JP2007180250A - Electrode paint, and electrode and electrochemical device formed by using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an improved electrode paint using a water-dispersible polymer or a water-soluble polymer as a binder. <P>SOLUTION: The electrode paint includes an active material 50, the binder 52 made of at least either of the water-dispersible polymer and the water-soluble polymer, a solvent 54, and a dispersant 56 made of at least either of a maleic acid copolymer and its salt. Dispersibility is improved by adding the maleic acid copolymer or its salt into the electrode paint L1 in which the water-dispersible polymer or the water-soluble polymer is used as the binder. Consequently, it allows to weaken a shear force applied during a kneading step. By this, it is possible to suppress deterioration in binding force since it is possible to reduce the cutting of a molecular chain of the water-dispersible polymer or the water-soluble polymer during the kneading step. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrode paint used for manufacturing an electrochemical element such as an electric double layer capacitor and a lithium ion secondary battery, and an electrode and an electrochemical element formed using the same.

  Electrochemical elements such as electric double layer capacitors and lithium ion secondary batteries are widely used in mobile phones, notebook computers, PDAs and the like. In particular, the electric double layer capacitor does not use an electrochemical reaction as in a secondary battery, but accumulates charges in the electric double layer of the electrode, so that it can be charged and discharged at an extremely high speed. It has characteristics. Taking advantage of these features, for example, it is expected to be used as a backup power source for portable devices (small electronic devices), an auxiliary power source for electric vehicles and hybrid vehicles, etc. Consideration has been made.

  The basic structure of the electrochemical element has a structure in which an electrolyte solution is filled between a pair of current collectors on which electrode layers are formed via a separator. As the simplest method of forming an electrode layer on a current collector, a method of bonding them together is known, but this method has a problem that it is difficult to increase productivity.

  In order to solve this problem, the electrode layer is formed on the current collector by applying electrode paint on the current collector and drying it, instead of bonding the current collector and the electrode layer together. It is preferable.

  The electrode paint is mainly composed of an active material, a binder, a solvent, and, if necessary, a conductive aid such as carbon black. When a soluble binder is used as the binder, a solvent for dissolving the binder is selected, and when an insoluble binder is used as the binder, a solvent for imparting plasticity to enable molding is used. Selected.

  As a binder, in addition to a fluorine-based binder such as polyvinylidene fluoride (PVDF), a mixture of styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC) (see Patent Document 1), carboxystyrene that defines butadiene bond content and gel content. Butadiene rubber (see Patent Document 2), vinyl polymer thermoreversible thickener and water-dispersible polymer (see Patent Document 3) whose hydrophilicity and hydrophobicity change reversibly at a certain transition temperature are known. ing. Are often used.

  Among them, polyvinylidene fluoride (PVDF) has excellent properties as a binder, but contains a fluorine atom with high electronegativity (high oxidizing power), so that it is altered when coexisting with an easily oxidizable substance. There was a problem. Further, when pyrolysis occurs, fluoride ions are generated, which makes it difficult to use in an environment exposed to high heat (see Patent Document 4).

In contrast, a mixture of styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC) is a solvent because styrene butadiene rubber (SBR) is a water-dispersed polymer and carboxymethyl cellulose (CMC) is a water-soluble polymer. As water can be used. For this reason, there exists an advantage that it is excellent in the safety | security in a manufacturing process, and the load given to an environment is small. In addition, there is an advantage that the produced electrochemical element has high safety.
JP2005-11808 JP 2002-256129 A JP-A-9-320604 JP-A-9-92288

  However, since water-dispersed polymers and water-soluble polymers are vulnerable to shearing forces, the molecular weight of the water-dispersed polymer and water-soluble polymer is cut during the kneading process included in the electrode paint preparation process, resulting in a decrease in molecular weight. As a result, there is a problem that the binding force is reduced. In order to increase the binding force, it is necessary to add more binder, but in this case, since the ratio of the active material in the electrode is reduced, the energy density of the electrochemical device to be manufactured becomes insufficient. There was a problem.

  In order to prevent the molecular chain from being broken, the shearing force applied during the kneading step may be weakened. In this case, the active material or conductive auxiliary agent aggregates may be formed in the electrode, or the coating composition may be reduced. Problems such as non-uniformity occur in dispersibility.

  The present invention has been made to solve such problems, and an object thereof is to provide an improved electrode paint using a water-dispersed polymer or a water-soluble polymer as a binder.

