TWI788039B - electric double layer capacitor - Google Patents

Abstract

Problem: To provide an electric double-layer capacitor capable of suppressing an increase in impedance over time. Solution: it has at least one capacitor unit, The above capacitor unit, having: separate plates; a pair of internal electrodes, which are laminated with the above-mentioned separation plate; an electrolytic solution impregnated with the above-mentioned separator sheet and the pair of the above-mentioned internal electrodes, Inorganic substances of Na (sodium), K (potassium), and Si (silicon) are contained inside the capacitor unit.

Description

electric double layer capacitor

The present disclosure relates to electric double layer capacitors (EDLCs).

As a power storage device, an electric double layer capacitor is known. In this electric double layer capacitor, charges can be stored by allowing ions to be adsorbed on the surface of polarized electrodes containing active materials to form an electric double layer at the interface between the polarized electrodes and the electrolyte solution. In such a power storage method, unlike conventional secondary batteries that are charged and discharged through chemical reactions, it can be charged and discharged indefinitely in principle. However, even an electric double layer capacitor having the above-mentioned characteristics may deteriorate over time due to an increase in impedance due to diffusion (volatilization, etc.) of the electrolyte solution to the outside.

In view of these problems, Patent Document 1 discloses a technology for optimizing the packaging structure of capacitor cells filled with electrolyte. By optimizing the packaging structure and suppressing the diffusion of the electrolyte to the outside, it helps to extend the service life of the electric double layer capacitor. However, when reducing the capacity of an electric double-layer capacitor to cope with high-speed charging and discharging, the impedance may increase due to factors other than the diffusion of the electrolyte solution. Therefore, further measures are required to suppress the rise in impedance. [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2019-145755

[Problem to be solved by the invention]

The present disclosure is made in view of such circumstances, and an object thereof is to provide an electric double layer capacitor capable of suppressing an increase in impedance over time. [means used to solve a problem]

In order to achieve the above object, the electric double layer capacitor of the present disclosure has at least one capacitor unit, The above capacitor unit, having: separate plates; a pair of internal electrodes, which are laminated with the above-mentioned separation plate; an electrolytic solution impregnated with the above-mentioned separator sheet and the pair of the above-mentioned internal electrodes, Inorganic substances of Na (sodium), K (potassium), and Si (silicon) are contained inside the capacitor unit.

As a result of intensive research, the present inventors have found that by including an inorganic substance having predetermined characteristics inside the capacitor unit, the increase in impedance can be suppressed, and the life of the device can be prolonged, thereby completing the present disclosure. Furthermore, the form of the above-mentioned inorganic substance may be particle, fiber, foil, block or the like.

In addition, in the electric double layer capacitor of the present disclosure, it is preferable that the composition of the inorganic substance contained in the capacitor unit satisfies the following conditions. That is, the Na content of the inorganic substance is αwt% in Na ₂ O conversion, the K content in the inorganic substance is βwt% in K ₂ O conversion, and α+β is preferably 1.0 wt% or more. More than 7.0wt% is more preferable. In inorganic substances, it is particularly important to contain Na and K, and by satisfying the above-mentioned composition, an increase in impedance can be more favorably suppressed. As a result, the lifetime of the electric double layer capacitor can be further improved.

In addition, when viewed from the plane of the stacking direction, when the area of a pair of opposing internal electrodes is the effective electrode area, the effective electrode area of the single capacitor unit is preferably ¹² cm or less, and ¹ cm or less. for better. In the electric double layer capacitor of the present disclosure, the smaller the effective electrode area, the higher the impedance rise suppression effect tends to be. In addition, by reducing the effective electrode area, the capacity of the electric double-layer capacitor can be reduced, and the electric double-layer capacitor of the present disclosure can be applied to an electric storage device suitable for high-speed charging and discharging.

Hereinafter, the present disclosure will be described based on the embodiments shown in the drawings.

1st embodiment As shown in FIG. 1A , an electric double-layer capacitor (EDLC) 2 according to an embodiment of the present disclosure has an outer plate 4 . The exterior panel 4 has a front panel 4a and a back panel 4b, which are formed by bending one panel at a folded peripheral edge portion 4c. Furthermore, the exterior plate 4 is not limited to the above configuration, and can also be formed by bonding two independent plates up and down.

In this embodiment, although the exterior panel 4 has a rectangular shape in which the length L0 in the X-axis direction is longer than the length W0 in the Y-axis direction, it is not limited thereto, and may be a square, other polygons, circles, or ellipses. shape, other shapes. In this embodiment, the direction in which the front panel 4a and the back panel 4b of the exterior panel 4 overlap is the thickness direction (Z-axis direction), and the mutually perpendicular directions are the X-axis and the Y-axis.

In addition, in the EDLC 2 of this embodiment, a single capacitor unit 9 is accommodated in the inner area covered by the front panel 4a and the back panel 4b of the exterior panel 4, and the capacitor unit 9 is formed by four packaging parts (40, 40, 42, 44, 46) Sealing. This capacitor unit has an element body 10 and an electrolytic solution as basic components. More specifically, an element body 10 is built inside the capacitor unit 9, and the element body 10 is filled with an electrolytic solution and impregnated (see FIG. 2A ).

The element body 10 has: a separator sheet 11 permeated with an electrolytic solution; and a pair of internal electrodes (first internal electrode 16, second internal electrode 26). The first internal electrode 16 and the second internal electrode 26 are laminated in the Z-axis direction so as to sandwich the separator sheet 11, and one of them is a positive electrode, and the other is a negative electrode.

Furthermore, in this embodiment, the so-called "positive electrode" refers to an electrode that adsorbs anions in the electrolyte solution when a voltage is applied to the electric double-layer capacitor, and the so-called "negative electrode" refers to an electrode that adsorbs the electrolyte solution when a voltage is applied to the electric double-layer capacitor. The cation electrode in the. Which of the first internal electrode 16 and the second internal electrode 26 is a positive electrode and which one is a negative electrode is determined according to the direction of the applied voltage. However, in electric double-layer capacitors, once a voltage is applied in a specific positive and negative direction to charge, then when charging, it is usually charged in the same direction as the first time, and it is rarely charged by applying a voltage in the opposite direction.

The first internal electrode 16 is composed of the first active layer 12 and the first current collector layer 14 . The first active layer 12 is laminated so as to be in contact with the separator sheet 11, and the first current collector layer is laminated so as to be in contact with the first active layer. The second internal electrode 26 is also composed of the second active layer 22 and the second current collector layer 24 similarly to the first internal electrode 16 . The second active layer 22 is laminated so as to be in contact with the other separator sheet 11 of the first active layer 12 , and the second current collector layer 24 is laminated so as to be in contact with the second active layer 22 .

Here, the characteristics of each element constituting the element body 10 will be described in detail. First, the separator sheet 11 is made of a material that can electrically insulate the pair of internal electrodes 16 and 26 and at the same time allow the electrolyte solution to permeate, for example, an electrically insulating porous sheet. More specifically, examples of the electrically insulating porous sheet include polyethylene, polypropylene, and polyolefin films, single-layer bodies, laminates, stretched films of mixtures of the above resins, and fiber nonwoven fabrics.

Furthermore, as the fibrous non-woven fabric constituting the separation plate 11, for example, an organic-based non-woven fabric composed of at least one organic fiber selected from cellulose, polyester, polypropylene, nylon, polyacrylonitrile, etc. can be used. Inorganic nonwoven fabrics composed of inorganic fibers such as glass fibers and carbon fibers, and organic-inorganic composite nonwoven fabrics containing both inorganic fibers and organic fibers as described above are used. In addition, the thickness of the separator sheet 11 is not particularly limited, for example, it may be about 5-50 μm.

