WO2021246376A1 - Binder for non-aqueous secondary battery electrode and slurry for non-aqueous secondary battery electrode - Google Patents
Binder for non-aqueous secondary battery electrode and slurry for non-aqueous secondary battery electrode Download PDFInfo
- Publication number
- WO2021246376A1 WO2021246376A1 PCT/JP2021/020727 JP2021020727W WO2021246376A1 WO 2021246376 A1 WO2021246376 A1 WO 2021246376A1 JP 2021020727 W JP2021020727 W JP 2021020727W WO 2021246376 A1 WO2021246376 A1 WO 2021246376A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- secondary battery
- binder
- aqueous secondary
- monomer
- battery electrode
- Prior art date
Links
- 0 *C(N(*)C=C)=O Chemical compound *C(N(*)C=C)=O 0.000 description 1
Classifications
-
- 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
- C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
- C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
- C08F220/04—Acids; Metal salts or ammonium salts 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
- H01M4/62—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 relates to a binder for a non-aqueous secondary battery electrode and a slurry for a non-aqueous secondary battery electrode.
- non-aqueous secondary battery A secondary battery using a non-aqueous electrolyte (non-aqueous secondary battery) is superior to a secondary battery using an aqueous electrolyte in terms of high voltage, miniaturization, and weight reduction. Therefore, non-aqueous secondary batteries are widely used as power sources for notebook computers, mobile phones, power tools, and electronic / communication devices. Recently, non-aqueous batteries have been used for electric vehicles and hybrid vehicles from the viewpoint of application to environmental vehicles, but there is a strong demand for higher output, higher capacity, longer life, and the like. As a non-aqueous secondary battery, a lithium ion secondary battery is a typical example.
- Non-aqueous secondary batteries include a positive electrode using a metal oxide as an active material, a negative electrode using a carbon material such as graphite as an active material, and a non-aqueous electrolyte solvent mainly composed of carbonates or flame-retardant ionic liquids.
- a non-aqueous secondary battery is a secondary battery in which ions move between a positive electrode and a negative electrode to charge and discharge the battery.
- the positive electrode is obtained by applying a slurry composed of a metal oxide and a binder to the surface of a positive electrode current collector such as an aluminum foil, drying the slurry, and then cutting the slurry into an appropriate size.
- the negative electrode is obtained by applying a slurry composed of a carbon material and a binder to the surface of a negative electrode current collector such as a copper foil, drying the slurry, and then cutting the slurry into an appropriate size.
- the binder has a role of binding the active materials to each other and the active material and the current collector at the positive electrode and the negative electrode, and prevents the active material from peeling off from the current collector.
- PVDF polyvinylidene fluoride
- NMP N-methyl-2-pyrrolidone
- aqueous dispersion binder As a method to solve these problems, the development of an aqueous dispersion binder is underway.
- a water dispersion type binder for example, a styrene-butadiene rubber (SBR) type water dispersion used in combination as a carboxymethyl cellulose (CMC) thickener is known.
- SBR styrene-butadiene rubber
- CMC carboxymethyl cellulose
- Patent Document 1 discloses a pressure-sensitive adhesive composition for a patch containing a sodium acrylate-N-vinylacetamide copolymer. Further, Patent Document 2 discloses a composition for a hydrogel containing a sodium acrylate-N-vinylacetamide (55/45 (molar ratio)) copolymer.
- Patent Document 4 a copolymer for a binder for a non-aqueous battery electrode containing a structural unit derived from N-vinylacetamide, a structural unit derived from sodium (meth) acrylate, and a structural unit derived from methoxypolyethylene glycol methacrylate is described. Has been described.
- the SBR-based binder described in Patent Document 1 needs to be used in combination with carboxymethyl cellulose, which is a thickener, and the slurry preparation process is complicated. Moreover, even in this binder, the binding property between the active materials and the active material and the current collector is insufficient, and when the electrode is produced with a small amount of the binder, a part of the active material is separated in the process of cutting the current collector. There was a problem of peeling.
- the sodium acrylate-N-vinylacetamide copolymer disclosed in Patent Documents 1 and 2 contains a large amount of components derived from N-vinylacetamide. When such a polymer is mixed with a negative electrode active material and water to form an electrode slurry, agglomerates are likely to be generated in the slurry.
- the binder for non-aqueous battery electrodes disclosed in Patent Document 3 has a problem that cracks are likely to occur in an electrode having a thick film thickness, that is, a large basis weight, as shown in Comparative Example 1 described later. rice field.
- the binder for non-aqueous battery electrodes described in Patent Document 4 has room for improvement in the peel strength of the electrode active material layer with respect to the current collector, as shown in Comparative Example 2 described later.
- the present invention is a binder for a non-aqueous secondary battery electrode that can greatly improve the peeling strength of the electrode active material layer with respect to the current collector while suppressing the generation of cracks in the electrode active material layer formed on the current collector.
- An object of the present invention is to provide a slurry for a non-aqueous secondary battery electrode.
- Another object of the present invention is to provide a non-aqueous secondary battery electrode having few cracks and high peel strength of the electrode active material layer with respect to the current collector.
- the present invention is as follows [1] to [15].
- the solubility in water at 23 ° C. is less than 11.1 g / 100 g.
- the weight average molecular weight is 600,000 or more and 7.5 million or less.
- Binder for battery electrodes [2] The binder for a non-aqueous secondary battery electrode according to [1], wherein the viscosity is 29000 mPa ⁇ s or more.
- the polymer (P) is a copolymer of a monomer having an ethylenically unsaturated bond, and has a structural unit derived from a monomer having an anionic functional group and a polar functional group.
- the polymer (P) is Selected from the group consisting of a structural unit (a) derived from a monomer (A) having an ethylenically unsaturated bond and an amide bond, a compound having an ethylenically unsaturated bond and an anionic functional group, and a salt of those compounds.
- the monomer (A) is a binder represented by the formula (1) for a non-aqueous secondary battery electrode according to [7].
- R 1 and R 2 are each independently a hydrogen atom or an alkyl group having 1 or more and 5 or less carbon atoms.
- a binder composition for a non-aqueous secondary battery electrode which comprises the binder for a non-aqueous secondary battery electrode according to any one of [1] to [10] and an aqueous medium.
- the content of the polymer (P) in 100 g of the aqueous medium is larger than the solubility of the polymer (P) in water at 23 ° C., and the polymer (P) is dispersed in the aqueous medium.
- a binder for a non-aqueous secondary battery electrode that can greatly improve the peeling strength of the electrode active material layer with respect to the current collector while suppressing the generation of cracks in the electrode active material layer formed on the current collector.
- a slurry for a non-aqueous secondary battery electrode can be provided. Further, according to the present invention, it is possible to provide a non-aqueous secondary battery electrode having few cracks and high peel strength of the electrode active material layer with respect to the current collector. Further, according to the present invention, it is possible to provide a non-aqueous secondary battery provided with an electrode having few cracks and high peel strength of the electrode active material layer with respect to the current collector.
- the battery is a secondary battery in which ions are transferred between the positive electrode and the negative electrode during charging and discharging.
- the positive electrode comprises a positive electrode active material
- the negative electrode comprises a negative electrode active material.
- These electrode active materials are materials capable of inserting and desorbing ions (Deintercation).
- a preferred example of the secondary battery having such a configuration is a lithium ion secondary battery.
- (Meta) acrylic acid means one or both of methacrylic acid and acrylic acid.
- the "(meth) acrylic acid monomer” means one or both of the methacrylic acid monomer and the acrylic acid monomer.
- “(Meta) acrylate” means either methacrylate and acrylate or both.
- Weight average molecular weight is a pullulan conversion value calculated using gel permeation chromatography (GPC).
- Binder for non-aqueous secondary battery electrodes The binder for a non-aqueous secondary battery electrode (or a non-aqueous secondary battery electrode binder; hereinafter, may be referred to as an “electrode binder”) according to the present embodiment includes the polymer (P) described below.
- the electrode binder may contain other components, and may contain, for example, a polymer other than the polymer (P), a surfactant, or the like.
- the electrode binder is composed of a component that remains without volatilizing in a process involving heating in the battery manufacturing process described later. Specifically, the components constituting the electrode binder remained after weighing 1 g of the mixture containing the electrode binder in an aluminum dish having a diameter of 5 cm and drying at 110 ° C. for 5 hours while circulating air in a dryer at atmospheric pressure. It is an ingredient.
- the content of the polymer (P) in the electrode binder is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, and 98% by mass or more. Is more preferable. This is to increase the contribution of the polymer (P) to the desired effect of the present invention.
- the weight average molecular weight of the polymer (P) is 7.5 million or less, preferably 5 million or less, and more preferably 4 million or less.
- the weight average molecular weight of the polymer (P) may be 3 million or less.
- the polymer (P) of the present embodiment has a solubility in water at 23 ° C. of less than 11.1 g / 100 g (a polymer (P) that can be dissolved in 100 g of water is less than 11.1 g).
- the solubility of less than 11.1 g / 100 g is determined by visually confirming the presence of insoluble matter in the mixed solution consisting of 10.0 parts by mass of the polymer and 90.0 parts by mass of water.
- the polymer (P) has a solubility in water at 23 ° C. of less than 5.26 g / 100 g (a mixed solution of 5.0% by mass of the polymer (P) and 95.0% by mass of water is turbid). It is preferably less than 3.09 g / 100 g (a mixed solution of 3.0% by mass of the polymer (P) and 97.0% by mass of water is turbid).
- the weight average molecular weight of the polymer (P) is a pullulan-equivalent value calculated by using gel permeation chromatography (GPC)
- the polymer (P) is contained in water to the extent that GPC measurement is possible. It is preferably soluble.
- the solubility of the polymer (P) in water at 40 ° C. is preferably 0.1 g / 100 g or more, and more preferably 0.3 g / 100 g or more.
- the viscosity of the aqueous dispersion at 23 ° C. containing 10% by mass of the polymer (P) is 27,000 mPa ⁇ s or more, preferably 29000 mPa ⁇ s or more, and more preferably 31000 mPa ⁇ s or more. This is because it is possible to suppress the generation of cracks in the electrode active material layer, improve the peel strength of the electrode active material layer, and suppress the swelling of the electrode active material layer in the electrode described later. This is also to improve the cycle characteristics (discharge capacity retention rate) in the non-aqueous secondary battery described later.
- the "water dispersion at 23 ° C. containing 10% by mass of the polymer (P)” is composed of 10% by mass of the polymer (P) and 90% by mass of water, and the polymer (P) is dispersed in water. It means a mixed solution that remains turbid without causing supernatant and precipitation even when the mixed solution is allowed to stand at 23 ° C. for 24 hours.
- the viscosity of the aqueous dispersion at 23 ° C. containing 10% by mass of the polymer (P) is 100,000 mPa ⁇ s or less, preferably 80,000 mPa ⁇ s or less, and more preferably 50,000 mPa ⁇ s or less. This is to efficiently disperse the electrode active material and the like when the electrode slurry is prepared by mixing with the electrode active material and the like described later.
- the viscosity is a value measured by a Brookfield type viscometer at a liquid temperature of 23 ° C. and a rotation speed of 10 rpm.
- the polymer (P) is a polymer obtained by radically polymerizing a monomer having an ethylenically unsaturated bond, and has a structural unit derived from the monomer having an anionic functional group and a polar functional group. It is preferable that the polymer contains a structural unit derived from a monomer having no ethylene.
- the copolymer (cP) is derived from the structural unit (a) derived from the monomer (A), the structural unit (b) derived from the monomer (B), and the monomer (C). Includes structural unit (c).
- the monomer (A) has an ethylenically unsaturated bond and an amide bond.
- the monomer (B) is at least one selected from the group consisting of compounds having an ethylenically unsaturated bond and an anionic functional group, and salts of those compounds.
- the monomer (C) is a carboxylic acid ester compound having an ethylenically unsaturated bond.
- the copolymer (cP) is a structural unit (d) derived from another monomer (D) that does not correspond to any of the monomer (A), the monomer (B), and the monomer (C). May include.
- the monomer (A) is a compound having an ethylenically unsaturated bond and an amide bond.
- Examples of the monomer (A) include N-vinylamide, N-alkyl-N-vinylamide, (meth) acrylamide, N-alkyl (meth) acrylamide, N, N-dialkyl (meth) acrylamide, and N-hydroxyalkyl (meth). ) Acrylamide, diacetone (meth) acrylamide, dimethylaminoalkyl (meth) acrylamide, (meth) acrylamide-2-methylpropanesulfonic acid and the like.
- the monomer (A) may contain a plurality of types of compounds. Preferable examples of the monomer (A) include compounds represented by the following formula (1).
- R 1 and R 2 are each independently a hydrogen atom or an alkyl group having 1 or more and 5 or less carbon atoms.
- R 1, R 2 is more preferably each independently hydrogen atom or C 1 to 3 alkyl group carbon, is R 1, R 2 each independently represent a hydrogen atom or a methyl group Is even more preferable.
- R 1 and R 2 are R 1 : H, R 2 : H (that is, the monomer (A) is N-vinylformamide), or R 1 : H, R 2 : CH 3. (That is, the monomer (A) is N-vinylacetamide).
- the monomer (B) comprises at least one selected from the group consisting of compounds having ethylenically unsaturated bonds and anionic functional groups or salts thereof.
- Examples of the monomer (B) include (meth) acrylic acid and a salt thereof, carboxyethyl (meth) acrylic acid and a salt thereof, polystyrene sulfonic acid and a salt thereof, a dicarboxylic acid having an ethylenically unsaturated bond, a half ester thereof, and the like. Examples thereof include salts thereof.
- the (meth) acrylate is preferably composed of a salt of (meth) acrylate and a monovalent cation, preferably sodium (meth) acrylate, potassium (meth) acrylate, and ammonium (meth) acrylate. Among them, it is more preferable to contain at least one selected from sodium (meth) acrylate and ammonium (meth) ammonium acrylate, and sodium acrylate is most preferable.
- the (meth) acrylic acid salt is obtained by neutralizing (meth) acrylic acid with, for example, hydroxide, aqueous ammonia, or the like, but from the viewpoint of easy availability, it can be neutralized with sodium hydroxide. preferable.
- the monomer (B) contains 60% by mass or more of a salt of a compound having an ethylenically unsaturated bond and an anionic functional group (here, the monomer (B1) may be used). Is more preferable, 80% by mass or more is more preferable, and 95% by mass or more is further preferable.
- the anionic functional group (anion) of the monomer (B2) is contained.
- the valence of valence ⁇ the number of moles of anion, the same applies hereinafter) is considered to form a salt by the equivalent of the cation contained in the neutralizing agent (the valence of the cation ⁇ the number of moles of the cation, the same applies hereinafter).
- the equivalent of the cation contained in the neutralizing agent is larger than the anion equivalent of the monomer (B2) used for the polymerization, it is considered that all the monomers (B2) form a salt.
- the equivalent of the cation contained in the neutralizing agent is smaller than the anion equivalent of the monomer (B2) used for the polymerization, it is considered that all the cations form a salt with the monomer (B2) (that is,). , The monomer (B2) forms a salt by the equivalent of the cation contained in the neutralizing agent).
- the monomer (C) is a carboxylic acid ester compound having an ethylenically unsaturated other than the monomer (A) and the monomer (B).
- the ethylenically unsaturated carboxylic acid ester compound include (meth) acrylic acid ester and vinyl carboxylate.
- the monomer (C) may contain only one kind of compound, or may contain two or more kinds of compounds.
- An example of the (meth) acrylic acid ester will be described later.
- Examples of vinyl carboxylate include vinyl acetate, vinyl propionate, vinyl benzoate and the like.
- the monomer (C) preferably contains a (meth) acrylic acid ester, and may contain at least one of a (meth) acrylic acid ester and a (meth) acrylic acid alkyl ester of an aromatic alcohol. More preferably, it contains a (meth) acrylic acid ester of an aromatic alcohol.
- Examples of the (meth) acrylic acid ester of the aromatic alcohol include benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxyethylene glycol (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, and phenoxypolyethylene glycol (meth). ) Acrylate, ethoxylated-o-phenylphenol (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate and the like.
- the monomer (C) more preferably contains benzyl (meth) acrylate and phenoxyethyl (meth) acrylate.
- Examples of the (meth) acrylic acid alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and n- (meth) acrylic acid. Examples thereof include butyl and -2-ethylhexyl (meth) acrylate.
- the monomer (C) may contain one or more compounds represented by the following formula (2).
- R 3 , R 4 , and R 6 are each independently a hydrogen atom or an alkyl group having 1 or more and 5 or less carbon atoms.
- R 5 is an alkyl group having 1 or more and 6 or less carbon atoms, and is derived from R 4. Also has a large number of carbon atoms.
- N is an integer of 1 or more, m is an integer of 0 or more, and n + m ⁇ 20.
- R 3, R 4, R 6 is more preferably each independently hydrogen atom or C 1 to 3 alkyl group carbon
- R 3, R 4, R 6 are each independently hydrogen It is more preferably an atom or a methyl group. It is particularly preferred that R 6 is a methyl group.
- R 5 is preferably an alkyl group having 1 or more carbon atoms and 6 or less carbon atoms. R 5 has more carbon atoms than R 4.
