Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
  • H01M4/621—Binders
  • H01M4/622—Binders being polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F257/00—Macromolecular compounds obtained by polymerising monomers on to polymers of aromatic monomers as defined in group C08F12/00
  • C08F257/02—Macromolecular compounds obtained by polymerising monomers on to polymers of aromatic monomers as defined in group C08F12/00 on to polymers of styrene or alkyl-substituted styrenes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F279/00—Macromolecular compounds obtained by polymerising monomers on to polymers of monomers having two or more carbon-to-carbon double bonds as defined in group C08F36/00
  • C08F279/02—Macromolecular compounds obtained by polymerising monomers on to polymers of monomers having two or more carbon-to-carbon double bonds as defined in group C08F36/00 on to polymers of conjugated dienes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
  • H01G11/22—Electrodes
  • H01G11/30—Electrodes characterised by their material
  • H01G11/32—Carbon-based
  • H01G11/38—Carbon pastes or blends; Binders or additives therein
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
  • H01G11/22—Electrodes
  • H01G11/30—Electrodes characterised by their material
  • H01G11/46—Metal oxides
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
  • H01G11/22—Electrodes
  • H01G11/30—Electrodes characterised by their material
  • H01G11/50—Electrodes characterised by their material specially adapted for lithium-ion capacitors, e.g. for lithium-doping or for intercalation
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/134—Electrodes based on metals, Si or alloys
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the present invention includes a composition for a power storage device, a slurry for a power storage device electrode containing the composition and an active material, a power storage device electrode formed by applying and drying the slurry on a current collector, and the electrode. Storage device.
• An electrode used in such an electricity storage device is manufactured by applying a composition (slurry for an electrode) containing an active material and a polymer that functions as a binder to the surface of a current collector and drying the composition.
• the properties required for the polymer used as a binder include the bonding ability between the active materials and the adhesion ability between the active material and the current collector, the abrasion resistance in the step of winding the electrode, the subsequent cutting, and the like. Examples include powder falling resistance in which fine powder of the active material does not fall off from the applied and dried composition coating film (hereinafter, also referred to as “active material layer”).
• an active material using such a material having a large lithium storage capacity involves a large volume change due to insertion and extraction of lithium. For this reason, when a conventionally used electrode binder is applied to such a material having a large lithium occlusion amount, the active material may not be able to maintain the adhesion, and the active material may be peeled off. Large capacity reduction occurs.
• Techniques for improving the adhesiveness of the electrode binder include a technique for controlling the surface acid content of the particulate binder particles (see Patent Documents 2 and 3), and a technique using an epoxy or hydroxy group-containing binder. Techniques for improving characteristics (see Patent Documents 4 and 5) have been proposed. In addition, a technique has been proposed in which the active material is bound by a rigid molecular structure of polyimide to suppress a change in volume of the active material (see Patent Document 6). A technique using a water-soluble polymer such as polyacrylic acid (see Patent Document 7) has also been proposed.
• JP-A-2004-185810 International Publication No. 2011/096463 International Publication No. 2013/191080 JP 2010-205722 A JP 2010-3703 A JP 2011-204592 A WO 2015/099800
• the electrode binders disclosed in Patent Documents 1 to 7 use a new active material typified by a silicon material having a large lithium occlusion amount and a large volume change due to occlusion / release of lithium.
• the adhesiveness was not sufficient for the formation.
• the electrode binder When such an electrode binder is used, the electrode deteriorates due to, for example, dropping of the active material due to repeated charging and discharging, and thus there has been a problem that the durability required for practical use cannot be sufficiently obtained.
• some embodiments according to the present invention provide a composition for an electricity storage device that is excellent in flexibility and adhesion and that can produce an electricity storage device electrode exhibiting good charge / discharge durability characteristics. Some embodiments according to the present invention also provide a slurry for an electrode of a power storage device containing the composition. Further, some aspects of the present invention provide an electricity storage device electrode having excellent flexibility and adhesion, and exhibiting good charge / discharge durability characteristics. Further, some embodiments according to the present invention provide an electricity storage device having excellent charge / discharge durability characteristics.
• the present invention has been made to solve at least a part of the problems described above, and can be realized as any of the following embodiments.
• composition for an electricity storage device contains polymer particles (A) and a liquid medium (B),
• the number average particle diameter of the polymer particles (A) is 50 nm or more and 500 nm or less;
• the polymer particles (A) are: 1 to 50 parts by mass of a repeating unit (a1) derived from a conjugated diene compound, 5 to 90 parts by mass of a repeating unit (a2) derived from an unsaturated carboxylic acid, A repeating unit (a3) derived from (meth) acrylamide in an amount of 5 to 90 parts by mass,
• the total amount of the repeating unit (a2) and the repeating unit (a3) is 50 parts by mass or more.
• the pH can be between 6 and 11.
• the 5% by mass aqueous dispersion of the polymer particles (A) at pH 9 may have a viscosity of 500 to 150,000 mPa ⁇ s.
• the liquid medium (B) can be water.
• composition for an electricity storage device electrode according to the present invention The composition for a power storage device according to any one of the above-described embodiments and an active material are included.
• the active material may include a silicon material.
• the slurry for the electricity storage device electrode may further contain at least one polymer selected from the group consisting of a styrene-butadiene copolymer, an acrylic polymer and a fluoropolymer.
• Thickeners may be further included.
• One embodiment of the electricity storage device electrode according to the present invention A current collector; and an active material layer formed by applying and drying the slurry for the power storage device electrode according to any one of the above aspects on the surface of the current collector.
• One embodiment of the power storage device according to the present invention includes: The power storage device electrode of the above aspect is provided.
• composition for an electric storage device since flexibility and adhesion can be improved, an electric storage device electrode exhibiting good charge / discharge durability characteristics can be manufactured.
• the composition for a power storage device according to the present invention exerts the above effects particularly when the power storage device electrode contains a material having a large lithium storage capacity as an active material, for example, a carbon material such as graphite or a silicon material. That is, since a material having a large lithium storage capacity can be used as an active material, battery performance is also improved.
• (meth) acrylic acid ⁇ is a concept that includes both “acrylic acid ⁇ ” and “methacrylic acid ⁇ ”.
• ⁇ (meth) acrylate is a concept that includes both “ ⁇ acrylate” and “ ⁇ methacrylate”.
• (meth) acrylamide” is a concept that includes both “acrylamide” and “methacrylamide”.
• a numerical range described using “to” means that the numerical values described before and after “to” are included as the lower limit and the upper limit.
• composition for electricity storage device contains polymer particles (A) and a liquid medium (B).
• the composition for a power storage device according to the present embodiment is used for producing a power storage device electrode (active material layer) having improved binding ability between active materials, adhesion between an active material and a current collector, and powder drop resistance. It can be used as a material, or can be used as a material for forming a protective film for suppressing a short circuit caused by dendrite generated during charge and discharge.
• active material layer active material layer having improved binding ability between active materials, adhesion between an active material and a current collector, and powder drop resistance. It can be used as a material, or can be used as a material for forming a protective film for suppressing a short circuit caused by dendrite generated during charge and discharge.
• the composition for an electric storage device contains the polymer particles (A).
• the polymer particles (A) are composed of a repeating unit (a1) derived from a conjugated diene compound (hereinafter simply referred to as a “repeating unit”).
• (A1) ) 1 to 50 parts by mass, and 5 to 90 parts by mass of a repeating unit (a2) derived from an unsaturated carboxylic acid (hereinafter, also simply referred to as” repeating unit (a2) ").
