Capacitor

Abstract

To provide an electrolytic capacitor capable of stably maintaining a characteristic for a long period.SOLUTION: In an electrolytic capacitor, a capacitor main body 2 comprises: a capacitor element 10; a main body case 3 housing the capacitor element 10; and a sealing body 5 that seals the main body case 3. The capacitor element 10 winds a positive electrode foil and a negative electrode foil via a separator to keep a predetermined solution between the positive electrode foil and the negative electrode foil. In the solution, a lipid solubility antioxidant inhibitor is dissolved into a lipophilic solvent, and the separator is contacted to the sealing body 5.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an electrolytic capacitor sealed with a sealing body. [Background technology]

[0002] A conventional electrolytic capacitor is disclosed in Patent Document 1. This electrolytic capacitor includes a main case, a capacitor element, and a sealing body. The main case is made of metal and has a cylindrical shape with a bottom, one end of the cylindrical peripheral wall is closed, and an opening is opened at the other end.

[0003] The capacitor element is made by winding an anode foil and a cathode foil, each having an oxide film formed thereon, with a separator between them, and storing them in a main case. An electrolyte is held between the anode foil and the cathode foil. Lead terminals are connected to the anode foil and the cathode foil, respectively. The opening of the main case storing the capacitor element is sealed with a sealer such as rubber, and the lead terminals are pulled out through the sealer to the outside of the main case.

[0004] It is said that when polymers such as rubber are exposed to heat or light energy in the presence of oxygen in the air, radicals are generated, which trigger a chain reaction of oxidation, resulting in a deterioration of physical properties. For this reason, it is said that antioxidants are mixed into the seal to suppress oxidation reactions.

[0005] Patent Document 2 discloses an electrolytic capacitor having a solid electrolyte instead of an electrolytic solution. This electrolytic capacitor includes a main case, a capacitor element, and a sealing body similar to those of Patent Document 1. A conductive polymer, which is a solid electrolyte, is held between the anode foil and the cathode foil of the capacitor element. Also, a hydrophilic polymer compound containing moisture is held between the anode foil and the cathode foil.

[0006] In the electrolytic capacitor having the above configuration, the conductive polymer can reduce the ESR, and the moisture contained in the hydrophilic polymer compound can repair defects in the oxide films of the anode foil and cathode foil. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2000-100670 A (pages 2-4, Figure 1) [Patent Document 2] International Publication No. 2014 / 050913 (pages 9-23, Figure 2) Summary of the Invention [Problem to be solved by the invention]

[0008] In recent years, electrolytic capacitors have come to be used in high-temperature environments such as near motors, engines, high-speed processing semiconductor devices, and the like that generate a lot of heat, due to the miniaturization and high performance of the devices in which they are mounted.

[0009] According to the electrolytic capacitor disclosed in the above-mentioned Patent Document 1, the antioxidant mixed into the sealing body is consumed as it performs its antioxidant function, and is gradually lost. When the electrolytic capacitor is used in a high-temperature environment, the sealing body rapidly deteriorates as the antioxidant disappears. This often causes the electrolyte to evaporate outside the main case, eventually resulting in a state known as "dry-up." This has led to a problem in that the characteristics of the electrolytic capacitor cannot be stably maintained for a long period of time.

[0010] Similarly, the electrolytic capacitor disclosed in Patent Document 2 also suffers from deterioration of the sealing body when used in a high-temperature environment. This causes moisture retained between the anode foil and the cathode foil to escape to the outside of the main case, making it impossible to repair the oxide film. This causes a problem in that the characteristics of the electrolytic capacitor cannot be stably maintained for a long period of time.

[0011] In addition to moisture for repairing the oxide film, when a capacitor element holds a functional liquid that has a function of improving the characteristics of an electrolytic capacitor, the functional liquid may leak out due to deterioration of the sealing body in a high-temperature environment, which may result in the problem that the characteristics of the electrolytic capacitor cannot be stably maintained for a long period of time.

