JP3884702B2 - Granules for electrode formation of electric double layer capacitor, manufacturing method thereof, electrode sheet, polarizable electrode and electric double layer capacitor using polarizable electrode - Google Patents

Description

【００４４】
この結果、４７μｍ未満の粉砕粉で作製した電極層は強度が極端に低下し、密度も低下していた。これにより４７未満μｍ未満の粉砕粉は結合力が弱く、成形性に悪影響を与える可能性が強いばかりか、脱落したり電解液に浮遊しやすいことが判った。
【００４５】
【表２】

【００４６】
実施例１および実施例２によれば、４７μｍ未満の微粉を除去することで、脱落する粒子が低減されるために高い電圧維持率が得られること（自己放電特性を改善できること）が判った。これに対して、３８μｍ未満の微粒子を除去した（３８μｍ以上の微粒子が存在する）比較例１および微粒子を除去しない比較例２では３１２時間後の電圧維持率が著しく低下している。
【００４７】
【発明の効果】
以上説明した通り、本発明は次ぎの優れた効果を奏する。
請求項１によると、炭素微粉や導電性フィラ等の微粒子が剥離や脱離して電解液中に浮遊したりセパレータ間に介在することがなくなり、電圧維持率の高い電気二重層コンデンサの電極を作製することが可能となる。
請求項２によると、炭素微粉や導電性フィラ等の微粒子が剥離や脱離して電解液中に浮遊したりセパレータ間に介在することがない電気二重層コンデンサの電極を作製するための顆粒を容易に製造することが可能となる。
【００４８】
請求項３によると、炭素微粉や導電性フィラ等の微粒子が剥離や脱離して電解液中に浮遊したりセパレータ間に介在することがない電圧維持率の高い、すなわち安定した性能を発揮することができる電気二重層コンデンサの電極が得られる。
請求項４によると、炭素微粉や導電性フィラ等の微粒子が剥離や脱離して電解液中に浮遊したりセパレータ間に介在することがないので、電気二重層コンデンサに組み込んだ際に、高い電圧維持率を達成することができる。従って、安定した電圧を供給することが可能で耐久性の高い電気二重層コンデンサが得られる。
請求項５によると、高い電圧維持率を有し、耐久性の高い電気二重層コンデンサが得られる。
【図面の簡単な説明】
【図１】 図１（ａ）は、本発明および従来技術の電気二重層コンデンサの一例を示す概略図であり、図１（ｂ）は、本発明および従来技術の電気二重層コンデンサの他の例を示す概略図である。
【図２】 電気二重層コンデンサの分極性電極を示す概略図である。
【図３】 電気二重層コンデンサの分極性電極の製造工程を示すフローチャートである。
【図４】 電気二重層コンデンサの基本構成を示す断面図である。
【符号の説明】
１ 電気二重層コンデンサ
２ 容器
３ 電極捲回体
９、１０ 分極性電極
１１、１４ 集電箔
ｅ 電極層
ｓ セパレータ[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an electrode-forming granule for an electric double layer capacitor, a manufacturing method thereof, an electrode sheet, a polarizable electrode and an electric double layer capacitor using the polarizable electrode.
[0002]
[Prior art]
  An electric double layer capacitor is also called an electric double layer capacitor, and has a farad-class large capacity, excellent charge / discharge cycle characteristics, and capable of rapid charging. It is used for applications such as batteries (energy buffers).
[0003]
  Outline of electric double layer capacitorabout,This will be described with reference to FIG.
  FIG. 4 is a cross-sectional view showing the basic configuration of the electric double layer capacitor.
  An electric double layer capacitor 101 shown in FIG. 4 includes a container 102, a pair of carbon electrodes (polarizable electrodes) 104 and 104 disposed in the container 102 with a separator 103 interposed therebetween, and a pair of current collectors (members). 105 and 105 are accommodated, and an ion conductive electrolyte is introduced into the container 102. The electric double layer capacitor 101 usually generates electric charges (indicated by + and-in the figure) that are generated at the interface between the solid carbon electrodes 104 and 104 and the liquid electrolyte, and exist at a molecular level. This capacitor is used as a dielectric in the capacitor.
