JP5663976B2 - Polarized electrodes, electrochemical devices and lead-acid batteries - Google Patents

Description

  The present invention relates to a polarizable electrode preferably used as a component of an electrochemical element such as a lead storage battery or an electric double layer capacitor, particularly a lead storage battery.

  Lead-acid batteries are used in many industries because they are cheaper and suitable for large current discharge than other secondary batteries, and high-capacity secondary batteries such as lithium-ion secondary batteries are also popular today. Its importance has not been lost, and studies for improving the performance of lead-acid batteries are still underway. The lead storage battery has an advantage that a large current can be discharged in a short time, but has a disadvantage that the capacity decreases, that is, the cycle characteristics deteriorate when the discharge depth is increased. Therefore, in recent years, a technique employing a polarizable electrode using activated carbon has been reported for the purpose of improving the disadvantages while further improving the advantages of the lead-acid battery.

    For example, Patent Document 1 describes an electrode for a lead storage battery in which an active material layer containing activated carbon, a binder, and a conductive material (hereinafter referred to as a polarizable electrode) is formed on the surface of the lead active material layer, and a lead storage battery including the electrode. Has been. In Patent Document 1, various binders for polarizable electrodes are exemplified, but in the examples, SBR (styrene butadiene rubber), PTFE (fluorine resin), and an acrylic polymer are used.

JP 2010-73355 A

  In lead-acid batteries, sulfuric acid is often used as the electrolytic solution, so that the binder is required to have sulfuric acid resistance, and the binder is also required to have low resistance. Furthermore, it is preferable that it is a water-system binder from a viewpoint of work environment and manufacturing efficiency.

  However, SBR used in the examples of Patent Document 1 has a relatively high resistance, and is not necessarily a satisfactory material as a binder material. PTFE is expensive, cost reduction is difficult, and productivity is inferior. Furthermore, the acrylic polymer is not sufficient in sulfuric acid resistance and has a problem in terms of product life.

  Moreover, since the electrolyte solution mainly used for lead acid battery is a sulfuric acid, it is preferable that a water-based binder is used also as a binder. However, in the case of a water-based binder, if the storage period is long, the binder itself or the electrode forming slurry produced using the binder may deteriorate over time.

The present invention for solving the above-mentioned problems includes the following matters as a gist.
(1) A polarizable electrode comprising an electrode active material, a conductive material, a binder and an isothiazoline compound,
The isothiazoline compound is included at a ratio of 0.001 to 2.0 parts by mass with respect to 100 parts by mass of the binder,
The amount of the binder containing a polymer containing 10 to 60 parts by mass of (meth) acrylonitrile units, 35 to 85 parts by mass of butadiene units and 0.5 to 10 parts by mass of ethylenically unsaturated carboxylic acid units in 100 parts by mass. Polar electrode.

(2) The polarizable electrode according to (1), which is obtained by dry-molding composite particles containing the electrode active material, conductive material, binder and isothiazoline compound.

(3) The polarizable electrode according to (2), wherein the composite particles are molded by a dry molding method including a step of roll pressing.

(4) An electrochemical element comprising the polarizable electrode according to any one of (1) to (3) and an aqueous electrolyte.

(5) The electrochemical device according to (4), wherein the electrochemical device is an electric double layer capacitor.

(6) The electrochemical element according to (4), wherein the electrochemical element is a lead storage battery.

  According to the present invention, since a specific polymer is used as a binder, a polarizable electrode having not only low internal resistance but also high tensile strength and excellent electrolyte solution impregnation property can be obtained. Moreover, as a result of using an isothiazoline compound in addition to the binder, the stability of the electrode-forming slurry is high over time and the working efficiency is improved. At the same time, the uniformity of the resulting electrode, internal resistance, tensile strength and It also has excellent electrolyte solution impregnation properties.

It is a schematic sectional drawing which shows the one aspect | mode of a lead storage battery.

Hereinafter, the present invention will be described more specifically.
The polarizable electrode according to the present invention comprises an electrode active material, a conductive material, a binder and an isothiazoline compound.

(Electrode active material)
As the electrode active material of the polarizable electrode, various carbonaceous materials used for the electric double layer capacitor are used without particular limitation. Examples of the carbonaceous material include a porous carbonaceous material and a layered carbonaceous material. Among these, a porous carbonaceous material is preferable because of its large specific surface area.

Since the porous carbonaceous material is used for the purpose of utilizing an electric double layer, a material having a large specific surface area that can form an interface having a larger area with the same weight is preferable. Specifically, the specific surface area of ^{30 m} 2 / g or more, preferably preferably 500~5,000m ² / g, more preferably 1,000~3,000m ² / g.

  Specific examples of the porous carbonaceous material include activated carbon, polyacene, carbon whisker, and graphite. These powders or fibers can be used.

  The porous carbonaceous material is preferably activated carbon, and specific examples include activated carbon obtained by activation treatment using a phenolic resin, rayon, acrylic fiber, pitch, coconut shell, or the like as a carbonaceous raw material. Examples of the activation treatment method include gas activation using water vapor, carbon dioxide, oxygen, etc., chemical activation using potassium hydroxide, phosphoric acid, and the like.

  The volume average particle diameter of the porous carbonaceous material is 0.1 to 100 μm, preferably 1 to 50 μm, and more preferably 3 to 35 μm. When the volume average particle diameter of the porous carbonaceous material is in this range, it is preferable because the electrode can be easily molded and the capacity of the electric double layer can be increased. These porous carbonaceous materials can be used alone or in combination of two or more. When using a combination of porous carbonaceous materials, two or more types of carbonaceous materials having different average particle diameters or particle size distributions may be used in combination. The porous carbonaceous material is usually 50% by mass or more based on the mass of the entire polarizable electrode.

  Specific examples of the layered carbonaceous material include graphite and graphene. Among these, graphite is preferable.

(Conductive material)
The polarizable electrode is blended with a conductive material for the purpose of improving conductivity. Specific examples of the conductive material include conductive carbon black such as furnace black, acetylene black, and ketjen black (registered trademark of Akzo Nobel Chemicals Bethloten Fennaut Shap); graphite such as natural graphite and artificial graphite; Examples thereof include carbon fibers such as acrylonitrile-based carbon fibers, pitch-based carbon fibers, and vapor grown carbon fibers; and carbon nanotubes. Among these, conductive carbon black is preferable, and acetylene black and ketjen black are more preferable.

    The volume average particle diameter of the conductive material is preferably smaller than the volume average particle diameter of the electrode active material, and is usually in the range of 0.001 to 10 μm, preferably 0.05 to 5 μm, more preferably 0.01 to 1 μm. is there. When the particle size of the conductive material is within this range, high conductivity can be obtained with a smaller amount of use. These conductive materials can be used alone or in combination of two or more.

    The amount of the conductive material is usually 0.1 to 50 parts by mass, preferably 0.5 to 15 parts by mass, and more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the electrode active material. When the amount of the conductive material is within this range, the conductivity is excellent, and the output characteristics after the cycle can be improved.

