HK1089725B - Reinforcing material-carrying functional sheet - Google Patents
Reinforcing material-carrying functional sheet Download PDFInfo
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- HK1089725B HK1089725B HK06110134.0A HK06110134A HK1089725B HK 1089725 B HK1089725 B HK 1089725B HK 06110134 A HK06110134 A HK 06110134A HK 1089725 B HK1089725 B HK 1089725B
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- layer capacitor
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Description
Technical Field
The present invention relates to a reinforced functional sheet, and more particularly to a reinforced thin functional sheet that can sufficiently exert the effect of a functional material and has sufficient strength in handling.
The present invention also relates to a sheet electrode used as an electrode of an electric double layer capacitor or the like, which is one of the above-mentioned functional sheets with a reinforcing material, and more particularly to a sheet electrode for an electric double layer capacitor with a reinforcing material, which has advantages that an electric double layer capacitor having a small internal resistance, a small deterioration of charge and discharge ability, an excellent durability and a long life can be manufactured; at the same time, the electrode has sufficient strength, can be continuously formed and can be large-sized, so that the electrode is excellent in mass productivity and operability.
Background
Conventionally, a general method for producing a sheet made of a material having various functions such as a catalytic function and an electric double layer capacitor, for example, a sheet having a catalytic function is: a resin having an adhesive effect and a material having various functions such as a catalyst function are kneaded and then roll-rolled into a sheet shape.
However, when the catalyst material having a fine particle diameter is bonded together with a binder resin to form a sheet, the sheet itself has no strength, and the functional material is detached or dropped.
If the amount of the binder is increased in order to secure a certain degree of strength, there is a problem that various functions of the functional material powder are deteriorated.
Japanese patent No. 3171454 discloses a sheet-like adsorptive filter comprising a polytetrafluoroethylene resin molded body containing 25 to 90 wt% of porous adsorbent powder having a particle size of 0.5mm or less. As described in the publication, the sheet can also be used in the form of a fabric laminated and bonded to a fabric.
However, there is a problem that the fabric and the polytetrafluoroethylene resin molded product are easily peeled off.
Therefore, it is desired to find a reinforcing-material-attached functional sheet which has strength even when it is thin, does not cause separation of the functional material, can be continuously formed, and has excellent mass productivity.
In addition, the electric double layer capacitor described above has the following problems.
That is, the electric double layer capacitor is a capacitor that stores electric energy using a polarizable electrode and an [ electric double layer ] formed at an electrolyte interface, and has a capability of faster charge and discharge than a secondary battery using a chemical reaction; because of the advantages of no heavy metal and no pollution, the method is expected to be widely applied to small-sized equipment such as electronic instruments and large-sized equipment such as vehicles.
The electric double layer is an interface phenomenon in which positive and negative charges are oppositely arranged with a very short distance therebetween at an interface where two different layers of a solid electrode and an electrolyte are in contact, for example, and positive ions and negative ions in the electrolyte are respectively arranged on opposite surfaces of the electrode in a charged state of the capacitor, and negative charges are respectively accumulated on the positive ion side and positive charges are accumulated on the negative ion side by the electric double layer phenomenon.
Electrodes of the electric double layer capacitor generally use electrodes mainly composed of carbon materials such as activated carbon, and mainly use sheet electrodes containing carbon and fluorine-containing resin.
The electrode manufacturing method includes a roll drawing method, a doctor blade method, and the like, and various improvements have been made for increasing the capacity and the life.
An electric double layer capacitor is a capacitor capable of being repeatedly charged and discharged, but if used for a long period of time, there is a problem that the charging and discharging capability of the capacitor gradually decreases.
Therefore, it is desired to develop an electric double layer capacitor having superior durability, small internal resistance, high capacity, and good operability as compared with the conventional capacitor.
An effective method for reducing the internal resistance is to minimize the amount of binder used, and at present, to ensure the conductivity and the impregnation property of the electrolyte, only a very small amount of binder PTFE is used, usually about 5 to 20 wt%.
Further, the PTFE particles are fiberized by being subjected to a shearing force in the kneading and rolling steps and the like. The fibrillated PTFE binds the activated carbon particles and the conductive carbon particles to each other. Therefore, it is conceivable to promote the fiberization of PTFE by kneading or the like as a method for increasing the sheet strength without increasing the amount of the binder.
However, although the binding force of the binder is increased by increasing the fiberizing process (i.e., promoting fiberization), even the electrode formed into a sheet shape has a certain strength that can be maintained by itself, and the strength of the sheet itself is poor, so that there is a problem that mass productivity is poor and workability in use is poor.
Further, if the fiberization is promoted, the electrode density becomes too high, and the impregnation of the electrolyte solution is deteriorated, and there is a problem that the number of man-hours in the kneading step and the rolling step is increased, and the mass productivity is deteriorated. In addition, in order to obtain a capacitor having a small capacity deterioration and a long life, it is necessary to perform a heat treatment at a higher temperature to remove moisture contained in the activated carbon electrode (in the case of using an organic electrolyte, electrolysis is promoted even if only a small amount of moisture is present, causing a significant capacity deterioration.)