[0004]
  Electrolytic solutions used for electric double layer capacitors are roughly classified into so-called aqueous electrolytic solutions in which an electrolyte is added to dilute sulfuric acid and so-called organic electrolytic solutions in which an electrolyte is added to an organic solvent, and are selected according to the purpose. . That is, an electric double layer capacitor using an aqueous electrolyte is advantageous in terms of power density because of its low internal resistance. On the other hand, the organic electrolyte solution is advantageous in terms of energy density because it can increase the withstand voltage per unit cell, and an inexpensive and light metal such as aluminum can be used.
[0005]
  In such an electric double layer capacitor, actually, as shown in FIG.Layer eAnd a current collector foil (metal foil) 11 (14) are optionally used and a polarizable electrode 9 (10) is used via an adhesive layer.
  And as shown in FIG. 1 (a) and FIG.Pole 9The electric double layer capacitor 1 is configured by alternately stacking (10) and the separator s and enclosing them in the container 2.
  An electric double layer capacitor 1 shown in FIG. 1A includes a cylindrical container 2 and a polarizable electrode housed in the container 2.9 (10)And separatorsAre mainly composed of an electrode winding body 3 composed of a laminated body composed of the above and an electrolyte injected into the container 2.
  On the other hand, the electric double layer capacitor 1 shown in FIG. 1B is a polarizable electrode accommodated in a coin-shaped container 2.9 (10)And separatorsComposed mainly of a laminate composed of and separatorsIs impregnated with an electrolyte.
[0006]
  Polarizable electrodes used in electric double layer capacitors are required to have a porous structure, and are not easily cracked or damaged and have high shape retention in order to be used in various forms for a long time. .
  In addition, the electrode material such as carbon constituting the electrode is desorbed, voltage drop and internal resistance increase, and the dropped electrode material floats in the electrolytic solution or intervenes in the separator. May be difficult to maintain for a long time.
  Electrodes in electric double layer capacitorsFormationAs a method for preventing omission of granules for use, for example, in Patent Document 1, a mixture of electrode raw materials such as carbon fine powder (activated carbon), conductive filler and binder and a liquid lubricant is formed into a sheet, and the lubricant A method for producing a polarizable electrode is disclosed in which a polarizable electrode for an electric double layer capacitor is produced by uniaxially or multiaxially stretching a molded sheet after removing the film.
  Patent Document 2 discloses an electrode sheet for an electric double layer capacitor in which the tensile strength of a polarizable electrode is specified to be 0.13 MPa in order to prevent carbon constituting the electrode from degranulating in the electrolytic solution. ing.
[0007]
[Patent Document 1]
    Japanese Patent Publication No. 7-105316
[Patent Document 2]
    JP 2001-267187 A
[0008]
[Problems to be solved by the invention]
  However, in the polarizable electrode produced by the method described in Patent Document 1 and Patent Document 2, the detachment of the particles themselves configured as an electrode is eliminated to some extent, but the polarizable electrode is not used during the polarizable electrode production process. When producing an electric double layer capacitor by enclosing it in a container, the active material, conductive fillers and other fine particles are peeled or detached and floated in the electrolyte or interposed between separators, resulting in a decrease in voltage maintenance ratio It was the cause.
  Accordingly, an object of the present invention is to provide an electrode for an electric double layer capacitor having a high voltage maintenance ratio (low self-discharge) by preventing the detachment of fine particles such as an active material and a conductive filler.
[0009]
[Means for Solving the Problems]
  As a cause of separation and desorption of fine particles such as carbon fine powder and conductive filler when the polarizable electrode is produced or when the electric double layer capacitor is produced by enclosing the polarizable electrode in a container, It was found that the granules constituting the electrodes themselves are fine particles that are inevitably generated during the production of the granules for electrode molding, as well as the granules themselves. And it discovered that the said subject was solved by using the granule for electrode formation of the electric double layer capacitor of a predetermined | prescribed particle size range as a starting material, and came to create this invention.