The current collector layers 14 and 24 are not particularly limited as long as they have higher conductivity than the active layers 12 and 22 described later, and the materials constituting the current collector layers 14 and 24 are not particularly limited. For example, as the current collector layers 14 and 24 , sheets of metal materials having low electrical resistance such as copper (Cu), aluminum (Al), and nickel (Ni) are used. The average thickness of the current collector layers 14 and 24 is, for example, 10 to 100 μm, preferably 80 μm or less, more preferably 60 μm or less, further preferably 15 to 80 μm, and most preferably 15 to 60 μm. On the X-Y plane, the size of the current collector layers 14, 24 is preferably smaller than that of the separation plate 11, and the current collector layers 14, 24 are preferably arranged at the center of the separation plate 11 in the Y-axis direction.

The active layers 12 and 22 include active materials and binders, preferably conductive additives. The active layers 12, 22 are formed by laminating on the surfaces of the sheets constituting the current collector layers 14, 24, respectively.

The active material is composed of various porous bodies with electronic conductivity, such as activated carbon, natural graphite, artificial graphite, mesophase microcarbon spheres, mesophase carbon fiber (MCF), coke, glassy carbon, organic compound calcined body, etc. carbon material. As the binder, various binders can be used as long as they have the property of being able to fix the active material and the conductive additive on the surface of the current collector layer 14 , 24 . For example, as the binder, fluororesins such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR) and water-soluble polymers (carboxymethyl cellulose, polyvinyl alcohol, sodium polyacrylate, dextrin, gluten, etc.) etc.

The conduction aid is a material for improving the electronic conductivity of the active layers 12 and 22 . Examples of the conductive aid include carbon materials such as carbon black and acetylene black, metal fine powders such as copper, nickel, stainless steel, and iron, mixtures of carbon materials and metal fine powders, and conductive oxides such as ITO.

The average thickness of the active layers 12 and 22 may be, for example, 1-100 μm. In addition, the active layer 12, 22 may be formed on the surface of the current collector layer 14, 24 with an area equal to or less than that of the separator sheet 11.

On the other hand, as the electrolytic solution filled in the capacitor unit 9 , an electrolytic solution obtained by dissolving an electrolyte in an organic solvent is used. As an electrolyte, use, for example, quaternary ammonium salts such as tetraethylammonium tetrafluoroborate (TEA ⁺ BF ^4- ), triethylmonomethylammonium tetrafluoroborate (TEMA ⁺ BF ^4- ), ammonium salts, and amine salts Or amidine salt is preferred. In addition, these electrolyte solutions may be used individually by 1 type, and may use 2 or more types together.

As the organic solvent, known solvents can be used, for example, propylene carbonate, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, γ-butyrolactone, dimethylformyl Amines, cyclobutylene, acetonitrile, propionitrile, methoxyacetonitrile, etc., among them, propylene carbonate is particularly preferably used. The above-mentioned solvents may be used alone, or two or more of them may be mixed and used in any ratio.

The exterior sheet 4 that accommodates the capacitor unit 9 is not only impermeable to the penetration of the electrolytic solution, but also needs to have the property of preventing the intrusion of air and moisture. In addition, it is preferable that the exterior sheet 4 has excellent airtightness, and it is preferable that the periphery of the exterior sheet 4 can be integrated by heat sealing. As long as the exterior sheet 4 has the above-mentioned characteristics, it can be a single-layer sheet, but as shown in FIG. 2A, a multi-layer sheet of laminated metal sheet 4A, inner layer 4B, and outer layer 4C is preferred. In the exterior panel 4 shown in FIG. 2A , the inner layer 4B and the outer layer 4C are laminated in such a way that the metal sheet 4A is sandwiched, the inner layer 4B is located inside the outer panel 4 , and the outer layer 4C is located in the outer panel. 4 on the outside surface.

The metal plate 4A is preferably made of, for example, aluminum (Al), stainless steel, or the like. The inner layer 4B is made of an electrical insulating material, preferably a heat-sealable polypropylene that does not easily react with the electrolyte solution. In addition, other than polypropylene, it can also be composed of resin materials having the same properties as polypropylene (for example, polyethylene, ionomer resin, acid-modified polyolefin, polymethylpentene, etc.). On the other hand, the outer layer 4C is not particularly limited, and may be made of, for example, polyethylene terephthalate (PET), polycarbonate (PC), polyethersulfone (PES), polyethylene naphthalate ( PEN), polyimide (PI), fluororesin, polyethylene (PE), polybutylene terephthalate (PBT), etc. The overall average thickness of the exterior panel 4 is preferably 5-150 μm.

In this embodiment, the durability of the exterior panel 4 is 390~1275N/mm ² according to JIS Z2241, preferably 785~980N/mm ² . In addition, the hardness of the exterior panel 4 is 230-480, preferably 280-380 in Vickers hardness (Hv) (JIS 2244). From this viewpoint, it is preferable to use stainless steel SUS304 (BA), SUS304 (1/2H), SUS304H, SUS301BA, SUS301 (1/2H), or SUS301 (3/4H) as the metal plate 4A of the exterior panel 4 .

In addition, in this embodiment, the exterior panel 4 is equipped with support piece 4f1, 4f2, as shown in FIG. 2A and FIG. 2B. Specifically, the ends on both sides of the back panel 4b in the X-axis direction of the exterior panel 4 extend to the outside of the surface panel 4a along the X-axis direction, and the extensions also serve as supporting pieces 4f1 and 4f2. Lead terminals 18 and 28 to be described later are arranged on the support pieces 4f1 and 4f2, and the lead terminals 18 and 28 can be effectively protected by the support pieces 4f1 and 4f2.

The lead terminals 18, 28 are substantially rectangular plate-shaped conductive members electrically connected to the current collector layers 14, 24, pulled out from the inside to the outside of the capacitor unit 9 in the X-axis direction, and arranged on the supporting pieces 4f1, 4f2. superior. The lead terminals 18, 28 can be connected to external terminals not shown in the figure by using bonding materials such as anisotropic conductive film (ACF) and anisotropic conductive paste (ACP). The electrical layer 14, 24 is a terminal for inputting and outputting electric current.

In this embodiment, the lead terminals 18, 28 are constituted by a metal plate integrated with the current collector layers 14, 24 (that is, constituted by the same members as the current collector layers 14, 24), and have the same structure as the current collector layer 14. , 24 the same thickness. However, the lead terminals 18 , 28 may also be constituted by conductive members different from the current collector layers 14 , 24 , and be electrically connected to the current collector layers 14 , 24 . At this time, the average thickness of the lead terminals 18, 28 may be different from the thickness of the collector layers 14, 24, for example, about 10-100 μm, preferably 60 μm or less, and more preferably 20-60 μm.

In addition, in the EDLC 2 of this embodiment, the first lead terminal 18 and the second lead terminal 28 are pulled out to opposite sides along the long side (X-axis direction) direction of the EDLC 2 . With such a configuration, the width of the EDLC 2 in the Y-axis direction can be reduced. In addition, the thickness of the packageable portion (40, 42) from which the lead terminals are drawn can be minimized, and the thickness of the entire EDLC 2 can also be reduced. As a result, miniaturization and thinning of the EDLC 2 can be achieved.