Japanese patent application laid-open No. 2000-208373 discloses a method for producing a polarizable electrode for an electric double layer capacitor with a collector electrode, in which a sheet-like molded body composed of a carbon fine powder containing a carbon material mainly contributing to the development of electrostatic capacity and a fluorine-containing resin as a binder, a sheet-like molded body composed of a carbon fine powder containing a carbon material mainly contributing to conductivity and a binder, and a conductive metal foil are laminated, and the laminated body is rolled and bonded together.
That is, in this publication, the polarized electrode and the current collector are bonded together by rolling them via a sheet-shaped formed body rich in conductivity, thereby reducing the contact resistance.
Further, Japanese patent laid-open Nos. 2000-150321 and 2000-182902 disclose a method for producing a polarizable electrode for an electric double layer capacitor, in which a mixture of a fine carbon powder and a fluorine-containing resin is formed into a sheet and has sufficient strength even when the thickness is reduced.
However, a functional sheet with a reinforcing material, such as an electrode sheet, which has sufficient strength, excellent mass productivity, high capacity, and can be produced at low cost, and which can be used as a sheet electrode having a smaller internal resistance and excellent durability, cannot be obtained.
The present invention has been made to solve the above-described problems of the conventional art, and an object of the present invention is to provide a thin functional sheet with a reinforcing material, which has sufficient strength and can exhibit high functionality.
Another object of the present invention is to provide an electrode for an electric double layer capacitor, which is one of the above-mentioned functional sheets with a reinforcing material, having advantages that an electric double layer capacitor having a large electrode strength, a considerably small internal resistance, a small decrease in charge and discharge capacity, an excellent durability, and a long life can be efficiently manufactured in a short time using the electrode.
It is another object of the present invention to provide an electric double layer capacitor having the above electrode for an electric double layer capacitor.
Disclosure of The Invention
The functional sheet with a reinforcing material of the present invention is a functional sheet with a reinforcing material, which is obtained by laminating a sheet-like functional material comprising a functional material powder and a binder resin and a reinforcing sheet, and is characterized in that the reinforcing sheet is made of a woven fabric or a nonwoven fabric and has a basis weight (weight per unit area of a woven fabric in Japan) of 10 to 400g/m2The fiber diameter of the fibers constituting the reinforcing sheet is 10 to 150 μm.
In the present invention, the binder resin is an unfired polytetrafluoroethylene resin, and the content thereof is preferably 50 to 1% by weight of the total amount of the sheet-like functional material.
The functional material powder is preferably 1 or more than 2 of activated carbon, graphite, carbon black, bamboo charcoal, titanium oxide, zinc oxide, lead oxide, silica, clay, metal powder, expanded graphite, water-absorbent polymer, silica gel, antifungal agent, and antibacterial agent.
The sheet is characterized in that the reinforcing material-equipped functional sheet is embossed.
The sheet is characterized in that the reinforcing material-equipped functional sheet is embossed.
The electrode for electric dipole layer capacitor according to the present invention is characterized in that a sheet-like electrode material comprising carbon fine powder and a fluoropolymer resin is laminated with a reinforcing sheet, wherein the reinforcing sheet is made of woven fabric or nonwoven fabric,the basis weight, i.e. the daily basis weight, of the fabric is 10 to 400g/m2The fiber diameter of the fiber constituting the reinforcing sheet is 10 to 150 [ mu ] m, and the thickness of the functional sheet with the reinforcing material is 0.8mm or less.
In the present invention, the reinforcing sheet is composed of any one of a woven fabric, a net, a nonwoven fabric and an expanding sheet, and the thickness of the reinforcing sheet is preferably 0.01 to 1.0mm or less.
The fine carbon powder in the sheet-like electrode material contains activated carbon and/or conductive carbon, and the fluoropolymer resin is preferably polytetrafluoroethylene.
The content of the fluorine-containing resin in the electrode material is preferably 15% by weight or less (wt%).
The electric double layer capacitor of the present invention has the electrode for an electric double layer capacitor.
The present invention can provide a thin functional sheet with a reinforcing material, which has sufficient strength, does not cause the functional material powder to fall off, and can effectively exhibit high functionality, in a large amount and at low cost.
The electrode for electric double layer capacitor and the electric double layer capacitor, which are one of the above-described functional sheets with a reinforcing material, can be provided at low cost with the advantages of a relatively small internal resistance, strength, no shedding of functional material powder such as a catalyst, continuous molding, large-sizing, mass productivity, and the like.
Brief description of the drawings
Fig. 1 is a schematic diagram of a peel test of a functional sheet.
FIG. 1(A) is a schematic view showing the peeling of the functional sheet obtained in comparative example A1. FIG. 1(B) is a schematic view showing the peeling of the functional sheet obtained in example A1.
Fig. 2 is a perspective view of a sheet electrode with a reinforcing material according to one embodiment of the present invention.
FIG. 3 is a cross-sectional view of an electric double layer capacitor incorporating plate electrodes with reinforcing materials in accordance with one embodiment of the present invention.
Fig. 4 is a perspective view of a part of an electric double layer capacitor in another form in which a functional sheet with a reinforcing material according to another embodiment of the present invention is mounted, with a cut-away view.