  That is, the invention according to claim 1The following process: (a) A step of kneading a raw material containing 50 to 97% by mass of an active material, 1 to 30% by mass of a conductive filler, and 2 to 20% by mass of a binder to fibrillate a binder component to form a lump, (b) Crushing the formed lump to form a pulverized product, (c) Classifying the pulverized product to remove particles having a particle size exceeding 840 μm, and (d) Granules for electrode formation of an electric double layer capacitor obtained by a method for producing granules for electrode formation of an electric double layer capacitor comprising the step of classifying the pulverized product to remove particles having a particle size of less than 47 μmIt is.
[0010]
  When an electrode for an electric double layer capacitor is formed using the electrode forming granule of the electric double layer capacitor thus configured as a starting material, fine particles such as carbon fine powder and conductive filler are peeled off and desorbed and float in the electrolyte. In other words, the electrode of the electric double layer capacitor having a high voltage maintenance rate can be produced.
[0011]
  Invention of Claim 2 is a manufacturing method of the granule for electrode formation of an electric double layer capacitor, Comprising:
(A) a step of kneading a raw material containing 50 to 97% by mass of an active material, 1 to 30% by mass of a conductive filler and 2 to 20% by mass of a binder to fibrillate a binder component to form a lump,
(B) a step of pulverizing the formed lump to form a pulverized product,
(C) classifying the pulverized product to remove particles having a particle size exceeding 840 μm; and
(D) The method includes the step of classifying the pulverized product to remove particles having a particle size of less than 47 μm.
[0012]
  By configuring in this way, granules for producing an electrode of an electric double layer capacitor in which fine particles such as carbon fine powder and conductive filler are separated or detached and are not suspended in the electrolytic solution or interposed between separators. Can be easily manufactured.
  In addition, in the manufacturing method of the granule for electrode formation of the electric double layer capacitor | condenser which concerns on this invention, the process (c) and the process (d) mean that any may be performed first.
  That is, the granules exceeding the predetermined particle size are removed from the crushed material prepared in step (b).After(Step (c)), the fine particles may be removed (Step (d)), or the fine particles may be removed first.After(Step (d)) means that granules exceeding a predetermined particle size may be removed (step (c)).
[0013]
  Invention of Claim 3 is the electrode sheet for electric double layer capacitors which shape | molded the granule for electrode formation of the electric double layer capacitor which concerns on this invention in the sheet form.
  By configuring in this way, fine particles such as carbon fine powder and conductive filler do not peel or desorb and float in the electrolyte or intervene between the separators. Therefore, the voltage maintenance rate is high, that is, stable performance. An electrode of an electric double layer capacitor capable of exhibiting the above is obtained.
[0014]
  The invention according to claim 4 is a polarizable electrode for an electric double layer capacitor, wherein the electrode sheet for an electric double layer capacitor according to the present invention is laminated on a current collector foil with or without an adhesive layer. It is.
  The polarizable electrode for an electric double layer capacitor thus configured does not float or detach from fine particles such as carbon fine powder or conductive filler and float in the electrolyte or intervene between separators. When incorporated in a double layer capacitor, a high voltage maintenance ratio can be achieved. Therefore, an electric double layer capacitor that can supply a stable voltage and has high durability can be obtained.
[0015]
  The invention according to claim 5 is an electric double layer capacitor comprising the polarizable electrode for electric double layer capacitor according to the present invention.
  With this configuration, an electric double layer capacitor having a high voltage maintenance ratio and high durability can be obtained.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, the present invention will be described with reference to the accompanying drawings.
(Electric double layer capacitor)
  First, granules for electrode formation of an electric double layer capacitor according to the present invention, a method for producing the same,Electrode layer (Electrode sheet)andPolarized electricityThe poleThe applied electric double layer capacitor will be described with reference to FIGS.
  FIG. 1 (a) is a schematic view showing an example of the electric double layer capacitor of the present invention and the prior art, and FIG. 1 (b) shows another example of the electric double layer capacitor of the present invention and the prior art.ExampleFIG. 2 is a schematic diagram illustrating a polarizable electrode of an electric double layer capacitor.
[0017]
  An electric double layer capacitor 1 shown in FIG. 1A includes a cylindrical container 2 and a polarizable electrode housed in the container 2.9, 10And strip separatorsAre mainly composed of an electrode winding body 3 composed of a laminated body composed of (see FIG. 2) and an electrolyte injected into the container 2.