  Another object of the present invention is to provide an electrode and an electrochemical device produced by using such an improved electrode paint.

  The electrode paint according to the present invention includes an active material, at least one of a water-dispersed polymer and a water-soluble polymer, and at least one of a maleic acid copolymer and a salt thereof. In this way, when a maleic acid copolymer or a salt thereof is added to an electrode paint having a water-dispersed polymer or a water-soluble polymer as a binder, the dispersibility is increased, so that the shearing force applied during the kneading step can be weakened. Become. Thereby, since the breakage of the molecular chain of the water-dispersed polymer or the water-soluble polymer during the kneading step can be reduced, it is possible to suppress a decrease in the binding force.

  In the present invention, “maleic acid copolymer” refers to a maleic acid copolymer in a broad sense. That is, it means not only a maleic acid copolymer (not anhydrous) that indicates a narrowly defined maleic acid copolymer but also a maleic anhydride copolymer.

  In the present invention, a styrene / maleic acid copolymer can be selected as the maleic acid copolymer, and the styrene / maleic acid copolymer can be selected from allyl alcohol / styrene / maleic anhydride copolymer and polyoxyalkylene. It is preferable to select a grafted product with a monoalkyl ether. Further, as the styrene / maleic acid copolymer, it is also preferable to select a styrene-maleic acid-alkyl maleate copolymer, and in this case, it is more preferable to select a styrene-maleic acid-butyl maleate copolymer. preferable. Furthermore, it is also preferable to select a vinyl acetate-maleic acid copolymer as the maleic acid copolymer.

  In the present invention, an olefin-maleic acid copolymer can be selected as the maleic acid copolymer. In this case, it is more preferable to select a sodium salt of 1-octadecene-maleic anhydride copolymer. It is also preferable to select an indene-maleic acid copolymer as the maleic acid copolymer.

  The electrode paint according to the present invention preferably further contains acetylene diol or an ethoxylated acetylene diol. According to this, since it becomes difficult to generate bubbles in the electrode paint, it is possible to improve the quality of the coating film. In this case, it is more preferable that the electrode paint further contains a surfactant. According to this, even when water is used as the solvent, acetylenic diol or ethoxylated acetylenic diol can be sufficiently dissolved.

  In the present invention, the water-dispersed polymer is preferably styrene butadiene rubber (SBR), and the water-soluble polymer is preferably carboxymethyl cellulose (CMC). According to this, a high binding force can be obtained.

  The electrode paint according to the present invention can be formed on a current collector made of aluminum or the like, and an electrode such as an electric double layer capacitor can be formed by laminating such electrodes via a separator. Can be produced.

  Thus, according to the present invention, the dispersibility is enhanced by adding a maleic acid copolymer or a salt thereof to an electrode paint having a water-dispersed polymer or a water-soluble polymer as a binder. It becomes possible to weaken the shear force applied during the process. Thereby, since the breakage of the molecular chain of the water-dispersed polymer or the water-soluble polymer during the kneading step can be reduced, it is possible to suppress a decrease in the binding force.

  Therefore, by using the electrode paint according to the present invention, it is possible to produce a high-performance electrode having excellent safety in the manufacturing process, less environmental load, and an electrochemical element using the electrode.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a diagram schematically illustrating an electrode paint adjustment method according to a preferred embodiment of the present invention.

  As shown in FIG. 1, the electrode paint L1 according to the present embodiment includes an active material 50, a binder 52, a solvent 54, a dispersant 56, and, if necessary, a conductive aid 58 in a mixing device 34 including a stirring unit 36. It can be prepared by charging and stirring. The preparation of the electrode paint L1 preferably includes a kneading operation and / or a dilution and mixing operation. Here, “kneading” means kneading the materials by stirring the liquid in a relatively high viscosity state, and “diluted mixing” means adding a solvent to the kneaded liquid to It means mixing in a low viscosity state. The operation time and the operation temperature are not particularly limited, but the kneading time is preferably about 5 minutes to 2 hours, and the kneading temperature is preferably about 10 to 80 ° C. in terms of uniform dispersion. The dilution mixing time is preferably about 5 minutes to 5 hours, and the temperature during dilution mixing is preferably about 10 to 80 ° C.