(binder)
The binder mainly comprises a polymer containing a (meth) acrylonitrile unit, a butadiene unit and an ethylenically unsaturated carboxylic acid unit. The (meth) acrylonitrile unit is a repeating unit derived from (meth) acrylonitrile. Here, (meth) acrylonitrile is used in the meaning including both acrylonitrile and methacrylonitrile. That is, (meth) acrylonitrile may be either acrylonitrile or methacrylonitrile, or may contain both at the same time.

The butadiene unit is a repeating unit derived from butadiene.

  The ethylenically unsaturated carboxylic acid unit is a repeating unit derived from an ethylenically unsaturated carboxylic acid. Examples of the ethylenically unsaturated carboxylic acid include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid. And mono- or dicarboxylic acid (anhydride), and the like can be used alone or in combination of two or more.

  Furthermore, in addition to the repeating units derived from the above monomers, the binder may contain repeating units derived from other monomers copolymerizable with these monomers. Examples of other monomers include aromatic vinyl monomers, unsaturated carboxylic acid alkyl ester monomers, unsaturated monomers containing hydroxyalkyl groups, and unsaturated carboxylic acid amide monomers. These can be used alone or in combination of two or more.

  Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, vinyl toluene, divinylbenzene, and the like, and one or a combination of two or more can be used.

  Examples of unsaturated carboxylic acid alkyl ester monomers include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, glycidyl methacrylate, dimethyl fumarate, diethyl fumarate, dimethyl maleate, diethyl maleate, dimethyl itaconate, Monomethyl fumarate, monoethyl fumarate, 2-ethylhexyl acrylate and the like can be mentioned, and one kind or a combination of two or more kinds can be used.

  Examples of unsaturated monomers containing a hydroxyalkyl group include β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, and 3-chloro-2-hydroxypropyl. Methacrylate, di- (ethylene glycol) maleate, di- (ethylene glycol) itaconate, 2-hydroxyethyl maleate, bis (2-hydroxyethyl) maleate, 2-hydroxyethyl methyl fumarate, etc. A combination of more than one species can be used.

  Examples of the unsaturated carboxylic acid amide monomer include acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, N, N-dimethylacrylamide, and the like, and one or a combination of two or more may be used. it can.

  Further, in addition to the above monomers, any of the monomers used in ordinary emulsion polymerization such as ethylene, propylene, vinyl acetate, vinyl propionate, vinyl chloride, vinylidene chloride can be used.

  The (meth) acrylonitrile unit is contained in a proportion of 10 to 60 parts by mass, preferably 20 to 60 parts by mass, particularly preferably 20 to 45 parts by mass in 100 parts by mass of the polymer constituting the binder. It is contained in a proportion of 35 to 85 parts by mass, preferably 40 to 75 parts by mass, particularly preferably 45 to 75 parts by mass, and the ethylenically unsaturated carboxylic acid unit is 0.5 to 10 parts by mass, preferably 1 to It is included at a ratio of 10 parts by mass.

In the present invention, when the (meth) acrylonitrile unit amount exceeds 60 parts by mass, the flexibility of the polarizable electrode is lowered and the internal resistance is increased. On the other hand, when the (meth) acrylonitrile unit amount is less than 10 parts by mass, the internal resistance increases and the electrode strength decreases. When the butadiene unit amount exceeds 85 parts by mass, the internal resistance increases or the handling property deteriorates. On the other hand, if it is less than 35 parts by mass, the adhesive strength and flexibility are lowered. When the ethylenically unsaturated carboxylic acid unit amount exceeds 10 parts by mass, the internal resistance increases. On the other hand, if the ethylenically unsaturated carboxylic acid unit amount is less than 0.5 parts by mass, the strength of the electrode is lowered.

  In addition, the repeating unit derived from the monomer other than (meth) acrylonitrile, butadiene and ethylenically unsaturated carboxylic acid is 54.5 parts by mass or less, preferably 39 parts by mass or less, in 100 parts by mass of the polymer. Particularly preferably, it may be contained at a ratio of 34 parts by mass or less, and may not be contained.

  In the present invention, since a specific polymer is used as a binder, a polarizable electrode having not only low internal resistance but also high tensile strength and excellent electrolyte solution impregnation property can be obtained.

  Content of the binder containing the said polymer in a polarizable electrode is 1-20 mass parts normally with respect to 100 mass parts of electrode active materials, Preferably it is the range of 3-15 mass parts. When the amount of the polymer is within this range, the binding property of the polarizable electrode is excellent, and the tensile strength is improved.

  The binder is mainly composed of the polymer, and the entire amount thereof may be composed of the polymer. However, in the ratio of 50 parts by mass or less in 100 parts by mass of the binder, instead of the polymer, other polymers may be used. It may be included. Specific examples of other polymers that may be used as the binder include polymer compounds such as halogen polymers, diene polymers, acrylate polymers, polyimides, polyamides, and polyurethanes. These other polymers can be used alone or in combination of two or more.

    The halogen-based polymer is a polymer containing a monomer unit containing a halogen atom. Of the halogen atoms, a fluorine polymer or a chlorine polymer containing a fluorine atom or a chlorine atom is preferred. Specific examples of the fluorine-based polymer and the chlorine-based polymer include polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, ethylene / tetrafluoroethylene copolymer, ethylene / chlorotrifluoro. Examples thereof include ethylene copolymers, perfluoroethylene / propene copolymers, chlorosulfonated polyethylene, and polychloroprene.

    The diene polymer is a homopolymer of a conjugated diene or a copolymer obtained by polymerizing a monomer mixture containing a conjugated diene, or a hydrogenated product thereof. Specific examples of the diene polymer include conjugated diene homopolymers such as polybutadiene, polyisoprene and polychloroprene; conjugated diene copolymers such as butyl rubber; carboxy-modified styrene / butadiene copolymers (SBR) And aromatic vinyl / conjugated diene copolymers; hydrogenated SBR, hydrogenated NBR, and the like.

    The acrylate polymer is a copolymer obtained by polymerizing a homopolymer of an acrylic ester or a methacrylic ester or a monomer mixture containing these.

    The glass transition temperature (hereinafter referred to as Tg) of the binder which may contain the specific polymer as described above and optionally other polymers is preferably 50 ° C. or less, more preferably −50 to 0 ° C. When the Tg of the binder is within this range, the binding property is excellent with a small amount of use, the electrode strength is high, the flexibility is high, and the electrode density can be easily increased by a pressing process during electrode formation. The binder may have a melting point.

  The shape of the binder is most preferably particulate in order to minimize binding, increase in electrode capacity, and increase in internal resistance. For example, binder resin particles such as latex are used. Examples include those dispersed in a solvent and powders obtained by drying such a dispersion.

  Although the particle diameter of a binder is not specifically limited, It is a volume average particle diameter, and is 0.001-100 micrometers normally, Preferably it is 0.01-10 micrometers, More preferably, it is 0.05-1 micrometers. When the volume average particle diameter of the binder is within this range, an excellent binding force can be imparted to the polarizable electrode even when a small amount of binder is used.