[0012] An object of the present invention is to provide an electrolytic capacitor capable of maintaining stable characteristics for a long period of time. [Means for solving the problem]

[0013] In order to achieve the above object, the present invention provides an electrolytic capacitor comprising a capacitor element in which an anode foil and a cathode foil are wound with a separator interposed therebetween to hold a predetermined solution between the anode foil and the cathode foil, a main case for accommodating the capacitor element, and a sealing body for sealing the main case, the solution comprising an oil-soluble antioxidant dissolved in a lipophilic solvent, the separator comes into contact with the sealing body, and the oil-soluble antioxidant covers an outer surface of the sealing body in the form of an oil film.

[0014] Furthermore, the present invention is characterized in that in the electrolytic capacitor having the above-mentioned configuration, the capacitor element holds a solid electrolyte.

[0015] Furthermore, the present invention is characterized in that in the electrolytic capacitor having the above-mentioned configuration, the solution comprises an electrolytic solution in which the fat-soluble antioxidant and an electrolyte are dissolved in the lipophilic solvent.

[0016] Furthermore, the present invention is characterized in that in the electrolytic capacitor having the above-mentioned configuration, the concentration of the fat-soluble antioxidant in the electrolyte is 1% by weight to 30% by weight.

[0017] Furthermore, the present invention is characterized in that in the electrolytic capacitor having the above-mentioned configuration, the concentration of the fat-soluble antioxidant in the electrolyte is 3% by weight to 20% by weight.

[0018] In the electrolytic capacitor of the present invention having the above-mentioned configuration, the lipophilic solvent is gamma-butyrolactone.

[0019] In the electrolytic capacitor of the present invention having the above-mentioned configuration, the lipophilic solvent contains at least one of sulfolane, ethylene glycol, and diethylene glycol, and a nonionic surfactant.

[0020] Furthermore, the present invention is characterized in that in the electrolytic capacitor having the above-mentioned configuration, the nonionic surfactant is polyethylene glycol or polyglycerin to which a lipophilic group is bonded.

[0021] Furthermore, the present invention is characterized in that in the electrolytic capacitor having the above configuration, the nonionic surfactant is a polyethylene glycol-polypropylene glycol copolymer.

[0022] Furthermore, the present invention is characterized in that in the electrolytic capacitor having the above configuration, the fat-soluble antioxidant is a fat-soluble vitamin.

[0023] Furthermore, the present invention is characterized in that in the electrolytic capacitor having the above-mentioned configuration, the fat-soluble vitamin is tocopherol or tocotrienol.

[0024] Furthermore, the present invention is characterized in that, in the electrolytic capacitor having the above configuration, the width of the separator in the short side direction is larger than the widths of the anode foil and the cathode foil in the short side direction, and the separator protrudes toward the sealing body further than the anode foil and the cathode foil and contacts the sealing body.

[0025] The present invention is also characterized in that, in the electrolytic capacitor having the above-mentioned configuration, the main body case has a protrusion that protrudes from the inner surface and presses against the outer peripheral surface of the sealing body, and the apex of the protrusion is positioned away from the capacitor element relative to the center of the thickness direction of the sealing body. Effect of the Invention