In addition, as mentioned above, although the lead terminals 18, 28 are disposed on the supporting pieces 4f1, 4f2, as shown in FIG. better. The insulating base plate 60 is bonded to the inner layer 4B of the support sheets 4f1 and 4f2 by thermal welding or adhesive, so as to be integrated. By providing the insulating base plate 60 between the lead terminals 18, 28 and the support pieces 4f1, 4f2, when the lead terminals 18, 28 are connected to external terminals, it can effectively prevent the metal sheet 4A of the exterior plate 4 from contacting the lead terminals. 18, 28 short circuit.

The insulating base plate 60 is preferably composed of a material that can maintain a predetermined thickness even when heat and pressure are applied, and as a result, can maintain insulation. For example, as the insulating base plate 60, polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA ), polycarbonate, polyimide, polyamide, polybutylene terephthalate, etc. In addition, a thermosetting resin such as polyurethane or epoxy resin can also be used, and a material composed of the above-mentioned various resin materials can also be used.

However, among the above-mentioned resin materials, it is particularly preferable to use a resin material excellent in heat resistance. For example, when using PE or PP, choose stretched OPE (stretched polyethylene), OPP (stretched polypropylene) than CPE (cast polyethylene) or CPP (cast polypropylene) manufactured by extrusion. better. Because OPE and OPP are stretched in the vertical and horizontal directions during the manufacturing process and show excellent crystal alignment, the heat resistance is better than that of CPE and CPP.

In addition, the insulating base plate 60 can have a single-layer structure or a multi-layer structure, but it is preferably composed of a resin film with a three-layer structure as shown in FIG. 2B . In the resin film of the three-layer structure, it is preferable to arrange a high-melting-point resin such as PET with excellent heat resistance in the center of the lamination direction, and to laminate a low-melting-point resin such as PP on the surface and back. When using ACF and ACP to connect the lead terminals 18 and 28 to the external terminals, high melting point resins such as PET do not melt and maintain thickness. On the other hand, the PP arranged on the front side and the back side is easy to melt, and can be thermally welded to the inner layer 4B of the back sheet 4b and the back side of the lead terminals 18,28.

Next, the packaging structure of the capacitor unit 9 will be described. First, both end portions in the X-axis direction of the capacitor unit 9 are packaged with the first package part 40 and the second package part 42, and the two package parts 40 and 42 have the same structure. In the first package part 40 and the second package part 42, the lead terminals 18 and 28 are pulled out respectively, and sealing properties are especially required. Therefore, in the first package part 40 and the second package part 42, as shown in FIG. Between the terminals 18 and 28, a sealing tape 40a (hereinafter, 42a may also be included in the same way) is interposed and heat-sealed.

More specifically, the first sealing portion 40 and the second sealing portion 42 are integrally formed by the sealing tapes 40a and 42a and the inner layer 4B of the exterior sheet 4 by heating during heat sealing. That is, a part of the inner layer (resin) 4B formed on the inner peripheral surface of the exterior sheet 4, together with the sealing tapes 40a, 42a, is closely adhered to the both sides surfaces in the Y-axis direction of the lead terminals 18, 28 to form thermal fusion. part, and the sealing properties in the first sealing part 40 and the second sealing part 42 are improved.

Furthermore, the packaging tapes 40a and 42a can be made of adhesive tape materials that can be melted by heat and can be bonded. For example, polypropylene, polyethylene, ionomer resin, acid-denatured polymer, etc. Olefin, polymethylpentene and other tape materials. In addition, the sealing tape 40a, 42a is not limited to a tape material, You may comprise by coating a sealing agent resin.

On the other hand, the 3rd encapsulation part 44 and the 4th encapsulation part 46 that do not pull out the lead terminals 18, 28 are as shown in FIG. , formed integrally by heating and melting during heat sealing.

Furthermore, each package part 40, 42, 44, 46 is integrally connected. Specifically, as shown in FIG. 1A , at both ends of the first package 40 in the Y-axis direction, one ends of the third package 44 and the fourth package 46 are respectively formed continuously, and the third packages 44 and 46 are continuously formed. The second sealing portion 42 is continuously formed in such a manner that the other ends of the sealing portion 44 and the fourth sealing portion 46 are connected. Therefore, the capacitor unit 9 is surrounded by four packages, and these packages are well sealed.

The EDLC 2 of this embodiment having the above features can be made very thin with an overall thickness of 1 mm or less (preferably 0.9 mm or less, more preferably 0.5 mm or less) and has sufficient withstand voltage. Therefore, EDLC2 can be suitably used in, for example, a power storage device built in a thin electronic device such as an IC card (such as an IC card).

In addition, the EDLC 2 of this embodiment has the following features in addition to the above features. That is, in the EDLC 2 , an inorganic substance having predetermined characteristics is contained inside the capacitor unit 9 . The inorganic substance may have a form such as particle, fiber, foil, or block (preferably particle or fiber), and is included in the capacitor unit 9 in the following manner.

For example, an inorganic substance may exist dispersed in an electrolyte solution as inorganic particles. At this time, a part of the inorganic particles is carried by the inside and the surface of the separation plate 11 by the electrolytic solution impregnated into the separation plate 11 .

Or, by spraying the slurry containing particulate inorganic substances on both sides of the separation plate 11 (upper and lower perpendicular to the Z-axis), and then drying it, it is also possible to add the slurry on the surface of the separation plate 11 Inorganic matter. Furthermore, the slurry containing inorganic substances can also be sprayed on the surfaces of the active layers 12 and 22 opposite to the separation plate 11 instead of the separation plate 11 . When adding an inorganic substance to the surfaces of the internal electrodes 16 and 26 in this way, it is preferable to spray a slurry containing the inorganic substance on both the positive electrode and the negative electrode.

Alternatively, an inorganic substance may be part of the constituent materials included in the separator sheet 11 . That is, by weaving the woven fiber-like inorganic substance into the organic or inorganic fiber non-woven fabric in advance, the inside of the capacitor unit 9 contains the inorganic substance.

The aspect in which the above-mentioned inorganic substance is included is merely an example, and the inorganic substance may be contained in the capacitor unit 9 in an aspect other than the above. However, an inorganic substance is preferably present between the opposing first active layer 12 and second active layer 22 .

Inorganic substances contained in the capacitor unit 9, including sodium (Na), potassium (K), and silicon (Si), may contain oxides of these elements, or exist as vitrified oxides. In addition, in inorganic substances, magnesium (Mg), calcium (Ca), aluminum (Al), barium (Ba), boron (B), phosphorus (P), zinc ( Elements such as Zn) are contained in the state of compounds such as oxides.

In addition, in the composition of inorganic substances, Na and K are preferably contained in a predetermined ratio. Specifically, when the content of Na contained in the inorganic substance is αwt% in terms of Na ₂ O, and the content of K contained in the inorganic substance is βwt% in terms of K ₂ O, α+β is 1.0wt%. The above is preferred. More than 7.0wt% is more preferable. The upper limit of α+β is not particularly limited, for example, it is preferably 50 wt% or less, more preferably 30 wt% or less. In addition, the content ratio α of Na is preferably larger than the content ratio β of K.

On the other hand, the Si content γ (wt%) contained in the inorganic substance is not particularly limited, for example, in terms of SiO ₂ , it may be 10wt%~99wt%, preferably 10wt%~70wt%.