  The method for producing the binder is not particularly limited, and a known polymerization method such as an emulsion polymerization method, a suspension polymerization method, a dispersion polymerization method or a solution polymerization method using a composition containing each monomer at a predetermined ratio is adopted. be able to. Among these, it is preferable to produce by an emulsion polymerization method because it is easy to control the particle diameter of the binder. In particular, an aqueous polymerization method using water as a main solvent is preferred.

(Isothiazoline compound)
The polarizable electrode of the present invention further contains an isothiazoline compound in addition to the above components.
An isothiazoline-based compound is a compound well known as a preservative and is generally represented by the following structural formula.

(In the formula, Y represents hydrogen or an optionally substituted hydrocarbon group, and X ¹ and X ² each represent hydrogen, halogen, or an alkyl group having 1 to 6 carbon atoms. X ¹ , X ² may jointly form an aromatic ring, wherein X ¹ and X ¹ may be the same or different.

First, the isothiazoline compound represented by the above formula 1 will be described.
In the above chemical formula 1, Y represents a hydrogen atom or an optionally substituted hydrocarbon group. Examples of the substituent of the optionally substituted hydrocarbon group represented by Y include a hydroxyl group, a halogen (eg, chlorine, fluorine, bromine, iodine, etc.), a cyano group, an amino group, a carboxyl group, and a carbon number of 1 to 4. Alkoxy groups (for example, methoxy group, ethoxy group, etc.), C6-C10 aryloxy groups (for example, phenoxy group, etc.), C1-C4 alkylthio groups (for example, methylthio group, ethylthio group, etc.) and C6 -10 arylthio groups (for example, phenylthio group) and the like. Among the substituents, a halogen atom and an alkoxy group having 1 to 4 carbon atoms are preferable. These substituents may be substituted with hydrogen of the hydrocarbon group in the range of 1 to 5, preferably 1 to 3, and the substituents may be the same or different.

  Examples of the hydrocarbon group of the optionally substituted hydrocarbon group represented by Y include an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, and carbon. A C3-C10 cycloalkyl group, a C6-C14 aryl group, etc. are mentioned. Among the hydrocarbon groups, an alkyl group having 1 to 10 carbon atoms and a cycloalkyl group having 3 to 10 carbon atoms are preferable, and an alkyl group having 1 to 10 carbon atoms is more preferable.

  Examples of the alkyl group having 1 to 10 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, Examples include an octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, a nonyl group, and a decyl group. Among these alkyl groups, an alkyl group having 1 to 3 carbon atoms such as a methyl group and an ethyl group, and an alkyl group having 7 to 10 carbon atoms such as an octyl group and a tert-octyl group are more preferable. An alkyl group of ˜3 is more preferred.

  Examples of the alkenyl group having 2 to 6 carbon atoms include a vinyl group, an allyl group, an isopropenyl group, a 1-propenyl group, a 2-propenyl group, and a 2-methyl-1-propenyl group. Among the alkenyl groups, a vinyl group and an allyl group are preferable. Examples of the alkynyl group having 2 to 6 carbon atoms include ethynyl group, 1-propynyl group, 2-propynyl group, butynyl group, pentynyl group and the like. Among the alkynyl groups, an ethynyl group and a propynyl group are preferable.

  Examples of the cycloalkyl group having 3 to 10 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Among the cycloalkyl groups, a cyclopentyl group and a cyclohexyl group are preferable.

  Examples of the aryl group having 6 to 14 carbon atoms include a phenyl group, a naphthyl group, an anthryl group, and a phenanthryl group. Of the aryl groups, a phenyl group is preferred.

  As described above, various examples of the optionally substituted hydrocarbon group represented by Y can be mentioned. Among these hydrocarbon groups, a methyl group and an octyl group are more preferable, and a methyl group is more preferable. .

In the above chemical formula 1, X ¹ and X ^{2 each} represent the same or different hydrogen, halogen, or alkyl group having 1 to 6 carbon atoms.
Examples of the halogen include fluorine, chlorine, bromine and iodine. Among these, chlorine is preferable.

  Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, and a pentyl group. Among the alkyl groups, an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, and a propyl group is preferable. Of the substituents described above, X1 is more preferably hydrogen or chlorine, and even more preferably chlorine. X2 is more preferably hydrogen or chlorine, more preferably hydrogen.

  Specific examples of the isothiazoline compounds represented by the above chemical formula 1 include, for example, 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, and 2-n- Octyl-4-isothiazolin-3-one, 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one, 2-ethyl-4-isothiazolin-3-one, 4,5-dichloro-2- Examples include cyclohexyl-4-isothiazolin-3-one, 5-chloro-2-ethyl-4-isothiazolin-3-one, and 5-chloro-2-t-octyl-4-isothiazolin-3-one.

  Among these compounds, 5-chloro-2-methyl-4-isothiazolin-3-one (hereinafter sometimes referred to as “CIT”), 2-methyl-4-isothiazolin-3-one (hereinafter referred to as “CIT”). "MIT"), 2-n-octyl-4-isothiazolin-3-one (hereinafter sometimes referred to as "OIT"), 4,5-dichloro-2-n-octyl- 4-isothiazolin-3-one is preferred, and 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one are more preferred.

The following structural formula shows a case where a benzene ring is formed among X ¹ and X ^{2 in} which X ¹ and X ² jointly form an aromatic ring.

(In the formula, Y is the same as in the case of Formula 1, and X ^{3 to} X ⁶ are hydrogen, halogen, hydroxyl group, cyano group, amino group, carboxyl group, alkyl group having 1 to 4 carbon atoms, or carbon number 1) -4 each represents an alkoxy group.)

In the above chemical formula 2, X ^{3 to} X ⁶ are hydrogen, hydroxyl group, halogen (eg, chlorine, fluorine, bromine, iodine, etc.), cyano group, amino group, carboxyl group, alkyl group having 1 to 4 carbon atoms (eg, Methyl group, ethyl group, propyl group, etc.), C1-C4 alkoxy groups (for example, methoxy, ethoxy, etc.) and the like. Among these, halogen and C1-C4 alkyl groups are preferred. These X ^{3 to} X ⁶ may be the same or different.

  Examples of the isothiazoline-based compounds represented by the above formula 2 include 1,2-benzisothiazolin-3-one (hereinafter sometimes referred to as “BIT”), N-methyl-1,2-benzisothiazoline-3- ON etc. are mentioned.

  These isothiazoline compounds can be used alone or in combination of two or more. Among the isothiazoline compounds, 2-methyl-4-isothiazolin-3-one and 1,2-benz-2-methyl-4-isothiazolin-3-one are more preferable.

  The isothiazoline compound is used in a proportion of 0.001 to 2.0 parts by weight, preferably 0.005 to 1.5 parts by weight, particularly preferably 0.005 to 1.0 parts by weight, based on 100 parts by weight of the binder. It is done.

  In the polarizable electrode of the present invention, since the isothiazoline compound is used in combination with the binder, the stability of the binder and the slurry for forming the electrode is high over time, the working efficiency is improved, and the uniformity and internal resistance of the electrode obtained Also, excellent tensile strength and electrolyte impregnation properties.