• a repeating unit (a3) derived from (meth) acrylamide (hereinafter, also simply referred to as “repeating unit (a3)”) in an amount of 5 to 90 parts by mass, and the repeating unit (a2) and the repeating unit (a3) Is 50 parts by mass or more.
• the polymer particles (A) may contain a repeating unit derived from another monomer copolymerizable therewith, in addition to the above-mentioned repeating unit.
• Examples of the other monomer include an unsaturated carboxylic acid ester having a hydroxyl group, an unsaturated carboxylic acid ester (however, excluding the unsaturated carboxylic acid ester having a hydroxyl group), an ⁇ , ⁇ -unsaturated nitrile compound, Examples thereof include a cationic monomer, an aromatic vinyl compound, and a compound having a sulfonic acid group.
• the polymer particles (A) contained in the composition for an electric storage device according to the present embodiment are preferably in the form of a latex dispersed in a liquid medium (B).
• the slurry for an electrode of an electricity storage device electrode hereinafter, simply referred to as “slurry” produced by mixing with the active material is stable. This is preferred because the coating properties are improved and the coating properties of the slurry on the current collector are improved.
• the content ratio of the repeating unit (a1) derived from the conjugated diene compound is 1 to 50 parts by mass when the total of the repeating units contained in the polymer particles (A) is 100 parts by mass.
• the lower limit of the content of the repeating unit (a1) is preferably 2 parts by mass, and more preferably 3 parts by mass.
• the upper limit of the content ratio of the repeating unit (a1) is preferably 48 parts by mass, and more preferably 45 parts by mass.
• the repeating unit (a1) When the repeating unit (a1) is contained in the above range, the dispersibility of the active material and the filler is improved, and a uniform active material layer and a protective film can be formed. High charge-discharge characteristics.
• the polymer particles (A) coated on the surface of the active material can be imparted with elasticity, and the polymer particles (A) can be expanded and contracted to improve the adhesion. Show.
• the conjugated diene compound is not particularly limited, but includes 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene and the like. And one or more selected from these. Among these, 1,3-butadiene is particularly preferred.
• the content ratio of the repeating unit (a2) derived from the unsaturated carboxylic acid is 5 to 90 parts by mass when the total of repeating units contained in the polymer particles (A) is 100 parts by mass.
• the lower limit of the content of the repeating unit (a2) is preferably 7 parts by mass, more preferably 10 parts by mass.
• the upper limit for the content of the repeating unit (a2) is preferably 85 parts by mass, and more preferably 80 parts by mass.
• unsaturated carboxylic acid examples include, but are not particularly limited to, acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, mono- or dicarboxylic acids such as itaconic acid, and one or more selected from these. be able to.
• the content ratio of the repeating unit (a3) derived from (meth) acrylamide is 5 to 90 parts by mass when the total of the repeating units contained in the polymer particles (A) is 100 parts by mass.
• the lower limit of the content of the repeating unit (a3) is preferably 7 parts by mass, and more preferably 10 parts by mass.
• the upper limit of the content of the repeating unit (a3) is preferably 85 parts by mass, and more preferably 80 parts by mass.
• the flexibility of the obtained active material layer becomes moderate, and the ability to adhere the current collector to the active material layer is improved. Furthermore, since the binding ability between active materials containing a carbon material and a silicon material such as graphite can be increased, the resulting active material layer has better flexibility and better adhesion to the current collector. .
• the (meth) acrylamide is not particularly limited, but is acrylamide, methacrylamide, N-isopropylacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N, N-diethylmethacryl Amide, N, N-dimethylaminopropyl acrylamide, N, N-dimethylaminopropyl methacrylamide, N-methylol methacrylamide, N-methylol acrylamide, diacetone acrylamide, maleic amide, acrylamide tert-butyl sulfonic acid and the like. .
• These (meth) acrylamides may be used alone or in combination of two or more.
• the total amount of the repeating units (a2) and (a3) is 50 parts by mass or more, and 55 parts by mass. Parts by weight or more, more preferably 60 parts by weight or more.
• the total amount of the repeating unit (a2) and the repeating unit (a3) is within the above range, the dispersibility of the active material and the filler becomes good, and the flexibility and the adhesion are improved. Is shown.
• the polymer particles (A) may contain, in addition to the repeating units (a1) to (a3), a repeating unit derived from another monomer copolymerizable therewith.
• a repeating unit examples include a repeating unit (a4) derived from an unsaturated carboxylic acid ester having a hydroxyl group (hereinafter, also simply referred to as “repeating unit (a4)”), an unsaturated carboxylic acid ester (provided that the hydroxyl group (A5) (hereinafter also simply referred to as “repeating unit (a5)”) derived from an ⁇ , ⁇ -unsaturated nitrile compound (a6).
• repeating unit (a6) a repeating unit (a7) derived from an aromatic vinyl compound (hereinafter, also simply referred to as “repeating unit (a7)”), and a sulfonic acid group.
• a repeating unit (a8) derived from a compound (hereinafter, also simply referred to as “repeating unit (a8)”), a repeating unit derived from a cationic monomer, and the like Is mentioned.
• the unsaturated carboxylic acid ester having a hydroxyl group include, but are not particularly limited to, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl.
• Examples include (meth) acrylate, 5-hydroxypentyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, glycerin mono (meth) acrylate, and glycerin di (meth) acrylate.
• 2-hydroxyethyl (meth) acrylate and glycerin mono (meth) acrylate are preferred. These monomers can be used alone or in combination of two or more.
• the unsaturated carboxylic acid ester is not particularly limited, but (meth) acrylic acid ester is preferable.
• Specific examples of the (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, and n- (meth) acrylate.
• methyl (meth) acrylate it is preferable to be at least one selected from methyl (meth) acrylate, ethyl (meth) acrylate and 2-ethylhexyl (meth) acrylate, and particularly preferable is methyl (meth) acrylate. preferable.
• ⁇ , ⁇ -unsaturated nitrile compound examples include, but are not particularly limited to, acrylonitrile, methacrylonitrile, ⁇ -chloroacrylonitrile, ⁇ -ethylacrylonitrile, vinylidene cyanide, and the like. It can be one or more. Among these, one or more selected from acrylonitrile and methacrylonitrile are preferable, and acrylonitrile is particularly preferable.
• aromatic vinyl compound examples include, but are not particularly limited to, styrene, ⁇ -methylstyrene, p-methylstyrene, vinyltoluene, chlorostyrene, divinylbenzene, and the like. It can be more than a species. Of these, styrene is particularly preferred.
• the compound having a sulfonic acid group include, but are not particularly limited to, vinyl sulfonic acid, styrene sulfonic acid, allyl sulfonic acid, sulfoethyl (meth) acrylate, sulfopropyl (meth) acrylate, sulfobutyl (meth) acrylate, Compounds having a sulfonic acid group such as acrylamido-2-methylpropanesulfonic acid, 2-hydroxy-3-acrylamidopropanesulfonic acid, 3-allyloxy-2-hydroxypropanesulfonic acid, and alkali salts thereof may be used. .