Description of the symbols
10 … … electrode with reinforcing material
12. 12A, 12B … … sheet-like electrode material
14. 14A, 14B … … reinforced sheet material (reinforcing material, diaphragm)
16 … … stuffing
18. 18A, 18B … … aluminum current collector and current collector pair
20 … … electric dipole layer capacitor
22 … … capacitor internal member
24 … … casing
30 … … electric dipole layer capacitor
34 … … casing
36 … … sealing gasket
38. 38A, 38B … … lead
Best Mode for Carrying Out The Invention
Hereinafter, the reinforcing material-equipped functional sheet (functional sheet) of the present invention and an electrode for an electric double layer capacitor, and the like, which are one of the reinforcing material-equipped functional sheets, will be described in detail.
[ functional sheet with reinforcing Material ]
The reinforcing material-equipped functional sheet of the present invention is formed by joining a reinforcing sheet and a functional material in a sheet form, which is formed from a functional material powder and a binder resin, in a laminated state.
In such a functional sheet, the sheet-like functional material layer may be formed only on one side of the reinforcing sheet, or may be formed on both the front and back sides.
The size of the reinforcing-material-attached functional sheet may be changed in design as appropriate depending on the application, the scale of the equipment, and the like, and is not particularly limited. However, in order to achieve miniaturization, the thickness is required to be thin, and is preferably 0.8mm or less.
In addition, the thickness of the sheet-like functional layer in the functional sheet is usually 0.1 to 0.8 mm.
[ functional powder (functional material powder) ]
The functional material powder may be suitably changed depending on the use, and examples thereof include carbonaceous materials such as activated carbon, graphite, carbon black, bamboo charcoal, and charcoal; metal oxides such as titanium oxide, zinc oxide, lead oxide, and silicon dioxide; powders of clay (aluminum silicate), metal powder, expanded graphite, water-absorbent polymer, silica gel, mildewproofing agent, antibacterial agent, and the like.
These functional material powders may be used in combination of 1 kind or 2 or more kinds.
When the functional material powder is a carbonaceous material of 1 or more selected from the group consisting of activated carbon, bamboo charcoal, graphite and carbon black, the reinforcing material-equipped functional sheet is preferably used for applications such as deodorization, water quality improvement and solvent adsorption, and when the functional material powder is titanium oxide, it is preferably used for photocatalysis, and in short, the functional material powder has various functions depending on the functional material powder used.
[ Binder resin ]
The binder resin is a resin capable of bonding and binding the functional powders and the like to each other, and conventionally known binders can be widely used, and may be a natural resin type or a synthetic resin type, and for example, a fluorine-containing resin such as PTFE; olefin resins such as polyethylene and polypropylene.
Among these, the fluorine-containing resin is fibrillated when a shearing force is applied, and since the fibril has a fiber diameter of about 0.01 to 0.05 μm and functional powders having a particle diameter of 80 μm or less can be collectively bonded to each other, the fluorine-containing resin is preferably used for molding a powdery solid into a sheet, and in particular, an unfired Polytetrafluoroethylene (PTFE) resin is particularly preferable because it is excellent in weather resistance, heat resistance, acid resistance, and the like.
The unfired PTFE resin is molded powder obtained by suspension polymerization; ultrafine powder obtained by emulsion polymerization. Any one may be used, but it is preferable to use a dispersion. When the dispersion is used, the dispersion of the catalyst is good when the dispersion is kneaded with the functional powder, and the functional powder is sufficiently supported by the PTFE fibrils, so that the moldability is good.
The content of the binder represented by the unfired PTFE resin in the sheet-like functional material is preferably 50 to 1% by weight, more preferably 30 to 5% by weight. If the amount is less than 1% by weight, it is difficult to sufficiently support the functional material powder, and it is difficult to form the functional material powder into a sheet. On the other hand, if it is 50% by weight or more, the content of the functional material powder in the sheet-like functional material decreases, and therefore the resulting functional sheet cannot have high functionality.
[ reinforcing sheet (reinforcing layer) ]
The kneaded product containing the functional material powder and the binder resin or the sheet-like functional material in a softened state, which is joined to the reinforcing sheet by pressure bonding or the like, is inserted between fibers of the reinforcing sheet and joined to the reinforcing sheet by the fixing effect, and therefore, a certain degree of voids must be present in the reinforcing sheet.
Therefore, the fiber diameter of the fibers constituting the reinforcing sheet should be 10 to 150. mu.m, preferably 20 to 100. mu.m,preferably, the woven or nonwoven fabric satisfies the requirement that the basis weight (weight of the fabric per unit area) is 10 to 400g/m2More preferably 50 to 200g/cm2。
Since the reinforcing sheet has many voids, the exposed surface of the sheet-like functional material can be increased to the maximum extent, and the function of the sheet-like functional material can be improved by making the surface of the sheet contain a large amount of functional material.
If the fiber diameter in the reinforcing material is smaller than the above range, a sufficient fixing effect of the kneaded product or the softened sheet catalyst to the reinforcing sheet cannot be obtained, and the reinforcing material is more likely to peel off than the sheet-like functional material. If the fiber diameter is larger than this range, the entanglement of the reinforcing fibers decreases, and sufficient strength as a reinforcing material cannot be obtained.