(Other ingredients)
In addition, the polarizable electrode according to the present invention can also contain a dispersant for the purpose of dispersing each component for slurry production described later. Specific examples of the dispersant include cellulose polymers such as carboxymethylcellulose, methylcellulose, ethylcellulose, hydroxypropylcellulose, and hydroxypropylmethylcellulose, and ammonium salts or alkali metal salts thereof; ammonium salts of polyacrylic acid or polymethacrylic acid Or alkali metal salt; polyvinyl alcohol, modified polyvinyl alcohol, polyethylene oxide; polyvinyl pyrrolidone, polycarboxylic acid, oxidized starch, phosphate starch, casein, various modified starches, chitin, chitosan derivatives and the like can also be used.

    These dispersants can be used alone or in combination of two or more. Among them, as the dispersant, a cellulose-based polymer is preferable, and carboxymethyl cellulose, an ammonium salt or an alkali metal salt thereof is particularly preferable. Although the usage-amount of a dispersing agent is not specifically limited, Usually, 0.1-10 mass parts with respect to 100 mass parts of electrode active materials, Preferably it is 0.5-5 mass parts, More preferably, it is 0.8-2. .5 parts by mass. By using a dispersing agent, sedimentation and aggregation of solid content in the slurry can be suppressed.

  The polarizable electrode may further contain other additives as necessary. Specifically, in order to improve the electrical stability of the slurry described later, amphoteric surfactants such as anionic, cationic, nonionic or nonionic anions, aminocarboxylic acid chelate compounds, phosphonic acids And chelate compounds such as chelates, gluconic acid, citric acid, malic acid and tartaric acid.

(Manufacture of polarizable electrodes)
The polarizable electrode of the present invention includes the electrode active material and the like, and the formation method is not particularly limited.
A method for forming an electrode active material slurry, a conductive material, a binder, an isothiazoline compound, and various additives that are added as necessary, by applying and drying the slurry on an arbitrary support, and forming it into a sheet ( Wet molding method),

  Examples include a method of preparing composite particles containing an electrode active material, a conductive material, a binder, an isothiazoline compound, and various additives added as necessary, and roll-pressing the composite particles (dry molding method). In particular, the dry molding method is preferable in terms of working environment because it does not use a solvent, and is excellent in the electrolyte impregnation property of the polarizable electrode obtained.

  The production of the polarizable electrode by the dry molding method will be described in detail. In the dry molding method, composite particles containing an electrode active material, a conductive material, a binder, an isothiazoline compound, and various additives added as necessary are prepared. The production method of the composite particles is not particularly limited, but if the production method has a step of dispersing an electrode active material or the like in a solvent to obtain a slurry and spray-drying the obtained slurry, it is highly spherical with good productivity. This is preferable because composite particles can be obtained.

<Slurry manufacturing process>
In the slurry production process, the electrode active material, the conductive material, the binder, the isothiazoline compound and various additives added as necessary are dispersed or dissolved in a solvent, and a slurry obtained by dispersing or dissolving these is prepared. obtain.

  The solvent used for obtaining the slurry is not particularly limited, but when the above dispersant is used, a solvent capable of dissolving the dispersant is preferably used. Specifically, water is usually used, but an organic solvent can also be used, and a mixed solvent of water and an organic solvent may be used. Moreover, you may adjust pH by adding the sulfuric acid which is the electrolyte solution of a lead acid battery.

  The amount of the solvent used when preparing the slurry is such that the solid content concentration of the slurry is usually in the range of 1 to 70% by mass, preferably 15 to 60% by mass. When the solid content concentration is in this range, the binder is preferably dispersed uniformly.

  The viscosity of the slurry is usually in the range of 10 to 5,000 mPa · s, preferably 50 to 2,000 mPa · s at room temperature. When the viscosity of the slurry is within this range, the productivity of the spray drying granulation process can be increased.

  The method or procedure for dispersing or dissolving the electrode active material, the conductive material, the binder, the isothiazoline compound, and various additives added as necessary, in the solvent is not particularly limited. A method of dissolving a dispersant in a solvent, a method of adding and mixing an isothiazoline compound and a binder (for example, latex) dispersed in a solvent, and finally adding and mixing an electrode active material and a conductive material; A method in which an electrode active material and a conductive material are added to and mixed with an isothiazoline compound and binder dispersed in the mixture, and a dispersant dissolved in a solvent is added to and mixed with the mixture; an isothiazoline compound and binder dispersed in a solvent A method of adding and mixing a dispersant dissolved in a solvent, an electrode active material and a conductive material; It is below. Examples of the mixing means include mixing equipment such as a ball mill, a sand mill, a bead mill, a pigment disperser, a crusher, an ultrasonic disperser, a homogenizer, a homomixer, and a planetary mixer. Mixing is usually performed in the range of room temperature to 60 ° C. for 10 minutes to several hours.

<Spray drying process>
Next, the slurry is spray-dried and granulated. The spray drying method is a method of spraying and drying a slurry in hot air. An atomizer is used as an apparatus used for spraying slurry. There are two types of atomizers: a rotating disk method and a pressure method. The rotating disk system is a system in which slurry is introduced almost at the center of a disk that rotates at a high speed, and the slurry is released out of the disk by the centrifugal force of the disk, and the slurry is atomized at that time. The rotational speed of the disc depends on the size of the disc, but is usually 5,000 to 30,000 rpm, preferably 15,000 to 30,000 rpm. The lower the rotational speed of the disk, the larger the spray droplets and the larger the primary average volume particle diameter of the composite particles.

  Examples of the rotating disk type atomizer include a pin type and a vane type, and a pin type atomizer is preferable. A pin-type atomizer is a type of centrifugal spraying device that uses a spraying plate, and the spraying plate has a plurality of spraying rollers removably mounted on a concentric circle along its periphery between upper and lower mounting disks. It consists of The slurry is introduced from the center of the spray platen, adheres to the spraying roller by centrifugal force, moves outside the roller surface, and finally sprays away from the roller surface. On the other hand, the pressurization method is a method in which the slurry is pressurized and sprayed from a nozzle to be dried.

  The temperature of the slurry to be sprayed is usually room temperature, but may be heated to room temperature or higher. Moreover, the hot air temperature at the time of spray-drying is 80-250 degreeC normally, Preferably it is 100-200 degreeC. In the spray drying method, the hot air blowing method is not particularly limited, for example, a method in which the hot air and the spraying direction flow in parallel, a method in which the hot air is sprayed at the top of the drying tower and descends with the hot air, and the sprayed droplets and hot air are countercurrent Examples include a contact method, and a method in which sprayed droplets first flow in parallel with hot air, then drop by gravity and contact countercurrent.

  The composite particles obtained by the above production method can be subjected to post-treatment after the production of the particles, if necessary, as long as the sphericity does not exceed 20%. As a specific example, continuous pressurization that improves or decreases the fluidity of the composite particle by modifying the particle surface by mixing the composite particle with the above electrode active material, conductive material, binder, and isothiazoline compound, etc. It is possible to improve the moldability, improve the electrical conductivity of the composite particles, and suppress gas generation in the operation of the lead storage battery.