• the cationic monomer is not particularly limited, but is at least one monomer selected from the group consisting of a secondary amine (salt), a tertiary amine (salt), and a quaternary ammonium salt. Is preferred. Specific examples of these cationic monomers include, but are not particularly limited to, 2- (dimethylamino) ethyl (meth) acrylate, quaternary salt of dimethylaminoethyl (meth) acrylate methyl chloride, 2- (meth) acrylate (Diethylamino) ethyl, 3- (dimethylamino) propyl (meth) acrylate, 3- (diethylamino) propyl (meth) acrylate, 4- (dimethylamino) phenyl (meth) acrylate, 2- (meth) acrylate [(3,5-dimethylpyrazolyl) carbonylamino] ethyl, 2- (0- [1'-methyl
• the polymer particle (A) has the repeating unit (a5), the repeating unit (a6), and the repeating unit (a7) when the total of the repeating units contained in the polymer particle (A) is 100 parts by mass. ), And the total amount of the repeating unit (a2) and the repeating unit (a2) is preferably from 5 to 50 parts by mass.
• the polymer particles (A) contain the repeating unit in the above-described ratio, the dispersibility of the active material and the filler is improved, and the flexibility and adhesion are further improved.
• the polymer particles (A) have the repeating unit (a2), the repeating unit (a3), and the repeating unit (a4) when the total of the repeating units contained in the polymer particles (A) is 100 parts by mass.
• the repeating unit (a8) are preferably from 50 to 95 parts by mass, more preferably from 52 to 92 parts by mass, and particularly preferably from 55 to 90 parts by mass.
• the polymer particles (A) have the repeating unit (a1), the repeating unit (a5), and the repeating unit (a6) when the total of the repeating units contained in the polymer particles (A) is 100 parts by mass.
• the repeating unit (a7) are preferably 50 parts by mass or less, more preferably 5 to 48 parts by mass, and particularly preferably 8 to 45 parts by mass.
• the number average particle diameter of the polymer particles (A) is 50 to 500 nm, preferably 60 to 450 nm, and more preferably 70 to 400 nm.
• the polymer particles (A) are easily adsorbed on the surface of the active material, and thus the polymer particles (A) also move with the movement of the active material. It can follow and move. As a result, only one of the particles can be prevented from migrating alone, so that the deterioration of the electrical characteristics can be reduced.
• the number average particle diameter of the polymer particles (A) can be calculated from the average value of 50 particle diameters obtained from an image of the polymer particles (A) observed by a transmission electron microscope (TEM).
• TEM transmission electron microscope
• Examples of the transmission electron microscope include “H-7650” manufactured by Hitachi High-Technologies Corporation.
• the polymer particles (A) preferably have only one endothermic peak in a temperature range of 60 ° C. to 160 ° C. when measured by differential scanning calorimetry (DSC) according to JIS K7121.
• the temperature of the endothermic peak ie, the glass transition temperature (Tg)
• Tg glass transition temperature
• the polymer particles (A) show good adhesion and have an active material layer. In contrast, better flexibility and adhesiveness can be imparted, which is preferable.
• the method for producing the polymer particles (A) is not particularly limited. For example, emulsification performed in the presence of a known emulsifier (surfactant), a chain transfer agent, a polymerization initiator, or the like.
• the polymerization method can be used.
• the emulsifier (surfactant), chain transfer agent, and polymerization initiator compounds described in Japanese Patent No. 5999399 can be used.
• the emulsion polymerization method for synthesizing the polymer particles (A) may be carried out by one-stage polymerization or by two-stage polymerization or more, but preferably by two-stage or more multi-stage polymerization.
• the mixture of the above-mentioned monomers is preferably used in the presence of a suitable emulsifier, chain transfer agent, polymerization initiator and the like, preferably at 40 to 80 ° C. Can be by emulsion polymerization for 4 to 18 hours.
• the ratio of the monomers used in the first-stage polymerization is calculated based on the total mass of the monomers (the sum of the mass of the monomers used in the first-stage polymerization and the mass of the monomers used in the second-stage polymerization). On the other hand, it is preferably in the range of 5 to 60% by mass, and more preferably in the range of 5 to 55% by mass.
• the type of the monomer used for the first-stage polymerization and its use ratio and the type of the monomer used for the second-stage polymerization and its use ratio may be the same or different.
• the polymerization conditions at each stage are preferably as follows from the viewpoint of the dispersibility of the obtained polymer particles (A).
• First-stage polymerization preferably a temperature of 40 to 80 ° C .: preferably a polymerization time of 2 to 36 hours: a polymerization conversion rate of preferably 50% by mass or more, more preferably 60% by mass or more.
• Second stage polymerization preferably at a temperature of 40 to 80 ° C .; preferably a polymerization time of 2 to 10 hours.
• the polymerization reaction can proceed with good dispersion stability of the obtained polymer.
• This total solid content concentration is preferably 45% by mass or less, and more preferably 40% by mass or less.
• the pH is adjusted to 6 by adding a neutralizing agent to the polymerization mixture. It is preferably adjusted to about 11 to 11, preferably 7 to 11, and more preferably 7 to 10.
• the neutralizing agent used here is not particularly limited, and examples thereof include metal hydroxides such as sodium hydroxide and potassium hydroxide; and ammonia.
• the composition for an electric storage device according to the present embodiment contains a liquid medium (B).
• the liquid medium (B) is preferably an aqueous medium containing water, and more preferably water.
• the aqueous medium may contain a non-aqueous medium other than water. Examples of the non-aqueous medium include amide compounds, hydrocarbons, alcohols, ketones, esters, amine compounds, lactones, sulfoxides, and sulfone compounds. One or more selected from these are used. Can be.
• the use of the aqueous medium as the liquid medium (B) in the composition for an electricity storage device according to the present embodiment reduces the degree of adverse effects on the environment and increases the safety for operators.
• the content ratio of the non-aqueous medium contained in the aqueous medium is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and particularly preferably not substantially contained, in 100 parts by mass of the aqueous medium. preferable.
• substantially not contained means that a non-aqueous medium is not intentionally added as a liquid medium, and a non-aqueous medium which is inevitably mixed when preparing a composition for an electricity storage device. May be included.
• composition for an electricity storage device according to the present embodiment can contain additives other than the above-described components as necessary.
• additives include polymers other than the polymer particles (A), preservatives, thickeners, and the like.
• the composition for an electricity storage device may contain a polymer other than the polymer particles (A).
• a polymer other than the polymer particles (A) examples include, but are not particularly limited to, SBR (styrene butadiene rubber) polymer, acrylic polymer containing unsaturated carboxylic acid ester or a derivative thereof as a constituent unit, PVDF (polyvinylidene fluoride), and the like. Fluorinated polymers and the like can be mentioned. These polymers may be used alone or in combination of two or more. By containing a polymer other than the polymer particles (A), flexibility and adhesion may be further improved.
• the content ratio of the polymer particles (A) in the composition for an electricity storage device according to the present embodiment is such that the polymer particles (A), the polymers other than the polymer particles (A) contained as needed, and the thickener are included. Is preferably 10 to 90 parts by mass, more preferably 20 to 80 parts by mass, and particularly preferably 25 to 75 parts by mass with respect to 100 parts by mass of the total.
• the composition for an electricity storage device according to the present embodiment may contain a preservative.
• a preservative When the composition for an electricity storage device is stored by containing a preservative, it may be possible to suppress the growth of bacteria and fungi and the generation of foreign substances when the composition for an electricity storage device is stored.
• preservatives include compounds described in Japanese Patent No. 5477610.
• the composition for an electricity storage device according to the present embodiment may contain a thickener.
• a thickener By containing a thickener, the applicability and the charge / discharge characteristics of the obtained electricity storage device may be further improved in some cases.