  The container 2 is made of, for example, aluminum (alloy) for reasons such as ease of processing and light weight. The container 2 includes a bottomed cylindrical main body 4 and a terminal plate 5 that closes an opening at one end thereof. The terminal plate 5 is provided with positive and negative terminals 6 and 7. In the drawing, positive and negative terminals 6 and 7 are provided on the same plane.Is the negative terminal 7 when viewed from the containerIt may be provided on the opposite side.
[0018]
  Moreover, as shown in FIG. 2, the electrode winding body 3 has a positive electrode side.Polarized electrode9 and the negative sidePolarized electrode10 and.
  Polarized electrode9 is aluminumNi foilBecomeCurrent collector foil11 on both sidesElectrode layere is affixed with a conductive adhesive,Electrode layere elongatePole 12 is configured.
  Polarized electrode10 is aluminumNi foilBecomeCurrent collector foil14 on both sidesElectrode layere is affixed with a conductive adhesive,Electrode layere strip-likePole 15 is configured.
  And the positive sidePolarized electrode9 and the negative sidePolarized electrode10 is divided by the separator s.
  That is, the electrode winding body 3 isStrip positive electrode12,Strip negative electrode15 and separators s are alternately stacked.
  In addition, the separator applicable to this invention will not be specifically limited if it is a separator normally used in the said technical field, Porous olefin resin (polyethylene, polypropylene), cellulose, polyester, etc. A mixed paper obtained by making a fiber can be used.
[0019]
  Further, the electrolytic solution used in the electric double layer capacitor shown in FIG. 1 (a) is not particularly limited as long as it is a conventionally known one. For example, perchloric acid, hexafluorophosphoric acid, tetrafluoride Examples include boric acid, tetraalkylammonium salt or amine salt of trifluoroalkylsulfonic acid and tetraalkylammonium salt or amine salt of tetrafluoroalkylsulfonic acid.
  Such an electrolyte is used as an electrolytic solution dissolved in a polar solvent such as propylene carbonate, γ-butyllactone, acetonitrile, dimethylformamide, 1,2-dimethoxyethane, sulfolane, nitroethane, and the like.
[0020]
  In addition, the electric double layer capacitor shown in FIG.Strip positive electrode12,Strip negative electrode15 is an electric double layer capacitor in the form of an electrode winding body 31Electric double layer capacitor as a laminated body as it is not applied to1As a representative example applied to the coin-type electrode double layer capacitor1An example is applied to. However, the present invention provides such a coin-type electric double layer capacitor.1Not limited to, polarizable electrodes9, 10The electrode winding body3The electric double layer capacitor applied to the electric double layer capacitor as a laminated body as it is instead of being applied to the electric double layer capacitor in the form of is also within the scope of the present invention.
  Note that the electric double layer capacitor shown in FIG.1In FIG. 1, the same members as those in FIG.
  The electric double layer capacitor 1 shown in FIG. 1B is housed in a conductive container 2, 2 'made of aluminum or the like.Polarized electrodeIt is mainly composed of a laminate composed of 9, 10 and the separator s, and the separator s is impregnated with an electrolytic solution.
  Positive sideofPolarized electricityPole 9And negative electrode sideofThe polarizable electrode 10 is a polarizable electrode shown in FIG.9, 10Like each, aluminumNiMade of foil (current collector foil)Current collector foil11 (14) on both sidesElectrode layer eIt is comprised from the laminated body which affixed with the conductive adhesive (adhesion layer) (refer also FIG. 2).
  like thisStrip positive electrode12 andStrip negative electrode15 is accommodated in the containers 2 and 2 'through the separator s impregnated with the electrolytic solution.ofAn electric double layer capacitor 1 is formed. In addition, a coin type with such a configurationofIn the electric double layer capacitor 1,Strip positive electrodeThe upper container 2 in contact with 12 functions as a positive electrode,Strip negative electrodeThe lower container 2 ′ in contact with 15 functions as a negative electrode.
  The present inventionCoin-shapedElectric double layer capacitor1It is also applicable to.
[0021]
(Polarizable electrode)
  Next, the polarizable electrode according to the present invention will be described with reference to FIG.9, 10Will be described in detail.