  The volume average particle diameter of the composite particles suitably used in the present invention is usually in the range of 0.1 to 1000 μm, preferably 5 to 500 μm, more preferably 10 to 100 μm. When the volume average particle diameter of the composite particles is in the above range, the composite particles are less likely to aggregate, are easy to handle, and are easy to form a polarizable electrode. The volume average particle diameter can be measured using a laser diffraction particle size distribution measuring apparatus.

<Dry molding of composite particles>
The polarizable electrode of the present invention can be obtained by forming the composite particles into a sheet by dry molding. As a method for obtaining a sheet-like molded product, roll pressure molding is suitable. The molding temperature is usually 0 to 200 ° C., preferably higher than the melting point or glass transition temperature of the binder contained in the composite particles, and more preferably 20 ° C. or more higher than the melting point or glass transition temperature. In roll press molding, the molding speed is usually 0.1 to 20 m / min, preferably 5 to 10 m / min. The press linear pressure between rolls is usually 0.2 to 30 kN / cm, preferably 3 to 15 kN / cm.

  In order to increase the capacity by making the thickness of the polarizable electrode uniform and increasing the density, post-pressurization may be further performed as necessary.

(Polarizable electrode)
The density of the polarizable electrode according to the present invention is not particularly limited, but is usually 0.30 to 10 g / cm ³ , preferably 0.35 to 5.0 g / cm ³ , more preferably 0.40 to 3.0 g. / Cm ³ . The thickness of the polarizable electrode is not particularly limited, but is usually 5 to 1000 μm, preferably 20 to 500 μm, more preferably 30 to 300 μm.

  Since the polarizable electrode of the present invention uses a specific polymer as a binder, a polarizable electrode having not only low internal resistance but also high tensile strength and excellent electrolyte solution impregnation property can be obtained. In addition, since the isothiazoline compound is used in addition to the binder, the stability of the electrode forming slurry is high over time, the working efficiency is improved, and the uniformity, internal resistance, tensile strength and electrolyte impregnation of the resulting electrode Also excellent.

  The polarizable electrode of the present invention is preferably used as a constituent element of various electrochemical elements in order to form an electric double layer. In particular, an electric double layer capacitor using an aqueous electrolyte and a lead storage battery using an aqueous electrolyte It is preferably used as a component.

(Electrochemical element)
The electrochemical element of the present invention comprises the polarizable electrode and an aqueous electrolyte.
Examples of the electrochemical element for the aqueous electrolyte include an electric storage device such as a lead storage battery, an alkaline battery, and an electric double layer capacitor. From the viewpoint of forming an electric double layer, an electric double layer capacitor and a lead storage battery are preferable.

(Electric double layer capacitor)
The electric double layer capacitor of the present invention comprises the polarizable electrode of the present invention, or a laminated electrode formed by laminating the polarizable electrode and a current collector, and an aqueous electrolyte. When using a current collector, the material for the current collector used for the electrode may be selected according to the type of the electrolyte. For example, a metal, carbon, a conductive polymer, or the like can be used, and a metal is preferably used. As the current collector metal, aluminum, platinum, nickel, tantalum, titanium, stainless steel, other alloys and the like are usually used. The current collector is in the form of a film or a sheet, and the thickness thereof is appropriately selected depending on the purpose of use, but is usually 1 to 200 μm, preferably 5 to 100 μm, more preferably 10 to 60 μm. Further, the sheet-like current collector may have a shape having holes such as expanded metal, punching metal, and net-like shape.

  The current collector may be subjected to a surface chemical treatment or a surface roughening treatment in advance to reduce contact resistance with the polarizable electrode or improve adhesion to the polarizable electrode, if necessary. . Examples of the surface chemical treatment include acid treatment and chromate treatment. Examples of the surface roughening treatment include electrochemical etching treatment and etching treatment with acid or alkali.

  Moreover, you may use what applied the conductive adhesive to the surface as a collector. As the conductive adhesive, various conductive adhesives are used without particular limitation.

  As a method of forming the polarizable electrode of the present invention on the current collector, a previously prepared polarizable electrode may be bonded onto the current collector via a conductive adhesive layer. In addition, when manufacturing a polarizable electrode by the dry molding method described above, a metal foil as a current collector is inserted between rolls at the same time, and the polarizable electrode and the current collector are laminated simultaneously with powder molding. May be.

  The electric double layer capacitor can be produced according to a conventional method using the polarizable electrode of the present invention and components such as a current collector, an aqueous electrolyte, and a separator. Specifically, for example, a polarizable electrode or an electrode formed by laminating the polarizable electrode or a current collector is cut to an appropriate size, and then the electrodes are overlapped via a separator, and this is wound into a capacitor shape and folded. Etc., and can be manufactured by injecting an electrolyte into the container and sealing it.

  As the aqueous electrolyte, conventionally known ones can be used, and examples thereof include a sulfuric acid aqueous solution, a sodium sulfate aqueous solution, a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, an ammonium hydroxide aqueous solution, a potassium chloride aqueous solution, and a potassium carbonate aqueous solution. In addition, as the electrolyte, those including a polymer electrolyte, a liquid state or a solid state ionic liquid electrolyte, and the like can also be used.

  As the separator, for example, a microporous membrane or non-woven fabric made of polyolefin such as polyethylene or polypropylene, or a porous membrane mainly made of pulp called electrolytic capacitor paper can be used. Moreover, it can replace with a separator and a solid electrolyte can also be used.

(Lead battery)
The schematic block diagram of the electrode laminated body which comprises the lead storage battery which is one embodiment of this invention was shown in FIG. In the figure, the constituent layers are shown separated from each other, but in an actual lead-acid battery, the constituent layers are in close contact and integrated.

  In the illustrated electrode laminate, the lead active material layer 2 and the polarizable electrode 3 in the negative electrode active material layer (lead active material layer 2 and polarizable electrode 3) may be directly laminated, or an adhesive layer may be used. It may be laminated via.

<Lead active material layer 2.4>
Lead active material layer contains lead and lead compounds such as lead, lead monoxide, lead dioxide, dilead trioxide, trilead tetroxide (lead red), lead sulfate, etc. Refers to the main layer. These lead and lead compounds can be used alone or in a suitable mixture. The proportion of lead atoms in the lead active material layer is usually 50% by mass or more, preferably 70% by mass or more, based on the mass of the entire layer. When the amount of lead atoms is within this range, the energy density of the active material layer can be increased. The lead-containing material used for the positive electrode active material layer 4 is preferably lead dioxide or lead monoxide, and the lead-containing material used for the lead active material layer 2 of the negative electrode active material layer is preferably lead monoxide or lead.

  The lead active material layer may contain a reinforcing material such as polyester fiber, a surfactant such as lignin, barium sulfate and the like in addition to lead and a lead compound. Further, an additive selected from oxides, hydroxides or sulfates of antimony, zinc, cadmium, silver and bismuth can be used. Further, when a lead active material layer is formed by producing a paste of a lead-containing material, an aqueous sulfuric acid solution can be added.

<Adhesive layer>
By providing an adhesive layer between the lead active material layer 2 and the polarizable electrode 3 in the negative electrode active material layer, the adhesion between the lead active material layer 2 and the polarizable electrode 3 in the negative electrode active material layer is improved. In addition, the contact resistance can be reduced.