Furthermore, the content of the above-mentioned elements can be analyzed by X-ray fluorescence analysis (XRF: X-Ray Fluorescebece), inductively coupled plasma emission spectrometry (ICP: Inductively Coupled Plasma), or electronic micro-probe analyzer (EPMA: Electron Probe Micro Analyzer), etc., for elemental analysis and measurement of inorganic substances. For example, when performing compositional analysis by XRF, the oxide-converted content of all detected elements (except for elements derived from organic matter such as carbon (C)) is calculated by the FP quantitative method (fundamental parameter quantitative method), and in The proportions of Na ₂ O, K ₂ O, and SiO ₂ in the total content may be derived as content ratios α, β, and γ. Furthermore, when light elements such as B exist in inorganic substances, component analysis by ICP is preferable.

In the above component analysis, for example, the separation plate 11 can be used as an analysis sample. Specifically, after decomposing the EDLC 2 and drying the electrolytic solution filled in the capacitor unit 9, the dried separator sheet 11 may be taken out and used as an analysis sample. At the same time, the inorganic substances (particles, fibers) present in the dry separation plate 11 and on the surface are identified, and the components of the inorganic substances are analyzed. In addition, when ICP is used, the dried separation plate piece 11 may be dissolved in a solvent such as hydrofluoric acid, and the component analysis may be performed using the solution sample.

When the inorganic substance is dispersed in the electrolytic solution, when the separation plate 11, the active layer 12, 22 are sprayed with the inorganic substance, and when the separation plate 11 is woven with the inorganic substance, the inorganic substance will be added to the separation plate 11. The surface, interior (or support) of the surface, so the sample for analysis can be prepared by the above method. Then, by analyzing the composition of the inorganic substance contained in the sample, the composition of the inorganic substance contained in the capacitor unit can be identified. In addition, when spraying the slurry containing an inorganic substance on the internal electrode side, instead of the separator 11, the internal electrodes 16, 26 may be used as analysis samples, and the surface of the internal electrodes 16, 26 may be analyzed.

Furthermore, when the inorganic substance added to the capacitor unit 9 is in the form of particles, the particle diameter and particle shape are not particularly limited. For example, what is necessary is just to select the particle diameter and shape which are easy to hold on the separator sheet 11. In addition, when the fibrous inorganic material is woven into the separation sheet 11, the diameter of the fibrous inorganic material is not particularly limited, for example, nano-scale fibers are preferred.

In addition, the content rate of the inorganic substance itself contained in the capacitor unit 9 is not easy to identify because it is conceivable that a plurality of inorganic substances are added. However, for example, the content rate of the inorganic substance itself interposed between the pair of internal electrodes 16 and 26 can be estimated by TG-DTA (thermogravimetric differential calorimetry). At this time, the separation plate piece 11 taken out from the completed EDLC 2 and dried was used as an analysis sample. Then, the sample is heated to 800° C. (in the air atmosphere, the temperature increase rate is preferably 20° C./min) with TG-DTA, and the weight loss rate of the sample is measured. The content rate of the inorganic substance itself interposed between the pair of internal electrodes 16 and 26 can be approximated by "100 wt% - weight loss rate".

When dispersing inorganic substances in the electrolyte solution, when spraying inorganic substances on the separation plate 11, etc., and when weaving inorganic substances into the separation plate 11, it can be estimated that it is interposed between the pair of internal electrodes 16 and 26 by the above-mentioned method. The content rate of the inorganic substance itself. It is estimated that the content of the inorganic substance itself between the electrodes is preferably 0.15wt%~45wt%, more preferably 1wt%~35wt%.

Next, an example of the manufacturing method of the EDLC 2 of the present embodiment will be described.

First, an inorganic substance to be added to the capacitor unit 9 is prepared. Hereinafter, as an example, the method of adding the inorganic substance by spraying the slurry to the surface of the separator sheet 11 will be described in detail. First, sodium carbonate, potassium carbonate, and silicon oxide are prepared as starting materials, and these are weighed in a desired composition ratio. After that, using a mortar or the like, the weighed starting materials are mixed. In addition, the starting material is not limited to the above, and compounds that become oxides after calcination, for example, carbonates, nitrates, oxalates, hydroxides, etc., can be used. In addition, when the inorganic substance contains elements other than Na, K, and Si, it is only necessary to mix a starting material containing the element with a starting material such as Na, K, and Si.

After mixing the starting materials, the mixed powder is put into a crucible for high-temperature calcination, such as a platinum crucible, to be calcined. Calcination may be carried out under the conditions that the above-mentioned starting materials can react with each other, and the detailed conditions are not particularly limited. For example, when vitrifying an inorganic substance, put the mixed powder into a platinum crucible, raise the temperature at a rate of 100°C/h~500°C/h, and keep it at a temperature of 1200°C~1500°C for 1~10 hours , the molten material is dropped into water to obtain vitrified inorganic raw material powder. Furthermore, after the above-mentioned calcination, the obtained inorganic raw material powder is subjected to appropriate grinding treatment and classification treatment.

Next, a slurry was produced using the above-mentioned inorganic raw material powder. After the inorganic raw material powder is added to the solvent and mixed, the mixture is subjected to ultrasonic treatment to fully disperse the inorganic raw material powder in the solvent. Thereafter, the mixture is pulverized using a pulverizer such as a ball mill to obtain a slurry containing an inorganic substance. In addition, as the solvent used above, aqueous solvents, such as distilled water, and various organic solvents, such as ethanol, acetone, hexane, and methyl ethyl ketone, can be used.

Inorganic particles can be added to the separation plate 11 by spraying the slurry obtained above onto the upper and lower surfaces of the separation plate 11 . Furthermore, the spraying of the slurry is preferably carried out plural times. The number of times of spraying can be appropriately determined as long as it is based on the amount of inorganic raw material powder included in the slurry. For example, the number of times of spraying when using a slurry with an added amount of inorganic raw material powder of 20wt% is preferably 2 to 10 times. It is better to take 3~8 times. When the inorganic substance is added by spraying the slurry, the total amount of the inorganic substance added to the capacitor unit 9 can be adjusted by the number of sprays. In addition, after spraying, the separator sheet 11 may be sufficiently dried by means of vacuum drying or the like to volatilize the solvent contained in the slurry. In addition, when the slurry is sprayed onto the surfaces of the internal electrodes 16 and 26 instead of separating the plate pieces 11, the inorganic substance may be added in the same manner as above.

In addition, when adding an inorganic substance to an electrolytic solution, what is necessary is just to prepare an electrolytic solution by the method shown below. First, the slurry containing the inorganic substance obtained by the above method is sufficiently dried to evaporate the solvent to obtain inorganic particles. Then, the inorganic particles are added to the electrolyte solution and subjected to ultrasonic treatment to obtain an electrolyte solution in which the inorganic particles are dispersed. At this time, the amount of the inorganic particles to be added is preferably 0.2 to 60 parts by weight, more preferably 1 to 50 parts by weight, based on 100 parts by weight of the electrolyte solution.

In addition, when weaving the inorganic material into the separation plate 11, the fibrous inorganic material is mixed with the raw material of the separation plate 11, and a fiber nonwoven fabric is produced by a known method.

In the above-described method, the inorganic substance added to the capacitor unit 9 can be prepared.

Next, a method for assembling EDLC2 will be described. First, as shown in FIGS. 3A and 4A , the element body 10 is manufactured. To manufacture the element body 10 , the first internal electrodes 16 are prepared, and the sealing tape 40 a is pasted on the boundary between the first internal electrodes 16 and the first lead terminals 18 . In addition, the second internal electrode 26 on the other side is prepared, and the sealing tape 42 a is pasted on the boundary portion between the second internal electrode 26 and the second lead terminal 28 . Then, the separator sheet 11 is disposed between the first internal electrode 16 and the second internal electrode 18 .