The active material 50 contained in the electrode paint L1 differs depending on the type of electrochemical element to be produced. For example, if the electrochemical device to be produced is an electric double layer capacitor, porous particles having electron conductivity that contributes to charge storage and discharge are used as the active material 50. Examples of such porous particles include granular or fibrous activated activated carbon such as phenol-based activated carbon and coconut shell activated carbon. Further, when the electrochemical device to be manufactured is a lithium ion secondary battery, the positive electrode active material 50 includes lithium manganate (LiMn ₂ O ₄ ), lithium cobaltate (LiCoO ₄ ), and lithium nickelate (LiNiO _2). ) LiNi _x Mn _y Co _1-xy is used, and examples of the active material 50 for the negative electrode include carbonaceous materials such as artificial graphite, natural graphite, mesocarbon microbeads (MCMB), coke, and fibrous carbon. Used.

  As the binder 52 contained in the electrode paint L1, at least one of a water-dispersed polymer and a water-soluble polymer is used. Styrene butadiene rubber (SBR) is preferably selected as the water-dispersed polymer, and carboxymethyl cellulose (CMC) and polyvinyl alcohol are preferably selected as the water-soluble polymer. In particular, it is more preferable to use both styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC).

  Water can be used as the solvent 54 contained in the electrode paint L1. This is because the binder 52 used is a water-dispersed polymer or a water-soluble polymer. For this reason, it is excellent in the safety in a manufacturing process, and it becomes possible to reduce the load given to an environment.

  As the dispersant 56 contained in the electrode paint L1, at least one of a maleic acid copolymer and a salt thereof is used. When at least one of a maleic acid copolymer and a salt thereof is added to the electrode paint L1, the dispersibility of the active material 50, the conductive auxiliary agent 58, etc. contained in the electrode paint L1 can be improved. As described above, the “maleic acid copolymer” refers to a maleic acid copolymer in a broad sense, and includes not only a maleic acid copolymer in a narrow sense that is not anhydrous but also a maleic anhydride copolymer.

  As the maleic acid copolymer, a styrene / maleic acid copolymer can be selected. As the styrene / maleic acid copolymer, an allyl alcohol / styrene / maleic anhydride copolymer, a polyoxyalkylene monoalkyl ether, It is preferable to select a grafted product. A graft product of an allyl alcohol / styrene / maleic anhydride copolymer and a polyoxyalkylene monoalkyl ether is a material represented by the following chemical formulas (1) to (3). The weight average molecular weights of the chemical formulas (1) to (3) are thousands to tens of thousands.

  Further, as the styrene / maleic acid copolymer, it is also preferable to select a styrene-maleic acid-alkyl maleate copolymer, and in this case, it is more preferable to select a styrene-maleic acid-butyl maleate copolymer. preferable. A styrene-maleic acid-alkyl maleate copolymer is a material represented by the following chemical formulas (4), (5) and the like. In the chemical formula (5), k = 2 to 7. Moreover, the weight average molecular weights of chemical formulas (4) and (5) are thousands to tens of thousands. In the chemical formula (5), when k = 4, it is a styrene-maleic acid-butyl maleate copolymer.

  Furthermore, it is also preferable to select a vinyl acetate-maleic acid copolymer as the maleic acid copolymer. As the maleic acid copolymer, an olefin-maleic acid copolymer can be selected. In this case, it is more preferable to select a sodium salt of 1-octadecene-maleic anhydride copolymer. It is also preferable to select an indene-maleic acid copolymer as the maleic acid copolymer. In this case, it is more preferable to select a sodium salt.

  Furthermore, it is preferable to add a conductive additive 58 to the electrode paint L1 as necessary. The conductive auxiliary agent 58 is not particularly limited as long as it has electronic conductivity capable of sufficiently proceeding charge transfer between the current collector and the active material, and between the active materials. It is preferable to use carbon black or graphite. Examples of the carbon black include acetylene black, ketjen black, and furnace black. Among them, acetylene black is preferably used. Examples of graphite include natural graphite, artificial graphite, and expanded graphite, and artificial graphite is particularly preferably used.

  Although not particularly limited, it is preferable to add acetylene diol or an ethoxylated acetylene diol to the electrode paint L1. Acetylene diol is a material represented by the following chemical formula (6), and an ethoxy group of acetylene diol is a material represented by the following chemical formula (7).

  When acetylenic diol or acetylenic diol ethoxy is added, bubbles are less likely to be generated in the electrode paint L1, and the quality of the coating film can be improved. In this case, it is more preferable to add a surfactant to the electrode paint L1. According to this, even when water is used as the solvent 54, acetylenic diol or ethoxylated acetylenic diol can be sufficiently dissolved.