Examples of the reinforcing material (reinforcing sheet) forming the reinforcing layer include a net or woven fabric (knitted fabric) in which fibers composed of a synthetic resin such as polypropylene (PP) or Polyethylene (PE), a natural fiber such as cellulose, a carbon fiber such as a glass fiber or a carbon fiber, and a polymer material such as a polymer material are orthogonal to each other, and a cloth-like material such as a nonwoven fabric in which fibers are randomly entangled with each other.
[ production of functional sheet with reinforcing Material ]
When producing a sheet-like functional material, a functional powder and a binder resin are mixed to prepare a kneaded product. In this case, an additive such as water or alcohol may be added to improve processability. The kneading operation is usually carried out by a conventionally known kneading machine such as a kneader or a banbury mixer, but the kneading operation is not limited thereto, and any kneading machine can be used as long as it can efficiently knead the materials together by applying shear, compression, or the like thereto. Then, the kneaded product may be preformed, and then press-molded with a press or the like, or by roll-forming with a roll press or both, to obtain a sheet-like functional material.
Then, the sheet can be efficiently manufactured by a method in which the sheet-like functional material and the reinforcing sheet thus obtained are simultaneously passed through a roll press, or by attaching the reinforcing sheet and the sheet-like functional material in a laminated state to a compressor and pressure-bonding them together. Alternatively, the kneaded material may be spread over the entire surface of the reinforcing sheet and pressurized by a press.
[ embossing processing ]
For example, when a functional powder having a catalytic effect is used, the functional powder on the surface exerts a catalytic function, and since the effect is effective only on the surface, the effective area must be increased.
Therefore, the functional sheet with a reinforcing material obtained by the present invention can be embossed by an embossing machine (manufactured by サトウエンジニア - ズ) to obtain a final molded article.
It is preferable that the thickness of the functional sheet with a reinforcing material used in this case is 0.2 to 1.0mm because good embossing can be performed.
[ electrode for electric double layer capacitor ]
Next, the electrode for electric double layer capacitor of the present invention, which is one of the functional sheets with a reinforcing material, will be described in detail.
Fig. 2 is a perspective view showing an electrode for an electric double layer capacitor according to the present invention.
First, the electrode for an electric dipole layer capacitor shown in fig. 2 is in a form in which a reinforcing sheet 14 (separator, reinforcing material) is bonded to one surface, i.e., the upper surface, of a sheet-like electrode material (electrode layer) 12.
In this electrode 10 for an electric dipole layer capacitor, the sheet-like electrodes 12 are embedded in the reinforcing sheet 14, exhibit a fixing effect, and are joined together in a laminated state.
The reinforcing sheet 14 may be made of a synthetic resin such as PP, PE, or the like; natural fibers such as cellulose; inorganic fibers such as glass; metals such as aluminum and nickel; woven or knitted fabric, net, nonwoven fabric, and expanded sheet made of carbon fibers such as carbon fibers. These reinforcing materials not only have a reinforcing effect, but also have a function and an effect as a separator and a current collector, depending on the kind of the raw material of the reinforcing material.
The thickness of the reinforcing material 14 is not particularly limited, but is preferably 0.01 to 1.0mm (thick). If the thickness is less than 0.01mm, it is difficult to obtain a sufficient reinforcing effect, and if it exceeds 1.0mm, the reinforcing sheet has a cushioning effect and hardly sinks into the sheet-like electrode, so that it is difficult to join the reinforcing sheet and the sheet-like electrode together.
The reinforcing sheet material is not particularly limited, but may be suitably provided with a suitable gap so as to obtain an excellent fixing effect.
When the reinforcing sheet used is a synthetic resin such as PP, PE, phenol resin, or fluorine-containing resin, or a natural fiber such as cellulose, these materials are insulating materials, and therefore, they have a function and an effect as a separator. In this case, the basis weight of the reinforcing sheet is preferably 50g/m2The above. If the basis weight is less than 50g/m2The electrode may be detached from the reinforcing material, and thus may not sufficiently function as a separator.
The material is metal such as aluminum, nickel and the like; carbon fibers such as carbon fibers have a function and an effect as a current collector. In this case, although the handling of the reinforcing sheet is not particularly limited, if the thickness of the reinforcing sheet is more than 0.5mm, the workability is deteriorated, and the winding is difficult due to the rigidity of the metal.
The thickness of the sheet-like electrode 12 in the electrode for electric dipole layer capacitor is not particularly limited, but is usually 0.1 to 1.0mm, preferably 0.2 to 0.8 mm.
The sheet electrode 12 contains carbon fine powder and fluorine-containing resin.
The carbon fine powder preferably contains activated carbon and/or conductive carbon. To the activated carbon and leadThe particle size of the electrically conductive carbon is not particularly limited, but the particle size of the activated carbon is preferably about 1 to 100 μm. The specific surface area of the activated carbon and the conductive carbon is not particularly limited, but the specific surface area of the activated carbon is preferably 1000 to 3000m2/g。
The fluoropolymer resin contained in the sheet electrode of the present invention is preferably Polytetrafluoroethylene (PTFE), modified PTFE, PVDF, ETFE, PCTFE, FEP, PFA, or the like, and among these, Polytetrafluoroethylene (PTFE) is particularly preferably used because it is easily fiberized by a shearing force, and the bonding effect of bonding and binding carbon fine powder is good.