[0026] According to the present invention, the capacitor element holds a solution of a fat-soluble antioxidant dissolved in a lipophilic solvent, and the separator comes into contact with the sealing body, so that the fat-soluble antioxidant is continuously supplied to the sealing body by the separator. The fat-soluble antioxidant supplied to the sealing body reaches the inside and the outer surface of the sealing body through the intermolecular gaps inside the sealing body. As a result, the fat-soluble antioxidant covers the surface of the sealing body in the form of an oil film, making it possible to suppress deterioration of the sealing body over the long term. This prevents the solution held in the capacitor element from escaping, and makes it possible to stably maintain the characteristics of the electrolytic capacitor over the long term. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a perspective view of an electrolytic capacitor according to a first embodiment of the present invention, as viewed from above; [Diagram 2] FIG. 1 is a perspective view of an electrolytic capacitor according to a first embodiment of the present invention, as viewed from below; [Diagram 3] FIG. 1 is a front cross-sectional view showing a capacitor body of an electrolytic capacitor according to a first embodiment of the present invention. [Figure 4] FIG. 1 is a perspective view showing a capacitor element of an electrolytic capacitor according to a first embodiment of the present invention; [Diagram 5] Detailed view of part H in Fig. 3 [Figure 6] FIG. 13 is a diagram showing the rate of change in capacitance in a durability test of the electrolytic capacitor according to the first embodiment of the present invention. [Figure 7] FIG. 1 shows a sealing body of the electrolytic capacitor according to the first embodiment of the present invention after a durability test. [Figure 8] FIG. 13 shows a sealing body of an electrolytic capacitor according to a comparative example of the present invention after a durability test. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] First Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Figures 1 and 2 show a perspective view of an electrolytic capacitor 1 of a first embodiment as seen from above and below. The electrolytic capacitor 1 comprises a capacitor body 2 and a seat plate 6. The seat plate 6 is made of synthetic resin and holds the capacitor body 2. The seat plate 6 is provided with a pair of through holes 6a, 6b. Lead terminals 7, 8 provided on the capacitor body 2, which will be described later, are inserted into the through holes 6a, 6b, bent, and soldered to a circuit board.

[0029] 3 shows a front cross-sectional view of the capacitor body 2. The capacitor body 2 comprises a main case 3, a capacitor element 10, and a sealing body 5. The main case 3 is made of a metal such as aluminum and is formed into a cylindrical shape with a circular cross section and a bottom, with an opening 3c at one end. The capacitor element 10 is housed in the main case 3, and the opening 3c is sealed by the sealing body 5.

[0030] 4 shows a perspective view of capacitor element 10. Capacitor element 10 has anode foil 11, cathode foil 12, and separator 13. Anode foil 11 and cathode foil 12 are each formed into a long strip of metal foil. Separator 13 is also formed into a long strip of nonwoven fabric or the like.

[0031] Capacitor element 10 is formed by winding anode foil 11 and cathode foil 12 into a cylindrical shape with separator 13 between them. The end of anode foil 11 or cathode foil 12 is fixed with stop tape 14. Lead terminal 7 is connected to anode foil 11, and lead terminal 8 is connected to cathode foil 12.

[0032] The width of separator 13 in the short side direction (axial direction) is formed to be larger than the width of anode foil 11 and cathode foil 12 in the short side direction. As a result, separator 13 protrudes upward (opposite side of opening 3c) and downward (toward opening 3c) relative to anode foil 11 and cathode foil 12, thereby preventing a short circuit between anode foil 11 and cathode foil 12.

[0033] The anode foil 11 is made of a valve metal such as aluminum, tantalum, niobium, titanium, etc. The cathode foil 12 faces the anode foil 11 via a separator 13 and is made of aluminum or the like. An oxide film (not shown) is formed on the surface of the anode foil 11 and the cathode foil 12.

[0034] In addition, an electrolyte is held between anode foil 11 and cathode foil 12 of capacitor element 10. By immersing capacitor element 10 in the electrolyte for a predetermined time, the electrolyte permeates separator 13 and is held between anode foil 11 and cathode foil 12. The electrolyte essentially functions as a cathode. In addition, defects in the oxide films of anode foil 11 and cathode foil 12 can be repaired by the electrolyte.

[0035] The electrolyte consists of a solution of an electrolyte dissolved in a lipophilic solvent. Gamma-butyrolactone can be used as the lipophilic solvent. A liquid containing at least one of sulfolane, ethylene glycol, and diethylene glycol and a non-ionic surfactant can also be used as the lipophilic solvent. As the non-ionic surfactant, a polyethylene glycol or polyglycerin bonded to a lipophilic group, a polyethylene glycol-polypropylene glycol copolymer, etc. can be used.

[0036] The electrolyte dissociates into ions when dissolved in a solvent and exhibits electrical conductivity, and an organic amine salt of a boric acid compound or a carboxylic acid compound is used.