  As described above, the electrode paint L1 is stirred in the mixing device 34 including the stirring unit 36, and is adjusted through a kneading operation and / or a dilution and mixing operation. At this time, especially during kneading, a shearing force is applied to the water-dispersed polymer or water-soluble polymer as the binder 52, and in some cases, the molecular chains of the water-dispersed polymer or water-soluble polymer are broken.

  However, in the electrode paint L1 according to the present embodiment, at least one of a maleic acid copolymer and a salt thereof is added as the dispersant 56, whereby the active material 50, the conductive auxiliary agent 58, etc. contained in the electrode paint L1. Therefore, the kneading operation or the like can be performed with a small shearing force. That is, the active material 50, the conductive auxiliary agent 58, and the like can be sufficiently dispersed only by performing a kneading operation or the like with a force that does not break the molecular chain of the water-dispersed polymer or water-soluble polymer that is the binder 52. .

  FIG. 2 is a diagram schematically showing the structure of an electrochemical device electrode manufacturing apparatus.

  As shown in FIG. 2, the electrochemical device electrode manufacturing apparatus 100 includes a supply roll 101 around which a strip-shaped current collector 16 is wound, and a current collector 16 and an electrode layer 18 that are rotated at a predetermined speed. A winding roll 102 for winding the laminate 20, and a coating unit 110, a drying unit 120, and a roll press unit 130 provided in this order between the supply roll 101 and the winding roll 102.

  The application part 110 is a part for applying the electrode paint L1 which is a material of the electrode layer 18 on the surface of the current collector 16. The coating unit 110 includes a backup roll 111 and a knife coater (electrode coating means) 112 that coats the surface of the current collector 16 curved by the backup roll 111 with the electrode paint L1. As shown in FIG. 2, the current collector 16 supplied from the supply roll 101 is conveyed to the coating unit 110 via the guide roll 103 and the tension roll 104, and thereby, one surface of the current collector 16. A coating film L <b> 2 that is the base of the electrode layer 18 is formed on the top.

  The electrode coating means 112 for applying the electrode paint L1 is not limited to the knife coating method, and various known coating methods can be used without particular limitation. For example, methods such as an extrusion nozzle method, an extrusion lamination method, a doctor blade method, a gravure roll method, a reverse roll method, an applicator coating method, a kiss coating method, a bar coating method, and a screen printing method can be employed.

  As the current collector 16, a current collector material used for known electrochemical element electrodes, for example, aluminum (Al) can be used. The thickness of the current collector 16 is not particularly limited, but when aluminum (Al) is used as the material of the current collector 16, the thickness is preferably set to 10 μm or more and 100 μm or less, and is preferably 15 μm or more and 50 μm. It is more preferable to set the following.

  Although not particularly limited, the surface of the current collector 16 is preferably roughened. According to this, the adhesion between the current collector 16 and the electrode layer 18 can be improved. It becomes. A method for roughening the surface of the current collector 16 is not particularly limited, but the current collector 16 can be roughened by chemical etching using a chemical such as an acid.

  The drying unit 120 is a part for removing the solvent 54 and the like contained in the coating film L2. The electrochemical device electrode manufacturing apparatus 100 according to the present embodiment includes two dryers 121 and 122 arranged so as to sandwich the current collector 16, and the coating film is heated by the dryers 121 and 122. The solvent 54 contained in L2 is removed, and the electrode layer 18 is formed. Specifically, it is preferable to perform drying under conditions of 70 to 130 ° C. and 0.1 to 10 minutes. Thereby, the electrode layer 18 is formed on the surface of the current collector 16.

However, in this state, the density of the electrode layer 18 is low, and a high volume capacity cannot be obtained in this state. The density of the electrode layer 18 after drying depends on the type and particle size of the active material 50, but when activated carbon is used as the active material 50, it is about 0.5 to 0.6 g / cm ³ .

  The roll press part 130 is a part for compressing the electrode layer 18 in order to increase the volume capacity. The electrochemical device electrode manufacturing apparatus 100 according to the present embodiment includes a first roller 131 disposed on the electrode layer 18 side and a second roller 132 disposed on the current collector 16 side. The laminate 20 is roll-pressed by 132 to compress the electrode layer 18 included in the laminate 20.