The packaging tapes 40a, 42a are attached to one surface or both sides of the lead terminals 18, 28 at the positions of the first packaging part 40 and the second packaging part 42, respectively. At this time, the width of the sealing tape 40a, 42a in the Y-axis direction is larger than the width of the lead terminals 18, 28 in the Y-axis direction.

Next, to cover the entire element body 10 , the exterior plate 4 is folded back to bend the peripheral portion 4 c , and the element body 10 is covered with the surface plate 4 a and the back plate 4 b of the plate 4 . Furthermore, the exterior panels 4 are formed long in the Y-axis direction in advance. The width of the surface plate 4a of the exterior plate 4 in the X-axis direction is adjusted so that the tip portions 4d1 and 4d2 of the surface plate 4a in the X-axis direction are located inside the X-axis direction of the sealing tapes 40a and 42a respectively.

Next, as shown in Fig. 3B and Fig. 4B, in order to form the first encapsulation part 40 and the second encapsulation part 42, the thermal welding jig 50 is pressed on the outside of the Z-axis direction of the surface sheet 4a and the back sheet 4b, and heating is carried out. Press (heat seal). More specifically, the thermal welding jig 50 is pressed at a position where the sealing tapes 40a, 42a are sandwiched between the front sheet 4a and the back sheet 4b. At this time, the adhesive tapes 40a and 42a for sealing are adhesive resins that become fluid by pressurization and heating, are adhered to and integrated with the inner layer 4B of the exterior sheet 4, and become the sealing parts 40 and 42 after curing. In addition, when the sealing tapes 40a, 42a are welded, the resin constituting the sealing tapes 40a, 42a overflows, and it is preferable to cover the exposed surfaces of the metal pieces 4A located at the tip portions 4d1, 4d2 of the surface sheet 4a in the X-axis direction. Thereby, the short circuit between the metal sheet 4A and the surface sheet 4a of the lead terminals 18 and 28 can be effectively prevented.

As described above, the first sealing portion 40 is formed by heat-sealing (thermocompression bonding) the inner layer 4B of the exterior sheet 4 with the sealing tape 40 a attached to the first lead terminal 18 . Similarly, the second sealing portion 42 is formed by heat-sealing (thermocompression bonding) the inner layer 4B of the exterior sheet 4 with the sealing tape 42 a attached to the second lead terminal 28 .

Before forming the first sealing portion 40 and the second sealing portion 42 or after forming, the folded peripheral edge portion 4c of the exterior sheet 4 is pressurized and heated to form the third sealing portion 44 . Next, the electrolytic solution is injected from the open end 52 of the exterior sheet 4 where the 4th packaged part 46 is not formed, and then the final 4th packaged part 46 is used to form the 3rd packaged part 44 using the same jig as that used to form the 3rd packaged part 44, Formed by heat and pressure. Afterwards, the exterior sheet 4 is cut along the outer cutting line 54 of the fourth package portion 46, and the redundant exterior sheet 4' is removed to obtain the EDLC 2 of this embodiment.

Furthermore, the insulating base plate 60 shown in FIGS. 3A and 3B can be bonded to a predetermined position of the exterior plate 4 before the component body 10 is packaged in the exterior plate 4, or it can be set at a predetermined position of the exterior plate 4 after encapsulation. Between the lead terminals 18, 28 and the supporting pieces 4f1, 4f2.

(Summary of the first embodiment) In the EDLC 2 of the present embodiment, the capacitor unit 9 contains inorganic substances including Na, K, and Si. By having this characteristic, in EDLC2, the rise of impedance can be suppressed, and the lifetime of an element can be extended. The reason why the increase in impedance can be suppressed by a predetermined inorganic substance is not necessarily clear, but for example, the following reasons can be considered.

The main factor of the increase in impedance over time is the diffusion of the electrolytic solution to the outside of the capacitor unit, but in addition to this factor, the deterioration of the internal electrodes over time is also considered to be one of the causes of the increase in impedance. Usually, a metal plate such as Cu, Al, or Ni is used as a current collector layer constituting the internal electrode, and an oxide film of constituent elements derived from the metal plate exists on the surface layer of the current collector layer. Therefore, the presence of the oxide film on the surface of the current collector layer suppresses corrosion of the current collector layer by the electrolytic solution. However, it is considered that in the capacitor unit, the moisture remaining in the capacitor unit reacts with ions contained in the electrolytic solution to generate fluoride such as HF. In the conventional EDLC, it is considered that the generated fluoride destroys the oxide film of the current collector layer, and corrosion of the internal electrodes (especially the current collector layer) progresses, resulting in an increase in impedance over time.

In addition, in the EDLC 2 of the present embodiment, even if fluoride is generated inside the capacitor cell 9, it is considered that an inorganic substance having predetermined characteristics adsorbs the fluoride. As a result, the fluoride is prevented from destroying the oxide film of the current collector layer, and an increase in impedance due to deterioration of the internal electrodes 16 and 26 can be suppressed. In particular, inorganic substances are present between the first active layer 12 and the second active layer (that is, the position where the separator sheet 11 permeated with the electrolyte solution is located), and fluoride is adsorbed on the inorganic material far away from the collector layers 14 and 24. Materially, it is considered that the deterioration of the internal electrodes 16 and 26 can be suppressed more favorably.

In addition, in the EDLC 2 of the present embodiment, the smaller the effective electrode area, the higher the impedance rise suppression effect due to the inorganic substance tends to be. Here, the "effective electrode area" refers to the area of a region where a pair of internal electrodes 16 and 26 face each other (overlap) when viewed on a plane in the lamination direction (Z-axis direction). Generally speaking, the smaller the effective electrode area, the lower the capacity of EDLC, which can be charged and discharged at a high speed.

However, in conventional EDLCs, when the effective electrode area is reduced, the impedance tends to increase over time. As described above, the corrosion of the current collector layer by fluoride is particularly likely to occur near the edge of the current collector layer. Therefore, the smaller the effective electrode area, the larger the ratio of the edge length to the effective electrode area, and it is considered that corrosion of the current collector layer tends to progress. On the other hand, in the EDLC 2 of this embodiment, fluoride is adsorbed by the inorganic substance to suppress free dissociation of fluoride inside the capacitor unit 9, so even if the effective electrode area is reduced, the increase in impedance can be effectively suppressed.

Specifically, in the EDLC 2 of this embodiment, the effective electrode area is preferably 12 cm ² or less, more preferably 1 cm ² or less. In this way, the effective electrode area is reduced, and the rate of increase in impedance over time can be further reduced compared with conventional EDLCs. In addition, the EDLC 2 of this embodiment can be charged and discharged more quickly by the above-mentioned structure.

In addition, in the EDLC 2 of this embodiment, the sum (α+β) of Na content α and K content β contained in the inorganic substance is 1.0 wt % or more, preferably 7.0 wt % or more. It is particularly important that the inorganic substance contains Na and K, and by satisfying the above composition, the increase in impedance can be more favorably suppressed. As a result, the service life of the EDLC2 can be further improved.

Second Embodiment Hereinafter, a second embodiment of the present disclosure will be described based on FIGS. 5 and 6 . As shown in FIGS. 5 and 6, in the EDLC 2b of the second embodiment, two capacitor units 9a and 9b arranged in the Y-axis direction are accommodated inside the exterior sheet 4. As shown in FIG. Others are the same as the first embodiment. Therefore, descriptions of components common to the second embodiment and the first embodiment will be omitted, and the same reference numerals will be used.