The binder content of the non-conductive fluoropolymer resin in the sheet-like electrode material is preferably 15% by weight (wt%) or less, more preferably 1 to 10 wt%, particularly preferably 1 to 5 wt%, relative to the content of the carbon fine powder contained in the sheet-like electrode 12, in order to control the internal resistance of the electrode layer to a low level.
If the amount of the binder is less than 1% by weight, a sufficient binding effect cannot be obtained, and the carbon fine powder may fall off and scatter from the electrode for electric dipole layer capacitors. On the other hand, if the binder amount exceeds the above range, particularly exceeds 15% by weight, it is difficult to control the internal resistance of the electrode layer to a low level.
When the above-mentioned sheet-like electrode material containing the respective components and the reinforcing sheet are used in combination in an amount within this range, the handling properties of the electrode for electric double layer capacitors produced from the fine carbon powder as the raw material functional material powder are remarkably improved due to the reinforcing effect of the reinforcing sheet. The sheet-like electrode with a reinforcing material can be easily produced with high productivity and at low cost by using the reinforcing material and the sheet-like electrode material formed of the carbon fine powder and the binder resin, and by any of a doctor blade method (bonding method using a doctor blade), a roll-rolling method, and the like.
In the electrode for an electric double layer capacitor of the present invention, the amount of the binder contributing to the increase in the strength of the electrode in the sheet-like electrode 12 can be reduced, and the internal resistance of the electrode can be reduced. In addition, when a thermosetting phenol resin or a reinforcing material such as glass or metal is used, since heat treatment can be performed at a higher temperature, moisture can be completely removed, and the product life can be extended. When the electric double layer capacitors 20 and 30 shown in fig. 3 and 4 described later are manufactured using the electrode 10 for an electric double layer capacitor, the electrolyte can rapidly permeate into the electrodes.
The electrode for an electric dipole layer capacitor of the present invention has the reinforcing sheet 14, and the strength of the electrode is maintained by the reinforcing sheet 14, so that the sheet electrode can be made large in size and is excellent in mass productivity.
As shown in fig. 2, the electrode for an electric dipole layer capacitor of the present invention may be formed by providing the reinforcing sheet 14 only on one surface of the sheet-like electrode 12, or may be formed by providing the reinforcing sheet 14 on both surfaces of the reinforcing sheet 14 as shown in fig. 3 described later.
As shown in fig. 4 described later, the sheet-like electrode 12 and the reinforcing sheet (separator and/or collector) 14 may be wound in a state of being laminated in this order (in fig. 4, 2 layers are laminated).
[ electric double layer capacitor ]
An electric double layer capacitor using such an electrode for an electric double layer capacitor will be described in more detail below with reference to fig. 3 to 4.
Fig. 3 is a sectional view of an electric double layer capacitor equipped with an electrode for an electric double layer capacitor according to one embodiment of the present invention.
In the electric double layer capacitor 20, the sheet-like electrodes 12A and 12B are provided on both the upper and lower surfaces of the reinforcing sheet (separator) 14, and the aluminum current collectors 18A and 18B are provided on the lower surface of the electrode 12A and the upper surface of the electrode layer 12B, respectively.
In this way, the capacitor internal member 22, which is composed of the separator (reinforcing material layer) 14, the electrode layers 12A and 12B laminated on the upper and lower surfaces of the separator through the separator 14, and the aluminum collectors 18A and 18B, is housed in the case 24 and sealed with the filler 16.
The electrode layer in the case is also filled (impregnated) with an electrolyte.
The electric double layer capacitor 20 formed by using the electrode for electric double layer capacitor is particularly excellent in light weight, downsizing, performance, cost reduction, and the like. Further, since the binder is small, impregnation with an electrolyte is excellent, and the strength is high, the electrode for an electric double layer capacitor of the present invention is excellent in handling property, and the assembly work at the time of manufacturing the electric double layer capacitor is easy, and the work time can be shortened.
Fig. 4 is a schematic diagram of an electric double layer capacitor in which an electrode for an electric double layer capacitor according to another embodiment of the present invention is partially cut away.
In the electric double layer capacitor 30, the reinforcing sheet (separator) 14 and the sheet-like electrode 12 are wound in a state of being laminated in order (2 layers are laminated in the whole), and are housed in the case 34. A pair of collectors 18A, 18B is provided at the end of each sheet-like electrode 12A, 12B, and leads 38A, 38B that can be electrically connected to the outside of the electric double layer capacitor 30 are provided on the pair of collectors 18A, 18B. Further, a sealing gasket 36 is provided at an upper end portion inside the housing 34 to close the end portion.
The tab electrode 12A and the collector pair 18A are electrically connected with the lead 38A, the tab electrode 12B and the collector pair 18B are electrically connected with the lead 38B, and the group A and the group B do not influence each other.
The electrode layer in the case is also filled (impregnated) with an electrolyte.