  As shown in FIG. 2, polarizable electrodes9, 10Current collector foil such as aluminum foil11On the top (one side or both sides)Layer eAre stacked.
  Current collector foil11The electrodeLayer eSurface treatment such as etching may be performed for the purpose of improving the adhesiveness.
(electrodelayer)
  Electrode in the present inventionLayer eIs formed by forming a raw material composition containing (a) active material 50 to 97% by mass, (b) conductive filler 1 to 30% by mass and (c) binder 2 to 20% by mass into a sheet shape. .
[0022]
  Polarizable electrode according to the present invention9, 10The active material that composes the conventionalofIt will not specifically limit if it is used for the electrode of an electrical double layer capacitor, Activated carbon, carbon fiber, etc. can be used. In particular, for the purpose of obtaining an electric double layer capacitor having a large capacitance, activated carbon or activated carbon fiber having a large specific surface area on an electrode, preferably activated carbon obtained by carbonizing an easily graphitized material and then alkali-activated, for example, mesophase charcoal is used in the present invention. It can be used as an electrode material according to the above.
[0023]
  The average particle diameter of the active material is not particularly limited, for example1 toAn active material having an average particle size of 50 μm, preferably about 2-15 μm is used. The ratio of the active material which comprises the electrode which concerns on this invention is used in a conventionally well-known range, ie, 50-97 mass%. The amount of active materialin frontIf it is less than the above range, the desired capacitance cannot be obtained, and the amount of active material is converselyin frontIf the amount is larger than the above range, the conductivity deteriorates, which is not preferable.
[0024]
  The conductive filler is used for the purpose of imparting conductivity to the electrode, and a conductive fine powder, for example, carbon black, which is usually used in the art is used. The amount of the conductive filler constituting the electrode according to the present invention may be a conventionally known amount, and is generally in the range of 1 to 30% by mass. The amount of conductive filler used isin frontIf the amount is less than the above range, the conductivity of the obtained electrode is deteriorated, and conversely, the amount of conductive filler used is small.in frontIf the amount is more than the above range, the capacitance is decreased, which is not preferable.
[0025]
  The binder is used for binding and granulating these particulate components, and various binders known in the art can be used in the present invention. Examples of binders that can be suitably used in the present invention include, but are not limited to, for example, polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene copolymer, chlorotrifluoroethylene polymer, and vinylidene fluoride polymer. And fluororesins such as tetrafluoroethylene-fluoroalkyl vinyl ether copolymer. Among these binders, polytetrafluoroethylene (PTFE) is preferably used as a binder in the present invention from the viewpoints of heat resistance, chemical resistance, and the like.
  The amount of the binder constituting the electrode according to the present invention may also be a conventionally known amount, and is generally in the range of 2 to 20% by mass. That is, the amount of binder used isin frontIf it is less than the above range, the function as a binder cannot be fully achieved, while the amount of binder used is not sufficient.in frontExceeding the range is not preferable because the capacitance of the obtained electrode decreases.
[0026]
  After kneading and pulverizing a predetermined amount of such an electrode raw material, the electrode forming granule of the electric double layer capacitor according to the present invention is obtained. The particle size range of the electrode forming granule of the electric double layer capacitor according to the present invention is 47 ~It is characterized by being defined in the range of 840 μm.
  That is, when the electrode forming granules of the electric double layer capacitor according to the present invention contain fine granules having a particle size of less than 47 μm,Electrode layer eAs a result, fine granules having a particle size of less than 47 μm are present on the sheet surface. The fine granules present on this surface are preserved during storage, post-processing, and assembly of electric double layer capacitors.InEasily detached. In particular, after the electric double layer capacitor is assembled, fine granules having a particle size of less than 47 μm are detached and intercalated in the separator or floated in the electrolyte solution, thereby reducing the voltage maintenance rate of the electric double layer capacitor. Therefore, it is not preferable.
  On the other hand, the upper limit of the electrode-forming granules of the electric double layer capacitor according to the present invention is produced.Electrode layer eIs selected as appropriate according to the thickness of the, especially in the specification that requires output of automobiles, etc.Electrode layer eThis kind of need to be molded relatively thinElectrode layer eIn the present invention, a particle size of 840 μm, which is the upper limit of the granules used in the present invention, was adopted.