In the second embodiment, the exterior panel 4 is composed of a front panel 4a1 and a back panel 4b1, and has a size approximately twice that of the exterior panel 4 shown in FIG. 1A in the Y-axis direction. . Inside the exterior sheet 4, as shown in FIG. 6, two capacitor units 9a, 9b are housed. These capacitor units 9a, 9b have element bodies 10a, 10b, respectively. Both the element bodies 10a and 10b have the same structure as the element body 10 of the first embodiment.

In the second embodiment, the second lead terminals 28, 28 of the element bodies 10a, 10b are formed separately, and the first lead terminals 18a and the connecting portion 18b of the element bodies 10a, 10b are integrally formed to be continuous with each other. That is, the respective element bodies 10a, 10b are connected in series via the first lead terminal 18a and the connecting portion 18b as shown in FIG. 5 .

In the central portion of the exterior sheet 4 in the Y-axis direction, a third sealing portion 44a is formed along the X-axis direction to block the flow of the electrolytic solution between the two capacitor units 9a, 9b. The capacitor unit 9a is packaged by the first package part, the second package part 42, the third package part 44a, and the fourth package part 46a formed continuously on the exterior sheet 4, and is filled with an electrolytic solution. Similarly, the capacitor unit 9b is packaged by the first package part 40, the second package part 42, the third package part 44a, and the fourth package part 46b formed continuously on the exterior sheet 4, and the electrolyte solution is filled therein.

Generally, in EDLC, the withstand voltage of a single capacitor unit is set at a maximum of about 2.85V. As shown in EDLC2b of the second embodiment, the withstand voltage of EDLC2b can be increased by connecting two capacitor units 9a and 9b in series. Furthermore, the number of connected capacitor units is not particularly limited, and by connecting a plurality of capacitor units to form an EDLC, an optimum withstand voltage can be ensured according to the application of the EDLC. In addition, in the EDLC 2b of the second embodiment, the two capacitor units 9a, 9b are connected in series, but these may be connected in parallel.

In the EDLC 2b of the second embodiment, each capacitor unit 9a, 9b includes an inorganic substance having the same characteristics as that of the first embodiment, and this structure suppresses an increase in impedance and improves the life of the EDLC 2b. In addition, the effective electrode areas of the capacitor units 9a and 9b may be the same or different from each other. Even if there are multiple capacitor units 9a and 9b in EDLC 2b, the effective electrode area of a single capacitor unit is preferably 12 cm ² or less, more preferably 1 cm ² or less.

As mentioned above, although the embodiment of this disclosure was demonstrated, this disclosure is not limited to the said embodiment, Various changes are possible within the range of this disclosure. For example, in EDLC2 shown in FIG. 1A, support pieces 4f1 and 4f2 are provided in the exterior panel 4, but these support pieces 4f1 and 4f2 are not essential components. As shown in FIG. 1B EDLC2a, the exterior panel 4 does not have the supporting pieces 4f1 and 4f2, and the front panel 4a and the back panel 4b have approximately the same length in the X-axis direction. Furthermore, in the EDLC 2a shown in FIG. 1B , one plate can be bent to form the exterior plate 4 , and individual plates can be stacked to form the exterior plate 4 .

In addition, in the first embodiment and the second embodiment, the first lead terminal 18 and the second lead terminal 28 are pulled out to opposite sides along the long side direction (X-axis direction) of the EDLC, but they can also be drawn as shown in FIG. 7 As shown in the EDLC2d, all lead terminals are pulled out only to one side in the X-axis direction. In addition, as shown in FIG. 7 , when the lead terminals are pulled out in the same direction, two or more lead terminals having the same polarity may be pulled out in a stacking direction.

Furthermore, the packaging tapes 40a and 42a shown in FIG. 4A are not limited to single-layer resin tapes, and may also be multi-layer resin tapes. For example, an adhesive tape having a three-layer laminated structure having a high-melting-point resin (such as PP) layer at the center in the lamination direction and a low-melting-point resin (such as PP) layer on both sides can be used. By using the adhesive tapes 40a, 42a having such a structure, the encapsulation properties in the encapsulation parts 40, 42 can be further improved, and even if burrs occur on the lead terminals 18, 28, the high-melting point resin layer can prevent the burrs from penetrating the exterior board. The inner layer 4B of the sheet 4 . Therefore, it is possible to more effectively prevent short-circuit faults in the package parts 40 and 42 , and at the same time, it is possible to effectively prevent lead terminals from being broken during thermocompression bonding. [Example]

Hereinafter, the disclosure will be described in more detail based on the embodiments, but the disclosure is not limited to the embodiments.

Experiment 1 In Experiment 1, inorganic particles were added to the electrolytic solution to prepare an EDLC sample having the structure shown in FIG. 1A. Especially in Experiment 1, a plurality of example samples (1 to 11) in which the composition and addition amount of inorganic particles were changed were produced, and the life characteristics of each example sample were evaluated. Hereinafter, the experimental conditions in each example will be described.

(Example 1) First, sodium carbonate, potassium carbonate, and silicon oxide were prepared as starting materials of inorganic particles, and these were weighed at a predetermined ratio, and then mixed using an agate mortar. At this time, in addition to the above starting materials, an appropriate amount of aluminum hydroxide, calcium carbonate, magnesium carbonate, boric acid, zinc oxide, barium carbonate, etc. is added and mixed together with the above starting materials.

Then, put the resulting mixed powder into a platinum crucible to control the temperature rise. Electric furnace calcination at high temperature rate. Calcination conditions, at a heating rate of 300°C/h, keep the temperature at 1200°C~1500°C, and hold the temperature for 2 hours. After the holding time, drop the molten raw material into water to obtain vitrified inorganic raw material powder . After calcining, the inorganic raw material powder was coarsely pulverized with an agate mortar.

Next, 10 parts by weight of the inorganic raw material powder obtained in the above procedure was added to 100 parts by weight of hexane as an organic solvent. Then, this solution was ultrasonically treated for 30 minutes, and the inorganic raw material powder was dispersed in hexane. Thereafter, the inorganic raw material powder added to hexane was ground with a ball mill for 48 hours to obtain a slurry containing inorganic particles. In addition, the slurry was dried at 100° C. to 140° C. for 12 hours, and the solvent was evaporated to obtain the inorganic particles used in Example 1. Furthermore, the composition of the inorganic particles obtained in this step was analyzed by XRF or ICP. As a result, the inorganic particles in Example 1 were confirmed to contain Na, K, and Si in the composition ratio shown in Table 1.

Then, the inorganic particles obtained above were added to the electrolytic solution, and then, for about 30 minutes, the inorganic particles were dispersed in the electrolytic solution by ultrasonic treatment. At this time, the amount of the inorganic particles added was 20 parts by weight relative to 100 parts by weight of the electrolytic solution.

Finally, using the above electrolytic solution, an EDLC sample related to Example 1 was produced. In the manufacture of EDLC, use Al metal sheets as current collector layers 14, 24, use activated carbon as the active material of active layers 12, 22, use cellulose fiber non-woven fabrics as separator sheets 11, and use the method described in the first embodiment (Figure 3A-4B) Assemble the EDLC. In addition, the effective electrode area of the internal electrodes was 0.21 cm ² . As a result of measuring the capacity of the EDLC sample obtained by this method, it was 10 mF.