- the electrode when the electrode is produced by using the copolymer (cP) as an electrode binder for the electrode active material, the flexibility of the electrode is improved. This is because the occurrence of cracks is suppressed. From this point of view, it is more preferable that n + m ⁇ 30, and it is further preferable that n + m ⁇ 40. Further, n + m ⁇ 500 is more preferable, n + m ⁇ 200 is further preferable, and n + m ⁇ 150 is particularly preferable. This is because the binder has a higher binding force.
- the formula (2) is limited to include n structural units including R 4 and m structural units including R 5 , the arrangement of these structural units is not limited. That is, when m ⁇ 1, the portion of the polyoxyalkylene chain of the formula (2) may have a block structure in which all or part of the structural units are continuous, and the two structural units alternate. It may be a structure arranged with periodic regularity such as an arranged structure, or a structure in which two structural units are randomly arranged.
- the preferred form of the polyoxyalkylene chain of the formula (2) is a structure arranged with periodic regularity or a structure arranged at random. This is to suppress the bias of the distribution of each structural unit in the molecular chain forming the formula (2).
- a more preferable form of the polyoxyalkylene chain of the formula (2) is a randomly arranged structure. This is because polymerization can be carried out with a radical polymerization initiator without using a special catalyst, and the manufacturing cost can be reduced.
- examples of preferable combinations of R 3 , R 4 , R 5 , R 6 , n, and m include the examples in Table 1 below.
- methoxypolyethylene glycol methacrylate is VISIOMER® MPEG5005 MA W manufactured by EVONIK INDUSTRIES.
- R 3 CH 3
- R 4 H
- R 6 CH 3
- n 113
- m 0.
- Examples of other (meth) acrylic acid esters include (meth) acrylic acid-2-hydroxyethyl, (meth) acrylic acid-2-hydroxypropyl, and (meth) acrylic acid-4-hydroxybutyl.
- Examples of the other monomer (D) that does not fall under any of the monomer (A), the monomer (B), and the monomer (C) include vinyl alcohol, (meth) acrylonitrile, styrene, and styrene. Derivatives and the like can be mentioned.
- the vinyl alcohol may contain a product obtained by subjecting an ester such as vinyl acetate as a monomer to a treatment such as saponification after polymerization.
- the content of the structural unit (a) is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, further preferably 3.0% by mass or more, and 7. It is particularly preferable that it is 0% by mass or more. This is because it is possible to produce an electrode slurry having excellent dispersibility of the electrode active material, the conductive auxiliary agent, etc. at the time of producing the electrode slurry, which will be described later, and having good coatability.
- the content of the structural unit (a) is preferably 20.0% by mass or less, more preferably 15.0% by mass or less, and further preferably 12.5% by mass or less. This is because the occurrence of cracks in the electrodes, which will be described later, is suppressed and the productivity of the electrodes is improved.
- the content of the structural unit (b) is preferably 50.0% by mass or more, more preferably 60.0% by mass or more, and further preferably 70.0% by mass or more. This is because it is possible to obtain an electrode active material layer having high peel strength with respect to the current collector.
- the content of the structural unit (b) is preferably 98.0% by mass or less, more preferably 94.5% by mass or less, further preferably 93.0% by mass or less, and 90. It is particularly preferable that it is 0% by mass or less. This is because the dispersibility of solids such as the electrode active material and the conductive auxiliary agent at the time of producing the electrode slurry described later is further improved.
- the content of the aromatic alcohol in the copolymer (cP) of the structural unit derived from the (meth) acrylic acid ester is preferably 0.3% by mass or more, preferably 0.5. It is more preferably 3% by mass or more, further preferably 3.0% by mass or more, and particularly preferably 6.0% by mass or more. This is because the occurrence of cracks in the electrodes, which will be described later, is suppressed and the productivity of the electrodes is improved.
- the content of the aromatic alcohol in the copolymer (cP) of the structural unit derived from the (meth) acrylic acid ester is preferably 28.0% by mass or less, 23.0.
- the content of the structural units derived from the compound represented by the formula (2) in the copolymer (cP) is preferably 0.3% by mass or more, preferably 0.9% by mass. % Or more, more preferably 3.0% by mass or more.
- the content of the structural units derived from the compound represented by the formula (2) in the copolymer (cP) is preferably 18.0% by mass or less, preferably 12.0% by mass. % Or less, more preferably 7.0% by mass or less. This is to suppress the occurrence of cracks in the electrode, which will be described later, to improve the peel strength of the electrode active material layer, and to suppress the swelling of the electrode active material layer. This is also to improve the cycle characteristics (discharge capacity retention rate) in the non-aqueous secondary battery described later.
- the copolymer (cP) is preferably synthesized by radical polymerization in an aqueous medium.
- the polymerization method for example, a method of charging all the monomers used for polymerization in a batch and polymerizing, a method of polymerizing while continuously supplying the monomers used for polymerization, and the like can be applied.
- the content of each monomer in all the monomers used for the synthesis of the copolymer (cP) is regarded as the content of the structural unit corresponding to the monomer in the copolymer (cP).
- the content of the monomer (A) in all the monomers used for the synthesis of the copolymer (cP) is the content of the structural unit (a) in the copolymer (cP) to be synthesized.
- the monomer (B) contains a monomer (B2) that does not form a salt
- the anionic functional group of the monomer (B2) is salted by the equivalent of the cation contained in the neutralizing agent. Is considered to have formed.
- the equivalent of the cation contained in the neutralizing agent is larger than the anion equivalent of the monomer (B2) used for the polymerization, it is considered that all the monomers (B2) form a salt.
- the equivalent of the cation contained in the neutralizing agent is smaller than the anion equivalent of the monomer (B2) used for the polymerization, it is considered that all the cations form a salt with the monomer (B2) (that is,). , The monomer (B2) forms a salt by the equivalent of the cation contained in the neutralizing agent).
- the radical polymerization is preferably carried out at a temperature of 30 to 90 ° C., although it depends on the type of the polymerization initiator. Specific examples of the copolymer (cP) polymerization method will be described in detail in Examples described later.
- radical polymerization initiator examples include, but are not limited to, ammonium persulfate, potassium persulfate, hydrogen peroxide, t-butyl hydroperoxide, and azo compounds.
- examples of the azo compound include 2,2'-azobis (2-methylpropionamidine) dihydrochloride.
- a radical polymerization initiator and a reducing agent may be used in combination at the time of polymerization for redox polymerization.
- the reducing agent examples include sodium bisulfite, longalit, ascorbic acid and the like.
- water to which a hydrophilic solvent is added may be used as the aqueous medium as long as the polymerization stability of the obtained copolymer (cP) is not impaired.
- the hydrophilic solvent added to water include methanol, ethanol, N-methylpyrrolidone and the like.
- Binder composition for non-aqueous secondary battery electrodes is an aqueous electrode binder and an aqueous medium. Includes medium. Further, the electrode binder composition may contain other components such as a pH adjuster and a surfactant, if necessary.
- the aqueous medium contained in the electrode binder composition contains water.
- the aqueous medium contained in the electrode binder composition may contain a hydrophilic solvent.
- the hydrophilic solvent include methanol, ethanol, N-methylpyrrolidone and the like.
- the content of water in the aqueous medium is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more. ..
- the aqueous medium contained in the electrode binder composition may be the same as the aqueous medium used for the synthesis of the polymer (P), or may be a solvent such as water added to the aqueous medium.
- the content of the polymer (P) in 100 g of the aqueous medium is preferably higher than the solubility of the polymer (P) in 100 g of water at 23 ° C.
- the solubility of the polymer (P) in water is less than 3.09 g / 100 g, the condition is satisfied if the content of the polymer (P) is 3.09 g or more with respect to 100 g of the aqueous medium (in water). Sufficient conditions for the polymer (P) not to be completely dissolved).
- the polymer (P) is dispersed in an aqueous medium.
- the fact that the polymer (P) is dispersed means that the supernatant and the polymer (P) do not precipitate even after being allowed to stand at 23 ° C. for 24 hours, and the turbid state is maintained. do.
- the content of the electrode binder in the electrode binder composition is preferably 30% by mass or less, more preferably 20% by mass or less. This is to suppress an increase in the viscosity of the electrode binder composition and efficiently disperse the electrode active material or the like when the electrode slurry is prepared by mixing with the electrode active material or the like described later.
- the content of the electrode binder in the electrode binder composition is preferably 3.0% by mass or more, more preferably 5.0% by mass or more, and further preferably 8.0% by mass or more. .. This is because the electrode slurry and the electrode can be produced from a smaller amount of the electrode binder composition.
- the pH of the electrode binder composition is preferably 4.0 or higher, more preferably 5.0 or higher, and even more preferably 6.0 or higher. This is to efficiently disperse the electrode active material and the like when the electrode slurry is prepared by mixing with the electrode active material and the like described later.
- the pH of the electrode binder composition is preferably 10 or less, more preferably 9.0 or less, and even more preferably 8.0 or less. This is to efficiently disperse the electrode active material and the like when the electrode slurry is prepared by mixing with the electrode active material and the like described later.
- the pH is a value measured by a pH meter at a liquid temperature of 23 ° C.
- the electrode binder and the electrode active material are an aqueous medium. Dissolved or dispersed in.
- the electrode slurry of the present embodiment may contain a conductive auxiliary agent, a thickener and the like, if necessary, but it is preferable that the electrode slurry does not contain a thickener in order to simplify the process of producing the electrode slurry.
- the method for preparing the electrode slurry is not particularly limited, and examples thereof include a method of mixing necessary components using a mixing device such as a stirring type, a rotary type, or a shaking type.
- the non-volatile content concentration of the electrode slurry is preferably 30% by mass or more, more preferably 40% by mass or more. This is to form a larger electrode active material layer with a smaller amount of electrode slurry.
- the non-volatile content concentration of the electrode slurry is preferably 70% by mass or less, more preferably 60% by mass or less. The non-volatile content concentration can be adjusted by the amount of the aqueous medium.
- the non-volatile content concentration means that, unless otherwise specified, 1 g of the mixture is weighed in an aluminum dish having a diameter of 5 cm, dried at 130 ° C. for 1 hour while circulating air in a dryer at atmospheric pressure, and the remaining components. The ratio of mass to mass before drying.
- Electrode binder content The content of the electrode binder in the electrode slurry is preferably 0.5% by mass or more with respect to the total mass of the electrode active material (described later), the conductive auxiliary agent (described later), and the electrode binder. It is more preferably 1.0% by mass or more, and further preferably 2.0% by mass or more. This is because the electrode binder can ensure the binding property between the electrode active materials and between the electrode active material and the current collector.
- the content of the electrode binder in the electrode slurry is preferably 7.0% by mass or less, preferably 5.0% by mass or less, based on the total mass of the electrode active material, the conductive auxiliary agent, and the electrode binder. More preferably, it is more preferably 4.0% by mass or less. This is because the charge / discharge capacity of the electrode active material layer formed from the electrode slurry can be increased, and the internal resistance of the battery can be reduced.
- the non-aqueous secondary battery is not particularly limited, and in the case of a lithium ion secondary battery, examples of the negative electrode active material include a conductive polymer, a carbon material, lithium titanate, silicon, a silicon compound and the like.
- examples of the conductive polymer include polyacetylene and polypyrrole.
- examples of the carbon material include coke such as petroleum coke, pitch coke, and coal coke; carbon dioxide of organic compounds, carbon fiber, carbon black such as acetylene black; and graphite such as artificial graphite and natural graphite.
- Examples of the silicon compound include SiO x (0.1 ⁇ x ⁇ 2.0).
- the negative electrode active material a composite material (Si / graphite) containing Si and graphite may be used.
- these active materials it is preferable to use a carbon material, lithium titanate, silicon, or a silicon compound because the energy density per volume is large.
- a carbide of an organic compound, a carbon material such as graphite, or a silicon-containing material such as SiO x (0.1 ⁇ x ⁇ 2.0), Si, Si / graphite is used, the electrode binder of the present embodiment is used. The effect of improving the binding property is remarkable.
- specific examples of artificial graphite include SCMG (registered trademark) -XRs (manufactured by Showa Denko KK).
- As the negative electrode active material two or more kinds of the materials listed here may be combined.
- lithium cobalt oxide LiCoO 2
- lithium composite oxide containing nickel spinel-type lithium manganate (LiMn 2 O 4 ); olivine-type iron phosphate lithium; TiS 2 , MnO 2, MoO 3, V 2 O chalcogen compounds such as 5 and the like.
- the positive electrode active material may contain any one of these compounds alone, or may contain a plurality of types. In addition, oxides of other alkali metals can also be used.
- the lithium composite oxide containing nickel include a Ni—Co—Mn-based lithium composite oxide, a Ni—Mn—Al based lithium composite oxide, and a Ni—Co—Al based lithium composite oxide.
- Specific examples of the positive electrode active material include LiNi 1/3 Mn 1/3 Co 1/3 O 2 and LiNi 3/5 Mn 1/5 Co 1/5 .
- the electrode slurry may contain carbon black, vapor phase carbon fiber, or the like as the conductive auxiliary agent.
- vapor phase carbon fiber include VGCF (registered trademark) -H (Showa Denko KK).
- the aqueous medium of the electrode slurry contains water.
- the aqueous medium of the electrode slurry may contain a hydrophilic solvent.
- the hydrophilic solvent include methanol, ethanol, N-methylpyrrolidone and the like.
- the content of water in the aqueous medium is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more.
- the aqueous medium may be the same as the medium contained in the electrode binder composition.
- the electrode of the present embodiment has a current collector and an electrode active material layer formed on the surface of the current collector.
- the electrode active material layer contains the electrode active material and the electrode binder of the present embodiment.
- Examples of the shape of the electrode include a laminated body and a wound body, but the shape is not particularly limited.
- the current collector is preferably a sheet-shaped metal having a thickness of 0.001 to 0.5 mm. Examples of the metal include iron, copper, aluminum, nickel, stainless steel and the like.
- the non-aqueous secondary battery is a lithium ion secondary battery
- aluminum is preferable as the material of the positive electrode current collector
- copper is preferable as the material of the negative electrode current collector.
- the electrode of the present embodiment can be manufactured, for example, by applying an electrode slurry on a current collector and drying it, but the method is not limited to this method.
- Examples of the method for applying the electrode slurry onto the current collector include a reverse roll method, a direct roll method, a doctor blade method, a knife method, an extrusion method, a curtain method, a gravure method, a bar method, a dip method and a squeeze method. Can be mentioned.
- the doctor blade method, the knife method, or the extrusion method is preferable, and it is more preferable to apply using the doctor blade. This is because it is suitable for various physical properties such as viscosity of the electrode slurry and drying property, and a coating film having a good surface condition can be obtained.
- the electrode slurry may be applied to only one side of the current collector or may be applied to both sides. When the electrode slurry is applied to both sides of the current collector, it may be applied to each side or both sides at the same time. Further, the electrode slurry may be continuously applied to the surface of the current collector, or may be applied intermittently.
- the coating amount and coating range of the electrode slurry can be appropriately determined according to the size of the battery and the like.
- the basis weight of the electrode active material layer after drying is preferably 4 to 20 mg / cm 2 , and more preferably 6 to 16 mg / cm 2 .
- An electrode sheet can be obtained by drying the electrode slurry applied to the current collector.
- the drying method is not particularly limited, and for example, hot air, vacuum, (far) infrared rays, electron beams, microwaves, and low temperature air can be used alone or in combination.
- the drying temperature is preferably 40 ° C. or higher and 180 ° C. or lower, and the drying time is preferably 1 minute or longer and 30 minutes or lower.
- the electrode sheet may be used as it is as an electrode, but it may be cut to obtain an appropriate size and shape as an electrode.
- the method for cutting the electrode sheet is not particularly limited, but for example, a slit, a laser, a wire cut, a cutter, a Thomson, or the like can be used.
- the electrode active material is firmly bound to the electrode, and the electrode can be made thinner, so that the non-aqueous battery can be made compact.
- a pressing method a general method can be used, and it is particularly preferable to use a die pressing method or a roll pressing method.
- the press pressure is not particularly limited, but is preferably 0.5 to 5 t / cm 2 , which is a range that does not affect the doping / dedoping of lithium ions or the like on the electrode active material by the press.
- a lithium ion secondary battery will be described as a preferred example of the battery according to the present embodiment, but the battery configuration is not limited to the configuration described below.
- parts such as a positive electrode, a negative electrode, an electrolytic solution, and, if necessary, a separator are housed in an exterior body.
- At least one of the positive electrode and the negative electrode contains the electrode binder according to the present embodiment.
- Electrolyte As the electrolytic solution, a non-aqueous liquid having ionic conductivity is used. Examples of the electrolytic solution include a solution in which an electrolyte is dissolved in an organic solvent, an ionic liquid, and the like, but the former is preferable because a battery having a low manufacturing cost and a low internal resistance can be obtained.
- an alkali metal salt can be used and can be appropriately selected depending on the type of the electrode active material and the like.
- the electrolyte for example, LiClO 4, LiBF 6, LiPF 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiB 10 Cl 10, LiAlCl 4, LiCl, LiBr, LiB (C 2 H 5) 4 , CF 3 SO 3 Li, CH 3 SO 3 Li, LiCF 3 SO 3 , LiC 4 F 9 SO 3 , Li (CF 3 SO 2 ) 2 N, lithium aliphatic carboxylate and the like can be mentioned.
- other alkali metal salts can also be used as the electrolyte.
- the organic solvent that dissolves the electrolyte is not particularly limited, and is, for example, ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), dimethyl carbonate (DMC), and fluoroethylene carbonate.