The electrode for an electric double layer capacitor of the present invention can be easily assembled because it can be formed into a large-sized sheet with an integrated separator, has excellent impregnation with an electrolyte, and improves workability in manufacturing an electric double layer capacitor.
The electric double layer capacitor 30 using the electrode for an electric double layer capacitor is particularly excellent in light weight, downsizing, performance, cost reduction, and the like.
The reinforcing material-equipped functional sheet (functional sheet) of the present invention has a basis weight of 10 to 400g/m, particularly when the reinforcing sheet is used2And a reinforcing sheet (reinforcing material) in which the fibers constituting the reinforcing sheet have a fiber diameter of 10 to 150 μm and contain many voids. When a kneaded product of a functional powder and a binder resin or a softened sheet-like functional material is stuck on the reinforcing sheet, the kneaded product can sufficiently enter the gaps between the numerous fine fibers of the reinforcing sheet, and a sufficient fixing effect is exhibited, whereby the interlayer peel strength is excellent. As a result, the reinforcing sheet (layer) and the sheet-like functional material (layer) of the reinforcing material-equipped functional sheet do not peel off, and the workability is excellent.
If the reinforcing sheet is thin, the amount of the sheet-like functional material (kneaded product) to be pressure-bonded thereto can be reduced by a small amount, and a thin functional sheet with a reinforcing material having sufficient strength can be produced at low cost.
That is, a functional sheet having a larger size and exhibiting sufficient functions and effects can be produced from the same amount of kneaded material as compared with conventional products.
Further, since the functional sheet is thin and has sufficient strength, embossing can be performed, so that a highly efficient catalytic sheet can be provided.
In particular, in the electric double layer capacitor which is one of the above-described functional sheets with a reinforcing material, the strength of the electrode is maintained by the reinforcing sheet in the sheet electrode for an electric double layer capacitor, and therefore the amount of the binder in the electrode which contributes to the strength enhancement of the electrode can be minimized.
Therefore, the internal resistance is greatly reduced, and the deterioration of the charging and discharging capability of the capacitor can be suppressed, so that the capacitor having excellent durability and a long life can be provided.
Further, since a step of increasing the strength (e.g., kneading) is not required in the production as in the conventional sheet electrode, the production process can be simplified.
Further, the electrode of the present invention having mechanical strength is excellent in handling property at the time of production and at the time of use. Since the amount of binder in the electrode can be reduced, the impregnation of the electrolyte into the electrode is also good, and the workability in the production of the capacitor is greatly improved.
As a result, the electrode can be incorporated into the battery in a short time in a state in which the electrode is sufficiently impregnated with the electrolyte solution, and therefore, the working time in manufacturing the electric double layer capacitor can be shortened.
[ examples ]
Hereinafter, the functional sheet with a reinforcing material according to the present invention will be described in more detail with reference to examples of a deodorizing device using activated carbon as a functional powder and examples of an electric double layer capacitor, but the present invention is not limited to these examples.
(deodorizing device)
Examples A1 to A4
The active carbon powder is mixed in an amount of 1000 to 1500 (unit: m) in terms of an average particle diameter of 30 μm and a specific surface area (measurement method: in accordance with JIS-K-1474)2Coal-based activated carbon powder/g)]The resulting PTFE particle dispersion (containing 60% by weight of PTFE particles having an average particle diameter of 200nm, a dispersant: water) was kneaded at 10 ℃ for 5 minutes by a kneader.
Subsequently, the obtained kneaded material was pressed at a pressure of 150kg/cm by a roll press machine in which the roll surface temperature was maintained at 60 ℃ to form a sheet having a thickness of 0.4 mm.
Then, the obtained sheet-like functional material was pressure-bonded to a polypropylene nonwoven fabric (fiber diameter: 30 μm, basis weight: 15 g/cm) having a thickness of 0.1mm2) A flat plate-like functional sheet (thickness: 0.4 mm).
Comparative examples A1 to A2
The kneaded product of the above-mentioned activated carbon powder and fluorine-containing resin was formed into a sheet having a thickness of 0.5mm by a roll press in the same manner as in example A1, but it was directly used as a functional sheet (sample) without being pressure-bonded to one surface of a nonwoven fabric in the same manner as in example A1.
Comparative examples A3 to A4
Except that the kneaded product of the activated carbon powder and the fluorine-containing resin was formed into a sheet having a thickness of 0.5mm by a roll press, and then the sheet was pressure-bonded to a polypropylene net having a thickness of 0.3mm (comparative example A3: fiber diameter: 300 μm, basis weight: 200 g/cm)2Comparative example a 4: fiber diameter: 300 mu m, eye payment 450g/cm2) The operation was the same as in example A1, except that a flat plate-like functional sheet (thickness: 0.6mm) was prepared.
The following tests were carried out using the functional sheets with a reinforcing material obtained in examples A1 to A4 and comparative examples A1 to A4.
[ test A1]
(deodorizing Effect)
The adsorption capacity of ammonia was measured.
(Strength)
The tensile strength was measured.
The results are shown in Table 1 below.