  Thus, the compressed electrode layer 18 is formed on the current collector 16, and the completed laminate 20 is wound around the take-up roll 102.

  Then, as shown in FIG. 3 (a), the laminate 20 wound around the take-up roll 102 is cut into a predetermined size, and as shown in FIG. If the laminated body 20 is punched in accordance with the above, the electrochemical element electrode 10 is completed as shown in FIG. At this time, as shown in FIG. 3C, if a part of the current collector 16 not covered with the electrode layer 18 is taken out at the same time, it can be used as the lead electrode 12.

  Then, at least two electrochemical device electrodes 10 prepared as shown in FIG. 4 are prepared, and the separator 40 is sandwiched between the two electrochemical device electrodes 10 so that the electrode layers 18 face each other. The electrochemical device is completed when it is housed in a case and filled with an electrolyte solution.

  The separator 40 is a film for physically separating the electrode layers 18 and 18 while allowing movement of ions in the electrolyte solution between the electrode layers 18 and 18. The separator 40 is preferably formed of an insulating porous body, for example, a laminate of films made of polyethylene, polypropylene or polyolefin, a stretched film of a mixture of the above resins, or a group consisting of cellulose, polyester and polypropylene A fiber nonwoven fabric made of at least one kind of constituent material selected more can be used. The thickness of the separator 40 is not particularly limited, but is preferably 5 μm or more and 200 μm or less, and more preferably 10 μm or more and 100 μm or less.

  Moreover, as an electrolyte solution, the electrolyte solution (electrolyte aqueous solution, electrolyte solution using an organic solvent) used for the well-known electrochemical element can be used. The type of the specific electrolyte solution is not particularly limited. In the case of an electric double layer capacitor, a quaternary ammonium salt such as tetraethylammonium tetrafluoroborate is dissolved in an organic solvent such as propylene carbonate, diethylene carbonate, and acetonitrile. What was done can be used preferably.

  As described above, in this embodiment, since at least one of a water-dispersed polymer and a water-soluble polymer is used as the binder 52 included in the electrode paint L1, water can be used as a solvent. . For this reason, there exists an advantage that it is excellent in safety | security in a manufacturing process, and the load given to an environment is small. In addition, there is an advantage that the produced electrochemical element has high safety.

  Moreover, since at least one of a maleic acid copolymer and a salt thereof is added as the dispersant 56 to the electrode paint L1, the dispersibility of the active material 50, the conductive auxiliary agent 58 and the like contained in the electrode paint L1 is improved. It becomes possible to raise. A maleic acid copolymer and a salt thereof are effective materials when a water-dispersed polymer or a water-soluble polymer is used as the binder 52. In particular, styrene-butadiene rubber (SBR) and carboxymethylcellulose (CMC) are used as the binder 52. When both are used, the material is optimum.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Needless to say, it is included in the range.

(Production of electrode paint)

  In a plastic container, 29.69 g of activated carbon (RP-20, manufactured by Kuraray Chemical Co., Ltd.) as an active material, and carbon black (CB) (manufactured by Denki Kagaku Kogyo Co., Ltd., DAB50) as a conductive auxiliary agent are 0. .31 g, 10 g of water as a solvent, and a grafted product of an allyl alcohol / styrene / maleic anhydride copolymer represented by the above chemical formula (1) and a polyoxyalkylene monoalkyl ether as a dispersant (Japan) What mixed 0.3 g of oil and fat Co., Ltd. product and Marialim AKM-053) was added.

  This was mixed with a hybrid mixer (manufactured by Keyence Corporation) for 1 minute. A hybrid mixer is a device that stirs and mixes substances in a container by rotating and revolving the container. Next, 13.92 g of a 2 wt% CMC aqueous solution (manufactured by Nippon Paper Chemicals Co., Ltd., Sunrose F1400MC) was placed in the container, and dispersed with a hybrid mixer for 3 minutes. Next, 1.34 g of an appropriate amount of water and SBR (manufactured by Nippon Synthetic Rubber Co., Ltd., TRD2001) were added and dispersed with a hybrid mixer for 3 minutes. Next, water was added until the viscosity became suitable for coating, and the mixture was dispersed with a hybrid mixer for 3 minutes to prepare an electrode paint. The composition of the following substances in this electrode paint is as follows.