(Example 2~7) In Examples 2 to 7, inorganic particles having a composition different from that of Example 1 were prepared, and EDLC samples were produced using the inorganic particles. Specifically, in Examples 2 to 7, the composition of the inorganic particles is controlled by adjusting the mixing ratio of the starting materials. In Examples 2 to 5, the content ratios α and β of Na and K are mainly changed. In Examples 6 to 7, the Si content γ was mainly changed. Table 1 shows the compositions (component analysis results of XRF) of the inorganic particles of Examples 2 to 7. In Examples 2 to 7, except that the composition of the inorganic particles was changed, EDLC samples related to the respective examples were produced in the same manner as in Example 1.

(Example 8~11) In Examples 8 to 11, an electrolytic solution having a different addition amount of inorganic particles from that in Example 1 was prepared, and an EDLC sample was produced using the electrolytic solution. Table 1 shows the addition amount of inorganic particles (weight ratio of inorganic particles to 100 parts by weight of electrolyte solution) in each of Examples 8 to 11. In Examples 8-11, except having changed the addition amount of the inorganic particle, it carried out similarly to Example 1, and manufactured the EDLC sample concerning each Example.

(comparative example 1) In Comparative Example 1, unlike the above-mentioned embodiment, an EDLC sample was produced without adding inorganic particles to the capacitor unit. Except that no inorganic particles were used, other conditions were the same as in Example 1.

(Comparative Example 2) In Comparative Example 2, although inorganic particles were added to the electrolyte solution, the inorganic particles used in Comparative Example 2 were _SiO2 particles (glass) with high purity and did not contain Na and K. In Comparative Example 2, an EDLC sample related to Comparative Example 2 was obtained in the same manner as in Example 1 under the experimental conditions other than those described above.

(Characteristic evaluation: Durability test) In order to evaluate the life characteristics of each of the above-mentioned Examples and Comparative Examples, an endurance test was conducted. In the endurance test, the prepared EDLC sample was stored in an environment of 85°C for 1000 hours, and the increase rate of impedance before and after the test was measured. A rise rate of impedance of 200% or less was judged to be acceptable, and the lower the rise rate was, the higher the reliability was and it was judged to have a high life. Table 1 shows the evaluation results of each Example and Comparative Example.

[Table 1] Table 1 Sample No. Characteristics of Inorganic Substances capacitor element Endurance test results Addition amount to electrolyte solution composition Effective electrode area capacity Impedance before test Impedance after test Impedance rise rate Na ₂ O K ₂ O SiO ₂ other parts by weight α(wt%) β(wt%) γ(wt%) wt% cm ² f Ω Ω % Comparative example 1 0 - - - - 0.21 10 3.56 17.6 494 Comparative example 2 20 - - 100 - 0.21 10 3.64 17.5 479 Example 1 20 13 2 65 20 0.21 10 3.51 4.23 121 Example 2 20 0.6 0.3 58 41.1 0.21 10 3.78 7.46 197 Example 3 20 4 1 65 30 0.21 10 3.73 6.06 163 Example 4 20 10 10 65 15 0.21 10 3.54 4.36 123 Example 5 20 18 2 65 15 0.21 10 3.61 4.44 123 Example 6 20 13 2 40 45 0.21 10 3.61 4.56 126 Example 7 20 13 2 10 75 0.21 10 4.11 5.27 128 Example 8 0.2 13 2 65 20 0.21 10 3.71 7.35 198 Example 9 1 13 2 65 20 0.21 10 3.61 6.60 183 Example 10 48 13 2 65 20 0.21 10 5.84 6.60 113 Example 11 52 13 2 65 20 0.21 10 6.25 9.10 146

As shown in Table 1, in Comparative Example 1 in which no inorganic particles were added to the capacitor unit, the impedance after the test increased to about 500%, and the target life characteristics could not be satisfied. In addition, in Comparative Example 2 in which SiO ₂ particles containing no Na and K were added, the impedance increase rate was about the same as that of Comparative Example 1, and the target lifetime characteristics could not be satisfied. From the results of Comparative Example 2, it can be seen that the effect of suppressing the increase in impedance cannot be obtained only with Si oxide particles.

In contrast, in Examples 1 to 11 in which inorganic particles containing Na, K, and Si were added, the rate of increase in impedance was 200% or less, which satisfied the reference value. From this result, it was confirmed that by adding inorganic particles containing a predetermined element in the capacitor cell, the increase in impedance can be suppressed, and the lifetime of EDLC can be improved.

In addition, comparing Examples 1 to 5, it was confirmed that the higher the content ratios of Na and K and (α+β), the more suppressed the increase in impedance. In addition, comparing the results of Examples 6 to 7 with Example 1, it can be confirmed that reducing the Si content γ contained in the inorganic particles and increasing the ratio of other inorganic components tends to increase the initial impedance.

Furthermore, from the results of Examples 8 to 11, it was confirmed that as long as inorganic particles containing Na, K, and Si are included in the electrolyte solution in a small amount (addition amount 0.2 parts by weight), there is an effect of suppressing the increase in impedance. Then, it can be seen that when the inorganic particles are dispersed in the electrolyte solution, the addition amount of the inorganic particles to the electrolyte solution is preferably 0.2 to 60 parts by weight, more preferably 1 to 50 parts by weight.

Experiment 2 In Experiment 2, a plurality of samples with different EDLC capacities were produced, and the correlation between the effective electrode area and the impedance increase rate was investigated. Hereinafter, each sample prepared in Experiment 2 will be described.

(Examples 12 to 14) In Examples 12 to 14, an element body having an effective electrode area different from that in Example 1 of Experiment 1 was prepared, and an EDLC sample was produced using the element body. Specifically, the effective electrode area of each sample was 0.84 cm ² in Example 12, 4.2 cm ² in Example 13, and 14 cm ² in Example 14. In Examples 12 to 14, the manufacturing conditions other than the effective electrode area were the same as in Example 1, and the same evaluation as in Example 1 was performed. The evaluation results are shown in Table 2.

(Example 15) In Example 15, the effective electrode area was set to 14 cm ² as in Example 14, and the capacity was increased by making the active layers 12 and 24 thicker than in Example 14. In Example 15, EDLC samples were produced in the same manner as in Example 1 under the experimental conditions other than those described above, and the same evaluations as in Example 1 were performed. The evaluation results are shown in Table 2.

(Comparative example 3~6) In Comparative Examples 3 to 6, EDLC samples were produced by changing the effective electrode area and capacity in the same manner as in Examples 12 to 15 above. In Comparative Examples 3 to 6, the production conditions other than the effective electrode area and capacity were the same as those in Example 1. The evaluation results are shown in Table 2.

[Table 2] Table 2 Sample No. Characteristics of Inorganic Substances capacitor element Endurance test results Addition amount to electrolyte solution composition Effective electrode area capacity Impedance before test Impedance after test Impedance rise rate Na ₂ O K ₂ O SiO ₂ other parts by weight α(wt%) β(wt%) γ(wt%) wt% cm ² f Ω Ω % Comparative example 1 0 - - - - 0.21 10 3.56 17.6 494 Comparative example 3 0 - - - - 0.84 40 0.734 2.48 338 Comparative example 4 0 - - - - 4.2 200 0.158 0.421 266 Comparative Example 5 0 - - - - 14 1000 0.064 0.134 209 Comparative example 6 0 - - - - 14 1200 0.06 0.132 220 Example 1 20 13 2 65 20 0.21 10 3.51 4.23 121 Example 12 20 13 2 65 20 0.84 40 0.721 0.795 110 Example 13 20 13 2 65 20 4.2 200 0.152 0.164 108 Example 14 20 13 2 65 20 14 1000 0.068 0.072 106 Example 15 20 13 2 65 20 14 1200 0.062 0.065 105

From the evaluation results of Comparative Examples 1 and 3 to 6 in Table 2, it can be confirmed that when the effective electrode area becomes smaller, the increase rate of impedance becomes higher, and the lifetime characteristics tend to deteriorate. On the other hand, in Examples 1, 12 to 15, even if the effective electrode area is reduced, the increase in impedance can be suppressed.