TABLE 1
| Sample name | Activated carbon/PTFE (% by weight) | Reinforcing material (fiber)Wei footpath, eye payment) | The deodorization effect is as follows 1 | Strength (N) |
| Comparative example 1 | 80/20 | Is free of | Breakage during processing | 0.3 |
| Comparative example 2 | 40/60 | Is free of | 40％ | 1.1 |
| Example 1 | 80/20 | Has a thickness of (30 μm 15 g/cm)) | 85％ | 2.5 |
| Example 2 | 90/10 | Has a thickness of (30 μm 15 g/cm)) | 95％ | 2.5 |
| Example 3 | 95/5 | Has a thickness of (30 μm 15 g/cm)) | 100％ | 2.5 |
Corresponding to 1) relative value of 100% of the example A3
[ test 2]
(Peel Strength)
The peel strength of each functional sheet obtained in example A1 and comparative example A1 was measured in accordance with JIS C6471 "peel strength of copper foil".
That is, the reinforcing material side of the functional sheet obtained in example a1 was joined to a support, and the peel strength was measured. The peel strength of the functional sheet obtained in comparative example a1 was measured in the same manner as above.
In addition, as comparative data, a sample without the pressure-bonding reinforcing material was joined to the support, and the same measurement was performed.
The results are shown in Table 2.
The peeling of the sample is also shown in Table 2.
TABLE 2
| Sample name | Activated carbon/PTFE (% by weight) | Reinforcing material (fiber diameter. eye payment) | Peel strength (N) | Peeling off of the film |
| Comparative example A3 | 80/20 | Has the following components (300 mu m.200 g/cm)) | Less than 0.3(N) (less than strength of functional material) | The functional material and the reinforcing material were easily peeled off and could not be measured. |
| Comparative example A4 | 80/20 | Has a thickness of (30 μm 450 g/cm)) | 1.1(N) or less (strength of functional material or less) | The functional material and the reinforcing material were easily peeled off and could not be measured. |
| Example A1 | 80/20 | Has a thickness of (30 μm 15 g/cm)) | 2.5(N) or more (strength of functional material or more) | The functional material layer was peeled off and could not be measured |
| Example A4 | 90/10 | Has a thickness of (100 μm 350 g/cm)) | 2.5(N) or more (strength of functional material or more) | The functional material layer was peeled off and could not be measured. |
From the above test A2, it was found that the reinforcing material-equipped functional sheet obtained in example A1 had a strong bonding force with the reinforcing material.
(electric double layer capacitor)
Next, the electrode for an electric dipole layer capacitor of the present invention will be described in more detail with reference to examples.
Example B1
Activated carbon (average particle diameter: 25 μm, palm shell activated carbon), conductive carbon black (made by kitchen International Co., Ltd., kitchen black EC), and a binder (polytetrafluoroethylene ═ PTFE) were mixed at a weight ratio of 80: 15: 5, and a molding aid ethanol was added thereto in an amount of 150 wt%, and the mixture was kneaded at 20 ℃ and then rolled to a thickness of 0.65mm with a roll press having a surface temperature of 40 ℃ to form a sheet.
A reinforcing sheet (PP nonwoven fabric, thickness: 0.1mm) was pressure-bonded to the obtained sheet-like electrode using a roll press (interval between rolls: 0.65mm) having a surface temperature of 40 ℃.
2 test pieces (thickness: 0.65mm, area: 2 cm) cut out from the electrode film with the reinforcing material2) A separator (cellulose filter paper, thickness: 0.12mm) was placed in a state where both electrodes (test pieces) were opposed to each other, and an electrolytic solution was injected to prepare a capacitor.
The initial electrostatic capacity (F/cm) of the capacitor was measured under the following conditions under the conditions of a charging voltage of 2.5V and a discharge current of 5.0mA3Note 1) and volume resistivity (Ω · cm, note 2).
As a result, the initial electrostatic capacity was 12.1 (F/cm)3) The volume resistivity was 0.73 (. omega. cm).
Since the amount of PTFE can be reduced, the amount of PTFE in the electrode film is 5% which is half that of the sheet-like electrode of comparative example B1 described below, and the amount of conductive carbon in the electrode film is increased by 5% as compared with comparative example B1 described below, thereby reducing the resistance.
<Note 1>Initial electrostatic capacity (F/cm)3)：
2 pieces of the powder with the thickness of 0.65mm and the area of 2cm are added2The electrode films were opposed to each other with a separator (cellulose filter paper, thickness: 0.12mm) interposed therebetween, and a capacitor was formed using a propylene carbonate solution (1M) containing tetraethylammonium tetrafluoroborate as a solute as an electrolyte.
The initial electrostatic capacity was measured under the conditions of a charging voltage of 2.5V and a discharging current of 5 mA.
< Note 2> volume resistivity (Ω · cm): according to "JIS K7194".
< note 3> tensile strength measurement method:
the electrode film sheet was cut into a rectangular shape having a width of 10mm and a length of 60mm, and the tensile strength was measured by an Instron (universal precision tensile tester).
Example B2
A test piece was produced in the same manner as in example B1, except that the thickness of the reinforcing sheet was changed to 0.3 mm. In this case, since the reinforcing sheet can function as a separator, the same test was performed without using a separator.