[0037] The electrolyte also contains a fat-soluble antioxidant dissolved in a lipophilic solvent. The fat-soluble antioxidant undergoes an oxidation reaction with oxygen, and as will be described later in detail, suppresses the oxidation of the sealing body 5. An antioxidant that dissolves in a lipophilic solvent is used as the fat-soluble antioxidant, and for example, a fat-soluble vitamin can be used. Examples of fat-soluble vitamins include vitamin A (retinol, α-carotene, β-carotene, β-cryptoxanthin), vitamin D (vitamin D2, vitamin D3), vitamin E (tocopherol, tocotrienol), and vitamin K (vitamin K1, vitamin K2, menaquinone 7).

[0038] If the concentration of the fat-soluble antioxidant in the electrolyte is less than 1% by weight, the oxidation suppression effect on the sealing body 5 cannot be maintained for a long period of time. If the concentration of the fat-soluble antioxidant in the electrolyte exceeds 30% by weight, the viscosity of the electrolyte increases, so that the time for which the electrolyte is held in the capacitor element 10 is long and the number of steps increases. For this reason, it is preferable to set the concentration of the fat-soluble antioxidant in the electrolyte to 1% to 30% by weight. It is also more preferable to set the concentration of the fat-soluble antioxidant in the electrolyte to 3% to 20% by weight, since this can provide a stronger oxidation suppression effect and reduce the number of steps.

[0039] In Fig. 3, the sealing body 5 is a molded product of an insulating elastic material such as rubber, and is formed into a disk shape having a pair of through holes 5a, 5b. The lead terminals 7, 8 of the capacitor element 10 are inserted into the through holes 5a, 5b by press-fitting. The sealing body 5 can be made of butyl rubber, which has high environmental resistance such as heat aging resistance, chemical resistance, and light resistance, high electrical insulation properties, and low gas permeability. The sealing body 5 may also contain an antioxidant that suppresses deterioration.

[0040] With sealing body 5 placed at opening 3c of main case 3, the open end of main case 3 is folded back onto sealing body 5. In addition, main case 3 is subjected to a drawing process that presses the outer circumferential surface, forming protrusion 3d that protrudes toward the inner surface of main case 3. This fixes sealing body 5 together with capacitor element 10, preventing sealing body 5 from falling off, and seals opening 3c of main case 3 with sealing body 5.

[0041] At this time, the apex of protrusion 3d is disposed on the side farther from capacitor element 10 than the center in the thickness direction of sealing body 5. As a result, the outer peripheral surface of sealing body 5 is pressed from below in the figure, and the top surface of sealing body 5 (the capacitor element 10 side) is curved upwardly and the central portion protrudes toward capacitor element 10.

[0042] Fig. 5 shows a detailed view of part H in Fig. 3. At least a portion of separator 13 that protrudes downward beyond anode foil 11 and cathode foil 12 contacts sealing body 5. At this time, because the central portion of sealing body 5 is curved so as to protrude upward, separator 13 reliably abuts against sealing body 5 at multiple points or surfaces while following sealing body 5.

[0043] The fat-soluble antioxidant of the electrolyte is continuously supplied to the sealing body 5 via the separator 13 in contact with the sealing body 5. The fat-soluble antioxidant reaches the inside of the sealing body 5 and the outer surface of the sealing body 5 (the surface opposite the capacitor element 10) through intermolecular gaps inside the sealing body 5. As a result, the outer surface of the sealing body 5 is covered with the fat-soluble antioxidant in an oily film state.

[0044] Furthermore, the fat-soluble antioxidant has a high boiling point and a low melting point (for example, the boiling point of tocopherol is 235°C and the melting point is 3°C). This prevents the fat-soluble antioxidant covering the surface of the sealing body 5 from evaporating. This allows the fat-soluble antioxidant to remain liquid between 25°C and 150°C, which is near room temperature, and form a stable oil film state.

[0045] This prevents the sealing body 5 from coming into contact with oxygen in the air, and the fat-soluble antioxidant undergoes an oxidation reaction with oxygen on the surface or inside of the sealing body 5. This makes it possible to prevent deterioration of the sealing body 5 due to oxidation over the long term. This makes it possible to prevent the electrolyte from evaporating through cracks in the sealing body 5, etc.