    The adhesive layer preferably contains a filler. A well-known thing can be used for a filler, Although an electroconductive filler and a metal oxide filler are mentioned, Among these, an electroconductive filler is preferable. The conductive filler includes all fillers added to impart conductive performance to the resin.

    The conductive filler is not particularly limited as long as it has conductivity, among which conductive carbon black, graphite and the like are particularly preferable. The volume average particle diameter of the conductive filler is usually in the range of 0.001 to 10 μm. These conductive fillers can be used alone or in combination of two or more.

    Examples of the metal oxide filler include silica, iron oxide, and titanium oxide.

  The adhesive layer contains a filler, but preferably further contains a binder. Examples of the binder include high molecular compounds such as halogen polymers, diene polymers, acrylate polymers, polyimides, polyamides, and polyurethanes. 1-10 mass parts is preferable with respect to 100 mass parts of fillers, and, as for the quantity of a binder, 2-8 mass parts is more preferable.

  The adhesive layer may further contain a dispersant. Examples of the dispersant include cellulose derivatives. As for the quantity of a dispersing agent, 1-10 mass parts is preferable with respect to 100 mass parts of fillers.

  The adhesive may contain a solvent as necessary. As the solvent component, toluene, acetone, water, methanol, ethanol, propanol, butanol, tetrachloroethylene, trichloroethylene, bromochloromethane, diacetone, dimethylformamide, ethyl Examples include ether, cresol, xylene, chloroform, and dimethyl ether, which can be used alone or in combination of two or more.

    The adhesive can be produced by mixing the above-described components using a mixer. As the mixer, a ball mill, a sand mill, a pigment disperser, a pulverizer, an ultrasonic disperser, a homogenizer, a planetary mixer, a Hobart mixer, and the like can be used.

    The method for applying the adhesive is not particularly limited. Examples thereof include a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, and a brush coating method.

    The thickness of the adhesive layer is usually in the range of 1 to 25 μm. When the thickness of the adhesive layer is within the above range, the anchor effect can be satisfactorily exhibited and the electron transfer resistance can be reduced.

<Current collector 1>
The current collector is for taking electrical conduction between the electrode active material of the polarizable electrode and the lead-containing material and the outside of the lead storage battery. Examples of current collectors include plate-shaped, foil-shaped, clad-type porous tubes with lead alloy cores inserted in the center, and grid-shaped current collectors, which hold lead active material paste. A grid-like current collector that is optimal as a shape for efficiently extracting current is preferable. As the grid current collector, any of a standard grid, a radial grid, and an expanded type can be used.

    As the material of the grid-like current collector, a lead-containing alloy such as a lead-calcium alloy, a lead-antimony alloy, or a lead-tin alloy is used. Arsenic, tin, copper, silver, aluminum, or the like may be included as part of the composition of the lead alloy.

    The lead acid battery of the present invention includes an electrode laminate in which a positive electrode active material layer and a negative electrode active material layer are laminated via a separator, and the polarizability of the present invention is provided on at least a part of the positive electrode active material layer or the negative electrode active material layer. It is characterized by using an electrode.

  A lead-acid battery usually has a plurality of electrode pairs arranged such that a positive electrode and a negative electrode face each other with a separator interposed therebetween, and the positive electrodes or the negative electrodes are electrically short-circuited. By setting it as such a structure, the capacity | capacitance of a lead storage battery can be enlarged. In the present embodiment, as shown in FIG. 1, only the case where the electrode laminate is configured by using the polarizable electrode of the present invention for the negative electrode (negative electrode active material layer) is taken up. In the lead storage battery, the polarizable electrode of the present invention can be used for all of the positive electrode and the negative electrode, or can be used for any of the positive electrode and the negative electrode. The polarizable electrode of the present invention can also be used for a part of the positive electrode or a part of the negative electrode. Among these, it is preferable to use for all the electrodes of a negative electrode, or to use for a part of negative electrode.

<Separators 5 and 6>
As a lead-acid battery separator, conventionally known papermaking, microporous polyethylene, microporous polypropylene, microporous rubber, retainer mat, glass mat, and the like can be used in combination of one or more. .

<Electrolyte>
A sulfuric acid aqueous solution is usually used as an electrolyte for a lead storage battery. Although the density of sulfuric acid varies depending on the charge / discharge state, the density is preferably 1.25 to 1.30 g / cm ³ (20 ° C.) in a fully charged state after chemical conversion treatment of the lead storage battery.

<Battery, lid>
In the lead-acid battery, conventionally known ones can be used as the battery case and the lid for storing the electrolyte solution and the electrode pair arranged so that the positive electrode and the negative electrode face each other with the separator interposed therebetween. Specifically, those using ethylene-propylene copolymer, polyethylene, polypropylene, polyacrylonitrile-styrene copolymer, polyacrylonitrile-butadiene-styrene copolymer as raw materials can be used.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to such embodiment at all, Of course, in the range which does not deviate from the summary of this invention, it can implement in various aspects. .

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited to these Examples. In addition, the part and% in an Example and a comparative example are mass references | standards unless there is particular notice.

Measurement and evaluation of characteristics in Examples and Comparative Examples are performed by the following methods.
(Tensile strength)
It measured according to JIS K6251. After drying the polarizable electrode formed into a sheet shape at 160 ° C. for 40 minutes, it is punched into the shape of a No. 1 dumbbell-shaped test piece, subjected to a tensile test at an atmospheric temperature of 25 ° C. and a tensile speed of 10 mm / min, and at break The maximum load was measured. This measurement was repeated 6 times, and the value obtained by dividing the average value of the maximum load by the cross-sectional area of the sheet was taken as the tensile strength of the polarizable electrode. The higher the tensile strength of the polarizable electrode, the less likely it is to crack and break, and the better the shape retention.

(Electrolytic solution impregnation)
Electrolyte impregnation of the electrode was evaluated by dropping one drop of 5 μL of electrolyte onto the electrode cut into 2 cm × 2 cm at an ambient temperature of 25 ° C., and the electrolyte droplet was absorbed from the electrode surface and could not be confirmed with the naked eye. The time (min) up to was measured. It shows that an electrode is excellent in the impregnation property of electrolyte solution, so that this time is short. Here, 38% sulfuric acid aqueous solution was used as the electrolytic solution.

(Electrical characteristics of electric double layer capacitor)
(Capacitance)
The electric characteristics of the electric double layer capacitor were determined by a charge / discharge test of the electric double layer capacitor. Charging current is performed using a current value at which the current value per unit area of the electrode is 6.6 mA / cm ^2, and when the voltage reaches 1.0 V, the voltage is maintained for 10 minutes for constant voltage charging. To complete. Then, immediately after the end of charging, constant current discharging is performed until the voltage reaches 0 V at a current value similar to that used during charging. The capacitance is calculated from the amount of electric power at the time of discharge using an energy conversion method.

  Next, using this capacitance, charging is started at a constant current of 5 mA / F so that the charging / discharging speed of the electric double layer capacitor is constant, and the charging times of constant current charging and constant voltage charging are matched. When the charging is completed for 20 minutes, the charging is completed. Then, immediately after the charging is completed, constant current discharging is performed until the voltage reaches 0 V at a current value similar to that used for charging.