• the thickener include cellulose compounds such as carboxymethylcellulose, methylcellulose, and hydroxypropylcellulose; poly (meth) acrylic acid; an ammonium salt or an alkali metal salt of the cellulose compound or the poly (meth) acrylic acid; Polyvinyl alcohol-based (co) polymers such as alcohols, modified polyvinyl alcohols and ethylene-vinyl alcohol copolymers; copolymers of vinyl esters with unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid and fumaric acid Water-soluble polymers such as saponified products can be mentioned. Among these, alkali metal salts of carboxymethyl cellulose, alkali metal salts of poly (meth) acrylic acid and the like are preferable.
• Examples of commercial products of these thickeners include alkali metal salts of carboxymethyl cellulose such as CMC1120, CMC1150, CMC2200, CMC2280, and CMC2450 (all manufactured by Daicel Corporation).
• the content ratio of the thickener is 5 parts by mass or less based on 100 parts by mass of the total solid content of the composition for an electricity storage device. And more preferably 0.1 to 3 parts by mass.
• composition for power storage device is, for example, a multi-stage or more multi-stage polymerization performed in the presence of a known emulsifier (surfactant), a chain transfer agent, a polymerization initiator, and the like. It can be produced by emulsion polymerization.
• the composition for an electricity storage device is obtained by polymerizing a repeating unit group containing a repeating unit (a1) derived from a conjugated diene compound and a repeating unit (a2) derived from an unsaturated carboxylic acid.
• the composition for an electric storage device obtained by the above-mentioned production method is preferably in the form of a latex dispersed in a liquid medium (B).
• the composition for a power storage device is in the form of a latex dispersed in a liquid medium (B)
• the stability of a slurry for a power storage device electrode prepared by mixing with an active material is improved, and the slurry is used as a current collector. Is preferable since the coating property of the resin becomes good.
• the emulsifier include, for example, sulfates of higher alcohols, alkylbenzene sulfonates, alkyl diphenyl ether disulfonates, aliphatic sulfonates, aliphatic carboxylates, dehydroabietic acid salts, naphthalenesulfonic acid / formalin condensation
• anionic surfactants such as sulfates of nonionic surfactants
• nonionic surfactants such as alkyl esters of polyethylene glycol, alkylphenyl ethers of polyethylene glycol and alkyl ethers of polyethylene glycol
• chain transfer agent examples include alkyl mercaptans such as n-hexyl mercaptan, n-octyl mercaptan, tert-octyl mercaptan, n-dodecyl mercaptan, tert-dodecyl mercaptan, and n-stearyl mercaptan; dimethyl xanthogen disulfide; Xanthogen compounds such as diisopropylxanthogen disulfide; thiuram compounds such as terpinolene, tetramethylthiuram disulfide, tetraethylthiuram disulfide and tetramethylthiuram monosulfide; 2,6-di-tert-butyl-4-methylphenol and styrenated phenol Phenolic compounds; allyl compounds such as allyl alcohol; halogenated carbons such as dichloromethane, dibromome
• polymerization initiator examples include, for example, water-soluble polymerization initiators such as lithium persulfate, potassium persulfate, sodium persulfate, and ammonium persulfate; cumene hydroperoxide, benzoyl peroxide, tert-butyl hydroperoxide, acetyl Oil-soluble polymerization initiators such as peroxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, azobisisobutyronitrile, and 1,1'-azobis (cyclohexanecarbonitrile) Can be appropriately selected and used.
• water-soluble polymerization initiators such as lithium persulfate, potassium persulfate, sodium persulfate, and ammonium persulfate
• cumene hydroperoxide benzoyl peroxide
• tert-butyl hydroperoxide tert-butyl hydroperoxide
• potassium persulfate sodium persulfate
• cumene hydroperoxide or tert-butyl hydroperoxide
• a redox initiator combining an oxidizing agent and a reducing agent, such as the above-mentioned persulfate and sodium bisulfite.
• the use ratio of the polymerization initiator is not particularly limited, but is appropriately set in consideration of the monomer composition, the pH of the polymerization reaction system, the combination of other additives, and the like.
• composition for an electricity storage device can be produced by multistage emulsion polymerization of two or more stages, but is preferably performed by two or more stages of multistage polymerization.
• the ratio of the monomers used in the first-stage polymerization is calculated based on the total mass of the monomers (the sum of the mass of the monomers used in the first-stage polymerization and the mass of the monomers used in the second-stage polymerization). On the other hand, it is preferably in the range of 5 to 60% by mass, and more preferably in the range of 5 to 55% by mass.
• the type of the monomer used for the first-stage polymerization and its use ratio and the type of the monomer used for the second-stage polymerization and its use ratio may be the same or different.
• the polymerization conditions at each stage are preferably as follows from the viewpoint of the dispersibility of the obtained composition for an electricity storage device.
• First-stage polymerization preferably a temperature of 40 to 80 ° C .: preferably a polymerization time of 2 to 36 hours: a polymerization conversion rate of preferably 50% by mass or more, more preferably 60% by mass or more.
• Second stage polymerization preferably at a temperature of 40 to 80 ° C .; preferably a polymerization time of 2 to 10 hours.
• the polymerization reaction can proceed with good dispersion stability of the obtained polymer.
• This total solid content concentration is preferably 45% by mass or less, and more preferably 40% by mass or less.
• the pH can be adjusted to about 6 to 11, preferably 7 to 11, more preferably 7 to 10 by adding a neutralizing agent to the polymerization mixture after the completion of the emulsion polymerization.
• the neutralizing agent used here is not particularly limited, and examples thereof include metal hydroxides such as sodium hydroxide and potassium hydroxide; and ammonia.
• the composition for an electric storage device thus obtained can be made into a powder by removing the liquid medium (B).
• a means for removing the liquid medium (B) in this case there is a method of drying and removing the liquid medium (B) by using a high-viscosity concentrator or a hot-air dryer.
• the content ratio of the repeating unit (a1) derived from the conjugated diene compound is from 1 to 50 parts by mass when the total of all the repeating units contained in the composition for an electric storage device is 100 parts by mass. It is preferable that The lower limit of the content of the repeating unit (a1) is more preferably 2 parts by mass, and particularly preferably 3 parts by mass. The upper limit of the content of the repeating unit (a1) is more preferably 48 parts by mass, and particularly preferably 45 parts by mass.
• the content of the repeating unit (a1) derived from the conjugated diene compound is from 0 to 10 parts by mass when the total of all repeating units contained in the composition for an electric storage device is 100 parts by mass. It is preferable that The upper limit of the content of the repeating unit (a1) is more preferably 5 parts by mass.
• the repeating unit (a1) When the repeating unit (a1) is contained in the above range, the dispersibility of the active material and the filler is improved, and a uniform active material layer and a protective film can be formed. High charge-discharge characteristics.
• the composition for an electricity storage device coated on the surface of the active material can be provided with elasticity, and the composition for an electricity storage device can be expanded and contracted to improve the adhesiveness, and thus exhibit good charge / discharge durability characteristics.
• the conjugated diene compound is not particularly limited, but includes 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene and the like. And one or more selected from these. Among these, 1,3-butadiene is particularly preferred.
• the content ratio of the repeating unit (a2) derived from the unsaturated carboxylic acid is 1 to 10 parts by mass when the total of all the repeating units contained in the composition for an electric storage device is 100 parts by mass. Part.
• the lower limit of the content of the repeating unit (a2) is more preferably 2 parts by mass, and particularly preferably 3 parts by mass.