- EC ethylene carbonate
- PC propylene carbonate
- DEC diethyl carbonate
- MEC methyl ethyl carbonate
- DMC dimethyl carbonate
- fluoroethylene carbonate ethylene carbonate
- Carbonic acid ester compounds such as (FEC) and vinylene carbonate (VC); nitrile compounds such as acetonitrile; carboxylic acid esters such as ethyl acetate, propyl acetate, methyl propionate, ethyl propionate and propyl propionate.
- the exterior body a metal, an aluminum laminated material, or the like can be appropriately used.
- the shape of the battery may be any shape such as a coin type, a button type, a sheet type, a cylindrical type, a square type, and a flat type.
- Monomer (A-1) N-vinylacetamide (NVA) (manufactured by Showa Denko KK)
- negative electrode binder compositions Q1 to Q7, and CQ1 to CQ8 were prepared.
- “each of the polymers P1 to P7 and CP1 to CP8” is referred to as “polymer (P)”
- “each of the negative electrode binder compositions Q1 to Q7 and CQ1 to CQ8” is referred to as “negative electrode binder composition”. It may be called "thing (Q)”.
- GPC device GPC-101 (manufactured by Showa Denko KK)) Solvent: 0.1M NaNO 3 aqueous solution
- Sample column Shodex Volume Ohpak SB-806 HQ (8.0 mm ID x 300 mm) x 2 Reference column: Shodex Colon Ohpak SB-800 RL (8.0 mm ID x 300 mm) x 2
- Column temperature 40 ° C
- Pump DU-H2000 (manufactured by Shimadzu Corporation) Pressure: 1.3MPa Flow rate: 1 ml / min
- Molecular weight standard Pullulan (P-5, P-10, P-20, P-50, P-100, P-200, P-400, P-800, P-1300, P-2500 (Showa Denko KK) Made))
- Viscosity> The viscosity of the negative electrode binder composition (Q) was measured by a Brookfield type viscometer (manufactured by Toki Sangyo) at a liquid temperature of 23 ° C., a rotation speed of 10 rpm, and No. 5, No. 6 and No. It was measured using any of the rotors of 7. The rotor is selected according to the viscosity of each sample.
- the viscosity of the negative electrode binder composition (Q) according to each Example and Comparative Example is the viscosity of an aqueous solution or an aqueous dispersion containing 10% by mass of the polymer (P) at 23 ° C.
- the pH of the electrode binder composition (Q) was measured using a pH meter (manufactured by DKK-TOA Corporation) at a liquid temperature of 23 ° C.
- the prepared positive electrode slurry was placed on one side of an aluminum foil (current collector) having a thickness of 20 ⁇ m by the doctor blade method, and the basis weight after drying was 22.5 mg / cm 2 (22.5 ⁇ 10 -3 g / cm 2 ). It was applied using a doctor blade so as to be.
- the aluminum foil coated with the positive electrode slurry was dried at 120 ° C. for 5 minutes and then pressed by a roll press to prepare a positive electrode sheet on which a positive electrode active material layer having a thickness of 100 ⁇ m was formed.
- the obtained positive electrode sheet was cut into 20 mm ⁇ 20 mm (2.0 cm ⁇ 2.0 cm), and a conductive tab was attached to prepare a positive electrode.
- the theoretical capacity of the prepared positive electrode is the amount of the positive electrode slurry after drying (22.5 ⁇ 10 -3 g / cm 2 ) ⁇ the coating area of the positive electrode slurry (2.0 cm ⁇ 2.0 cm) ⁇ LiNi 1/3 Mn. 1/3 Co 1/3 O 2 capacity as positive electrode active material (160 mAh / g) x LiNi 1/3 Mn 1/3 Co 1/3 O 2 ratio (0.90) in solid content , The calculated value is 13 mAh.
- a mixed solvent was prepared by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and fluoroethylene carbonate (FEC) at a volume ratio of 30:60:10.
- An electrolytic solution was prepared by dissolving LiPF 6 in this mixed solvent at a concentration of 1.0 mol / L and vinylene carbonate (VC) at a concentration of 1.0% by mass.
- Battery assembly> The positive electrode and the negative electrode were arranged so that the active material layers faced each other via a separator made of a polyolefin porous film, and were housed in an aluminum laminated exterior body (battery pack). An electrolytic solution was injected into this exterior body and packed with a vacuum heat sealer to obtain a laminated battery.
- the average value (mN) of the peeling force at the peeling length of 10 to 45 mm was calculated, and the value obtained by dividing the average value of the peeling force by the width of the test piece of 25 mm was the peeling strength (mN / mN /) of the negative electrode active material layer. mm).
- peeling between the double-sided tape and the SUS plate and interfacial peeling between the double-sided tape and the negative electrode active material layer did not occur during the test.
- the initial efficiency of the battery was measured under the condition of 25 ° C. according to the following procedure. First, it was charged with a current of 0.2 C until it reached 4.2 V (CC charging), and then it was charged with a voltage of 4.2 V until it reached a current of 0.05 C (CV charging). After leaving it for 30 minutes, it was discharged (CC discharge) with a current of 0.2 C until the voltage reached 2.75 V. A series of operations of CC charging, CV charging, and CC discharging were set as one cycle, and 5 cycles were repeated.
- the sum of the time integral values of the currents in the nth cycle CC charge and CV charge is the charge capacity (mAh) in the nth cycle
- the time integral value of the current in the CC discharge in the nth cycle is the discharge capacity (mAh) in the nth cycle.
- the average value of the discharge capacities in the 4th cycle and the 5th cycle was used as the initial discharge capacity, and the initial efficiency was calculated by the following formula [1].
- the positive electrode theoretical capacity is a value obtained in the description of manufacturing the positive electrode.
- Negative electrode swelling The electrode swelling of the negative electrode was measured by the following procedure. First, before assembling the battery, the thickness of the negative electrode was measured at 5 points using a micrometer (MDH-25MB manufactured by Mitutoyo Co., Ltd.), and the average value was taken as the initial thickness ( ⁇ m). Next, the battery was assembled, and after the above initial efficiency was measured, CC charging and CV charging were performed in the same manner as described above to fully charge the battery. Then, the battery was disassembled, the negative electrode was taken out, the thickness of the negative electrode was measured at 5 points without drying, and the average value was taken as the dismantling thickness ( ⁇ m). The negative electrode swelling was calculated by the following formula [2].
- Negative electrode swelling (%) ⁇ 1- (thickness at the time of dismantling / initial thickness) ⁇ x 100 [2]
- Battery discharge capacity retention rate (100 cycles)> The measurement of the battery discharge capacity retention rate (battery charge / discharge cycle test) was performed under the condition of 25 ° C. according to the following procedure. First, it was charged with a current of 1 C until the voltage reached 4.2 V (CC charging), and then charged with a voltage of 4.2 V until the current reached 0.05 C (CV charging). After leaving it for 30 minutes, it was discharged with a current of 1 C until the voltage reached 2.75 V (CC discharge). A series of operations of CC charging, CV charging, and CC discharging is regarded as one cycle.
- the sum of the time integral values of the currents in the nth cycle CC charge and CV charge is the charge capacity (mAh) in the nth cycle
- the time integral value of the current in the CC discharge in the nth cycle is the discharge capacity (mAh) in the nth cycle.
- the discharge capacity retention rate in the nth cycle of the battery is the ratio (%) of the discharge capacity in the nth cycle to the discharge capacity in the first cycle. In this example and the comparative example, the discharge capacity retention rate at the 100th cycle was evaluated.
- the negative electrodes produced in Examples 1 to 7 have few cracks and the peel strength of the electrode active material layer with respect to the current collector is high. It can be seen that when the negative electrodes produced in Examples 1 to 7 are incorporated into a lithium ion secondary battery, the swelling of the negative electrode due to the use of the battery is small.
- the lithium ion secondary batteries produced in Examples 1 to 7 have a negative electrode having few cracks and high peel strength of the electrode active material layer with respect to the current collector.
- the lithium ion secondary batteries produced in Examples 1 to 7 have high initial efficiency and discharge capacity retention rate, and can suppress swelling of the negative electrode.
- the polymers CP1 to CP3 of Comparative Examples 1 to 3 and the polymers CP5 to CP8 of Comparative Examples 5 to 8 are all 10% by mass of water at a liquid temperature of 23 ° C. measured at a rotation speed of 10 rpm by a Brookfield type viscometer. The viscosity of the dispersion is low.
- Each of these comparative examples corresponded to at least one of whether cracks were found in the negative electrode or the peel strength of the negative electrode active material layer was low.
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
Provided are a binder for a non-aqueous secondary battery electrode and a slurry for a non-aqueous secondary battery electrode that are capable of greatly improving the peel strength of an electrode active material layer relative to a current collector while suppressing the occurrence of cracks in the electrode active material layer, which is formed on the current collector. The binder for a non-aqueous secondary battery electrode includes a polymer having a solubility in water at 23°C of less than 11.1 g/100 g and a weight-average molecular weight of 600,000-7,500,000 (inclusive), the viscosity of a 10 mass% aqueous dispersion of the polymer at a solution temperature of 23°C measured at a rotation speed of 10 rpm by a Brookfield viscometer being 27,000-100,000 mPa·s (inclusive).
Description
本発明は、非水系二次電池電極用バインダー及び非水系二次電池電極用スラリーに関する。
本願は、2020年6月5日に、日本に出願された特願2020-098515号に基づき優先権を主張し、その内容をここに援用する。 The present invention relates to a binder for a non-aqueous secondary battery electrode and a slurry for a non-aqueous secondary battery electrode.
This application claims priority based on Japanese Patent Application No. 2020-098515 filed in Japan on June 5, 2020, the contents of which are incorporated herein by reference.
本願は、2020年6月5日に、日本に出願された特願2020-098515号に基づき優先権を主張し、その内容をここに援用する。 The present invention relates to a binder for a non-aqueous secondary battery electrode and a slurry for a non-aqueous secondary battery electrode.
This application claims priority based on Japanese Patent Application No. 2020-098515 filed in Japan on June 5, 2020, the contents of which are incorporated herein by reference.
非水系電解質を用いる二次電池(非水系二次電池)は高電圧化、小型化、軽量化の面において水系電解質を用いる二次電池よりも優れている。そのため、非水系二次電池は、ノート型パソコン、携帯電話、電動工具、電子・通信機器の電源として広く使用されている。また、最近では環境車両適用の観点から電気自動車やハイブリッド自動車用にも非水系電池が使用されているが、高出力化、高容量化、長寿命化等が強く求められてきている。非水系二次電池としてリチウムイオン二次電池が代表例として挙げられる。
A secondary battery using a non-aqueous electrolyte (non-aqueous secondary battery) is superior to a secondary battery using an aqueous electrolyte in terms of high voltage, miniaturization, and weight reduction. Therefore, non-aqueous secondary batteries are widely used as power sources for notebook computers, mobile phones, power tools, and electronic / communication devices. Recently, non-aqueous batteries have been used for electric vehicles and hybrid vehicles from the viewpoint of application to environmental vehicles, but there is a strong demand for higher output, higher capacity, longer life, and the like. As a non-aqueous secondary battery, a lithium ion secondary battery is a typical example.
非水系二次電池は、金属酸化物などを活物質とした正極と、黒鉛等の炭素材料を活物質とした負極と、カーボネート類または難燃性のイオン液体を中心した非水系電解液溶剤とを備える。非水系二次電池は、イオンが正極と負極との間を移動することにより電池の充放電が行われる二次電池である。詳細には、正極は、金属酸化物とバインダーから成るスラリーをアルミニウム箔などの正極集電体表面に塗布し、乾燥させた後に、適当な大きさに切断することにより得られる。負極は、炭素材料とバインダーから成るスラリーを銅箔などの負極集電体表面に塗布し、乾燥させた後に、適当な大きさに切断することにより得られる。バインダーは、正極及び負極において活物質同士及び活物質と集電体を結着させ、集電体からの活物質の剥離を防止させる役割がある。
Non-aqueous secondary batteries include a positive electrode using a metal oxide as an active material, a negative electrode using a carbon material such as graphite as an active material, and a non-aqueous electrolyte solvent mainly composed of carbonates or flame-retardant ionic liquids. To prepare for. A non-aqueous secondary battery is a secondary battery in which ions move between a positive electrode and a negative electrode to charge and discharge the battery. Specifically, the positive electrode is obtained by applying a slurry composed of a metal oxide and a binder to the surface of a positive electrode current collector such as an aluminum foil, drying the slurry, and then cutting the slurry into an appropriate size. The negative electrode is obtained by applying a slurry composed of a carbon material and a binder to the surface of a negative electrode current collector such as a copper foil, drying the slurry, and then cutting the slurry into an appropriate size. The binder has a role of binding the active materials to each other and the active material and the current collector at the positive electrode and the negative electrode, and prevents the active material from peeling off from the current collector.
バインダーとしては、有機溶剤系のN-メチル-2-ピロリドン(NMP)を溶剤としたポリフッ化ビニリデン(PVDF)系バインダーがよく知られている。しかしながら、このバインダーは活物質同士及び活物質と集電体との結着性が低く、実際に使用するには多量のバインダーを必要とする。そのため、非水系二次電池の容量が低下する欠点がある。また、バインダーに高価な有機溶剤であるNMPを使用しているため、製造コストを抑えることが困難であった。
As a binder, a polyvinylidene fluoride (PVDF) -based binder using an organic solvent-based N-methyl-2-pyrrolidone (NMP) as a solvent is well known. However, this binder has low binding properties between active materials and between active materials and current collectors, and requires a large amount of binder for actual use. Therefore, there is a drawback that the capacity of the non-aqueous secondary battery is reduced. Further, since NMP, which is an expensive organic solvent, is used as the binder, it is difficult to suppress the production cost.
これらの問題を解決する方法として、水分散系バインダーの開発が進められている。水分散系バインダーとして、例えば、カルボキシメチルセルロース(CMC)増粘剤として併用したスチレン-ブタジエンゴム(SBR)系の水分散体が知られている。
As a method to solve these problems, the development of an aqueous dispersion binder is underway. As the water dispersion type binder, for example, a styrene-butadiene rubber (SBR) type water dispersion used in combination as a carboxymethyl cellulose (CMC) thickener is known.
特許文献1では、アクリル酸ナトリウム-N-ビニルアセトアミド共重合体を含む貼付材用粘着剤組成物が開示されている。また、特許文献2では、アクリル酸ナトリウム-N-ビニルアセトアミド(55/45(モル比))共重合体を含む含水ゲル体用組成物が開示されている。
Patent Document 1 discloses a pressure-sensitive adhesive composition for a patch containing a sodium acrylate-N-vinylacetamide copolymer. Further, Patent Document 2 discloses a composition for a hydrogel containing a sodium acrylate-N-vinylacetamide (55/45 (molar ratio)) copolymer.
特許文献3では、N-ビニルアセトアミド-アクリル酸ナトリウム共重合体(共重合比:N-ビニルアセトアミド/アクリル酸ナトリウム=10/90質量比)を含む非水系電池電極用バインダーが開示されている。
Patent Document 3 discloses a binder for non-aqueous battery electrodes containing an N-vinylacetamide-sodium acrylate copolymer (copolymerization ratio: N-vinylacetamide / sodium acrylate = 10/90 mass ratio).
特許文献4では、N-ビニルアセトアミド由来の構造単位と、(メタ)アクリル酸ナトリウム由来の構造単位と、メトキシポリエチレングリコールメタクリレート由来の構造単位と、を含む非水系電池電極用バインダー用共重合体が記載されている。
In Patent Document 4, a copolymer for a binder for a non-aqueous battery electrode containing a structural unit derived from N-vinylacetamide, a structural unit derived from sodium (meth) acrylate, and a structural unit derived from methoxypolyethylene glycol methacrylate is described. Has been described.
しかしながら、特許文献1に記載のSBR系バインダーは、増粘剤であるカルボキシメチルセルロースを併用する必要があり、スラリー作製工程が複雑である。かつこのバインダーにおいても活物質同士、及び活物質と集電体との結着性が足りず、少量のバインダーで電極を生産した場合に、集電体を切断する工程で活物質の一部が剥離する問題があった。
However, the SBR-based binder described in Patent Document 1 needs to be used in combination with carboxymethyl cellulose, which is a thickener, and the slurry preparation process is complicated. Moreover, even in this binder, the binding property between the active materials and the active material and the current collector is insufficient, and when the electrode is produced with a small amount of the binder, a part of the active material is separated in the process of cutting the current collector. There was a problem of peeling.
特許文献1及び2に開示されているアクリル酸ナトリウム-N-ビニルアセトアミド共重合体は、N-ビニルアセトアミド由来の成分を多く含んでいる。このような重合体を負極活物質及び水と混合して電極用スラリーとした場合、スラリーに凝集物が発生しやすい。
The sodium acrylate-N-vinylacetamide copolymer disclosed in Patent Documents 1 and 2 contains a large amount of components derived from N-vinylacetamide. When such a polymer is mixed with a negative electrode active material and water to form an electrode slurry, agglomerates are likely to be generated in the slurry.
特許文献3で開示されている非水系電池電極用バインダーでは、後述する比較例1に示されるように、膜厚が厚い、つまり目付量が大きな電極では、クラックが発生しやすくなるという課題があった。
The binder for non-aqueous battery electrodes disclosed in Patent Document 3 has a problem that cracks are likely to occur in an electrode having a thick film thickness, that is, a large basis weight, as shown in Comparative Example 1 described later. rice field.