[0046] 6 is a diagram showing the change in capacitance due to a durability test of the electrolytic capacitor 1 of this embodiment. In this figure, the vertical axis represents the rate of change in capacitance (unit: %), and the horizontal axis represents the elapsed time.

[0047] In the figure, A is the electrolytic capacitor 1 of this embodiment, in which gamma-butyrolactone is used as the lipophilic solvent of the electrolyte and tocopherol is used as the fat-soluble antioxidant. The concentration of the fat-soluble antioxidant in the electrolyte is 10% by weight. The sealing body 5 is made of butyl rubber and an antioxidant is added.

[0048] In the figure, B shows an electrolytic capacitor of a comparative example, in which the fat-soluble antioxidant is omitted from the electrolyte of electrolytic capacitor 1 shown in A.

[0049] The electrolytic capacitors 1 of this embodiment and the comparative example were subjected to a durability test in a high-temperature environment at 150° C., and the capacitance was measured. Fig. 7 shows a photograph of the sealing body 5 of the electrolytic capacitor 1 shown in A after 8000 hours. Fig. 8 shows a photograph of the sealing body 5 of the electrolytic capacitor shown in B after 4000 hours.

[0050] As a result of the durability test, it was confirmed that the surface of the sealing body 5 of the electrolytic capacitor of the comparative example lost the effect of the antioxidant after 1500 hours and was in a dry state. In addition, cracks occurred in the sealing body 5 after 4000 hours (see FIG. 8), the electrolyte evaporated rapidly, and the capacitance rapidly decreased.

[0051] In contrast, it was confirmed that the surface of the sealing body 5 of the electrolytic capacitor 1 of this embodiment had a glossy appearance, covered with an oil film of the fat-soluble antioxidant, at the 1500-hour and 8000-hour time points. That is, tocopherol evaporates more slowly than gamma-butyrolactone on the surface of the sealing body 5, and the oil film state of the fat-soluble antioxidant was able to be stably maintained even in the high temperature range of 150°C, where the oxidative deterioration of the sealing body 5 becomes rapid.

[0052] In addition, the electrolytic capacitor 1 of this embodiment has a capacitance change rate of less than 20% after 8000 hours. Therefore, it can exhibit stable characteristics over a long period of time even in a high-temperature environment. At this time, the ESR also remains low, and the fat-soluble antioxidant does not have an adverse effect on the electrolyte in the electrolytic solution.

[0053] According to this embodiment, capacitor element 10 holds an electrolyte solution in which a fat-soluble antioxidant is dissolved in a lipophilic solvent, and separator 13 contacts sealing body 5. This allows the fat-soluble antioxidant in the electrolyte solution to be continuously supplied to sealing body 5 via separator 13, making it possible to suppress deterioration of sealing body 5 over the long term. This prevents the electrolyte solution held in capacitor element 10 from evaporating, and allows the characteristics of electrolytic capacitor 1 to be stably maintained over the long term.

[0054] Furthermore, since the concentration of the fat-soluble antioxidant in the electrolyte is 1% by weight to 30% by weight, an increase in the number of steps is suppressed, and the oxidation suppression effect on the sealing body 5 can be maintained for a long period of time.

[0055] In addition, since the concentration of the fat-soluble antioxidant in the electrolyte is 3% by weight to 20% by weight, the oxidation suppression effect can be prolonged and the number of steps can be reduced.

[0056] Furthermore, the lipophilic solvent of the electrolyte can be easily realized by gamma-butyrolactone.

[0057] Furthermore, the lipophilic solvent of the electrolyte can be easily realized by a liquid containing at least one of sulfolane, ethylene glycol, and diethylene glycol, and a nonionic surfactant.

[0058] Moreover, this can be easily realized by using a liquid in which a nonionic surfactant is bound to a lipophilic group in polyethylene glycol or polyglycerin.