  The term “particle diameter” used in the present invention means the diameter of passing through a sieve.
[0027]
  Therefore, the electrode-forming granules of the electric double layer capacitor according to the present invention having such a predetermined particle size range are formed into a sheet shape andElectrode layer eAnd then this is the current collector foil11And a polarizable electrode for an electric double layer capacitor according to the present invention as shown in FIG.9, 10Make up this polarizable electrode9, 10As shown in FIG. 1 (a) and FIG. 1 (b)1Incorporated into a separator, fine granules with a particle size of less than 47 μm are detached and the separatorsElectric double layer capacitors that have little voltage drop due to self-discharge (ie, have a high voltage maintenance ratio) because they do not intervene or float in the electrolyte solution1The effect that can be provided.
[0028]
(Production method)
  Next, using FIG. 3, the electrode forming granules and electrodes of the electric double layer capacitor according to the present inventionlayerA method for manufacturing a polarizable electrode will be described. Fig. 3 shows the electrodes of an electric double layer capacitorlayerIt is a flowchart which shows the manufacturing process of (polarizable electrode). However, the present invention is not limited to such a manufacturing method.
[0029]
(Raw material mixing process)
  In the present invention, as step S1, first, an active material, a conductive filler, a binder and other additives that are added as desired are added to the mixer at a predetermined ratio in a powder form, and the mixture is uniformly dispersed. (For example, stirring for about 20 minutes at a rotational speed of several thousand rpm).
[0030]
(Kneading process)
  Next, step S2The raw material mixture uniformly dispersed in is reduced in pressure by a kneader, preferably a biaxial kneader as shown in FIG. 3 at a low rotational speed (for example, about 10 to 40 rpm) under heating (for example, 60 to 90 ° C.). The kneading is performed for several minutes, for example, about 8 minutes under (for example, 0.2 to 0.5 MPa). By kneading the raw material mixture under predetermined conditions in the kneading step in this way, BaThe inda fibrils to bind the active material and the conductive filler to form relatively large electrode granules.
[0031]
(Crushing and classification process)
  In step S3, the granules of relatively large particles produced in the kneading step are pulverized so as to have a size suitable for the electrode particles of the electric double layer capacitor.
  The particles pulverized in the pulverization step S3 include particles that are not suitable for constituting an electrode, that is, fine particles and giant particles. Therefore, in the present invention, these particles are removed in step S4. For example, the particles are classified by a sieve having an opening of 840 μm to remove particles having a particle size exceeding 840 μm. The removed granules having a particle diameter exceeding 840 μm are preferably returned to the pulverization step S3 and pulverized. Next, the electrode of the electric double layer capacitor according to the present invention having a predetermined particle size range by removing fine particles with a sieve having an opening of 47 μm, for example.FormationGranules can be obtained. The removed fine particles may be granulated by returning to the kneading step of step S2.
[0032]
  In addition, about classification order,RecordIn this example, the fine particles are removed after the giant particles are removed. However, the fine particles may be removed first, and then the giant particles may be removed. Therefore, the present invention is not limited to the classification order.
[0033]
(Primary molding process)
  In the present invention, the electrode of the electric double layer capacitor according to the present invention is thus performed through steps S1 to S4.FormationThe granules made for this are made in this wayFormationThe granules for use are then preformed in step S6 and formed into electrode pre-sheets.
  The electrode pre-sheet is a conventionally known method, for example, the electric double layer capacitor according to the present invention.Electrode formationGranules and solvents such as isopropylPanoIt is possible to mold by passing a pair of rollers having a predetermined gap together with the tool.
[0034]
(Rolling process)
  Next, in step S7, the electrode pre-sheet has a predetermined thickness.Electrode layerTo form.Electrode layerIn order to fabricate, the electrode pre-sheet has a predetermined thickness by passing between the rolls according to a conventionally known method.Electrode layerTo form. For example, as shown in FIG. 3, the sheet thickness is 130 to 160 μm.Electrode layerIs desired, for example, by gradually passing three pairs of rolls having different roll gaps (the downstream roll is narrower than the upstream roll).Electrode layerReduce the sheet thickness. In this way step by stepElectrode layerBy reducing the sheet thicknessElectrode layerBecause there is no sudden load at once in the thickness direction ofElectrode layerIt is possible to prevent defects such as cracks.