Activated carbon: CB: SBR: CMC = 96.0: 1.0: 2.1: 0.9 mass%
(Measurement of dispersion)

  In order to determine the degree of dispersion, the adjusted electrode paint was measured with a particle size gauge (manufactured by Tester Sangyo Co., Ltd., 0 to 200 μm). In this method, electrode paint is applied to a recess having a predetermined depth with a blade, and it is visually determined whether or not there is a particle.

When the electrode paint was tested with this particle size gauge, no particles (agglomerates) were found.
(Production of electrodes)

When dispersed with a hybrid mixer, the temperature of the paint rises due to frictional heat of the substance contained in it. After the temperature of the coating material dropped to room temperature, an electrode was prepared by applying and drying the current collector on an etched aluminum foil (trade name: 40C054, manufactured by Nippon Denki Kogyo Kogyo) by the doctor blade method. Furthermore, this electrode was rolled with a rolling roll (linear pressure 600 kgf / cm) to obtain an electrode.
(Production of electric double layer capacitor)

  The electrode was punched into a predetermined size (about 17 mm × 32 mm), and an aluminum foil (width 4 mm × length 40 mm × thickness 0.1 mm) for external lead was ultrasonically welded.

  The electrode was dried at 150 ° C. for 3 hours. The two electrodes were laminated so as to sandwich a separator (manufactured by Nippon Kogyo Paper Industry Co., Ltd., model number: TF4030, thickness 30 μm). A polypropylene (PP) film grafted with maleic anhydride was wrapped around this external lead terminal and thermally bonded. This is to improve the sealing performance between the external terminal and the exterior body. This was inserted into the battery case and the electrolyte was injected, and then the opening was vacuum heat sealed to produce an electric double layer capacitor. Here, the exterior body is made of an aluminum laminate material, and its configuration is PET (12) / Al (40) / PP (50). PET is polyethylene terephthalate and PP is polypropylene. The value in parentheses represents the thickness of each layer (unit: μm). At this time, bags were made so that PP was inside. An appropriate amount of PC (propylene carbonate) in which triethylmethylammonium tetrafluoroborate was dissolved in 1.2 M was added to the electrolytic solution.

This electric double layer capacitor was charged / discharged between 2.0 and 2.5 V (since the voltage after fabrication is 0 V, only the first charge starts from 0 V). The average value of the electrostatic capacity during the first to 15 cycles of discharge per electrode volume (excluding the current collector) was 18.8 F / cm ³ .

(Production of electrode paint)

  Instead of a grafted product of allyl alcohol / styrene / maleic anhydride copolymer and polyoxyalkylene monoalkyl ether (Marialim AKM-053, manufactured by NOF Corporation), this substance and acetylenic diol (Nisshin Chemical) Product name: Surfynol 104E, 2,4,7,9-tetramethyl-5-decyne-4,7-diol and ethylene glycol) and polyoxyethylene octylphenyl ether (trade name: Triton X-) An electrode paint was prepared in the same manner as in Example 1 except that 0.3 g of the mixture 100) was added. Triton X-100 was used to dissolve acetylenic diol in water. The composition ratio is the same as in Example 1 as shown below.

Activated carbon: CB: SBR: CMC = 96.0: 1.0: 2.1: 0.9 mass%
(Measurement of dispersion)

When the electrode paint was tested with this particle size gauge, no particles (agglomerates) were found.
(Production of electrodes and electric double layer capacitors)

In the same manner as in Example 1, an electrode and an electric double layer capacitor were produced. The average capacitance per electrode volume (excluding the current collector) during the first to fifteen cycles of discharge was 18.8 F / cm ³ .

(Production of electrode paint)

  PD-301 sold as a dispersant in place of a grafted product of an allyl alcohol / styrene / maleic anhydride copolymer and polyoxyalkylene monoalkyl ether (Marialim AKM-053 manufactured by NOF Corporation) (Manufactured by Nissin Chemical Industry Co., Ltd., acetylene diol (2,4,7,9-tetramethyl-5-decyne-4,7-diol), styrene-maleic acid-butyl maleate copolymer (the above chemical formula (9) An electrode paint was prepared in the same manner as in Example 1 except that 0.3 g of the mixture shown in FIG. 1 and a mixture of polyoxyethylene polyoxypropylene alkyl ether, 2-butoxyethanol and water) was added. Here, acetylene diol serves as a wetting agent, polyoxyethylene polyoxypropylene alkyl ether serves as a surfactant, and 2-butoxyethanol serves as a solvent in the dispersant. The composition ratio is the same as in Example 1 as shown below.

