the particulate solid electrolyte is in a range of 1 nm to 300 nm. In the manufacturing method of the solid electrolytic capacitor of Claim 6 or 7 ,
In the second step, the space is filled with a solid electrolyte dispersion solution in which the solid electrolyte is dispersed in a solvent by a vacuum impregnation method or a dip impregnation method, and then the solvent is removed from the space, thereby removing the space. A method for producing a solid electrolytic capacitor, comprising introducing the solid electrolyte into a solid electrolytic capacitor. In the manufacturing method of the solid electrolytic capacitor in any one of Claims 6-8 ,
In the third step, the liquid water-soluble polymer compound is introduced into the voids by filling the voids with the liquid water-soluble polymer compound by vacuum impregnation or immersion impregnation. A method for producing a solid electrolytic capacitor characterized by the above.

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