(Internal resistance)
The internal resistance is a value obtained by dividing the amount of voltage drop at the start of discharge from the extrapolation of the approximate curve by the least square method of the voltage data from the start of discharge to the predetermined time divided by the discharge current value, and the resistivity per volume, that is, the volume Expressed as resistivity. However, the predetermined time is 10% of the total discharge time.

Example 1
In a nitrogen-substituted polymerization reactor, 45 parts of acrylonitrile, 50 parts of 1,3-butadiene, 5 parts of methacrylic acid, 0.2 part of t-dodecyl mercaptan (TDM), 132 parts of soft water, 3.0 parts of sodium dodecylbenzenesulfonate , Β-naphthalenesulfonic acid formalin condensate sodium salt 0.5 part, potassium persulfate 0.3 part and ethylenediaminetetraacetic acid sodium salt 0.05 part were charged, and the polymerization conversion was 90% while maintaining the polymerization temperature at 40 ° C. The reaction was continued until Thereafter, when the polymerization conversion rate reached 98%, 0.1 part of sodium dimethyldithiocarbamate was added as a polymerization terminator to terminate the polymerization reaction. After removing unreacted monomers from the aqueous dispersion of copolymer particles obtained, a copolymer (composition of copolymer: 45 parts of acrylonitrile unit, 50 parts of butadiene unit, 5 parts of methacrylic acid unit) The pH and solid content concentration of the particle aqueous dispersion were adjusted to obtain a copolymer particle aqueous dispersion having a solid content concentration of 40% and a pH of 8. The obtained copolymer particle aqueous dispersion was stored for 1 week, and then BIT (1,2-benz-2-methyl-4-isothiazolin-3-one) was added to 100 parts of the solid content of the copolymer particle aqueous dispersion. The binder A was obtained by adding 0.2 parts to the mixture and stirring.

100 parts of high-purity activated carbon powder having a specific surface area of 1,700 m ² / g and a weight average particle diameter of 5 μm, 5 parts of acetylene black as a conductive material, and 1.5% aqueous solution of carboxymethyl cellulose as a dispersant in terms of solid content Then, 1.4 parts and 10 parts of binder A in terms of solid content were mixed, and ion-exchanged water was further added so that the solid content concentration was 20%, followed by mixing and dispersing to obtain a slurry. This slurry is spray-dried (manufactured by Okawara Chemical Co., Ltd.), is rotated at a rotational speed of 25,000 rpm, hot air temperature is 150 ° C., and the temperature of the particle recovery outlet is 90 ° C. using a rotating disk type atomizer (65 mm in diameter). Spray drying granulation was performed to obtain composite particles. The average volume particle diameter of the composite particles was 63 μm.

Next, the obtained composite particles are supplied to a roll (roll temperature 100 ° C., press linear pressure 4.0 kN / cm) of a roll press machine (pressed rough surface heat roll, manufactured by Hirano Giken Kogyo Co., Ltd.), and a molding speed of 20 m / cm Minutes to obtain a polarizable electrode having a thickness of 200 μm and a density of 0.54 g / cm ³ .

  The above polarizable electrode is punched into a circular shape with a diameter of 12 mm, the polarizable electrode and a glass fiber separator are sufficiently impregnated with an electrolyte, and then the two polarizable electrodes are opposed to each other through the separator. The electric double layer capacitor was fabricated by arranging so that the electrodes were not in electrical contact. Sulfuric acid was used as the electrolyte. Table 1 shows the result of measuring the electrical characteristics of this electric double layer capacitor.

(Example 2)
Composite particles were obtained in the same manner as in Example 1 except that the amount of acrylonitrile constituting the binder used for preparation of the composite particles was 30 parts and the amount of 1,3-butadiene was 65 parts. Then, an electric double layer capacitor was produced and each characteristic was measured in the same manner as in Example 1 except that a polarizable electrode was produced using this composite particle. The results are shown in Table 1.

Example 3
Composite particles were obtained in the same manner as in Example 1 except that the isothiazoline compound of binder A used for preparation of the composite particles was changed from BIT to MIT (2-methyl-4-isothiazolin-3-one). Then, an electric double layer capacitor was produced and each characteristic was measured in the same manner as in Example 1 except that a polarizable electrode was produced using this composite particle. The results are shown in Table 1.

Example 4
A composite particle was obtained in the same manner as in Example 1 except that the isothiazoline compound of binder A used for preparation of the composite particle was changed from BIT to CIT (5-chloro-2-methyl-4-isothiazolin-3-one). . And except having produced a polarizable electrode using this composite particle, it carried out similarly to Example 1, and produced the electrical double layer capacitor, and measured each characteristic. The results are shown in Table 1.

(Example 5)
Composite particles were obtained in the same manner as in Example 1 except that the amount of the isothiazoline compound of binder A used for preparation of the composite particles was 0.005 part. Then, an electric double layer capacitor was produced and each characteristic was measured in the same manner as in Example 1 except that a polarizable electrode was produced using this composite particle. The results are shown in Table 1.

(Example 5)
Composite particles were obtained in the same manner as in Example 1 except that the amount of the isothiazoline compound of binder A used for preparation of the composite particles was 0.6 parts. Then, an electric double layer capacitor was produced and each characteristic was measured in the same manner as in Example 1 except that a polarizable electrode was produced using this composite particle. The results are shown in Table 1.

(Comparative Example 1)
Composite particles were obtained in the same manner as in Example 1 except that the amount of acrylonitrile constituting the binder used for preparation of the composite particles was 65 parts and the amount of 1,3-butadiene was 30 parts. Then, an electric double layer capacitor was produced and each characteristic was measured in the same manner as in Example 1 except that a polarizable electrode was produced using this composite particle. The results are shown in Table 1.

(Comparative Example 2)
Composite particles were obtained in the same manner as in Example 1 except that the amount of acrylonitrile constituting the binder used for preparation of the composite particles was 5 parts and the amount of 1,3-butadiene was 90 parts. Then, an electric double layer capacitor was produced and each characteristic was measured in the same manner as in Example 1 except that a polarizable electrode was produced using this composite particle. The results are shown in Table 1.

(Comparative Example 3)
A composite particle was obtained in the same manner as in Example 1 except that the amount of acrylonitrile constituting the binder used for preparation of the composite particle was 50 parts, the amount of 1,3-butadiene was 50 parts, and the amount of methacrylic acid was 0 parts. . Then, an electric double layer capacitor was produced and each characteristic was measured in the same manner as in Example 1 except that a polarizable electrode was produced using this composite particle. The results are shown in Table 1.

(Comparative Example 4)
Composite particles were obtained in the same manner as in Example 1 except that the amount of the isothiazoline compound in binder A used for preparation of the composite particles was 2.3 parts. Then, an electric double layer capacitor was produced and each characteristic was measured in the same manner as in Example 1 except that a polarizable electrode was produced using this composite particle. The results are shown in Table 1.