  Activated carbon: CB: SBR: CMC = 96.0: 1.0: 2.1: 0.9 mass%

In addition, 2,4,7,9-tetramethyl-5-decyne-4,7-diol means that R ¹ shown in the chemical formula (10) is the following chemical formula (12), and R ² is the following chemical formula ( 13).

（分散度の測定）

(Measurement of dispersion)

When the electrode paint was tested with this particle size gauge, no particles (agglomerates) were found.
(Production of electrodes and electric double layer capacitors)

In the same manner as in Example 1, an electrode and an electric double layer capacitor were produced. The average capacitance per electrode volume (excluding the current collector) during the first to fifteen cycles of discharge was 18.8 F / cm ³ .

(Preparation of paint)

  Instead of the grafted product of allyl alcohol / styrene / maleic anhydride copolymer and polyoxyalkylene monoalkyl ether used in Example 1 (Marialim AKM-053, manufactured by NOF Corporation), 1-octadecene- A coating material was prepared in the same manner as in Example 1 except that 0.3 g of sodium salt of maleic anhydride copolymer (sodium salt of olefin-maleic anhydride copolymer) was added. The composition ratio is the same as in Example 1 as shown below.

Activated carbon: CB: SBR: CMC = 96.0: 1.0: 2.1: 0.9 mass%
(Measurement of dispersion)

When the above-mentioned paint was tested with this particle size gauge, no particles (agglomerates) were found.
(Production of electrodes and electric double layer capacitors)

In the same manner as in Example 1, an electrode and an electric double layer capacitor were produced. The average value of the electrostatic capacity during the first to 15 cycles of discharge per electrode volume (excluding the current collector) was 18.7 F / cm ³ .

(Preparation of paint)

  Instead of the grafted product of allyl alcohol / styrene / maleic anhydride copolymer and polyoxyalkylene monoalkyl ether used in Example 1 (Marialim AKM-0531 manufactured by NOF Corporation), vinyl acetate-anhydrous A paint was prepared in the same manner as in Example 1 except that 0.3 g of maleic acid copolymer was added. The composition ratio is the same as in Example 1 as shown below.

Activated carbon: CB: SBR: CMC = 96.0: 1.0: 2.1: 0.9 mass%
(Measurement of dispersion)

When the above-mentioned paint was tested with this particle size gauge, no particles (agglomerates) were found.
(Production of electrodes and electric double layer capacitors)

In the same manner as in Example 1, an electrode and an electric double layer capacitor were produced. The average value of the electrostatic capacity during the first to 15 cycles of discharge per electrode volume (excluding the current collector) was 18.7 F / cm ³ .

(Preparation of paint)

  Instead of the grafted product of allyl alcohol / styrene / maleic anhydride copolymer and polyoxyalkylene monoalkyl ether used in Example 1 (Marialim AKM-053 manufactured by NOF Corporation), indene-anhydrous maleic anhydride. A paint was prepared in the same manner as in Example 1 except that 0.3 g of the sodium salt of the acid copolymer was added. The composition ratio is the same as in Example 1 as shown below.

Activated carbon: CB: SBR: CMC = 96.0: 1.0: 2.1: 0.9 mass%
(Measurement of dispersion)

When the above-mentioned paint was tested with this particle size gauge, no particles (agglomerates) were found.
(Production of electrodes and electric double layer capacitors)

In the same manner as in Example 1, an electrode and an electric double layer capacitor were produced. The average value of the electrostatic capacity during the first to 15 cycles of discharge per electrode volume (excluding the current collector) was 18.7 F / cm ³ .
[Comparative Example 1]

In Example 1, the electrode paint was prepared without adding the grafted product of allyl alcohol / styrene / maleic anhydride copolymer and polyoxyalkylene monoalkyl ether (Marialim AKM-0531 manufactured by NOF Corporation). Produced.
(Measurement of dispersion)

When the above electrode paint was tested with this particle size gauge, it was found that many particles (aggregates) of 30 to 200 μm were seen and not dispersed.
(Production of electrodes)

An attempt was made to apply this electrode paint by the doctor blade method, but an agglomerate was caught on the doctor blade (blade), and the aluminum foil of the current collector was torn and could not be applied.
[Comparative Example 1]
(Production of electrode paint)