• the content of the repeating unit (a2) derived from the unsaturated carboxylic acid is from 4 to 90 parts by mass when the total of all the repeating units contained in the composition for an electric storage device is 100 parts by mass.
• the lower limit of the content of the repeating unit (a2) is more preferably 7 parts by mass, and particularly preferably 10 parts by mass.
• the upper limit of the content of the repeating unit (a2) is more preferably 85 parts by mass, and particularly preferably 80 parts by mass.
• the repeating unit (a2) in the above range By containing the repeating unit (a2) in the above range, the dispersibility of the active material and the filler is improved. Furthermore, by improving affinity with a silicon material as an active material and suppressing swelling of the silicon material, good charge / discharge durability is exhibited.
• unsaturated carboxylic acid examples include, but are not particularly limited to, acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, mono- or dicarboxylic acids such as itaconic acid, and one or more selected from these. be able to.
• the content of the repeating unit (a3) derived from (meth) acrylamide is from 5 to 90 parts by mass when the total of all the repeating units contained in the composition for an electric storage device is 100 parts by mass. Part.
• the lower limit of the content of the repeating unit (a3) is more preferably 7 parts by mass, and particularly preferably 10 parts by mass.
• the upper limit of the content of the repeating unit (a3) is more preferably 85 parts by mass, and particularly preferably 80 parts by mass.
• the glass transition temperature (Tg) of the composition for an electric storage device becomes suitable.
• the dispersibility of the active material and the filler is improved.
• the flexibility of the obtained active material layer becomes moderate, and the ability to adhere the current collector to the active material layer is improved.
• the binding ability between active materials containing a carbon material and a silicon material such as graphite can be increased, the obtained active material layer has better flexibility and adhesion ability to the current collector. .
• the (meth) acrylamide is not particularly limited, but is acrylamide, methacrylamide, N-isopropylacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N, N-diethylmethacryl Amide, N, N-dimethylaminopropyl acrylamide, N, N-dimethylaminopropyl methacrylamide, N-methylol methacrylamide, N-methylol acrylamide, diacetone acrylamide, maleic amide, acrylamide tert-butyl sulfonic acid and the like. .
• These (meth) acrylamides may be used alone or in combination of two or more.
• the total amount of the repeating unit (a2) and the repeating unit (a3) is 50 parts by mass or more, and 55 parts by mass. Parts by weight or more, more preferably 60 parts by weight or more.
• the total amount of the repeating unit (a2) and the repeating unit (a3) is within the above range, the dispersibility of the active material and the filler becomes good, and the flexibility and the adhesion are improved. Is shown.
• the repeating unit group may include, in addition to the repeating units (a1), (a2), and (a3), It may contain a repeating unit derived from another copolymerizable monomer.
• a repeating unit include a repeating unit (a4) derived from an unsaturated carboxylic acid ester having a hydroxyl group, and a repeating unit derived from an unsaturated carboxylic acid ester (excluding the unsaturated carboxylic acid ester having a hydroxyl group).
• the unsaturated carboxylic acid ester having a hydroxyl group include, but are not particularly limited to, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl.
• Examples include (meth) acrylate, 5-hydroxypentyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, glycerin mono (meth) acrylate, and glycerin di (meth) acrylate.
• 2-hydroxyethyl (meth) acrylate and glycerin mono (meth) acrylate are preferred. These monomers can be used alone or in combination of two or more.
• the unsaturated carboxylic acid ester is not particularly limited, but (meth) acrylic acid ester is preferable.
• Specific examples of the (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, and n- (meth) acrylate.
• methyl (meth) acrylate it is preferable to be at least one selected from methyl (meth) acrylate, ethyl (meth) acrylate and 2-ethylhexyl (meth) acrylate, and particularly preferable is methyl (meth) acrylate. preferable.
• ⁇ , ⁇ -unsaturated nitrile compound examples include, but are not particularly limited to, acrylonitrile, methacrylonitrile, ⁇ -chloroacrylonitrile, ⁇ -ethylacrylonitrile, vinylidene cyanide, and the like. It can be one or more. Among these, one or more selected from acrylonitrile and methacrylonitrile are preferable, and acrylonitrile is particularly preferable.
• aromatic vinyl compound examples include, but are not particularly limited to, styrene, ⁇ -methylstyrene, p-methylstyrene, vinyltoluene, chlorostyrene, divinylbenzene, and the like. It can be more than a species. Of these, styrene is particularly preferred.
• the compound having a sulfonic acid group include, but are not particularly limited to, vinyl sulfonic acid, styrene sulfonic acid, allyl sulfonic acid, sulfoethyl (meth) acrylate, sulfopropyl (meth) acrylate, sulfobutyl (meth) acrylate, Compounds having a sulfonic acid group such as acrylamido-2-methylpropanesulfonic acid, 2-hydroxy-3-acrylamidopropanesulfonic acid, 3-allyloxy-2-hydroxypropanesulfonic acid, and alkali salts thereof may be used. .
• the cationic monomer is not particularly limited, but is at least one monomer selected from the group consisting of a secondary amine (salt), a tertiary amine (salt), and a quaternary ammonium salt. Is preferred. Specific examples of these cationic monomers include, but are not particularly limited to, 2- (dimethylamino) ethyl (meth) acrylate, quaternary salt of dimethylaminoethyl (meth) acrylate methyl chloride, 2- (meth) acrylate (Diethylamino) ethyl, 3- (dimethylamino) propyl (meth) acrylate, 3- (diethylamino) propyl (meth) acrylate, 4- (dimethylamino) phenyl (meth) acrylate, 2- (meth) acrylate [(3,5-dimethylpyrazolyl) carbonylamino] ethyl, 2- (0- [1'-methyl
• the total of all the repeating units contained in the composition for an electric storage device is 100 parts by mass, 1 selected from the group consisting of the repeating unit (a5), the repeating unit (a6), and the repeating unit (a7) It is preferable that the total amount of the seeds or more and the repeating unit (a2) is 5 to 50 parts by mass or more.
• composition for power storage device 1.5.1. pH
• the pH of the composition for an electricity storage device according to the present embodiment is preferably from 6 to 11, more preferably from 7 to 11, and particularly preferably from 7 to 10.5. If the pH is within the above range, it is possible to suppress the occurrence of problems such as insufficient leveling property and liquid dripping, and it is easy to manufacture an electric storage device electrode that has both good electrical characteristics and good adhesion. Become.
• ⁇ " PH in this specification refers to physical properties measured as follows. This is a value measured at 25 ° C. using a pH meter using a glass electrode calibrated with a neutral phosphate standard solution and a borate standard solution as the pH standard solution in accordance with JIS Z8802: 2011. Examples of such a pH meter include “HM-7J” manufactured by Toa DK Corporation and “D-51” manufactured by Horiba, Ltd.
• the pH of the composition for an electric storage device does not deny that the pH of the composition for an electric storage device is affected by the monomer composition constituting the polymer particles (A), but it is added that the pH is not determined only by the monomer composition. . That is, it is generally known that the pH of the composition for an electric storage device changes depending on polymerization conditions and the like even with the same monomer composition, and the examples in the specification of the present application show only one example. Absent.
• the polymerization reaction solution is charged with all of the unsaturated carboxylic acid from the beginning, and then the other monomers are sequentially added and added, and the monomer other than the unsaturated carboxylic acid is added. Is added to the polymerization reaction solution, and the amount of carboxyl groups derived from the unsaturated carboxylic acid exposed on the surface of the obtained polymer is different from the case where the unsaturated carboxylic acid is finally added. It is considered that the pH of the composition for an electric storage device is greatly different only by changing the order of adding the monomers by the polymerization method.