In addition, from the results shown in Table 2, it was confirmed that the smaller the effective electrode area, the higher the life-improving effect of the inorganic particles. When comparing Comparative Example 5 with an effective electrode area of 14 cm ² and Example 15, the increase rate of Example 15 was suppressed to about half of that of Comparative Example 5. On the other hand, when comparing Comparative Example 1 and Example 1 with an effective electrode area of 0.21 cm ² , the increase rate of Example 1 can be reduced to about 1/4 of that of Comparative Example 1. That is, it can be seen that the smaller the effective electrode area, the higher the effect of suppressing the increase in impedance. In view of this effect, the effective electrode area is preferably less than 14cm ² , more preferably less than 1cm ² .

Experiment 3 In Experiment 3, the addition method of the inorganic particles was changed to prepare EDLC samples related to Examples 21 to 23. Specifically, in each example of Experiment 3, in the same manner as Experiment 1 and Experiment 2, after preparing a slurry containing inorganic particles (addition amount 20 wt%), the slurry was sprayed on the active layer and the active layer. Separates the facing faces of the Pattern. At this time, the slurry is sprayed onto both the first active layer of the first internal electrode and the second active layer of the second internal electrode. In addition, the number of times of spraying, for the 1st and the 2nd active layer, is 1 time (total 2 times) in embodiment 21 respectively, is 3 times (total 6 times) in embodiment 22, is 5 times in embodiment 23 (total 10 times).

Then, after spraying the slurry, the organic solvent in the slurry was volatilized by vacuum drying, and inorganic particles were added to the surfaces of the first and second active layers. The composition of the inorganic particles was confirmed by component analysis by XRF and ICP in the same manner as in Experiment 1.

In each example of Experiment 3, EDLC was fabricated using the above-mentioned separation plate, and the same evaluation as in Example 1 was performed. In addition, in each Example of Experiment 3, the experimental conditions other than the above are the same as in Example 1. Table 3 shows the evaluation results of Experiment 3.

[Table 3] Table 3 Sample No. Characteristics of Inorganic Substances capacitor element Endurance test results Spray times (total) composition Effective electrode area capacity Impedance before test Impedance after test Impedance rise rate Na ₂ O K ₂ O SiO ₂ other Second-rate α(wt%) β(wt%) γ(wt%) wt% cm ² f Ω Ω % Example 21 2 13 2 65 20 0.21 10 3.58 7.1 199 Example 22 6 13 2 65 20 0.21 10 3.66 4.26 116 Example 23 10 13 2 65 20 0.21 10 5.76 6.8 118

As shown in Table 3, even if the method of adding the inorganic particles was changed, it was confirmed that the increase in impedance could be suppressed. In addition, when adding inorganic particles by spraying slurry, the total number of spraying times is preferably 2 to 10 times, and more preferably about 6 times.

Furthermore, in Experiments 1 to 3, the inorganic particles in the manufacturing process were used as measurement samples, and XRF and ICP component analysis were carried out, but the composition of the inorganic particles was also analyzed in the EDLC samples after manufacture. That is, after the manufactured EDLC sample is disassembled, and the electrolyte solution filled in the capacitor cell is dried, the inorganic particles present in the interior, surface, or surface of the internal electrode of the separator are identified, and component analysis is carried out by XRF and ICP. , to measure the composition of inorganic particles. As a result, component analysis results equivalent to those shown in Tables 1 to 3 were obtained.

2, 2a, 2b, 2d: Electric Double Layer Capacitor (EDLC) 4: Exterior plate 4a, 4a1, 4a2: surface plates 4b, 4b1, 4b2: back panel 4c: turn back peripheral part 4d1, 4d2: tip 4f1,4f2: support film 4A: sheet metal 4B: inner layer 4C: Outer layer 10: Component body 11: Separation of plates 12: The first active layer 14: The first collector layer 16: 1st internal electrode 18: 1st lead terminal 22: The second active layer 24: The second current collector layer 26: 2nd inner electrode 28: 2nd lead terminal 40: The first packaging department 42:Second Packaging Department 44: The third packaging department 46: The 4th Packaging Department 50: Thermal welding fixture 60: Insulation base plate

FIG. 1A is a perspective view of an electric double layer capacitor according to an embodiment of the present disclosure. Fig. 1B is a perspective view showing a modified example of the electric double layer capacitor shown in Fig. 1A. FIG. 2A is a schematic cross-sectional view along line IIA-IIA of FIG. 1A . FIG. 2B is an enlarged cross-sectional view of main parts of the package shown in FIG. 2A . FIG. 2C is an enlarged cross-sectional view of a main part along line IIC-IIC of FIG. 1A . FIG. 2D is an enlarged cross-sectional view of a main part along line IID-IID of FIG. 1A . 3A is a cross-sectional view showing an example of a method of manufacturing the electric double layer capacitor shown in FIG. 2A , showing an example. FIG. 3B is a perspective view illustrating a subsequent step of FIG. 3A. FIG. 4A is a schematic perspective view illustrating an example of a manufacturing method corresponding to FIG. 3A . FIG. 4B is a perspective view illustrating a subsequent step of FIG. 4A. FIG. 5 is a perspective view of an electric double layer capacitor according to another embodiment of the present disclosure. FIG. 6 is a cross-sectional view of main parts along line VI-VI of FIG. 5 . Fig. 7 is a perspective view showing a modified example of the electric double layer capacitor shown in Fig. 1A.

2: Electric Double Layer Capacitor (EDLC)

4: Exterior plate

4a: Surface plate

4b: Back panel

4f1,4f2: support film

4A: sheet metal

4B: inner layer

4C: Outer layer

10: Component body

11: Separation of plates

12: The first active layer

14: The first collector layer

16: 1st internal electrode

18: 1st lead terminal

22: The second active layer

24: The second current collector layer

26: 2nd inner electrode

28: 2nd lead terminal

40: The first packaging department

42:Second Packaging Department

Claims (4)

An electric double-layer capacitor, which is an electric double-layer capacitor having at least one capacitor unit, the capacitor unit having: a separation plate; a pair of internal electrodes laminated with the separation plate sandwiched; an electrolytic solution impregnated with the above-mentioned The separation plate and the pair of internal electrodes, inside the capacitor unit, contain an inorganic material of oxide glass containing Na (sodium), K (potassium), and Si (silicon), wherein the Na content contained in the inorganic material is , is αwt% in Na ₂ O conversion, and the K content contained in the above inorganic substances is βwt% in K ₂ O conversion, and α+β is 1.0 wt% or more. The electric double-layer capacitor according to claim 1, wherein the Na content of the above-mentioned inorganic substance is αwt% converted from Na ₂ O, and the K content of the above-mentioned inorganic substance is βwt% converted from K ₂ O, α+β It is more than 7.0wt%. As in the electric double layer capacitor of claim 1 or 2, when viewed from the plane of the lamination direction, when the area of a pair of opposite internal electrodes is the effective electrode area, the above-mentioned effective electrode area in a single capacitor unit is 12 cm ² or less. As in the electric double layer capacitor of claim 1 or 2, when viewed from the plane of the stacking direction, when the area of a pair of opposing internal electrodes is the effective electrode area, the above-mentioned effective electrode area in a single capacitor unit is 1 cm ² or less.

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