[0059] Furthermore, the non-ionic surfactant can be easily realized by using a polyethylene glycol-polypropylene glycol copolymer.

[0060] Furthermore, the fat-soluble antioxidant of the electrolyte can be easily realized by using a fat-soluble vitamin.

[0061] Furthermore, a fat-soluble vitamin that dissolves in the lipophilic solvent of the electrolyte can be easily realized by using tocopherol or tocotrienol.

[0062] Furthermore, since separator 13 protrudes toward sealing member 5 further than anode foil 11 and cathode foil 12, separator 13 can be easily brought into contact with sealing member 5.

[0063] In addition, the apex of protrusion 3d protruding onto the inner surface of main body case 3 is disposed on the side farther from capacitor element 10 than the center in the thickness direction of sealing body 5. This causes the center of sealing body 5 to protrude toward capacitor element 10, and separator 13 reliably abuts against sealing body 5 at multiple points or faces while aligned with sealing body 5.

[0064] <Second embodiment> Next, a second embodiment will be described. In this embodiment, the capacitor element 10 holds a solid electrolyte (not shown) instead of an electrolytic solution and a predetermined functional liquid. The other parts are the same as those of the first embodiment.

[0065] The solid electrolyte is composed of a conductive polymer, etc. The conductive polymer can reduce the ESR of the electrolytic capacitor 1. As the conductive polymer, polythiophene, polypyrrole, or derivatives thereof, etc. can be used, and polyethylenedioxythiophene is more preferable because of its high electrical conductivity.

[0066] By immersing capacitor element 10 in a dispersion liquid of a conductive polymer for a predetermined time and then drying it, a solid electrolyte made of a conductive polymer can be held between anode foil 11 and cathode foil 12.

[0067] In addition, a functional liquid having a function of increasing the withstand voltage is held between the anode foil 11 and the cathode foil 12. The functional liquid is composed of a solution in which a fat-soluble antioxidant is dissolved in a lipophilic solvent. As the lipophilic solvent, gamma-butyrolactone can be used. As the lipophilic solvent, a liquid containing at least one of sulfolane, ethylene glycol, and diethylene glycol and a nonionic surfactant can be used. As the nonionic surfactant, a polyethylene glycol or polyglycerin bonded with a lipophilic group, a polyethylene glycol-polypropylene glycol copolymer, etc. can be used. These lipophilic solvents can increase the withstand voltage and dissolve the fat-soluble antioxidant.

[0068] The fat-soluble antioxidant is an antioxidant that dissolves in a lipophilic solvent, such as fat-soluble vitamins, including vitamin A (retinol, α-carotene, β-carotene, β-cryptoxanthin), vitamin D (vitamin D2, vitamin D3), vitamin E (tocopherol, tocotrienol), vitamin K (vitamin K1, vitamin K2, menaquinone 7), etc.

[0069] In addition, the solid electrolyte is swollen by the functional liquid, which increases the adhesion of the solid electrolyte to the anode foil 11 and the cathode foil 12 that sandwich the solid electrolyte. This reduces the ESR of the electrolytic capacitor 1. Therefore, the functional liquid also has the function of reducing the ESR of the electrolytic capacitor 1.

[0070] As in the first embodiment, separator 13 of capacitor element 10 is in contact with sealing body 5, and the fat-soluble antioxidant in the functional liquid is supplied to sealing body 5 via separator 13. The fat-soluble antioxidant reaches the inside of sealing body 5 and the outer surface of sealing body 5 (the surface opposite capacitor element 10) through intermolecular gaps inside sealing body 5. As a result, the outer surface of sealing body 5 is covered in an oil film state with the fat-soluble antioxidant.

[0071] This prevents the sealing body 5 from coming into contact with oxygen in the air, and the fat-soluble antioxidant undergoes an oxidation reaction with oxygen on the surface or inside of the sealing body 5. This makes it possible to prevent deterioration of the sealing body 5 due to oxidation, and to prevent leakage of the functional liquid.