• the viscosity of the 5% by mass aqueous dispersion of the polymer particles (A) at pH 9 is preferably from 500 to 150,000 mPa ⁇ s, more preferably from 1,000 to 150,000 mPa ⁇ s, and It is particularly preferred that the viscosity is in the range of 2,000 to 150,000 mPa ⁇ s. It is preferable that the viscosity at pH 9 is equal to or higher than the lower limit, because the dispersibility of the active material and the filler becomes good and a uniform slurry can be prepared. It is preferable that the viscosity at pH 9 is equal to or less than the above upper limit because the dispersibility of the polymer particles (A) itself becomes good.
• the viscosity of the 5% by mass aqueous dispersion of the polymer particles (A) is a value measured at a temperature of 25.0 ° C. using a B-type viscometer in accordance with JIS Z 8803.
• a B-type viscometer for example, "RB-80L” or “TVB-10” manufactured by Toki Sangyo Co., Ltd. can be used.
• the number average particle size of the composition for an electricity storage device according to the present embodiment is preferably 50 to 500 nm, more preferably 60 to 450 nm, and particularly preferably 70 to 400 nm.
• the composition for a power storage device is easily adsorbed on the surface of the active material, so that the composition for a power storage device also moves following the movement of the active material. be able to.
• only one of the particles can be prevented from migrating alone, so that the deterioration of the electrical characteristics can be reduced.
• the number average particle diameter of the composition for a power storage device can be calculated from the average value of 50 particle diameters obtained from an image of the composition for a power storage device observed by a transmission electron microscope (TEM).
• TEM transmission electron microscope
• Examples of the transmission electron microscope include “H-7650” manufactured by Hitachi High-Technologies Corporation.
• the composition for an electricity storage device according to the present embodiment has only one endothermic peak in a temperature range of 60 ° C. to 160 ° C. when measured by differential scanning calorimetry (DSC) according to JIS K7121. It is preferable that The temperature of the endothermic peak (ie, the glass transition temperature (Tg)) is more preferably in the range of 70 ° C. to 150 ° C.
• Tg glass transition temperature
• the composition for an electricity storage device shows good adhesion and also has a good adhesion to the active material layer. It is preferable because better flexibility and tackiness can be imparted.
• the slurry for an electricity storage device according to the present embodiment contains the composition for an electricity storage device described above.
• the composition for an electricity storage device according to the present embodiment can also be used as a material for forming a protective film for suppressing a short circuit caused by dendrite generated due to charge and discharge, It can also be used as a material for producing an electricity storage device electrode (active material layer) having improved binding ability between active materials, adhesion between the active material and the current collector, and powder drop resistance.
• a slurry for an electricity storage device for forming a protective film (hereinafter, also referred to as a “slurry for forming a protection film”) and a slurry for an electricity storage device for forming an active material layer of an electrode for an electricity storage device (hereinafter, referred to as “storing electricity”) Also referred to as “device electrode slurry”).
• slurry for forming a protective film refers to coating the slurry on the surface of the electrode or the separator or both and then drying it to form a protective film on the surface of the electrode or the separator or both. Refers to a dispersion used for forming.
• the slurry for forming a protective film according to the present embodiment may be composed only of the above-described composition for a power storage device, or may further contain an inorganic filler.
• each component contained in the protective film forming slurry according to the present embodiment will be described in detail. Note that the composition for a power storage device is as described above, and a description thereof will be omitted.
• the protective film forming slurry according to the present embodiment can improve the toughness of the formed protective film by containing the inorganic filler.
• the inorganic filler it is preferable to use at least one kind of particles selected from the group consisting of silica, titanium oxide (titania), aluminum oxide (alumina), zirconium oxide (zirconia), and magnesium oxide (magnesia).
• titanium oxide and aluminum oxide are preferable from the viewpoint of further improving the toughness of the protective film.
• rutile-type titanium oxide is more preferable.
• the average particle size of the inorganic filler is preferably 1 ⁇ m or less, more preferably in the range of 0.1 to 0.8 ⁇ m.
• the average particle size of the inorganic filler is preferably larger than the average pore size of the separator that is a porous membrane. Thereby, damage to the separator can be reduced, and it is possible to prevent the inorganic filler from clogging the micropores of the separator.
• the slurry for forming a protective film according to the present embodiment preferably contains 0.1 to 20 parts by mass of the above-mentioned composition for an electric storage device in terms of solid content based on 100 parts by mass of the inorganic filler. More preferably, it is contained in an amount of up to 10 parts by mass.
• the content ratio of the composition for a power storage device is in the above range, the balance between the toughness of the formed protective film and the permeability of lithium ions is improved, and as a result, the resistance increase rate of the obtained power storage device is lower. can do.
• the material described in “1.2. Liquid Medium (B)” of the above-described composition for an electric storage device can be used as needed in the slurry for forming a protective film according to the present embodiment.
• the amount of the liquid medium to be added can be adjusted as necessary so as to obtain the optimum viscosity of the slurry according to the coating method or the like.
• the “slurry for power storage device electrode” in this specification is used to form an active material layer on the surface of the current collector by applying it to the surface of the current collector and then drying it. Refers to the resulting dispersion.
• the slurry for an electricity storage device electrode according to the present embodiment contains the above-described composition for an electricity storage device and an active material.
• the slurry for an electricity storage device electrode often contains a binder component such as an SBR-based copolymer and a thickener such as carboxymethyl cellulose in order to improve adhesion.
• the slurry for an electricity storage device electrode according to the present embodiment can improve flexibility and adhesion even with only the polymer particles (A) described above.
• the slurry for an electricity storage device electrode according to the present embodiment may contain a polymer other than the polymer particles (A) and a thickener in order to further improve the adhesion.
• Polymer particles (A) The composition, characteristics, and production method of the polymer particles (A) are as described above, and thus description thereof is omitted.
• the content ratio of the polymer particles (A) in the slurry for an electric storage device electrode according to the present embodiment is preferably 1 to 8 parts by mass, and more preferably 1 to 7 parts by mass with respect to 100 parts by mass of the active material. Is more preferably 1.5 to 6 parts by mass.
• the content ratio of the polymer particles (A) is in the above range, the dispersibility of the active material in the slurry becomes good, and the applicability of the slurry becomes excellent.
• the slurry for an electricity storage device electrode according to the present embodiment contains a polymer other than the polymer particles (A) and a thickener.
• active material used in the slurry for an electricity storage device electrode according to the present embodiment include a carbon material, a silicon material, an oxide containing a lithium atom, a lead compound, a tin compound, an arsenic compound, an antimony compound, and an aluminum compound. Is mentioned. Specific examples of these include compounds described in Japanese Patent No. 5999399.
• the active material layer may contain an active material exemplified below.
• a conductive polymer such as polyacene; A X B Y O Z (where A is an alkali metal or a transition metal, B is at least one selected from transition metals such as cobalt, nickel, aluminum, tin, and manganese; Represents an oxygen atom, and X, Y and Z are numbers in the range of 1.10>X> 0.05, 4.00>Y> 0.85, 5.00>Z> 1.5.) And other metal oxides and the like.
• the slurry for an electricity storage device electrode according to the present embodiment can be used when producing any of the electricity storage device electrodes of the positive electrode and the negative electrode, and is preferably used for both the positive electrode and the negative electrode.