As a result, the initial electrostatic capacity was 12.1 (F/cm)3) The volume resistivity was 0.73 (. omega. cm).
Example B3
The procedure was as in example B1, except that the functional material was used in an amount of 10% binder, i.e. 8: 1 weight ratio activated carbon to conductive carbon black to binder.
As a result, the initial electrostatic capacity was 12.0 (F/cm)3) The volume resistivity was 1.10 (. omega. cm).
Comparative example B1
The same procedure was followed as in the sheet electrode of example B1, except that an electrode film was used which had no reinforcing material and the amount of binder was 10%, i.e., the weight ratio of activated carbon to conductive carbon black to binder was 8: 1.
As a result, the initial electrostatic capacity was 12.0 (F/cm)3) The volume resistivity was 1.10 (. omega. cm).
Comparative example B2
The same procedure was followed as in the sheet electrode of example B1, except that an electrode film was used which had no reinforcing material and the amount of binder was 20%, i.e., the weight ratio of activated carbon to conductive carbon black to binder was 7: 1: 2.
As a result, the initial electrostatic capacity was 10.2 (F/cm)3) The volume resistivity was 2.26 (. omega. cm).
The results of examples B1 to B3 and comparative examples B1 to B2 are shown in Table 3.
TABLE 3
Feasibility of industrial utilization
As described above, the reinforcing material-equipped functional sheet of the present invention is excellent in the effect for deodorizing, water quality improvement, solvent adsorption and other uses when the functional material powder contained therein is carbonaceous such as activated carbon, and is excellent in the effect for photocatalytic use when the functional material powder is titanium oxide.
In particular, in the electric double layer capacitor electrode which is one of the above-described functional sheets with a reinforcing material, since the strength of the electrode is maintained by the reinforcing sheet in the sheet electrode for an electric double layer capacitor, the amount of the binder in the electrode which contributes to the strength enhancement of the electrode can be minimized, the impregnation of the electrolyte into the electrode is also improved, and the workability in the production of the capacitor is extremely good.
Therefore, according to the present invention, a capacitor having a significantly reduced internal resistance, suppressed deterioration in the charging and discharging capabilities of the capacitor, excellent durability, and a long life can be provided by a simpler manufacturing process. The method is very suitable for the field of manufacturing electric dipole layer capacitors.
Claims (9)
1. A functional sheet with a reinforcing material, which is obtained by laminating a sheet-like functional material comprising a functional material powder and a binder resin and a reinforcing sheet and bonding the functional material and the reinforcing sheet, characterized in that the reinforcing sheet is made of a woven fabric or a nonwoven fabric and has a basis weight of 10 to 400g/m2The fiber diameter of the fibers constituting the reinforcing sheet is 10 to 150 μm.
2. The reinforced functional sheet according to claim 1, wherein the binder resin is an unfired polytetrafluoroethylene resin and is contained in an amount of 50 to 1 wt% based on the total amount of the sheet-like functional material.
3. The functional sheet with a reinforcing material according to claim 1 or 2, wherein the functional material powder is any one of 1 or 2 or more of activated carbon, graphite, carbon black, bamboo charcoal, titanium oxide, zinc oxide, lead oxide, silica, clay, metal powder, water-absorbent polymer, silica gel, antifungal agent, and antibacterial agent.
4. The reinforced functional sheet according to claim 1 or 2, wherein the reinforced functional sheet is embossed.
5. An electrode for an electric double layer capacitor, which is formed by bonding a sheet-like electrode material comprising a carbon fine powder and a fluoropolymer resin to a reinforcing sheet in a laminated state, characterized in that the reinforcing sheet is made of a woven fabric or a nonwoven fabric and has a basis weight of 10 to 400g/m2The fiber diameter of the fiber constituting the reinforcing sheet is 10 to 150 [ mu ] m, and the thickness of the functional sheet with the reinforcing material is 0.8mm or less.
6. The electrode for an electric dipole layer capacitor as claimed in claim 5, wherein said reinforcing sheet is made of any one of a woven fabric, a net, a nonwoven fabric and an expanded sheet, and the thickness of said reinforcing sheet is 0.01 to 1.0 mm.
7. The electrode for an electric dipole layer capacitor as claimed in claim 5 or 6, wherein said carbon fine powder contains activated carbon and/or conductive carbon, and said fluorine-containing polymer resin is polytetrafluoroethylene.
8. The electrode for an electric dipole layer capacitor as claimed in claim 5 or 6, wherein a content of said fluorine-containing resin in said electrode material is 15% by weight or less.
9. An electric double layer capacitor comprising the electrode for an electric double layer capacitor according to any one of claims 5 to 8.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002244261A JP4176417B2 (en) | 2002-08-23 | 2002-08-23 | Functional sheet with reinforcement |
| JP2002-244261 | 2002-08-23 | ||
| PCT/JP2003/010448 WO2004018200A1 (en) | 2002-08-23 | 2003-08-19 | Reinforcing material-carrying functional sheet |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| HK1089725A1 HK1089725A1 (en) | 2006-12-08 |
| HK1089725B true HK1089725B (en) | 2009-05-15 |
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