特許文献4に記載の非水系電池電極用バインダーは、後述する比較例2に示されているように、集電体に対する電極活物質層の剥離強度に向上の余地がある。
The binder for non-aqueous battery electrodes described in Patent Document 4 has room for improvement in the peel strength of the electrode active material layer with respect to the current collector, as shown in Comparative Example 2 described later.
そこで、本発明は、集電体上に形成された電極活物質層のクラックの発生を抑制しつつ、集電体に対する電極活物質層の剥離強度を大きく向上できる非水系二次電池電極用バインダー及び非水系二次電池電極用スラリーを提供することを目的とする。
また、本発明は、クラックが少なく、集電体に対する電極活物質層の剥離強度が高い非水系二次電池電極を提供することを目的とする。
さらに、本発明は、クラックが少なく、集電体に対する電極活物質層の剥離強度が高い電極を備えた非水系二次電池を提供することを目的とする。 Therefore, the present invention is a binder for a non-aqueous secondary battery electrode that can greatly improve the peeling strength of the electrode active material layer with respect to the current collector while suppressing the generation of cracks in the electrode active material layer formed on the current collector. An object of the present invention is to provide a slurry for a non-aqueous secondary battery electrode.
Another object of the present invention is to provide a non-aqueous secondary battery electrode having few cracks and high peel strength of the electrode active material layer with respect to the current collector.
Further, it is an object of the present invention to provide a non-aqueous secondary battery provided with an electrode having few cracks and high peel strength of the electrode active material layer with respect to the current collector.
また、本発明は、クラックが少なく、集電体に対する電極活物質層の剥離強度が高い非水系二次電池電極を提供することを目的とする。
さらに、本発明は、クラックが少なく、集電体に対する電極活物質層の剥離強度が高い電極を備えた非水系二次電池を提供することを目的とする。 Therefore, the present invention is a binder for a non-aqueous secondary battery electrode that can greatly improve the peeling strength of the electrode active material layer with respect to the current collector while suppressing the generation of cracks in the electrode active material layer formed on the current collector. An object of the present invention is to provide a slurry for a non-aqueous secondary battery electrode.
Another object of the present invention is to provide a non-aqueous secondary battery electrode having few cracks and high peel strength of the electrode active material layer with respect to the current collector.
Further, it is an object of the present invention to provide a non-aqueous secondary battery provided with an electrode having few cracks and high peel strength of the electrode active material layer with respect to the current collector.
上記課題を解決するために、本発明は以下の〔1〕~〔15〕の通りである。
In order to solve the above problems, the present invention is as follows [1] to [15].
〔1〕 23℃における水への溶解度が11.1g/100g未満であり、
重量平均分子量は、60万以上750万以下であり、
ブルックフィールド型粘度計によって、回転数10rpmで測定した液温23℃における10質量%の水分散液の粘度が、27000mPa・s以上100000mPa・s以下である重合体(P)を含む非水系二次電池電極用バインダー。
〔2〕 前記粘度は、29000mPa・s以上である〔1〕に記載の非水系二次電池電極用バインダー。
〔3〕 前記粘度は、70000mPa・s以下である〔1〕または〔2〕に記載の非水系二次電池電極用バインダー。
〔4〕 23℃における水への溶解度が5.26g/100g未満である、〔1〕~〔3〕のいずれかに記載の非水系二次電池電極用バインダー。
〔5〕 前記重合体(P)の重量平均分子量は500万以下である〔1〕~〔4〕のいずれかに記載の非水系二次電池電極用バインダー。
〔6〕 前記重合体(P)は、エチレン性不飽和結合を有する単量体の共重合体であって、アニオン性官能基を有する単量体に由来する構造単位と、極性官能基を有さない単量体に由来する構造単位とを含む共重合体である〔1〕~〔5〕のいずれかに記載の非水系二次電池電極用バインダー。
〔7〕 前記重合体(P)が、
エチレン性不飽和結合及びアミド結合を有する単量体(A)由来の構造単位(a)と、 エチレン性不飽和結合及びアニオン性官能基を有する化合物及びそれらの化合物の塩からなる群から選択される少なくとも1種である単量体(B)由来の構造単位(b)と、 単量体(A)及び単量体(B)以外のエチレン性不飽和結合を有するカルボン酸エステル化合物である単量体(C)由来の構造単位(c)と、
を有する共重合体(cP)である〔1〕~〔6〕のいずれかに記載の非水系二次電池電極用バインダー。
〔8〕 前記単量体(A)は、式(1)で表される化合物である〔7〕に記載の非水系二次電池電極用バインダー。
(式中、R1、R2は各々独立に水素原子または炭素数1以上5以下のアルキル基である。)
〔9〕 前記単量体(B)は、(メタ)アクリル酸及びその塩からなる群から選択されるいずれかを含む〔7〕または〔8〕に記載の非水系二次電池電極用バインダー。
〔10〕 前記共重合体(cP)において、構造単位(b)の含有率は50.0質量%以上である〔7〕~〔9〕のいずれかに記載の非水系二次電池電極用バインダー。
〔11〕 〔1〕~〔10〕のいずれかに記載の非水系二次電池電極用バインダーと、水性媒体とを含む非水系二次電池電極用バインダー組成物。
〔12〕 水性媒体100gに対する前記重合体(P)の含有量は、前記重合体(P)の23℃の水への前記溶解度よりも多く、水性媒体中に前記重合体(P)が分散している〔11〕に記載の非水系二次電池電極用バインダー組成物。
〔13〕 前記非水系二次電池は、リチウムイオン二次電池である〔11〕または〔12〕に記載の非水系二次電池電極用バインダー組成物。
〔14〕 〔1〕~〔10〕のいずれかに記載の非水系二次電池電極用バインダーと、電極活物質と、水性媒体とを含む非水系二次電池電極用スラリー。
〔15〕 集電体と、
前記集電体表面に形成された〔1〕~〔10〕のいずれかに記載の非水系二次電池電極用バインダー及び電極活物質を含む電極活物質層と
を有する非水系二次電池電極。 [1] The solubility in water at 23 ° C. is less than 11.1 g / 100 g.
The weight average molecular weight is 600,000 or more and 7.5 million or less.
A non-aqueous secondary containing a polymer (P) having a viscosity of 10% by mass of an aqueous dispersion at a liquid temperature of 23 ° C. measured by a Brookfield viscometer at a rotation speed of 10 rpm of 27,000 mPa · s or more and 100,000 mPa · s or less. Binder for battery electrodes.
[2] The binder for a non-aqueous secondary battery electrode according to [1], wherein the viscosity is 29000 mPa · s or more.
[3] The binder for a non-aqueous secondary battery electrode according to [1] or [2], wherein the viscosity is 70,000 mPa · s or less.
[4] The binder for a non-aqueous secondary battery electrode according to any one of [1] to [3], which has a solubility in water at 23 ° C. of less than 5.26 g / 100 g.
[5] The binder for a non-aqueous secondary battery electrode according to any one of [1] to [4], wherein the polymer (P) has a weight average molecular weight of 5 million or less.
[6] The polymer (P) is a copolymer of a monomer having an ethylenically unsaturated bond, and has a structural unit derived from a monomer having an anionic functional group and a polar functional group. The binder for a non-aqueous secondary battery electrode according to any one of [1] to [5], which is a copolymer containing a structural unit derived from a non-aqueous monomer.
[7] The polymer (P) is
Selected from the group consisting of a structural unit (a) derived from a monomer (A) having an ethylenically unsaturated bond and an amide bond, a compound having an ethylenically unsaturated bond and an anionic functional group, and a salt of those compounds. A carboxylic acid ester compound having an ethylenically unsaturated bond other than the structural unit (b) derived from the monomer (B), which is at least one kind, and the monomer (A) and the monomer (B). The structural unit (c) derived from the metric (C) and
The binder for a non-aqueous secondary battery electrode according to any one of [1] to [6], which is a copolymer (cP) having the above.
[8] The monomer (A) is a binder represented by the formula (1) for a non-aqueous secondary battery electrode according to [7].
(In the formula, R 1 and R 2 are each independently a hydrogen atom or an alkyl group having 1 or more and 5 or less carbon atoms.)
[9] The binder for a non-aqueous secondary battery electrode according to [7] or [8], wherein the monomer (B) contains any one selected from the group consisting of (meth) acrylic acid and a salt thereof.
[10] The binder for a non-aqueous secondary battery electrode according to any one of [7] to [9], wherein the content of the structural unit (b) in the copolymer (cP) is 50.0% by mass or more. ..
[11] A binder composition for a non-aqueous secondary battery electrode, which comprises the binder for a non-aqueous secondary battery electrode according to any one of [1] to [10] and an aqueous medium.
[12] The content of the polymer (P) in 100 g of the aqueous medium is larger than the solubility of the polymer (P) in water at 23 ° C., and the polymer (P) is dispersed in the aqueous medium. [11] The binder composition for a non-aqueous secondary battery electrode according to [11].
[13] The binder composition for a non-aqueous secondary battery electrode according to [11] or [12], wherein the non-aqueous secondary battery is a lithium ion secondary battery.
[14] A non-aqueous secondary battery electrode slurry containing the binder for a non-aqueous secondary battery electrode according to any one of [1] to [10], an electrode active material, and an aqueous medium.
[15] Current collector and
A non-aqueous secondary battery electrode having the binder for the non-aqueous secondary battery electrode according to any one of [1] to [10] formed on the surface of the current collector and an electrode active material layer containing the electrode active material.
重量平均分子量は、60万以上750万以下であり、
ブルックフィールド型粘度計によって、回転数10rpmで測定した液温23℃における10質量%の水分散液の粘度が、27000mPa・s以上100000mPa・s以下である重合体(P)を含む非水系二次電池電極用バインダー。
〔2〕 前記粘度は、29000mPa・s以上である〔1〕に記載の非水系二次電池電極用バインダー。
〔3〕 前記粘度は、70000mPa・s以下である〔1〕または〔2〕に記載の非水系二次電池電極用バインダー。
〔4〕 23℃における水への溶解度が5.26g/100g未満である、〔1〕~〔3〕のいずれかに記載の非水系二次電池電極用バインダー。
〔5〕 前記重合体(P)の重量平均分子量は500万以下である〔1〕~〔4〕のいずれかに記載の非水系二次電池電極用バインダー。
〔6〕 前記重合体(P)は、エチレン性不飽和結合を有する単量体の共重合体であって、アニオン性官能基を有する単量体に由来する構造単位と、極性官能基を有さない単量体に由来する構造単位とを含む共重合体である〔1〕~〔5〕のいずれかに記載の非水系二次電池電極用バインダー。
〔7〕 前記重合体(P)が、
エチレン性不飽和結合及びアミド結合を有する単量体(A)由来の構造単位(a)と、 エチレン性不飽和結合及びアニオン性官能基を有する化合物及びそれらの化合物の塩からなる群から選択される少なくとも1種である単量体(B)由来の構造単位(b)と、 単量体(A)及び単量体(B)以外のエチレン性不飽和結合を有するカルボン酸エステル化合物である単量体(C)由来の構造単位(c)と、
を有する共重合体(cP)である〔1〕~〔6〕のいずれかに記載の非水系二次電池電極用バインダー。
〔8〕 前記単量体(A)は、式(1)で表される化合物である〔7〕に記載の非水系二次電池電極用バインダー。
〔9〕 前記単量体(B)は、(メタ)アクリル酸及びその塩からなる群から選択されるいずれかを含む〔7〕または〔8〕に記載の非水系二次電池電極用バインダー。
〔10〕 前記共重合体(cP)において、構造単位(b)の含有率は50.0質量%以上である〔7〕~〔9〕のいずれかに記載の非水系二次電池電極用バインダー。
〔11〕 〔1〕~〔10〕のいずれかに記載の非水系二次電池電極用バインダーと、水性媒体とを含む非水系二次電池電極用バインダー組成物。
〔12〕 水性媒体100gに対する前記重合体(P)の含有量は、前記重合体(P)の23℃の水への前記溶解度よりも多く、水性媒体中に前記重合体(P)が分散している〔11〕に記載の非水系二次電池電極用バインダー組成物。
〔13〕 前記非水系二次電池は、リチウムイオン二次電池である〔11〕または〔12〕に記載の非水系二次電池電極用バインダー組成物。
〔14〕 〔1〕~〔10〕のいずれかに記載の非水系二次電池電極用バインダーと、電極活物質と、水性媒体とを含む非水系二次電池電極用スラリー。
〔15〕 集電体と、
前記集電体表面に形成された〔1〕~〔10〕のいずれかに記載の非水系二次電池電極用バインダー及び電極活物質を含む電極活物質層と
を有する非水系二次電池電極。 [1] The solubility in water at 23 ° C. is less than 11.1 g / 100 g.
The weight average molecular weight is 600,000 or more and 7.5 million or less.
A non-aqueous secondary containing a polymer (P) having a viscosity of 10% by mass of an aqueous dispersion at a liquid temperature of 23 ° C. measured by a Brookfield viscometer at a rotation speed of 10 rpm of 27,000 mPa · s or more and 100,000 mPa · s or less. Binder for battery electrodes.
[2] The binder for a non-aqueous secondary battery electrode according to [1], wherein the viscosity is 29000 mPa · s or more.
[3] The binder for a non-aqueous secondary battery electrode according to [1] or [2], wherein the viscosity is 70,000 mPa · s or less.
[4] The binder for a non-aqueous secondary battery electrode according to any one of [1] to [3], which has a solubility in water at 23 ° C. of less than 5.26 g / 100 g.
[5] The binder for a non-aqueous secondary battery electrode according to any one of [1] to [4], wherein the polymer (P) has a weight average molecular weight of 5 million or less.
[6] The polymer (P) is a copolymer of a monomer having an ethylenically unsaturated bond, and has a structural unit derived from a monomer having an anionic functional group and a polar functional group. The binder for a non-aqueous secondary battery electrode according to any one of [1] to [5], which is a copolymer containing a structural unit derived from a non-aqueous monomer.
[7] The polymer (P) is
Selected from the group consisting of a structural unit (a) derived from a monomer (A) having an ethylenically unsaturated bond and an amide bond, a compound having an ethylenically unsaturated bond and an anionic functional group, and a salt of those compounds. A carboxylic acid ester compound having an ethylenically unsaturated bond other than the structural unit (b) derived from the monomer (B), which is at least one kind, and the monomer (A) and the monomer (B). The structural unit (c) derived from the metric (C) and
The binder for a non-aqueous secondary battery electrode according to any one of [1] to [6], which is a copolymer (cP) having the above.
[8] The monomer (A) is a binder represented by the formula (1) for a non-aqueous secondary battery electrode according to [7].
[9] The binder for a non-aqueous secondary battery electrode according to [7] or [8], wherein the monomer (B) contains any one selected from the group consisting of (meth) acrylic acid and a salt thereof.
[10] The binder for a non-aqueous secondary battery electrode according to any one of [7] to [9], wherein the content of the structural unit (b) in the copolymer (cP) is 50.0% by mass or more. ..
[11] A binder composition for a non-aqueous secondary battery electrode, which comprises the binder for a non-aqueous secondary battery electrode according to any one of [1] to [10] and an aqueous medium.
[12] The content of the polymer (P) in 100 g of the aqueous medium is larger than the solubility of the polymer (P) in water at 23 ° C., and the polymer (P) is dispersed in the aqueous medium. [11] The binder composition for a non-aqueous secondary battery electrode according to [11].
[13] The binder composition for a non-aqueous secondary battery electrode according to [11] or [12], wherein the non-aqueous secondary battery is a lithium ion secondary battery.
[14] A non-aqueous secondary battery electrode slurry containing the binder for a non-aqueous secondary battery electrode according to any one of [1] to [10], an electrode active material, and an aqueous medium.
[15] Current collector and
A non-aqueous secondary battery electrode having the binder for the non-aqueous secondary battery electrode according to any one of [1] to [10] formed on the surface of the current collector and an electrode active material layer containing the electrode active material.
本発明によれば、集電体上に形成された電極活物質層のクラックの発生を抑制しつつ、集電体に対する電極活物質層の剥離強度を大きく向上できる非水系二次電池電極用バインダー及び非水系二次電池電極用スラリーを提供することができる。
また、本発明によれば、クラックが少なく、集電体に対する電極活物質層の剥離強度が高い非水系二次電池電極を提供することができる。
さらに、本発明によれば、クラックが少なく、集電体に対する電極活物質層の剥離強度が高い電極を備えた非水系二次電池を提供することができる。 According to the present invention, a binder for a non-aqueous secondary battery electrode that can greatly improve the peeling strength of the electrode active material layer with respect to the current collector while suppressing the generation of cracks in the electrode active material layer formed on the current collector. And a slurry for a non-aqueous secondary battery electrode can be provided.
Further, according to the present invention, it is possible to provide a non-aqueous secondary battery electrode having few cracks and high peel strength of the electrode active material layer with respect to the current collector.
Further, according to the present invention, it is possible to provide a non-aqueous secondary battery provided with an electrode having few cracks and high peel strength of the electrode active material layer with respect to the current collector.