• Lithium iron phosphate has a fine primary particle size, and is known to be a secondary aggregate thereof. When charge and discharge are repeated, aggregation collapses in the active material layer and dissociation between the active materials occurs. This is considered to be one of the factors that peel off from the current collector and that the conductive network inside the active material layer is easily broken.
• the power storage device electrode manufactured using the slurry for a power storage device electrode according to the present embodiment does not have the above-described problem even when lithium iron phosphate is used, and exhibits good electrical characteristics. be able to.
• the reason for this is that the polymer particles (A) can bind lithium iron phosphate firmly, and at the same time, maintain the state in which lithium iron phosphate is firmly bound even during charge and discharge. It is thought that it is possible.
• the active material when producing a negative electrode, it is preferable that the active material contains a silicon material among the active materials exemplified above. Since the silicon material has a large lithium storage capacity per unit weight as compared with other active materials, by containing the silicon material as the negative electrode active material, the storage capacity of the obtained power storage device can be increased, As a result, the output and energy density of the power storage device can be increased.
• the negative electrode active material is a mixture of a silicon material and a carbon material. Since the change in volume of a carbon material due to charge and discharge is small, by using a mixture of a silicon material and a carbon material as a negative electrode active material, the effect of the volume change of the silicon material can be reduced, and the active material layer and the active material layer can be collected. The ability to adhere to the electric body can be further improved.
• silicon (Si) When silicon (Si) is used as an active material, while silicon has a high capacity, a large volume change occurs when occluding lithium. For this reason, the silicon material has the property that it is pulverized, peeled from the current collector, or separated from the active materials due to repeated expansion and contraction, and the conductive network inside the active material layer is easily broken. As a result, the cycle characteristics are extremely deteriorated in a short time.
• the electricity storage device electrode manufactured using the electricity storage device electrode slurry according to the present embodiment even when a silicon material is used, the above-described problem does not occur, and good electrical characteristics can be exhibited. it can. This is because the polymer particles (A) can firmly bind the silicon material, and the polymer particles (A) expand and contract even if the silicon material expands in volume by absorbing lithium. It is considered that the state in which the silicon material is firmly bound can be maintained.
• the content ratio of the silicon material in 100% by mass of the active material is preferably 1% by mass or more, more preferably 1 to 50% by mass, still more preferably 5 to 45% by mass. It is particularly preferred that the content be set to 4040% by mass.
• the content ratio of the silicon material in 100% by mass of the active material is within the above range, a power storage device having an excellent balance between improvement in output and energy density of the power storage device and charge / discharge durability characteristics can be obtained.
• the active material preferably has a granular shape.
• the average particle size of the active material is preferably from 0.1 to 100 ⁇ m, more preferably from 1 to 20 ⁇ m.
• the average particle size of the active material is a volume average particle size calculated from the particle size distribution measured by a particle size distribution measuring device using a laser diffraction method as a measurement principle. Examples of such a laser diffraction type particle size distribution measuring apparatus include HORIBA @ LA-300 series and HORIBA @ LA-920 series (all manufactured by Horiba, Ltd.).
• components may be added to the slurry for an electricity storage device electrode according to the present embodiment, if necessary.
• Such components include, for example, polymers other than the polymer particles (A), thickeners, conductivity-imparting agents, liquid media (excluding carry-on components from the composition for power storage devices), pH adjusters, Corrosion inhibitors and the like.
• the polymer other than the polymer particles (A) and the thickener may be selected from the compounds exemplified in the above “1.3.
• Examples of the conductivity imparting agent include compounds described in Japanese Patent No. 5999399 and the like.
• the liquid medium that can be additionally added to the slurry for an electricity storage device electrode according to the present embodiment may be the same as or different from the liquid medium (B) contained in the composition for an electricity storage device, It is preferable to use by selecting from the liquid media exemplified in “1.2. Liquid Medium (B)” above.
• the usage ratio of the liquid medium (including the amount brought in from the power storage device composition) in the slurry for the power storage device electrode according to the present embodiment is determined by the solid content concentration in the slurry (total mass of components other than the liquid medium in the slurry). Is the ratio to the total mass of the slurry. The same applies hereinafter.) Is preferably 30 to 70% by mass, more preferably 40 to 60% by mass.
• the slurry for a power storage device electrode according to the present embodiment can contain a pH adjuster or a corrosion inhibitor for the purpose of suppressing corrosion of the current collector according to the type of the active material.
• pH adjusting agent examples include, for example, hydrochloric acid, phosphoric acid, sulfuric acid, acetic acid, formic acid, ammonium phosphate, ammonium sulfate, ammonium acetate, ammonium formate, ammonium chloride, sodium hydroxide, potassium hydroxide and the like. Sulfuric acid, ammonium sulfate, sodium hydroxide and potassium hydroxide are preferred. Further, it can be used by selecting from the compounds described in the method for producing the polymer particles (A).
• ammonium metavanadate, sodium metavanadate, potassium metavanadate, ammonium metatungstate, sodium metatungstate, potassium metatungstate, ammonium paratungstate, sodium paratungstate, potassium paratungstate, molybdate examples thereof include ammonium, sodium molybdate, and potassium molybdate. Among these, ammonium paratungstate, ammonium metavanadate, sodium metavanadate, potassium metavanadate, and ammonium molybdate are preferable.
• the slurry for power storage device electrode according to the present embodiment is manufactured by any method as long as it contains the above-described composition for power storage device and an active material. Alternatively, it can be manufactured by a method described in, for example, Japanese Patent No. 5999399.
• the power storage device electrode according to the present embodiment includes a current collector, and an active material layer formed by applying and drying the above-described slurry for a power storage device electrode on the surface of the current collector. It is.
• Such a power storage device electrode is formed by applying the above-mentioned slurry for a power storage device electrode to a surface of a current collector such as a metal foil to form a coating film, and then drying the coating film to form an active material layer. Can be manufactured.
• the thus-produced power storage device electrode is obtained by binding the above-mentioned polymer particles (A), an active material, and an active material layer containing an optional component added as necessary to a current collector. Therefore, it is excellent in flexibility and adhesion, and shows good charge / discharge durability characteristics.
• the current collector is not particularly limited as long as it is made of a conductive material, and examples thereof include a current collector described in Japanese Patent No. 5999399.
• the electricity storage device electrode manufactured in this way has excellent flexibility and adhesion, and exhibits good charge / discharge durability.
• the content ratio of the silicon element in 100 parts by mass of the active material layer is preferably 2 to 30 parts by mass, and preferably 2 to 20 parts by mass. More preferably, it is particularly preferably 3 to 10 parts by mass.
• the content of the silicon element in the active material layer is within the above range, the power storage capacity of a power storage device manufactured using the same is improved, and an active material layer with a uniform distribution of the silicon element is obtained. .
• the content of the silicon element in the active material layer can be measured, for example, by a method described in Japanese Patent No. 5999399.
• the power storage device includes the above-described power storage device electrode, further contains an electrolytic solution, and can be manufactured using a component such as a separator according to a conventional method.
• a component such as a separator according to a conventional method.
• a specific manufacturing method for example, a negative electrode and a positive electrode are overlapped with a separator interposed therebetween, and this is wound in accordance with the shape of the battery, folded, stored in a battery container, and an electrolytic solution is injected into the battery container. And sealing.