The same kind of activated carbon, carbon black, SBR dispersion and CMC solution as used in Example 1 were kneaded for 5 minutes at 60 rpm with a kneader (Brabender, PLASTI-CORDER). At the time of kneading, a torque of 7 Nm was applied at the start of kneading, but after 5 minutes the torque decreased to 2 Nm, suggesting that the molecular chain of CMC was broken. A predetermined amount of this kneaded material was placed in a resin container, water was added so as to have a viscosity suitable for coating, and the mixture was dispersed with a disperser (hybrid mixer, manufactured by Keyence Corporation) to prepare an electrode paint.
(Measurement of dispersion)

When the electrode paint was tested with this particle size gauge, no particles (agglomerates) were found.
(Production of electrodes)

The electrodes were produced in the same manner as in Example 1.
(Production of electric double layer capacitor)

  The above electrode was punched into a predetermined size (about 17 mm × 32 mm), but the end of the electrode was chipped (considered because the molecular chain of CMC was cut and the electrode strength was reduced), and an electric double layer capacitor was produced. I couldn't.

  FIG. 5 summarizes the dispersants and mixers used in Examples 1 to 6 and Comparative Examples 1 and 2, and the obtained dispersion state and capacitance.

It is a schematic diagram for demonstrating the preparation method of the electrode coating material L1. It is the schematic which shows the structure of the manufacturing apparatus 100 of the electrode for electrochemical elements. It is a figure for demonstrating the method of cutting out the electrode 10 for electrochemical elements from the laminated body 20, (a) is a schematic plan view of the laminated body 20 cut | disconnected by the predetermined | prescribed magnitude | size, (b) is an electric diagram. It is a schematic plan view of the laminated body 20 by which the electrode 10 for chemical elements was cut out, (c) is a schematic plan view of the electrode 10 for electrochemical elements cut out. It is a schematic diagram for demonstrating the method of producing an electrical double layer capacitor using the electrode 10 for electrochemical elements. It is the table | surface which put together the dispersing agent and mixer which were used in Examples 1-6 and Comparative Examples 1 and 2, and the obtained dispersion state and an electrostatic capacitance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electrode for electrodes 12 Extraction electrode 16 Current collector 18 Electrode layer 20 Laminate 34 Mixing device 36 Stirrer 40 Separator 50 Active material 52 Binder 54 Solvent 56 Dispersant 58 Conductive aid 100 Electrochemical device electrode manufacturing apparatus DESCRIPTION OF SYMBOLS 101 Supply roll 102 Winding roll 103 Guide roll 104 Tension roll 110 Application | coating part 111 Backup roll 112 Electrode application means 120 Drying part 121,122 Dryer 130 Roll press part 131,132 Roller L1 Electrode paint L2 Coating film

Claims (15)

  An electrode paint comprising an active material, at least one of a water-dispersed polymer and a water-soluble polymer, and at least one of a maleic acid copolymer and a salt thereof.   The electrode paint according to claim 1, wherein the maleic acid copolymer is a styrene / maleic acid copolymer.   The electrode paint according to claim 2, wherein the styrene / maleic acid copolymer is a graft product of an allyl alcohol / styrene / maleic anhydride copolymer and a polyoxyalkylene monoalkyl ether.   The electrode paint according to claim 2, wherein the styrene / maleic acid copolymer is a styrene-maleic acid-alkyl maleate copolymer.   The electrode paint according to claim 4, wherein the styrene / maleic acid copolymer is a styrene-maleic acid-butyl maleate copolymer.   The electrode paint according to claim 1, wherein the maleic acid copolymer is an olefin-maleic acid copolymer.   The electrode paint according to claim 6, wherein the maleic acid copolymer is a 1-octadecene-maleic anhydride copolymer.   The electrode paint according to claim 1, wherein the maleic acid copolymer is a vinyl acetate-maleic acid copolymer.   The electrode paint according to claim 1, wherein the maleic acid copolymer is an indene-maleic acid copolymer.   The electrode paint according to any one of claims 1 to 9, further comprising acetylene diol or an ethoxylated acetylene diol.   The electrode paint according to claim 10, further comprising a surfactant.   The electrode paint according to any one of claims 1 to 11, wherein the water-dispersed polymer is styrene-butadiene rubber.   The electrode paint according to any one of claims 1 to 11, wherein the water-soluble polymer is carboxymethylcellulose.   The electrode formed by apply | coating the electrode coating material as described in any one of Claims 1 thru | or 13 on a collector.   An electrochemical device using the electrode according to claim 14.

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