また、本発明によれば、クラックが少なく、集電体に対する電極活物質層の剥離強度が高い非水系二次電池電極を提供することができる。
さらに、本発明によれば、クラックが少なく、集電体に対する電極活物質層の剥離強度が高い電極を備えた非水系二次電池を提供することができる。 According to the present invention, a binder for a non-aqueous secondary battery electrode that can greatly improve the peeling strength of the electrode active material layer with respect to the current collector while suppressing the generation of cracks in the electrode active material layer formed on the current collector. And a slurry for a non-aqueous secondary battery electrode can be provided.
Further, according to the present invention, it is possible to provide a non-aqueous secondary battery electrode having few cracks and high peel strength of the electrode active material layer with respect to the current collector.
Further, according to the present invention, it is possible to provide a non-aqueous secondary battery provided with an electrode having few cracks and high peel strength of the electrode active material layer with respect to the current collector.
以下、本発明の実施形態について詳細に説明する。本実施形態において、電池は、充放電において正極と負極との間でイオンの移動を伴う二次電池である。正極は正極活物質を備え、負極は負極活物質を備える。これらの電極活物質はイオンを挿入(Intercaration)及び脱離(Deintercalation)可能な材料である。このような構成の二次電池としての好ましい例として、リチウムイオン二次電池が挙げられる。
Hereinafter, embodiments of the present invention will be described in detail. In the present embodiment, the battery is a secondary battery in which ions are transferred between the positive electrode and the negative electrode during charging and discharging. The positive electrode comprises a positive electrode active material, and the negative electrode comprises a negative electrode active material. These electrode active materials are materials capable of inserting and desorbing ions (Deintercation). A preferred example of the secondary battery having such a configuration is a lithium ion secondary battery.
「(メタ)アクリル酸」とは、メタクリル酸及びアクリル酸の一方又は両方をいう。「(メタ)アクリル酸単量体」とは、メタクリル酸単量体及びアクリル酸単量体の一方又は両方をいう。「(メタ)アクリレート」とは、メタクリレート及びアクリレートの一方又は両方をいう。
"(Meta) acrylic acid" means one or both of methacrylic acid and acrylic acid. The "(meth) acrylic acid monomer" means one or both of the methacrylic acid monomer and the acrylic acid monomer. "(Meta) acrylate" means either methacrylate and acrylate or both.
「重量平均分子量」は、ゲルパーミエーションクロマトグラフィー(GPC)を用いて算出されるプルラン換算値である。
"Weight average molecular weight" is a pullulan conversion value calculated using gel permeation chromatography (GPC).
<1.非水系二次電池電極用バインダー>
本実施形態にかかる非水系二次電池電極用バインダー(または、非水系二次電池電極バインダー。以下、「電極バインダー」とすることがある)は、以下に説明する重合体(P)を含む。電極バインダーは、その他の成分を含んでもよく、例えば、重合体(P)以外の重合体、界面活性剤等を含んでもよい。 <1. Binder for non-aqueous secondary battery electrodes >
The binder for a non-aqueous secondary battery electrode (or a non-aqueous secondary battery electrode binder; hereinafter, may be referred to as an “electrode binder”) according to the present embodiment includes the polymer (P) described below. The electrode binder may contain other components, and may contain, for example, a polymer other than the polymer (P), a surfactant, or the like.
本実施形態にかかる非水系二次電池電極用バインダー(または、非水系二次電池電極バインダー。以下、「電極バインダー」とすることがある)は、以下に説明する重合体(P)を含む。電極バインダーは、その他の成分を含んでもよく、例えば、重合体(P)以外の重合体、界面活性剤等を含んでもよい。 <1. Binder for non-aqueous secondary battery electrodes >
The binder for a non-aqueous secondary battery electrode (or a non-aqueous secondary battery electrode binder; hereinafter, may be referred to as an “electrode binder”) according to the present embodiment includes the polymer (P) described below. The electrode binder may contain other components, and may contain, for example, a polymer other than the polymer (P), a surfactant, or the like.
ここで電極バインダーは、後述する電池の製造工程における加熱を伴う工程において揮発せずに残る成分からなる。具体的には電極バインダーを構成する成分は、電極バインダーを含む混合物を直径5cmのアルミ皿に1g秤量し、大気圧、乾燥器内で空気を循環させながら110℃で5時間乾燥させ後に残った成分である。
Here, the electrode binder is composed of a component that remains without volatilizing in a process involving heating in the battery manufacturing process described later. Specifically, the components constituting the electrode binder remained after weighing 1 g of the mixture containing the electrode binder in an aluminum dish having a diameter of 5 cm and drying at 110 ° C. for 5 hours while circulating air in a dryer at atmospheric pressure. It is an ingredient.
電極バインダー中の重合体(P)の含有率は、80質量%以上であることが好ましく、90質量%以上であることがより好ましく、95質量%以上であることがさらに好ましく、98質量%以上であることがさらに好ましい。重合体(P)による本発明の目的とする効果への寄与を大きくするためである。
The content of the polymer (P) in the electrode binder is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, and 98% by mass or more. Is more preferable. This is to increase the contribution of the polymer (P) to the desired effect of the present invention.
<1-1.重合体(P)>
重合体(P)の重量平均分子量は、60万以上であり、100万以上であることが好ましく、150万以上であることがより好ましく、200万以上であることがさらに好ましい。また、重合体(P)の重量平均分子量は、750万以下であり、500万以下であることが好ましく、400万以下であることがより好ましい。重合体(P)の重量平均分子量は300万以下であってもよい。 <1-1. Polymer (P)>
The weight average molecular weight of the polymer (P) is 600,000 or more, preferably 1 million or more, more preferably 1.5 million or more, and further preferably 2 million or more. The weight average molecular weight of the polymer (P) is 7.5 million or less, preferably 5 million or less, and more preferably 4 million or less. The weight average molecular weight of the polymer (P) may be 3 million or less.
重合体(P)の重量平均分子量は、60万以上であり、100万以上であることが好ましく、150万以上であることがより好ましく、200万以上であることがさらに好ましい。また、重合体(P)の重量平均分子量は、750万以下であり、500万以下であることが好ましく、400万以下であることがより好ましい。重合体(P)の重量平均分子量は300万以下であってもよい。 <1-1. Polymer (P)>
The weight average molecular weight of the polymer (P) is 600,000 or more, preferably 1 million or more, more preferably 1.5 million or more, and further preferably 2 million or more. The weight average molecular weight of the polymer (P) is 7.5 million or less, preferably 5 million or less, and more preferably 4 million or less. The weight average molecular weight of the polymer (P) may be 3 million or less.
本実施形態の重合体(P)は、23℃での水への溶解度が11.1g/100g未満(100gの水に対して、溶解できる重合体(P)が11.1g未満)である。溶解度が11.1g/100g未満であることは、重合体10.0質量部及び水90.0質量部からなる混合液において不溶分が存在することを目視で確認して判断される。重合体(P)は、23℃での水への溶解度が5.26g/100g未満(重合体(P)5.0質量%、水95.0質量%の混合液が濁っている)であることが好ましく、3.09g/100g未満(重合体(P)3.0質量%、水97.0質量%の混合液が濁っている)であることがより好ましい。
The polymer (P) of the present embodiment has a solubility in water at 23 ° C. of less than 11.1 g / 100 g (a polymer (P) that can be dissolved in 100 g of water is less than 11.1 g). The solubility of less than 11.1 g / 100 g is determined by visually confirming the presence of insoluble matter in the mixed solution consisting of 10.0 parts by mass of the polymer and 90.0 parts by mass of water. The polymer (P) has a solubility in water at 23 ° C. of less than 5.26 g / 100 g (a mixed solution of 5.0% by mass of the polymer (P) and 95.0% by mass of water is turbid). It is preferably less than 3.09 g / 100 g (a mixed solution of 3.0% by mass of the polymer (P) and 97.0% by mass of water is turbid).
また、重合体(P)の重量平均分子量は、ゲルパーミエーションクロマトグラフィー(GPC)を用いて算出されるプルラン換算値であることから、重合体(P)はGPC測定が可能な程度に水に可溶であることが好ましい。具体的には、重合体(P)の40℃における水への溶解度は0.1g/100g以上であることが好ましく、0.3g/100g以上であることがより好ましい。
Further, since the weight average molecular weight of the polymer (P) is a pullulan-equivalent value calculated by using gel permeation chromatography (GPC), the polymer (P) is contained in water to the extent that GPC measurement is possible. It is preferably soluble. Specifically, the solubility of the polymer (P) in water at 40 ° C. is preferably 0.1 g / 100 g or more, and more preferably 0.3 g / 100 g or more.
重合体(P)を10質量%含む23℃の水分散液の粘度は27000mPa・s以上であり、29000mPa・s以上であることが好ましく、31000mPa・s以上であることがより好ましい。後述する電極において、電極活物質層のクラック発生を抑制、電極活物質層の剥離強度の向上、及び電極活物質層の膨れを抑制できるためである。また、後述する非水系二次電池において、サイクル特性(放電容量維持率)を向上させるためである。
The viscosity of the aqueous dispersion at 23 ° C. containing 10% by mass of the polymer (P) is 27,000 mPa · s or more, preferably 29000 mPa · s or more, and more preferably 31000 mPa · s or more. This is because it is possible to suppress the generation of cracks in the electrode active material layer, improve the peel strength of the electrode active material layer, and suppress the swelling of the electrode active material layer in the electrode described later. This is also to improve the cycle characteristics (discharge capacity retention rate) in the non-aqueous secondary battery described later.
ここで、「重合体(P)を10質量%含む23℃の水分散液」とは、重合体(P)10質量%と水90質量%からなり、重合体(P)が水中に分散した混合液を23℃で24時間静置しても上澄み及び沈殿が生じずに濁っている状態を保っている混合液を意味する。
Here, the "water dispersion at 23 ° C. containing 10% by mass of the polymer (P)" is composed of 10% by mass of the polymer (P) and 90% by mass of water, and the polymer (P) is dispersed in water. It means a mixed solution that remains turbid without causing supernatant and precipitation even when the mixed solution is allowed to stand at 23 ° C. for 24 hours.
重合体(P)を10質量%含む23℃の水分散液の粘度は100000mPa・s以下であり、80000mPa・s以下であることが好ましく、50000mPa・s以下であることがより好ましい。後述する電極活物質等と混合して、電極スラリーを作製する場合に、効率よく電極活物質等を分散させるためである。
The viscosity of the aqueous dispersion at 23 ° C. containing 10% by mass of the polymer (P) is 100,000 mPa · s or less, preferably 80,000 mPa · s or less, and more preferably 50,000 mPa · s or less. This is to efficiently disperse the electrode active material and the like when the electrode slurry is prepared by mixing with the electrode active material and the like described later.
ここで、粘度は、ブルックフィールド型粘度計により、液温23℃、回転数10rpmで測定した値である。
Here, the viscosity is a value measured by a Brookfield type viscometer at a liquid temperature of 23 ° C. and a rotation speed of 10 rpm.
重合体(P)は、エチレン性不飽和結合を有する単量体をラジカル重合することにより得られる重合体であって、アニオン性官能基を有する単量体に由来する構造単位と、極性官能基を有さない単量体に由来する構造単位とを含む共重合体であることが好ましい。
The polymer (P) is a polymer obtained by radically polymerizing a monomer having an ethylenically unsaturated bond, and has a structural unit derived from the monomer having an anionic functional group and a polar functional group. It is preferable that the polymer contains a structural unit derived from a monomer having no ethylene.
<1-2.重合体(P)の例(共重合体(cP)>
以下、重合体(P)の化学的構造の例として共重合体(cP)について説明するが、例に過ぎず、重合体(P)は、以下に述べる構造に限られない。また、以下に述べられている単量体組成の全てが本発明の範囲ではなく、重合体(P)としての上記条件(重量平均分子量、水への溶解度、10質量%水分散液の粘度)を満たすことが、以下の述べる共重合体(cP)の前提条件となる。 <1-2. Example of polymer (P) (copolymer (cP)>
Hereinafter, the copolymer (cP) will be described as an example of the chemical structure of the polymer (P), but the copolymer (P) is not limited to the structure described below. Further, all of the monomer compositions described below are not within the scope of the present invention, and the above conditions (weight average molecular weight, solubility in water, viscosity of 10% by mass aqueous dispersion) as the polymer (P)). Satisfying this is a prerequisite for the copolymer (cP) described below.
以下、重合体(P)の化学的構造の例として共重合体(cP)について説明するが、例に過ぎず、重合体(P)は、以下に述べる構造に限られない。また、以下に述べられている単量体組成の全てが本発明の範囲ではなく、重合体(P)としての上記条件(重量平均分子量、水への溶解度、10質量%水分散液の粘度)を満たすことが、以下の述べる共重合体(cP)の前提条件となる。 <1-2. Example of polymer (P) (copolymer (cP)>
Hereinafter, the copolymer (cP) will be described as an example of the chemical structure of the polymer (P), but the copolymer (P) is not limited to the structure described below. Further, all of the monomer compositions described below are not within the scope of the present invention, and the above conditions (weight average molecular weight, solubility in water, viscosity of 10% by mass aqueous dispersion) as the polymer (P)). Satisfying this is a prerequisite for the copolymer (cP) described below.
この例にかかる共重合体(cP)は、単量体(A)由来の構造単位(a)と、単量体(B)由来の構造単位(b)と、単量体(C)由来の構造単位(c)とを含む。前記単量体(A)はエチレン性不飽和結合及びアミド結合を有する。前記単量体(B)はエチレン性不飽和結合及びアニオン性官能基を有する化合物、及びそれらの化合物の塩からなる群から選択される少なくとも1種である。前記単量体(C)は、エチレン性不飽和結合を有するカルボン酸エステル化合物である。共重合体(cP)は、単量体(A)、単量体(B)、及び単量体(C)のいずれにも該当しない他の単量体(D)由来の構造単位(d)を含んでもよい。
The copolymer (cP) according to this example is derived from the structural unit (a) derived from the monomer (A), the structural unit (b) derived from the monomer (B), and the monomer (C). Includes structural unit (c). The monomer (A) has an ethylenically unsaturated bond and an amide bond. The monomer (B) is at least one selected from the group consisting of compounds having an ethylenically unsaturated bond and an anionic functional group, and salts of those compounds. The monomer (C) is a carboxylic acid ester compound having an ethylenically unsaturated bond. The copolymer (cP) is a structural unit (d) derived from another monomer (D) that does not correspond to any of the monomer (A), the monomer (B), and the monomer (C). May include.
<1-2-1.単量体(A)>
単量体(A)は、エチレン性不飽和結合及びアミド結合を有する化合物である。単量体(A)としては、N-ビニルアミド、N-アルキル-N-ビニルアミド、(メタ)アクリルアミド、N-アルキル(メタ)アクリルアミド、N,N-ジアルキル(メタ)アクリルアミド、N‐ヒドロキシアルキル(メタ)アクリルアミド、ダイアセトン(メタ)アクリルアミド、ジメチルアミノアルキル(メタ)アクリルアミド、(メタ)アクリルアミド-2-メチルプロパンスルホン酸等が挙げられる。単量体(A)は、複数の種類の化合物を含んでいてもよい。単量体(A)の好適な例としては以下の式(1)で表される化合物が挙げられる。 <1-2-1. Monomer (A)>
The monomer (A) is a compound having an ethylenically unsaturated bond and an amide bond. Examples of the monomer (A) include N-vinylamide, N-alkyl-N-vinylamide, (meth) acrylamide, N-alkyl (meth) acrylamide, N, N-dialkyl (meth) acrylamide, and N-hydroxyalkyl (meth). ) Acrylamide, diacetone (meth) acrylamide, dimethylaminoalkyl (meth) acrylamide, (meth) acrylamide-2-methylpropanesulfonic acid and the like. The monomer (A) may contain a plurality of types of compounds. Preferable examples of the monomer (A) include compounds represented by the following formula (1).
単量体(A)は、エチレン性不飽和結合及びアミド結合を有する化合物である。単量体(A)としては、N-ビニルアミド、N-アルキル-N-ビニルアミド、(メタ)アクリルアミド、N-アルキル(メタ)アクリルアミド、N,N-ジアルキル(メタ)アクリルアミド、N‐ヒドロキシアルキル(メタ)アクリルアミド、ダイアセトン(メタ)アクリルアミド、ジメチルアミノアルキル(メタ)アクリルアミド、(メタ)アクリルアミド-2-メチルプロパンスルホン酸等が挙げられる。単量体(A)は、複数の種類の化合物を含んでいてもよい。単量体(A)の好適な例としては以下の式(1)で表される化合物が挙げられる。 <1-2-1. Monomer (A)>
The monomer (A) is a compound having an ethylenically unsaturated bond and an amide bond. Examples of the monomer (A) include N-vinylamide, N-alkyl-N-vinylamide, (meth) acrylamide, N-alkyl (meth) acrylamide, N, N-dialkyl (meth) acrylamide, and N-hydroxyalkyl (meth). ) Acrylamide, diacetone (meth) acrylamide, dimethylaminoalkyl (meth) acrylamide, (meth) acrylamide-2-methylpropanesulfonic acid and the like. The monomer (A) may contain a plurality of types of compounds. Preferable examples of the monomer (A) include compounds represented by the following formula (1).
式(1)中、R1、R2は各々独立に水素原子または炭素数1以上3以下のアルキル基であることがより好ましく、R1、R2は各々独立に水素原子またはメチル基であることがさらに好ましい。
Wherein (1), R 1, R 2 is more preferably each independently hydrogen atom or C 1 to 3 alkyl group carbon, is R 1, R 2 each independently represent a hydrogen atom or a methyl group Is even more preferable.