  The rolling process in the present invention is continuously passed through a plurality of pairs of rolls,Electrode layerBut was passed separately through each pair of rollsElectrode layerOf course, it is also within the scope of the present invention.
[0035]
  According to the present invention thus producedElectrode layerIs manufactured using the granule for electrode formation of the electric double layer capacitor according to the present invention having a predetermined particle size range from which fine particles and large particles are removed,Electrode layerNo fine particles are present on the surface.
[0036]
(Lamination process (adhesion process))
  Next, in step S8, for exampleElectrode layerIs bonded to a current collector foil such as an aluminum foil to form the polarizable electrode of the present invention. At this time, as shown in FIG. 3, first, the first roll and the first roll configured to apply the adhesive with a predetermined thickness to the current collector foil from the container in which the adhesive is accommodated. A predetermined thickness of adhesive was applied
Current collector foilElectrode layerAre bonded together by an adhesive line composed of a second roll for pressure bonding.
  In addition, on both sides of the current collector foilElectrode layerWhen the polarizable electrode according to the present invention is manufactured by laminating layers, it can be handled by performing Step 6 on both sides one by one.
  In this way on one or both sides of the current collector foilElectrode layerThe polarizable electrode according to the present invention to which is bonded is dried according to a conventional method to obtain a final product.
  In addition,in frontIn the description of the current collector foil using a conductive adhesiveElectrode layerA polarizable electrode that is a laminate ofElectrode layerMay be simply crimped without using an adhesive to form a polarizable electrode.
[0037]
【Example】
  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to these Examples.
Example 1
  Activated carbon was used as an active material, and acetylene black as a conductive filler and Teflon (registered trademark) as a binder were mixed therewith. The composition ratio was 84: 8: 8. Isopropanol was added to this mixture and kneaded under pressure, and Teflon (registered trademark) was fibrillated to obtain a kneaded product. The obtained kneaded product was pulverized to obtain a pulverized powder having an average particle size of about 0.5 mm.
[0038]
  The pulverized powder was sieved with a mesh to remove fine powder of less than 75 μm. Isopropyl alcohol was further added thereto, and a sheet-like molded product was obtained by calendaring. Add further rolling,Electrode layerWas made. This was bonded to an aluminum current collector to produce an electrode body. G-5780A manufactured by No Tape Industry Co., Ltd. was used for adhesion.
[0039]
  The obtained electrode body is cut into a predetermined length, and two separators of about 50 μm are used.rollThe sample was rotated and sealed in a test cell, followed by vacuum drying at 160 ° C. for 72 hours. A cell was produced by injecting a quaternary ammonium salt 1.8 mol / L propylene carbonate solution as an electrolyte.
  The obtained cell was impregnated at 60 ° C., subjected to predetermined aging treatment and defoamed, then charged to 2.5 V, and the voltage after 312 hours was measured. The voltage maintenance rate was measured from the voltage at that time. The results are shown in Table 2.
[0040]
(Example 2)
  in frontIn the capacitor manufacturing process described above, particles smaller than 53 μm were removed, and the other processes were the same to manufacture a cell, and the same test was performed. The results are shown in Table 2.
[0041]
(Comparative Example 1)
  in frontIn the capacitor manufacturing process, particles smaller than 38 μm were removed, and other processes were the same to manufacture a cell, and the same test was performed. The results are shown in Table 2.
[0042]
(Comparative Example 2)
  in frontIn the capacitor manufacturing process, the same process was performed by manufacturing the cell without removing the fine powder and using the same process. The results are shown in Table 2.
  As a preliminary experiment, the pulverized powder after granulation was divided into powders of less than 47 μm, 47-100 μm, 100 μm or more, and the physical properties after molding were measured.
[0043]
[Table 1]

[0044]
  As a result, it was produced with pulverized powder of less than 47 μm.Electrode layerThe strength was extremely lowered and the density was also lowered. thisInFurther, it was found that the pulverized powder of less than 47 μm has a weak binding force and has a strong possibility of adversely affecting the moldability, and also tends to fall off or float on the electrolyte.