• the shape of the battery can be an appropriate shape such as a coin type, a cylindrical type, a square type, a laminate type, and the like.
• the electrolyte may be liquid or gel, and may be selected from known electrolytes used for power storage devices that effectively exhibit the function as a battery, depending on the type of active material.
• the electrolytic solution can be a solution in which the electrolyte is dissolved in a suitable solvent.
• these electrolytes and solvents for example, compounds described in Japanese Patent No. 5999399 are exemplified.
• composition for power storage device A power storage device composition containing polymer particles (A1) was obtained by two-stage polymerization as described below. First, in the first-stage polymerization, 220 parts by mass of water, 22 parts by mass of a monomer mixture composed of 8 parts by mass of 1,3-butadiene, 12 parts by mass of styrene, and 2 parts by mass of acrylic acid were put into a reactor, followed by chain transfer.
• This graphite-coated silicon oxide is a conductive powder (active material) in which the surface of the silicon oxide is coated with graphite, the average particle diameter is 10.5 ⁇ m, and the obtained graphite-coated silicon oxide is 100% in total.
• the ratio of the graphite coating in the case of mass% was 2 mass%.
• the mixture was stirred for a time to obtain a paste.
• Water was added to the obtained paste, the solid content concentration was adjusted to 48% by mass, and then, using a stirring defoaming machine (trade name “Awatori Neritaro”, manufactured by Shinky Corporation) at 200 rpm for 2 minutes.
• a stirring defoaming machine trade name “Awatori Neritaro”, manufactured by Shinky Corporation
• PVDF Polymer # 1120
• conductive aid trade name "DENKA BLACK 50% pressed product” manufactured by Denka Corporation
• 100 parts by mass of LiCoO 2 manufactured by Hayashi Kasei Co., Ltd.
• NMP N-methylpyrrolidone
• the slurry for positive electrode was prepared by stirring and mixing at 1,800 rpm for 5 minutes and further under reduced pressure (about 2.5 ⁇ 10 4 Pa) at 1,800 rpm for 1.5 minutes.
• This positive electrode slurry was uniformly applied to the surface of the current collector made of aluminum foil by a doctor blade method so that the film thickness after solvent removal was 80 ⁇ m, and heated at 120 ° C. for 20 minutes to remove the solvent. .
• a counter electrode positive electrode was obtained by pressing with a roll press machine so that the density of the active material layer was 3.0 g / cm 3 .
• a lithium ion battery cell (power storage device) was assembled by mounting a positive electrode manufactured by punching out to a diameter of 16.16 mm, and closing the external body of the two-pole type coin cell with screws and sealing.
• Capacity retention (%) (discharge capacity at 100th cycle) / (discharge capacity at 1st cycle) (Evaluation criteria) 5 points: capacity retention rate is 95% or more. 4 points: Capacity retention is 90% or more and less than 95%. 3 points: Capacity retention is 85% or more and less than 90%. 2 points: Capacity retention is 80% or more and less than 85%. 1 point: Capacity retention is 75% or more and less than 80%. 0 point: capacity retention is less than 75%.
• “1C” indicates a current value at which a cell having a certain electric capacity is discharged at a constant current and discharge is completed in one hour.
• “0.1 C” refers to a current value at which discharge is completed in 10 hours
• “10 C” refers to a current value at which discharge is completed in 0.1 hours.
• composition for power storage device (1) Preparation of composition for power storage device”, the type and amount of each monomer are described in Table 1 or Table 2 below, respectively.
• a composition for an electricity storage device containing 20% by mass of a polymer component was obtained in the same manner as described above.
• the polymer particles (A) obtained in Example 1 are referred to as “polymer particles (A1)”, and similarly, the polymer particles (A) obtained in Example 5 are referred to as “polymer particles (A)”.
• the “polymer particles (A5)” and the polymer particles (A) obtained in Example 19 are referred to as “polymer particles (A19)” and the like.
• the polymer particles obtained in Comparative Example 1 are referred to as “polymer particles (B1)”, and similarly, the polymer particles obtained in Comparative Example 9 are referred to as “polymer particles (B9)”. I do.
• Example 2 in the same manner as in Example 1 except that the composition for an electricity storage device prepared above was used, a slurry for an electricity storage device electrode was prepared, and an electricity storage device electrode and an electricity storage device were prepared, respectively. Was evaluated in the same manner as described above.
• Example 32 In the same manner as in Example 5, a composition for an electric storage device having a pH of 9.0 and containing 20% by mass of the polymer particles (A5) was obtained. Next, 1 mass of a thickener (trade name "CMC2200", manufactured by Daicel Co., Ltd.) was added as a first component to a twin-shaft planetary mixer (trade name "TK Hibismix 2P-03" manufactured by Primix Co., Ltd.). Parts (as solid content, added as an aqueous solution having a concentration of 2% by mass), and 1 part by mass of polymer particles (A5) (solids equivalent, containing 20% by mass of polymer particles (A5) obtained above).
• a thickener trade name "CMC2200”, manufactured by Daicel Co., Ltd.
• TK Hibismix 2P-03 manufactured by Primix Co., Ltd.
• SBR (trade name “TRD105A”, manufactured by JSR Corporation) was added as an after-addition component in an amount corresponding to 2 parts by mass (solid content conversion value), and the mixture was further stirred for 1 hour to obtain a paste.
• Water was added to the obtained paste, the solid content concentration was adjusted to 48% by mass, and then, using a stirring defoaming machine (trade name “Awatori Neritaro”, manufactured by Shinky Corporation) at 200 rpm for 2 minutes.
• a stirring defoaming machine (trade name “Awatori Neritaro”, manufactured by Shinky Corporation) at 1800 rpm for 2 minutes.
• An electricity storage device electrode and an electricity storage device were prepared in the same manner as in Example 1 except that the slurry for an electricity storage device electrode prepared above was used, and evaluated in the same manner as in Example 1.
• Examples 27 to 31, 33 and Comparative Examples 11 to 17 Except that the composition of the slurry for the power storage device electrode was changed as shown in Table 3 below, slurry for the power storage device electrode was prepared in the same manner as in Example 32, and the power storage device electrode and the power storage device were produced. The same evaluation as for No. 32 was made.
• a power storage device lithium ion secondary battery
• these power storage device electrodes also has favorable charge / discharge rate characteristics.
• the reason for this is that the electricity storage device electrodes according to Examples 1 to 26 shown in Table 1 and Table 2 reduce the change in the thickness of the active material layer due to charging and discharging as compared with Comparative Examples 1 to 10. It is presumed that the formation allows the conductive network inside the active material layer to be maintained.
• the slurry for an electricity storage device electrode prepared using the composition for an electricity storage device according to the present invention shown in Examples 27 to 33 was the same as that of Comparative Examples 11 to 17.
• active materials having a large volume change due to charge / discharge can be preferably bonded to each other, and furthermore, the adhesion between the active material layer and the current collector can be improved. It was found that the properties could be maintained well.
• the present invention is not limited to the above embodiment, and various modifications are possible.
• the present invention includes a configuration substantially the same as the configuration described in the embodiment (for example, a configuration having the same function, method, and result, or a configuration having the same object and effect).
• the invention also includes a configuration in which a non-essential part of the configuration described in the above embodiment is replaced with another configuration.
• the invention also includes a configuration having the same function and effect as the configuration described in the above embodiment, or a configuration capable of achieving the same object.
• the invention also includes a configuration obtained by adding a known technique to the configuration described in the above embodiment.

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• 2019
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