R1、R2の組み合わせとして特に好ましい具体例は、R1:H、R2:H(すなわち、単量体(A)はN-ビニルホルムアミド)、またはR1:H、R2:CH3(すなわち、単量体(A)はN-ビニルアセトアミド)である。
Particularly preferred specific examples of the combination of R 1 and R 2 are R 1 : H, R 2 : H (that is, the monomer (A) is N-vinylformamide), or R 1 : H, R 2 : CH 3. (That is, the monomer (A) is N-vinylacetamide).
<1-2-2.単量体(B)>
単量体(B)は、エチレン性不飽和結合及びアニオン性官能基を有する化合物またはその塩からなる群から選択される少なくとも1種からなる。単量体(B)としては、(メタ)アクリル酸及びその塩、(メタ)アクリル酸カルボキシエチル及びその塩、ポリスチレンスルホン酸及びその塩、エチレン性不飽和結合を有するジカルボン酸、そのハーフエステル及びそれらの塩等が挙げられる。 <1-2-2. Monomer (B)>
The monomer (B) comprises at least one selected from the group consisting of compounds having ethylenically unsaturated bonds and anionic functional groups or salts thereof. Examples of the monomer (B) include (meth) acrylic acid and a salt thereof, carboxyethyl (meth) acrylic acid and a salt thereof, polystyrene sulfonic acid and a salt thereof, a dicarboxylic acid having an ethylenically unsaturated bond, a half ester thereof, and the like. Examples thereof include salts thereof.
単量体(B)は、エチレン性不飽和結合及びアニオン性官能基を有する化合物またはその塩からなる群から選択される少なくとも1種からなる。単量体(B)としては、(メタ)アクリル酸及びその塩、(メタ)アクリル酸カルボキシエチル及びその塩、ポリスチレンスルホン酸及びその塩、エチレン性不飽和結合を有するジカルボン酸、そのハーフエステル及びそれらの塩等が挙げられる。 <1-2-2. Monomer (B)>
The monomer (B) comprises at least one selected from the group consisting of compounds having ethylenically unsaturated bonds and anionic functional groups or salts thereof. Examples of the monomer (B) include (meth) acrylic acid and a salt thereof, carboxyethyl (meth) acrylic acid and a salt thereof, polystyrene sulfonic acid and a salt thereof, a dicarboxylic acid having an ethylenically unsaturated bond, a half ester thereof, and the like. Examples thereof include salts thereof.
(メタ)アクリル酸塩は、(メタ)アクリル酸と1価のカチオンとの塩からなることが好ましく、(メタ)アクリル酸ナトリウム、(メタ)アクリル酸カリウム、(メタ)アクリル酸アンモニウムが好ましい。その中でも、(メタ)アクリル酸ナトリウム、(メタ)アクリル酸アンモニウムから選ばれる少なくとも1種を含むことより好ましく、アクリル酸ナトリウムであることが最も好ましい。(メタ)アクリル酸塩は、例えば、(メタ)アクリル酸を水酸化物、及びアンモニア水等で中和して得られるが、中でも入手容易性の点から、水酸化ナトリウムで中和することが好ましい。
The (meth) acrylate is preferably composed of a salt of (meth) acrylate and a monovalent cation, preferably sodium (meth) acrylate, potassium (meth) acrylate, and ammonium (meth) acrylate. Among them, it is more preferable to contain at least one selected from sodium (meth) acrylate and ammonium (meth) ammonium acrylate, and sodium acrylate is most preferable. The (meth) acrylic acid salt is obtained by neutralizing (meth) acrylic acid with, for example, hydroxide, aqueous ammonia, or the like, but from the viewpoint of easy availability, it can be neutralized with sodium hydroxide. preferable.
pH調整のため、単量体(B)は、エチレン性不飽和結合及びアニオン性官能基を有する化合物の塩(ここでは単量体(B1)とすることもある)を60質量%以上含むことが好ましく、80質量%以上含むことがより好ましく、95質量%以上含むことがさらに好ましい。
For pH adjustment, the monomer (B) contains 60% by mass or more of a salt of a compound having an ethylenically unsaturated bond and an anionic functional group (here, the monomer (B1) may be used). Is more preferable, 80% by mass or more is more preferable, and 95% by mass or more is further preferable.
ここで、単量体(B)として塩を形成していない化合物(ここでは単量体(B2)とすることもある)を含む場合で、単量体(B2)のアニオン性官能基(アニオンの価数×アニオンのモル数、以下同様)は、中和剤に含まれるカチオンの当量(カチオンの価数×カチオンのモル数、以下同様)だけ塩を形成したものとして考える。中和剤に含まれるカチオンの当量が、重合に用いた単量体(B2)のアニオン当量より多い場合、単量体(B2)は全て塩を形成していると考える。一方、中和剤に含まれるカチオンの当量が、重合に用いた単量体(B2)のアニオン当量より少ない場合、カチオンは全て単量体(B2)と塩を形成していると考える(すなわち、単量体(B2)は中和剤に含まれるカチオンの当量だけ塩を形成している)。
Here, in the case of containing a compound which does not form a salt as the monomer (B) (here, the monomer (B2) may be used), the anionic functional group (anion) of the monomer (B2) is contained. The valence of valence × the number of moles of anion, the same applies hereinafter) is considered to form a salt by the equivalent of the cation contained in the neutralizing agent (the valence of the cation × the number of moles of the cation, the same applies hereinafter). When the equivalent of the cation contained in the neutralizing agent is larger than the anion equivalent of the monomer (B2) used for the polymerization, it is considered that all the monomers (B2) form a salt. On the other hand, when the equivalent of the cation contained in the neutralizing agent is smaller than the anion equivalent of the monomer (B2) used for the polymerization, it is considered that all the cations form a salt with the monomer (B2) (that is,). , The monomer (B2) forms a salt by the equivalent of the cation contained in the neutralizing agent).
<1-2-3.単量体(C)>
単量体(C)は、単量体(A)及び単量体(B)以外の、エチレン性不飽和を有するカルボン酸エステル化合物である。エチレン性不飽和カルボン酸エステル化合物としては、(メタ)アクリル酸エステル、カルボン酸ビニル等が挙げられる。単量体(C)は、1種類の化合物のみを含んでもよく、2種類以上の化合物を含んでもよい。(メタ)アクリル酸エステルの例は後述する。カルボン酸ビニルとしては、酢酸ビニル、プロピオン酸ビニル、安息香酸ビニル等が挙げられる。 <1-2-3. Monomer (C)>
The monomer (C) is a carboxylic acid ester compound having an ethylenically unsaturated other than the monomer (A) and the monomer (B). Examples of the ethylenically unsaturated carboxylic acid ester compound include (meth) acrylic acid ester and vinyl carboxylate. The monomer (C) may contain only one kind of compound, or may contain two or more kinds of compounds. An example of the (meth) acrylic acid ester will be described later. Examples of vinyl carboxylate include vinyl acetate, vinyl propionate, vinyl benzoate and the like.
単量体(C)は、単量体(A)及び単量体(B)以外の、エチレン性不飽和を有するカルボン酸エステル化合物である。エチレン性不飽和カルボン酸エステル化合物としては、(メタ)アクリル酸エステル、カルボン酸ビニル等が挙げられる。単量体(C)は、1種類の化合物のみを含んでもよく、2種類以上の化合物を含んでもよい。(メタ)アクリル酸エステルの例は後述する。カルボン酸ビニルとしては、酢酸ビニル、プロピオン酸ビニル、安息香酸ビニル等が挙げられる。 <1-2-3. Monomer (C)>
The monomer (C) is a carboxylic acid ester compound having an ethylenically unsaturated other than the monomer (A) and the monomer (B). Examples of the ethylenically unsaturated carboxylic acid ester compound include (meth) acrylic acid ester and vinyl carboxylate. The monomer (C) may contain only one kind of compound, or may contain two or more kinds of compounds. An example of the (meth) acrylic acid ester will be described later. Examples of vinyl carboxylate include vinyl acetate, vinyl propionate, vinyl benzoate and the like.
これらの中でも、単量体(C)は、(メタ)アクリル酸エステルを含むことが好ましく、芳香族アルコールの(メタ)アクリル酸エステル及び(メタ)アクリル酸アルキルエステルの少なくともいずれかを含むことがより好ましく、芳香族アルコールの(メタ)アクリル酸エステルを含むことがさらに好ましい。
Among these, the monomer (C) preferably contains a (meth) acrylic acid ester, and may contain at least one of a (meth) acrylic acid ester and a (meth) acrylic acid alkyl ester of an aromatic alcohol. More preferably, it contains a (meth) acrylic acid ester of an aromatic alcohol.
芳香族アルコールの(メタ)アクリル酸エステルとしては、例えば、(メタ)アクリル酸ベンジル、(メタ)アクリル酸フェノキシエチル、フェノキシエチレングリコール(メタ)アクリレート、フェノキシジエチレングリコール(メタ)アクリレート、フェノキシポリエチレングリコール(メタ)アクリレート、エトキシ化-o-フェニルフェノール(メタ)アクリレート、2-ヒドロキシ-3-フェノキシプロピル(メタ)アクリレート等が挙げられる。単量体(C)は、これらの化合物のうち、(メタ)アクリル酸ベンジル、(メタ)アクリル酸フェノキシエチルを含むことがさらに好ましい。
Examples of the (meth) acrylic acid ester of the aromatic alcohol include benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxyethylene glycol (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, and phenoxypolyethylene glycol (meth). ) Acrylate, ethoxylated-o-phenylphenol (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate and the like. Among these compounds, the monomer (C) more preferably contains benzyl (meth) acrylate and phenoxyethyl (meth) acrylate.
(メタ)アクリル酸アルキルエステルとしては、例えば、(メタ)アクリル酸メチル、(メタ)アクリル酸エチル、(メタ)アクリル酸n-プロピル、(メタ)アクリル酸イソプロピル、(メタ)アクリル酸-n-ブチル、(メタ)アクリル酸-2-エチルヘキシル等が挙げられる。
Examples of the (meth) acrylic acid alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and n- (meth) acrylic acid. Examples thereof include butyl and -2-ethylhexyl (meth) acrylate.
単量体(C)は、以下の式(2)で表される化合物を1種または2種以上含んでもよい。
The monomer (C) may contain one or more compounds represented by the following formula (2).
式(2)中、R3、R4、R6は各々独立に水素原子または炭素数1以上3以下のアルキル基であることがより好ましく、R3、R4、R6は各々独立に水素原子またはメチル基であることがさらに好ましい。R6はメチル基であることが特に好ましい。R5は、炭素数1以上6以下のアルキル基であることが好ましい。R5は、R4よりも炭素数が多い。
Wherein (2), R 3, R 4, R 6 is more preferably each independently hydrogen atom or C 1 to 3 alkyl group carbon, R 3, R 4, R 6 are each independently hydrogen It is more preferably an atom or a methyl group. It is particularly preferred that R 6 is a methyl group. R 5 is preferably an alkyl group having 1 or more carbon atoms and 6 or less carbon atoms. R 5 has more carbon atoms than R 4.
また、ポリオキシアルキレン鎖を有する単量体(C)を用いることで、共重合体(cP)を電極活物質のための電極バインダーとして電極を作製した場合、電極の可撓性が向上し、クラックの発生を抑制されるためである。この観点から、n+m≧30であることがより好ましく、n+m≧40であることがさらに好ましい。また、n+m≦500であることがより好ましく、n+m≦200であることがさらに好ましく、n+m≦150であることが特に好ましい。バインダーの結着力がより高くなるためである。
Further, by using the monomer (C) having a polyoxyalkylene chain, when the electrode is produced by using the copolymer (cP) as an electrode binder for the electrode active material, the flexibility of the electrode is improved. This is because the occurrence of cracks is suppressed. From this point of view, it is more preferable that n + m ≧ 30, and it is further preferable that n + m ≧ 40. Further, n + m ≦ 500 is more preferable, n + m ≦ 200 is further preferable, and n + m ≦ 150 is particularly preferable. This is because the binder has a higher binding force.
なお、式(2)では、R4を含む構造単位n個及びR5を含む構造単位m個が含まれるということを限定しているが、これらの構造単位の配列について限定はしていない。すなわち、m≧1の場合、式(2)のポリオキシアルキレン鎖の部分は、それぞれの構造単位が全てまたは一部が連続したブロック構造を有していてもよく、2つの構造単位が交互に配列した構造等の周期的な規則性をもって配列した構造でもよく、2つの構造単位がランダムに配列した構造でもよい。式(2)のポリオキシアルキレン鎖の好ましい形態としては、周期的な規則性をもって配列した構造、またはランダムに配列した構造である。式(2)を形成する分子鎖内での各構造単位の分布の偏りを抑制するためである。式(2)のポリオキシアルキレン鎖のより好ましい形態としては、ランダムに配列した構造である。特殊な触媒を用いずにラジカル重合開始剤により重合可能であり、製造コストを低減できるためである。
In addition, although the formula (2) is limited to include n structural units including R 4 and m structural units including R 5 , the arrangement of these structural units is not limited. That is, when m ≧ 1, the portion of the polyoxyalkylene chain of the formula (2) may have a block structure in which all or part of the structural units are continuous, and the two structural units alternate. It may be a structure arranged with periodic regularity such as an arranged structure, or a structure in which two structural units are randomly arranged. The preferred form of the polyoxyalkylene chain of the formula (2) is a structure arranged with periodic regularity or a structure arranged at random. This is to suppress the bias of the distribution of each structural unit in the molecular chain forming the formula (2). A more preferable form of the polyoxyalkylene chain of the formula (2) is a randomly arranged structure. This is because polymerization can be carried out with a radical polymerization initiator without using a special catalyst, and the manufacturing cost can be reduced.
式(2)において、R3、R4、R5、R6、n、mの組み合わせとして好ましい例としては、以下の表1の例が挙げられる。
In the formula (2), examples of preferable combinations of R 3 , R 4 , R 5 , R 6 , n, and m include the examples in Table 1 below.
式(2)においてm=0であることがより好ましい。m=0の単量体(C)の例として、ポリエチレングリコールのモノ(メタ)アクリレートが挙げられ、より具体的には、メトキシポリエチレングリコール(メタ)アクリレート(例えば、表1の単量体d1、d2)等を挙げることができる。メトキシポリエチレングリコールメタクリレートの一例としては、EVONIK INDUSTRIES製のVISIOMER(登録商標)MPEG2005 MA Wが挙げられる。この製品においてはR3=CH3、R4=H、R6=CH3、n=45、m=0である。メトキシポリエチレングリコールメタクリレートの他の例としては、EVONIK INDUSTRIES製のVISIOMER(登録商標)MPEG5005 MA Wが挙げられる。この製品においては、R3=CH3、R4=H、R6=CH3、n=113、m=0である。
It is more preferable that m = 0 in the formula (2). Examples of the monomer (C) having m = 0 include mono (meth) acrylate of polyethylene glycol, and more specifically, methoxypolyethylene glycol (meth) acrylate (for example, monomer d1 in Table 1). d2) and the like can be mentioned. As an example of methoxypolyethylene glycol methacrylate, VISIOMER® MPEG2005 MA W manufactured by EVONIK INDUSTRIES can be mentioned. In this product, R 3 = CH 3 , R 4 = H, R 6 = CH 3 , n = 45, m = 0. Another example of methoxypolyethylene glycol methacrylate is VISIOMER® MPEG5005 MA W manufactured by EVONIK INDUSTRIES. In this product, R 3 = CH 3 , R 4 = H, R 6 = CH 3 , n = 113, m = 0.
m=0の単量体(C)の別の例として、ポリプロピレングリコールのモノ(メタ)アクリレートが挙げられ、より具体的には、メトキシポリプロピレングリコール(メタ)アクリレート(例えば、表1の単量体d3、d4)等を挙げることができる。
Another example of the monomer (C) with m = 0 is a mono (meth) acrylate of polypropylene glycol, more specifically, a methoxypolypropylene glycol (meth) acrylate (eg, the monomer of Table 1). d3, d4) and the like can be mentioned.
その他の(メタ)アクリル酸エステルとしては、(メタ)アクリル酸-2-ヒドロキシエチル、(メタ)アクリル酸-2-ヒドロキシプロピル、(メタ)アクリル酸-4-ヒドロキシブチル等が挙げられる。
Examples of other (meth) acrylic acid esters include (meth) acrylic acid-2-hydroxyethyl, (meth) acrylic acid-2-hydroxypropyl, and (meth) acrylic acid-4-hydroxybutyl.
<1-2-4.他の単量体(D)>
単量体(A)、単量体(B)、及び単量体(C)のいずれにも該当しない他の単量体(D)としては、ビニルアルコール、(メタ)アクリロニトリル、スチレン及びスチレンの誘導体等が挙げられる。前記のビニルアルコールは、モノマーとして酢酸ビニル等のエステルを用いて重合後にけん化等の処理をして得られる物を含んでもよい。 <1-2-4. Other monomer (D)>
Examples of the other monomer (D) that does not fall under any of the monomer (A), the monomer (B), and the monomer (C) include vinyl alcohol, (meth) acrylonitrile, styrene, and styrene. Derivatives and the like can be mentioned. The vinyl alcohol may contain a product obtained by subjecting an ester such as vinyl acetate as a monomer to a treatment such as saponification after polymerization.