[0072] According to this embodiment, capacitor element 10 holds a functional liquid in which a fat-soluble antioxidant is dissolved in a lipophilic solvent, and a solid electrolyte, and separator 13 contacts sealing body 5. This allows the fat-soluble antioxidant in the functional liquid to be continuously supplied to sealing body 5 via separator 13, making it possible to suppress deterioration of sealing body 5 over the long term. This prevents the functional liquid held in capacitor element 10 from leaking out, and allows the characteristics of electrolytic capacitor 1 to be stably maintained over the long term.

[0073] In this embodiment, an electrolytic solution obtained by dissolving an electrolyte in the functional liquid may be held between the anode foil 11 and the cathode foil 12. By holding a solid electrolyte and an electrolytic solution between the anode foil 11 and the cathode foil 12, the function of repairing the oxide film can be improved and the ESR of the electrolytic capacitor 1 can be further reduced. [Industrial Applicability]

[0074] The present invention can be used in electrolytic capacitors and automobiles and electronic devices in which electrolytic capacitors are mounted in control circuits. [Explanation of symbols]

[0075] 1. Electrolytic capacitor 2. Capacitor body 3 Main unit case 3c opening 3d protrusion 5 Sealing body 5a, 5b through hole 6 Seat board 6a, 6b through hole 7, 8 Lead terminal 10 Capacitor element 11 Anode foil 12 Cathode foil 13 Separator 14 Tape

Claims

1. An electrolytic capacitor comprising: a capacitor element in which an anode foil and a cathode foil are wound with a separator therebetween to hold a predetermined solution between the anode foil and the cathode foil; a main case for accommodating the capacitor element; and a sealing body for sealing the main case, The solution is a solution in which a fat-soluble antioxidant is dissolved in a lipophilic solvent, The sealing body has a central portion protruding toward the capacitor element, the separator has a width in a short side direction that is larger than the widths of the anode foil and the cathode foil in the short side direction, protrudes toward the sealing body beyond the anode foil and the cathode foil, and abuts against the sealing body at multiple points or on multiple surfaces, The fat-soluble antioxidant is supplied to the sealing body through the separator that is in contact with the sealing body, the lipophilic solvent comprises at least one of sulfolane, ethylene glycol, and diethylene glycol, and a nonionic surfactant; The nonionic surfactant is a polyethylene glycol or polyglycerin having a lipophilic group bonded thereto, The electrolytic capacitor, wherein the sealing member is made of butyl rubber containing an antioxidant.

2. 2. The electrolytic capacitor of claim 1, wherein the capacitor element holds a solid electrolyte.

3. 3. The electrolytic capacitor according to claim 1, wherein the solution is an electrolytic solution in which the fat-soluble antioxidant and an electrolyte are dissolved in the lipophilic solvent.

4. 4. The electrolytic capacitor according to claim 3, wherein the concentration of the fat-soluble antioxidant in the electrolyte is 1% by weight to 30% by weight.

5. 4. The electrolytic capacitor according to claim 3, wherein the concentration of the fat-soluble antioxidant in the electrolyte is 3% by weight to 20% by weight.

6. 6. The electrolytic capacitor according to claim 1, wherein the lipophilic solvent is gamma-butyrolactone.

7. 2. The electrolytic capacitor according to claim 1, wherein the nonionic surfactant is a polyethylene glycol-polypropylene glycol copolymer.

8. 8. The electrolytic capacitor according to claim 1, wherein the fat-soluble antioxidant is a fat-soluble vitamin.

9. 9. The electrolytic capacitor according to claim 8, wherein the fat-soluble vitamin is a tocopherol or a tocotrienol.

10. 10. The electrolytic capacitor according to claim 1, wherein a width of the separator in a short side direction is larger than widths of the anode foil and the cathode foil in the short side direction, and the separator protrudes toward the sealing body further than the anode foil and the cathode foil and contacts the sealing body.

11. 11. The electrolytic capacitor according to claim 10, wherein the main body case has a protrusion that protrudes from an inner surface and presses against an outer peripheral surface of the sealing body, and an apex of the protrusion is positioned away from the capacitor element relative to the center of the thickness direction of the sealing body.

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