[0045]
[Table 2]

[0046]
  According to Example 1 and Example 2, it was found that by removing fine powder of less than 47 μm, the falling particles are reduced, so that a high voltage maintenance ratio can be obtained (self-discharge characteristics can be improved). On the other hand, in Comparative Example 1 in which fine particles of less than 38 μm were removed (there are fine particles of 38 μm or more) and Comparative Example 2 in which fine particles were not removed, the voltage maintenance rate after 312 hours was significantly reduced.
[0047]
【The invention's effect】
  As described above, the present invention has the following excellent effects.
  According to claim 1, fine particles such as carbon fine powder and conductive filler are not separated or detached from floating in the electrolytic solution or interposed between separators, and an electrode of an electric double layer capacitor having a high voltage maintenance rate is produced. It becomes possible to do.
  According to claim 2, granules for producing an electrode of an electric double layer capacitor in which fine particles such as carbon fine powder and conductive filler are separated or detached and do not float in the electrolytic solution or intervene between separators are easy. Can be manufactured.
[0048]
  According to claim 3, fine voltage such as carbon fine powder or conductive filler does not peel off or desorb to float in the electrolytic solution or intervene between the separators, that is, exhibits a stable performance. An electrode of an electric double layer capacitor that can be obtained is obtained.
  According to claim 4, since fine particles such as carbon fine powder and conductive filler do not exfoliate or detach and float in the electrolytic solution or intervene between separators, a high voltage when incorporated in an electric double layer capacitor A maintenance rate can be achieved. Therefore, an electric double layer capacitor that can supply a stable voltage and has high durability can be obtained.
  According to the fifth aspect, an electric double layer capacitor having a high voltage maintenance ratio and high durability can be obtained.
[Brief description of the drawings]
FIG. 1 (a) is a schematic diagram showing an example of an electric double layer capacitor according to the present invention and the prior art, and FIG. 1 (b) shows another example of the electric double layer capacitor according to the present invention and the prior art.ExampleFIG.
FIG. 2 is a schematic view showing a polarizable electrode of an electric double layer capacitor.
FIG. 3 is a flowchart showing a manufacturing process of a polarizable electrode of an electric double layer capacitor.
FIG. 4 is a cross-sectional view showing a basic configuration of an electric double layer capacitor.
[Explanation of symbols]
      1 Electric double layer capacitor
      2 containers
      3 Electrode wound body
      9, 10 minutes polar electrode
      11, 14 Current collector foil
      eElectrode layer
      s           Separator

Claims (5)

The following process:
(A) A step of kneading a raw material containing 50 to 97% by mass of an active material, 1 to 30% by mass of a conductive filler and 2 to 20% by mass of a binder to fibrillate a binder component to form a lump,
(B) A step of pulverizing the formed lump to form a pulverized product,
(C) Classifying the pulverized product to remove particles having a particle size exceeding 840 μm; and
(D) An electrode-forming granule for an electric double-layer capacitor obtained by a method for producing an electrode-forming granule for an electric double-layer capacitor comprising a step of classifying the pulverized product to remove particles having a particle size of less than 47 μm . The following process:
(A) a step of kneading a raw material containing 50 to 97% by mass of an active material, 1 to 30% by mass of a conductive filler and 2 to 20% by mass of a binder to fibrillate a binder component to form a lump,
(B) pulverizing the formed lump to form a pulverized product,
(C) classifying the pulverized product to remove particles having a particle size exceeding 840 μm, and (d) classifying the pulverized product to remove particles having a particle size of less than 47 μm. The manufacturing method of the granule for electrode formation of the electric double layer capacitor | condenser characterized by the above-mentioned.   The electrode sheet for electric double layer capacitors which shape | molded the granule for electrode formation of the electric double layer capacitor of Claim 1 in the sheet form.   A polarizable electrode for an electric double layer capacitor, wherein the electrode sheet for an electric double layer capacitor according to claim 3 is laminated on an electrode foil with or without an adhesive layer.   An electric double layer capacitor comprising the polarizable electrode for an electric double layer capacitor according to claim 4.

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