単量体(A)、単量体(B)、及び単量体(C)のいずれにも該当しない他の単量体(D)としては、ビニルアルコール、(メタ)アクリロニトリル、スチレン及びスチレンの誘導体等が挙げられる。前記のビニルアルコールは、モノマーとして酢酸ビニル等のエステルを用いて重合後にけん化等の処理をして得られる物を含んでもよい。 <1-2-4. Other monomer (D)>
Examples of the other monomer (D) that does not fall under any of the monomer (A), the monomer (B), and the monomer (C) include vinyl alcohol, (meth) acrylonitrile, styrene, and styrene. Derivatives and the like can be mentioned. The vinyl alcohol may contain a product obtained by subjecting an ester such as vinyl acetate as a monomer to a treatment such as saponification after polymerization.
<1-2-5.共重合体(cP)における構造単位の含有率>
以下、共重合体(cP)における各構造単位の含有率の好適な例について説明する。 ここで、単量体(B)として塩を形成していない化合物(ここでは単量体(B2)とすることもある)を含む場合で、単量体(B2)のアニオン性官能基は、中和剤に含まれるカチオンの当量だけ塩を形成したものとして考える。詳細は<1-2-2.単量体(B)>の項にて説明した通りである。 <1-2-5. Content of structural units in the copolymer (cP)>
Hereinafter, a suitable example of the content of each structural unit in the copolymer (cP) will be described. Here, when the monomer (B) contains a compound that does not form a salt (here, the monomer (B2) may be used), the anionic functional group of the monomer (B2) is It is considered that the salt is formed by the equivalent amount of the cation contained in the neutralizing agent. For details, see <1-2-2. As described in the section of monomer (B)>.
以下、共重合体(cP)における各構造単位の含有率の好適な例について説明する。 ここで、単量体(B)として塩を形成していない化合物(ここでは単量体(B2)とすることもある)を含む場合で、単量体(B2)のアニオン性官能基は、中和剤に含まれるカチオンの当量だけ塩を形成したものとして考える。詳細は<1-2-2.単量体(B)>の項にて説明した通りである。 <1-2-5. Content of structural units in the copolymer (cP)>
Hereinafter, a suitable example of the content of each structural unit in the copolymer (cP) will be described. Here, when the monomer (B) contains a compound that does not form a salt (here, the monomer (B2) may be used), the anionic functional group of the monomer (B2) is It is considered that the salt is formed by the equivalent amount of the cation contained in the neutralizing agent. For details, see <1-2-2. As described in the section of monomer (B)>.
構造単位(a)の含有率は、0.5質量%以上であることが好ましく、1.0質量%以上であることがより好ましく、3.0質量%以上であることがさらに好ましく、7.0質量%以上であることが特に好ましい。後述する電極スラリー作製時の電極活物質、導電助剤等の分散性に優れ、塗工性良好な電極スラリーを作製することができるためである。構造単位(a)の含有率は、20.0質量%以下であることが好ましく、15.0質量%以下であることがより好ましく、12.5質量%以下であることがさらに好ましい。後述する電極のクラックの発生が抑制され、電極の生産性が向上するためである。
The content of the structural unit (a) is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, further preferably 3.0% by mass or more, and 7. It is particularly preferable that it is 0% by mass or more. This is because it is possible to produce an electrode slurry having excellent dispersibility of the electrode active material, the conductive auxiliary agent, etc. at the time of producing the electrode slurry, which will be described later, and having good coatability. The content of the structural unit (a) is preferably 20.0% by mass or less, more preferably 15.0% by mass or less, and further preferably 12.5% by mass or less. This is because the occurrence of cracks in the electrodes, which will be described later, is suppressed and the productivity of the electrodes is improved.
構造単位(b)の含有率は、50.0質量%以上であることが好ましく、60.0質量%以上であることがより好ましく、70.0質量%以上であることがさらに好ましい。集電体に対する剥離強度の高い電極活物質層を得ることができるためである。構造単位(b)の含有率は、98.0質量%以下であることが好ましく、94.5質量%以下であることがより好ましく、93.0質量%以下であることがさらに好ましく、90.0質量%以下であることが特に好ましい。後述する電極スラリー作製時の電極活物質、導電助剤等の固形分の分散性がより向上するためである。
The content of the structural unit (b) is preferably 50.0% by mass or more, more preferably 60.0% by mass or more, and further preferably 70.0% by mass or more. This is because it is possible to obtain an electrode active material layer having high peel strength with respect to the current collector. The content of the structural unit (b) is preferably 98.0% by mass or less, more preferably 94.5% by mass or less, further preferably 93.0% by mass or less, and 90. It is particularly preferable that it is 0% by mass or less. This is because the dispersibility of solids such as the electrode active material and the conductive auxiliary agent at the time of producing the electrode slurry described later is further improved.
構造単位(c)のうち、芳香族アルコールの(メタ)アクリル酸エステルに由来する構造単位の共重合体(cP)における含有率は、0.3質量%以上であることが好ましく、0.5質量%以上であることがより好ましく、3.0質量%以上であることがさらに好ましく、6.0質量%以上であることが特に好ましい。後述する電極のクラックの発生が抑制され、電極の生産性が向上するためである。構造単位(c)のうち、芳香族アルコールの(メタ)アクリル酸エステルに由来する構造単位の共重合体(cP)における含有率は、28.0質量%以下であることが好ましく、23.0質量%以下であることがより好ましく、18.0質量%以下であることがさらに好ましく、15.0質量%以下であることが特に好ましい。後述する電極において、電極活物質層の剥離強度を向上させるため、及び電極活物質層の膨れを抑制するためである。また、後述する非水系二次電池において、サイクル特性(放電容量維持率)を向上させるためである。
Among the structural units (c), the content of the aromatic alcohol in the copolymer (cP) of the structural unit derived from the (meth) acrylic acid ester is preferably 0.3% by mass or more, preferably 0.5. It is more preferably 3% by mass or more, further preferably 3.0% by mass or more, and particularly preferably 6.0% by mass or more. This is because the occurrence of cracks in the electrodes, which will be described later, is suppressed and the productivity of the electrodes is improved. Among the structural units (c), the content of the aromatic alcohol in the copolymer (cP) of the structural unit derived from the (meth) acrylic acid ester is preferably 28.0% by mass or less, 23.0. It is more preferably 18.0% by mass or less, more preferably 18.0% by mass or less, and particularly preferably 15.0% by mass or less. This is to improve the peel strength of the electrode active material layer and to suppress the swelling of the electrode active material layer in the electrode described later. This is also to improve the cycle characteristics (discharge capacity retention rate) in the non-aqueous secondary battery described later.
構造単位(c)のうち、式(2)で表される化合物に由来する構造単位の共重合体(cP)における含有率は、0.3質量%以上であることが好ましく、0.9質量%以上であることがより好ましく、3.0質量%以上であることがさらに好ましい。構造単位(c)のうち、式(2)で表される化合物に由来する構造単位の共重合体(cP)における含有率は、18.0質量%以下であることが好ましく、12.0質量%以下であることがより好ましく、7.0質量%以下であることがより好ましい。後述する電極の、クラック発生を抑制するため、電極活物質層の剥離強度を向上させるため、及び電極活物質層の膨れを抑制するためである。また、後述する非水系二次電池において、サイクル特性(放電容量維持率)を向上させるためである。
Among the structural units (c), the content of the structural units derived from the compound represented by the formula (2) in the copolymer (cP) is preferably 0.3% by mass or more, preferably 0.9% by mass. % Or more, more preferably 3.0% by mass or more. Among the structural units (c), the content of the structural units derived from the compound represented by the formula (2) in the copolymer (cP) is preferably 18.0% by mass or less, preferably 12.0% by mass. % Or less, more preferably 7.0% by mass or less. This is to suppress the occurrence of cracks in the electrode, which will be described later, to improve the peel strength of the electrode active material layer, and to suppress the swelling of the electrode active material layer. This is also to improve the cycle characteristics (discharge capacity retention rate) in the non-aqueous secondary battery described later.
<1-2-6.共重合体(cP)の製造方法>
共重合体(cP)の合成は、水性媒体中におけるラジカル重合で行うことが好ましい。重合法としては、例えば、重合に使用する単量体を全て一括して仕込んで重合する方法、重合に使用する単量体を連続供給しながら重合する方法等が適用できる。共重合体(cP)の合成に用いる全単量体中の各単量体の含有率は、共重合体(cP)中のその単量体対応する構造単位の含有率と見なす。例えば、共重合体(cP)の合成に用いる全単量体中の単量体(A)の含有率は、合成しようとする共重合体(cP)中の構造単位(a)の含有率である。ただし、単量体(B)として塩を形成していない単量体(B2)を含む場合で、単量体(B2)のアニオン性官能基は、中和剤に含まれるカチオンの当量だけ塩を形成したものとして考える。中和剤に含まれるカチオンの当量が、重合に用いた単量体(B2)のアニオン当量より多い場合、単量体(B2)は全て塩を形成していると考える。一方、中和剤に含まれるカチオンの当量が、重合に用いた単量体(B2)のアニオン当量より少ない場合、カチオンは全て単量体(B2)と塩を形成していると考える(すなわち、単量体(B2)は中和剤に含まれるカチオンの当量だけ塩を形成している)。ラジカル重合は、重合開始剤の種類にもよるが、30~90℃の温度で行うことが好ましい。なお、共重合体(cP)の重合方法の具体的な例は、後述の実施例において詳しく説明する。 <1-2-6. Method for producing copolymer (cP)>
The copolymer (cP) is preferably synthesized by radical polymerization in an aqueous medium. As the polymerization method, for example, a method of charging all the monomers used for polymerization in a batch and polymerizing, a method of polymerizing while continuously supplying the monomers used for polymerization, and the like can be applied. The content of each monomer in all the monomers used for the synthesis of the copolymer (cP) is regarded as the content of the structural unit corresponding to the monomer in the copolymer (cP). For example, the content of the monomer (A) in all the monomers used for the synthesis of the copolymer (cP) is the content of the structural unit (a) in the copolymer (cP) to be synthesized. be. However, when the monomer (B) contains a monomer (B2) that does not form a salt, the anionic functional group of the monomer (B2) is salted by the equivalent of the cation contained in the neutralizing agent. Is considered to have formed. When the equivalent of the cation contained in the neutralizing agent is larger than the anion equivalent of the monomer (B2) used for the polymerization, it is considered that all the monomers (B2) form a salt. On the other hand, when the equivalent of the cation contained in the neutralizing agent is smaller than the anion equivalent of the monomer (B2) used for the polymerization, it is considered that all the cations form a salt with the monomer (B2) (that is,). , The monomer (B2) forms a salt by the equivalent of the cation contained in the neutralizing agent). The radical polymerization is preferably carried out at a temperature of 30 to 90 ° C., although it depends on the type of the polymerization initiator. Specific examples of the copolymer (cP) polymerization method will be described in detail in Examples described later.
共重合体(cP)の合成は、水性媒体中におけるラジカル重合で行うことが好ましい。重合法としては、例えば、重合に使用する単量体を全て一括して仕込んで重合する方法、重合に使用する単量体を連続供給しながら重合する方法等が適用できる。共重合体(cP)の合成に用いる全単量体中の各単量体の含有率は、共重合体(cP)中のその単量体対応する構造単位の含有率と見なす。例えば、共重合体(cP)の合成に用いる全単量体中の単量体(A)の含有率は、合成しようとする共重合体(cP)中の構造単位(a)の含有率である。ただし、単量体(B)として塩を形成していない単量体(B2)を含む場合で、単量体(B2)のアニオン性官能基は、中和剤に含まれるカチオンの当量だけ塩を形成したものとして考える。中和剤に含まれるカチオンの当量が、重合に用いた単量体(B2)のアニオン当量より多い場合、単量体(B2)は全て塩を形成していると考える。一方、中和剤に含まれるカチオンの当量が、重合に用いた単量体(B2)のアニオン当量より少ない場合、カチオンは全て単量体(B2)と塩を形成していると考える(すなわち、単量体(B2)は中和剤に含まれるカチオンの当量だけ塩を形成している)。ラジカル重合は、重合開始剤の種類にもよるが、30~90℃の温度で行うことが好ましい。なお、共重合体(cP)の重合方法の具体的な例は、後述の実施例において詳しく説明する。 <1-2-6. Method for producing copolymer (cP)>
The copolymer (cP) is preferably synthesized by radical polymerization in an aqueous medium. As the polymerization method, for example, a method of charging all the monomers used for polymerization in a batch and polymerizing, a method of polymerizing while continuously supplying the monomers used for polymerization, and the like can be applied. The content of each monomer in all the monomers used for the synthesis of the copolymer (cP) is regarded as the content of the structural unit corresponding to the monomer in the copolymer (cP). For example, the content of the monomer (A) in all the monomers used for the synthesis of the copolymer (cP) is the content of the structural unit (a) in the copolymer (cP) to be synthesized. be. However, when the monomer (B) contains a monomer (B2) that does not form a salt, the anionic functional group of the monomer (B2) is salted by the equivalent of the cation contained in the neutralizing agent. Is considered to have formed. When the equivalent of the cation contained in the neutralizing agent is larger than the anion equivalent of the monomer (B2) used for the polymerization, it is considered that all the monomers (B2) form a salt. On the other hand, when the equivalent of the cation contained in the neutralizing agent is smaller than the anion equivalent of the monomer (B2) used for the polymerization, it is considered that all the cations form a salt with the monomer (B2) (that is,). , The monomer (B2) forms a salt by the equivalent of the cation contained in the neutralizing agent). The radical polymerization is preferably carried out at a temperature of 30 to 90 ° C., although it depends on the type of the polymerization initiator. Specific examples of the copolymer (cP) polymerization method will be described in detail in Examples described later.
ラジカル重合開始剤としては、例えば、過硫酸アンモニウム、過硫酸カリウム、過酸化水素、t-ブチルハイドロパーオキサイド、アゾ化合物等が挙げられるが、これに限られない。アゾ化合物としては、例えば、2,2’-アゾビス(2-メチルプロピオンアミジン)2塩酸塩が挙げられる。重合を水中で行う場合は、水溶性の重合開始剤を用いることが好ましい。また、必要に応じて、重合の際にラジカル重合開始剤と、還元剤とを併用して、レドックス重合してもよい。還元剤としては、重亜硫酸ナトリウム、ロンガリット、アスコルビン酸等が挙げられる。
Examples of the radical polymerization initiator include, but are not limited to, ammonium persulfate, potassium persulfate, hydrogen peroxide, t-butyl hydroperoxide, and azo compounds. Examples of the azo compound include 2,2'-azobis (2-methylpropionamidine) dihydrochloride. When the polymerization is carried out in water, it is preferable to use a water-soluble polymerization initiator. Further, if necessary, a radical polymerization initiator and a reducing agent may be used in combination at the time of polymerization for redox polymerization. Examples of the reducing agent include sodium bisulfite, longalit, ascorbic acid and the like.
水性媒体として水を用いることが好ましいが、得られる共重合体(cP)の重合安定性を損なわない限り、水に親水性の溶媒を添加したものを水性媒体として用いてもよい。水に添加する親水性の溶媒としては、メタノール、エタノール及びN-メチルピロリドン等が挙げられる。
It is preferable to use water as the aqueous medium, but water to which a hydrophilic solvent is added may be used as the aqueous medium as long as the polymerization stability of the obtained copolymer (cP) is not impaired. Examples of the hydrophilic solvent added to water include methanol, ethanol, N-methylpyrrolidone and the like.
<2.非水系二次電池電極用バインダー組成物>
本実施形態の非水系二次電池電極用バインダー組成物(または、非水系二次電池バインダー組成物、以下、「電極バインダー組成物」とすることもある。)は、電極バインダー、及び媒体として水性媒体を含む。また、電極バインダー組成物は、必要に応じてpH調整剤、界面活性剤等、その他の成分を含んでもよい。 <2. Binder composition for non-aqueous secondary battery electrodes>
The binder composition for a non-aqueous secondary battery electrode of the present embodiment (or a non-aqueous secondary battery binder composition, hereinafter may be referred to as an “electrode binder composition”) is an aqueous electrode binder and an aqueous medium. Includes medium. Further, the electrode binder composition may contain other components such as a pH adjuster and a surfactant, if necessary.
本実施形態の非水系二次電池電極用バインダー組成物(または、非水系二次電池バインダー組成物、以下、「電極バインダー組成物」とすることもある。)は、電極バインダー、及び媒体として水性媒体を含む。また、電極バインダー組成物は、必要に応じてpH調整剤、界面活性剤等、その他の成分を含んでもよい。 <2. Binder composition for non-aqueous secondary battery electrodes>
The binder composition for a non-aqueous secondary battery electrode of the present embodiment (or a non-aqueous secondary battery binder composition, hereinafter may be referred to as an “electrode binder composition”) is an aqueous electrode binder and an aqueous medium. Includes medium. Further, the electrode binder composition may contain other components such as a pH adjuster and a surfactant, if necessary.
電極バインダー組成物に含まれる水性媒体は、水を含む。電極バインダー組成物に含まれる水性媒体は、親水性の溶媒を含んでもよい。親水性の溶媒としては、メタノール、エタノール及びN-メチルピロリドン等が挙げられる。電極バインダー組成物に含まれる水性媒体において、その中の水の含有率は80質量%以上であることが好ましく、90質量%以上であることがより好ましく、95質量%以上であることがさらに好ましい。
The aqueous medium contained in the electrode binder composition contains water. The aqueous medium contained in the electrode binder composition may contain a hydrophilic solvent. Examples of the hydrophilic solvent include methanol, ethanol, N-methylpyrrolidone and the like. In the aqueous medium contained in the electrode binder composition, the content of water in the aqueous medium is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more. ..