(Comparative Example 5)
Composite particles were obtained in the same manner as in Example 1 except that the amount of the isothiazoline compound of binder A used for preparation of the composite particles was 0 parts. Then, an electric double layer capacitor was produced and each characteristic was measured in the same manner as in Example 1 except that a polarizable electrode was produced using this composite particle. The results are shown in Table 1.

(Comparative Example 6)
The composite used in the same manner as in Example 1 except that SBR (styrene / butadiene / acrylic acid / methacrylic acid = 47/50 / 0.5 / 2.5 (mass ratio)) is used as the binder for producing the composite particles. Particles were obtained. Then, an electric double layer capacitor was produced and each characteristic was measured in the same manner as in Example 1 except that a polarizable electrode was produced using this composite particle. The results are shown in Table 1.

(Comparative Example 7)
Composite particles were obtained in the same manner as in Example 1 except that polyacrylate (butyl acrylate / ethyl methacrylate / methacrylic acid = 80/17/3 (mass ratio)) was used as a binder for producing the composite particles. Then, an electric double layer capacitor was produced and each characteristic was measured in the same manner as in Example 1 except that a polarizable electrode was produced using this composite particle. The results are shown in Table 1.

  As is clear from the above examples and comparative examples, the electric double layer capacitor of the present invention has a low internal resistance, a high tensile strength, and an excellent electrolyte solution impregnation property.

(Example 7)
(Positive electrode production)
As a lead-containing material, 10 parts of ion-exchanged water and 10 parts of dilute sulfuric acid having a specific gravity of 1.27 were added to 100 parts of lead oxide and mixed to produce a positive electrode active material mixture paste. After filling this paste into a grid-like current collector (100 mm × 100 mm × 3 mm) made of a lead-calcium alloy, the paste was aged in an atmosphere of 40 ° C. and a humidity of 95% for 24 hours and dried to form an unformed positive electrode. Produced.

(Negative electrode fabrication)
To 100 parts of lead oxide, 0.3 parts of carbon black as a conductive material, 0.3 parts of barium sulfate, 10 parts of ion exchange water, and 10 parts of dilute sulfuric acid with a specific gravity of 1.36 are added and mixed to obtain a paste. It was. The obtained paste was passed through a constant gap roll to obtain a sheet-like lead oxide paste having a thickness of 2,750 μm. This sheet-like lead oxide paste was filled into a grid-like current collector (100 mm × 100 mm × 3 mm) made of lead-calcium alloy to form a lead active material layer.

  The sheet molded product (polarizable electrode) molded in Example 1 was pressure-bonded to one surface of the grid-shaped current collector filled with the paste with a batch press at 100 ° C. and 10 MPa to produce a negative electrode.

A laminated lead acid battery shown in FIG. 1 was produced using the positive electrode and the negative electrode. As the separator, a glass microfiber separator 5 was disposed between the lead active material layer 2 and the positive electrode 1, and a microporous polypropylene separator 6 was disposed between the polarizable electrode 3 and the positive electrode 4. As the electrolyte, dilute sulfuric acid having a specific gravity of 1.225 (20 ° C.) was used. After the chemical conversion treatment is subjected to overcharge thereto, the density of the electrolyte solution to obtain a lead acid battery to adjust with sulfuric acid of density 1.4 g / cm ³ so that the 1.28 g / cm ^3.

(Input characteristics)
Charge and discharge the lead-acid battery at 25 ° C. at a charging voltage of 2.2 V to SOC 70% at a current of 2 CA 10 times at 25 ° C., measure the voltage 0.2 seconds after charging at 10 CA from the last discharge state, The difference from the voltage immediately before discharging at the time shown as a relative value with respect to Comparative Example 8 is defined as the input characteristic after the cycle. Here, SOC 70% refers to a state in which the capacity of the lead storage battery is fully charged, and 70% capacity remains. 2CA and 10CA are the capacity of the produced storage battery for 1/2 hour, respectively. It means the amount of current for discharging in 1/10 hours. The smaller the voltage value difference, the better the acceptance of large current charging.

(Example 8)
A negative electrode and a laminated lead-acid battery were prepared in the same manner as in Example 7 except that the polarizable electrode formed in Example 2 was used as the polarizable electrode, and the input characteristics were measured. The results are shown in Table 2.

(Comparative Example 8)
A negative electrode and a laminated lead-acid battery were produced in the same manner as in Example 7 except that the polarizable electrode formed in Comparative Example 1 was used as the polarizable electrode, and the input characteristics were measured. The results are shown in Table 2.

(Comparative Example 9)
A negative electrode and a laminated lead-acid battery were prepared in the same manner as in Example 7 except that the polarizable electrode formed in Comparative Example 4 was used as the polarizable electrode, and the input characteristics were measured. The results are shown in Table 2.

(Comparative Example 10)
A negative electrode and a laminated lead-acid battery were produced in the same manner as in Example 7 except that the polarizable electrode formed in Comparative Example 6 was used as the polarizable electrode, and the input characteristics were measured. The results are shown in Table 2.

(Comparative Example 11)
A negative electrode and a laminated lead-acid battery were produced in the same manner as in Example 7 except that the polarizable electrode formed in Comparative Example 7 was used as the polarizable electrode, and the input characteristics were measured. The results are shown in Table 2.

Table 2 shows the input characteristics after the cycles of the example and the comparative example. In addition, the input characteristic after a cycle is described as a relative value when the input characteristic after the charge / discharge cycle of Comparative Example 8 is 1 (100%). The smaller this value, the better the input characteristics because the voltage rise due to the charging current is small.

  In Examples 7 and 8, the internal resistance is low, the tensile strength is strong, and the impregnation property of the electrolytic solution is excellent. Therefore, the cycle characteristics are superior to those of Comparative Examples 8 to 11.

1: Grid-shaped current collector 2: Lead active material layer 3: Polarizable electrode 4: Positive electrode active material layer (lead active material layer)
5: Separator made of glass microfiber 6: Separator made of microporous polypropylene

Claims (4)

An electrochemical element comprising a polarizable electrode and an aqueous electrolyte,
The polarizable electrode is a polarizable electrode comprising an electrode active material, a conductive material, a binder and an isothiazoline compound,
The isothiazoline compound is included at a ratio of 0.001 to 2.0 parts by mass with respect to 100 parts by mass of the binder,
The amount of the binder containing a polymer containing 10 to 60 parts by mass of (meth) acrylonitrile units, 35 to 85 parts by mass of butadiene units and 0.5 to 10 parts by mass of ethylenically unsaturated carboxylic acid units in 100 parts by mass. Ri polarity electrode der,
An electrochemical element, wherein the electrochemical element is a lead acid battery . The isothiazoline compound is 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, 4,5. The at least one selected from the group of -dichloro-2-n-octyl-4-isothiazolin-3-one and 1,2-benz-2-methyl-4-isothiazolin-3-one. Electrochemical element . The electrochemical element according to claim 1 or 2, wherein the polarizable electrode is formed by dry molding composite particles containing the electrode active material, a conductive material, a binder, and an isothiazoline compound. The electrochemical element according to claim 3, wherein the polarizable electrode is formed by a dry forming method including a step of roll-pressure forming the composite particles.

Images