電極バインダー組成物に含まれる水性媒体は、重合体(P)の合成に用いた水性媒体と同じであってもよく、この水性媒体に水等の溶媒をさらに加えたものであってもよい。本実施形態の電極バインダー組成物において、水性媒体100gに対する重合体(P)の含有量は、23℃の水100gに対する重合体(P)の溶解度より多いことが好ましい。例えば、重合体(P)の水に対する溶解度が3.09g/100g未満の場合、水性媒体100gに対して、重合体(P)の含有量は3.09g以上であれば条件を満たす(水に重合体(P)が完全に溶解しないための十分条件)。
The aqueous medium contained in the electrode binder composition may be the same as the aqueous medium used for the synthesis of the polymer (P), or may be a solvent such as water added to the aqueous medium. In the electrode binder composition of the present embodiment, the content of the polymer (P) in 100 g of the aqueous medium is preferably higher than the solubility of the polymer (P) in 100 g of water at 23 ° C. For example, when the solubility of the polymer (P) in water is less than 3.09 g / 100 g, the condition is satisfied if the content of the polymer (P) is 3.09 g or more with respect to 100 g of the aqueous medium (in water). Sufficient conditions for the polymer (P) not to be completely dissolved).
ここで、電極バインダー組成物において、重合体(P)は水性媒体中に分散していることが好ましい。ここで重合体(P)が分散しているとは、23℃で24時間静置しても上澄み及び重合体(P)の沈殿が生じず、濁っている状態が維持されていることを意味する。
Here, in the electrode binder composition, it is preferable that the polymer (P) is dispersed in an aqueous medium. Here, the fact that the polymer (P) is dispersed means that the supernatant and the polymer (P) do not precipitate even after being allowed to stand at 23 ° C. for 24 hours, and the turbid state is maintained. do.
電極バインダー組成物中の電極バインダーの含有率は、30質量%以下であることが好ましく、20質量%以下であることがより好ましい。電極バインダー組成物の粘度の上昇を抑制し、後述する電極活物質等と混合して、電極スラリーを作製する場合に、効率よく電極活物質等を分散させるためである。
The content of the electrode binder in the electrode binder composition is preferably 30% by mass or less, more preferably 20% by mass or less. This is to suppress an increase in the viscosity of the electrode binder composition and efficiently disperse the electrode active material or the like when the electrode slurry is prepared by mixing with the electrode active material or the like described later.
電極バインダー組成物中の電極バインダーの含有率は、3.0質量%以上であることが好ましく、5.0質量%以上であることがより好ましく、8.0質量%以上であることがさらに好ましい。より少ない電極バインダー組成物から電極スラリー及び電極を作製することができるためである。
The content of the electrode binder in the electrode binder composition is preferably 3.0% by mass or more, more preferably 5.0% by mass or more, and further preferably 8.0% by mass or more. .. This is because the electrode slurry and the electrode can be produced from a smaller amount of the electrode binder composition.
電極バインダー組成物のpHは、4.0以上であることが好ましく、5.0以上であることがより好ましく、6.0以上であることがさらに好ましい。後述する電極活物質等と混合して、電極スラリーを作製する場合に、効率よく電極活物質等を分散させるためである。電極バインダー組成物のpHは、10以下であることが好ましく、9.0以下であることがより好ましく、8.0以下であることがさらに好ましい。後述する電極活物質等と混合して、電極スラリーを作製する場合に、効率よく電極活物質等を分散させるためである。ここで、pHは、液温23℃において、pHメーターにより測定された値である。
The pH of the electrode binder composition is preferably 4.0 or higher, more preferably 5.0 or higher, and even more preferably 6.0 or higher. This is to efficiently disperse the electrode active material and the like when the electrode slurry is prepared by mixing with the electrode active material and the like described later. The pH of the electrode binder composition is preferably 10 or less, more preferably 9.0 or less, and even more preferably 8.0 or less. This is to efficiently disperse the electrode active material and the like when the electrode slurry is prepared by mixing with the electrode active material and the like described later. Here, the pH is a value measured by a pH meter at a liquid temperature of 23 ° C.
<3.非水系二次電池電極用スラリー>
本実施形態の非水系二次電池電極用スラリー(または、非水系二次電池電極スラリー。以下、「電極スラリー」とすることもある。)では、電極バインダーと、電極活物質とが、水性媒体に溶解または分散している。本実施形態の電極スラリーは、必要に応じて導電助剤、増粘剤等を含んでもよいが、電極スラリー作製工程を簡単化するためには、増粘剤を含まないほうが好ましい。電極スラリーを調製するためには、各材料が均一に溶解、分散すれば特に制限は無い。電極スラリーを調製する方法としては、特に限定されないが、例えば、攪拌式、回転式、または振とう式などの混合装置を使用して必要な成分を混合する方法が挙げられる。 <3. Slurry for non-aqueous secondary battery electrodes >
In the non-aqueous secondary battery electrode slurry (or non-aqueous secondary battery electrode slurry; hereinafter, also referred to as “electrode slurry”) of the present embodiment, the electrode binder and the electrode active material are an aqueous medium. Dissolved or dispersed in. The electrode slurry of the present embodiment may contain a conductive auxiliary agent, a thickener and the like, if necessary, but it is preferable that the electrode slurry does not contain a thickener in order to simplify the process of producing the electrode slurry. In order to prepare the electrode slurry, there is no particular limitation as long as each material is uniformly dissolved and dispersed. The method for preparing the electrode slurry is not particularly limited, and examples thereof include a method of mixing necessary components using a mixing device such as a stirring type, a rotary type, or a shaking type.
本実施形態の非水系二次電池電極用スラリー(または、非水系二次電池電極スラリー。以下、「電極スラリー」とすることもある。)では、電極バインダーと、電極活物質とが、水性媒体に溶解または分散している。本実施形態の電極スラリーは、必要に応じて導電助剤、増粘剤等を含んでもよいが、電極スラリー作製工程を簡単化するためには、増粘剤を含まないほうが好ましい。電極スラリーを調製するためには、各材料が均一に溶解、分散すれば特に制限は無い。電極スラリーを調製する方法としては、特に限定されないが、例えば、攪拌式、回転式、または振とう式などの混合装置を使用して必要な成分を混合する方法が挙げられる。 <3. Slurry for non-aqueous secondary battery electrodes >
In the non-aqueous secondary battery electrode slurry (or non-aqueous secondary battery electrode slurry; hereinafter, also referred to as “electrode slurry”) of the present embodiment, the electrode binder and the electrode active material are an aqueous medium. Dissolved or dispersed in. The electrode slurry of the present embodiment may contain a conductive auxiliary agent, a thickener and the like, if necessary, but it is preferable that the electrode slurry does not contain a thickener in order to simplify the process of producing the electrode slurry. In order to prepare the electrode slurry, there is no particular limitation as long as each material is uniformly dissolved and dispersed. The method for preparing the electrode slurry is not particularly limited, and examples thereof include a method of mixing necessary components using a mixing device such as a stirring type, a rotary type, or a shaking type.
電極スラリーの不揮発分濃度は好ましくは30質量%以上であり、より好ましくは40質量%以上である。少ない電極スラリーの量でより多くの電極活物質層を形成させるためである。電極スラリーの不揮発分濃度は好ましくは70質量%以下であり、より好ましくは60質量%以下である。不揮発分濃度は、水性媒体の量により調整できる。
The non-volatile content concentration of the electrode slurry is preferably 30% by mass or more, more preferably 40% by mass or more. This is to form a larger electrode active material layer with a smaller amount of electrode slurry. The non-volatile content concentration of the electrode slurry is preferably 70% by mass or less, more preferably 60% by mass or less. The non-volatile content concentration can be adjusted by the amount of the aqueous medium.
ここで不揮発分濃度とは、特に断りがなければ、混合物を直径5cmのアルミ皿に1g秤量し、大気圧、乾燥器内で空気を循環させながら130℃で1時間乾燥させ後に残った成分の質量の、乾燥前の質量に対する割合である。
Here, the non-volatile content concentration means that, unless otherwise specified, 1 g of the mixture is weighed in an aluminum dish having a diameter of 5 cm, dried at 130 ° C. for 1 hour while circulating air in a dryer at atmospheric pressure, and the remaining components. The ratio of mass to mass before drying.
<3-1.電極バインダーの含有率>
電極スラリー中の電極バインダーの含有量は、電極活物質(後述する)と導電助剤(後述する)と電極バインダーとを合計した質量に対して、0.5質量%以上であることが好ましく、1.0質量%以上であることがより好ましく、2.0質量%以上であることがさらに好ましい。電極バインダーにより、電極活物質間、及び電極活物質と集電体との結着性を確保することができるためである。電極スラリー中の電極バインダーの含有量は、電極活物質と導電助剤と電極バインダーとを合計した質量に対して、7.0質量%以下であることが好ましく、5.0質量%以下であることがより好ましく、4.0質量%以下であることがさらに好ましい。電極スラリーから形成される電極活物質層の充放電容量を大きくすることができ、電池としたときの内部抵抗も低くすることができるためである。 <3-1. Electrode binder content>
The content of the electrode binder in the electrode slurry is preferably 0.5% by mass or more with respect to the total mass of the electrode active material (described later), the conductive auxiliary agent (described later), and the electrode binder. It is more preferably 1.0% by mass or more, and further preferably 2.0% by mass or more. This is because the electrode binder can ensure the binding property between the electrode active materials and between the electrode active material and the current collector. The content of the electrode binder in the electrode slurry is preferably 7.0% by mass or less, preferably 5.0% by mass or less, based on the total mass of the electrode active material, the conductive auxiliary agent, and the electrode binder. More preferably, it is more preferably 4.0% by mass or less. This is because the charge / discharge capacity of the electrode active material layer formed from the electrode slurry can be increased, and the internal resistance of the battery can be reduced.
電極スラリー中の電極バインダーの含有量は、電極活物質(後述する)と導電助剤(後述する)と電極バインダーとを合計した質量に対して、0.5質量%以上であることが好ましく、1.0質量%以上であることがより好ましく、2.0質量%以上であることがさらに好ましい。電極バインダーにより、電極活物質間、及び電極活物質と集電体との結着性を確保することができるためである。電極スラリー中の電極バインダーの含有量は、電極活物質と導電助剤と電極バインダーとを合計した質量に対して、7.0質量%以下であることが好ましく、5.0質量%以下であることがより好ましく、4.0質量%以下であることがさらに好ましい。電極スラリーから形成される電極活物質層の充放電容量を大きくすることができ、電池としたときの内部抵抗も低くすることができるためである。 <3-1. Electrode binder content>
The content of the electrode binder in the electrode slurry is preferably 0.5% by mass or more with respect to the total mass of the electrode active material (described later), the conductive auxiliary agent (described later), and the electrode binder. It is more preferably 1.0% by mass or more, and further preferably 2.0% by mass or more. This is because the electrode binder can ensure the binding property between the electrode active materials and between the electrode active material and the current collector. The content of the electrode binder in the electrode slurry is preferably 7.0% by mass or less, preferably 5.0% by mass or less, based on the total mass of the electrode active material, the conductive auxiliary agent, and the electrode binder. More preferably, it is more preferably 4.0% by mass or less. This is because the charge / discharge capacity of the electrode active material layer formed from the electrode slurry can be increased, and the internal resistance of the battery can be reduced.
<3-2.電極活物質>
非水系二次電池は、特に限定されないが、リチウムイオン二次電池である場合、負極活物質の例として、導電性ポリマー、炭素材料、チタン酸リチウム、シリコン、シリコン化合物等が挙げられる。導電性ポリマーとして、ポリアセチレン、ポリピロール等が挙げられる。炭素材料としては、石油コークス、ピッチコークス、石炭コークス等のコークス;有機化合物の炭化物、カーボンファイバー、アセチレンブラック等のカーボンブラック;人造黒鉛、天然黒鉛等の黒鉛などが挙げられる。シリコン化合物としては、SiOx(0.1≦x≦2.0)等が挙げられる。 <3-2. Electrode active material>
The non-aqueous secondary battery is not particularly limited, and in the case of a lithium ion secondary battery, examples of the negative electrode active material include a conductive polymer, a carbon material, lithium titanate, silicon, a silicon compound and the like. Examples of the conductive polymer include polyacetylene and polypyrrole. Examples of the carbon material include coke such as petroleum coke, pitch coke, and coal coke; carbon dioxide of organic compounds, carbon fiber, carbon black such as acetylene black; and graphite such as artificial graphite and natural graphite. Examples of the silicon compound include SiO x (0.1 ≦ x ≦ 2.0).
非水系二次電池は、特に限定されないが、リチウムイオン二次電池である場合、負極活物質の例として、導電性ポリマー、炭素材料、チタン酸リチウム、シリコン、シリコン化合物等が挙げられる。導電性ポリマーとして、ポリアセチレン、ポリピロール等が挙げられる。炭素材料としては、石油コークス、ピッチコークス、石炭コークス等のコークス;有機化合物の炭化物、カーボンファイバー、アセチレンブラック等のカーボンブラック;人造黒鉛、天然黒鉛等の黒鉛などが挙げられる。シリコン化合物としては、SiOx(0.1≦x≦2.0)等が挙げられる。 <3-2. Electrode active material>
The non-aqueous secondary battery is not particularly limited, and in the case of a lithium ion secondary battery, examples of the negative electrode active material include a conductive polymer, a carbon material, lithium titanate, silicon, a silicon compound and the like. Examples of the conductive polymer include polyacetylene and polypyrrole. Examples of the carbon material include coke such as petroleum coke, pitch coke, and coal coke; carbon dioxide of organic compounds, carbon fiber, carbon black such as acetylene black; and graphite such as artificial graphite and natural graphite. Examples of the silicon compound include SiO x (0.1 ≦ x ≦ 2.0).
また、負極活物質としては、Siと黒鉛とを含む複合材料(Si/黒鉛)等を用いてもよい。これら活物質の中でも、体積当たりのエネルギー密度が大きい点から、炭素材料、チタン酸リチウム、シリコン、シリコン化合物を用いることが好ましい。また、コークス、有機化合物の炭化物、黒鉛等の炭素材料、SiOx(0.1≦x≦2.0)、Si、Si/黒鉛等のシリコン含有材料であると、本実施形態の電極バインダーによる結着性を向上させる効果が顕著である。例えば、人造黒鉛の具体例としては、SCMG(登録商標)-XRs(昭和電工(株)製)が挙げられる。なお、負極活物質として、ここで挙げた材料を2種類以上複合化してもよい。
Further, as the negative electrode active material, a composite material (Si / graphite) containing Si and graphite may be used. Among these active materials, it is preferable to use a carbon material, lithium titanate, silicon, or a silicon compound because the energy density per volume is large. Further, if coke, a carbide of an organic compound, a carbon material such as graphite, or a silicon-containing material such as SiO x (0.1 ≦ x ≦ 2.0), Si, Si / graphite is used, the electrode binder of the present embodiment is used. The effect of improving the binding property is remarkable. For example, specific examples of artificial graphite include SCMG (registered trademark) -XRs (manufactured by Showa Denko KK). As the negative electrode active material, two or more kinds of the materials listed here may be combined.
リチウムイオン二次電池の正極活物質の例として、コバルト酸リチウム(LiCoO2);ニッケルを含むリチウム複合酸化物;スピネル型マンガン酸リチウム(LiMn2O4);オリビン型燐酸鉄リチウム;TiS2、MnO2、MoO3、V2O5等のカルコゲン化合物が挙げられる。正極活物質は、これらの化合物のいずれかを単独で含んでもよく、あるいは複数種を含んでもよい。また、その他のアルカリ金属の酸化物も使用することができる。ニッケルを含むリチウム複合酸化物として、Ni-Co-Mn系のリチウム複合酸化物、Ni-Mn-Al系のリチウム複合酸化物、Ni-Co-Al系のリチウム複合酸化物などが挙げられる。正極活物質の具体例として、LiNi1/3Mn1/3Co1/3O2やLiNi3/5Mn1/5Co1/5など挙げられる。
As an example of the positive electrode active material of a lithium ion secondary battery, lithium cobalt oxide (LiCoO 2 ); lithium composite oxide containing nickel; spinel-type lithium manganate (LiMn 2 O 4 ); olivine-type iron phosphate lithium; TiS 2 , MnO 2, MoO 3, V 2 O chalcogen compounds such as 5 and the like. The positive electrode active material may contain any one of these compounds alone, or may contain a plurality of types. In addition, oxides of other alkali metals can also be used. Examples of the lithium composite oxide containing nickel include a Ni—Co—Mn-based lithium composite oxide, a Ni—Mn—Al based lithium composite oxide, and a Ni—Co—Al based lithium composite oxide. Specific examples of the positive electrode active material include LiNi 1/3 Mn 1/3 Co 1/3 O 2 and LiNi 3/5 Mn 1/5 Co 1/5 .
<3-3.導電助剤>
電極スラリーは、導電助剤として、カーボンブラック、気相法炭素繊維等を含んでもよい。気相法炭素繊維の具体例としては、VGCF(登録商標)-H(昭和電工(株))が挙げられる。 <3-3. Conductive aid>
The electrode slurry may contain carbon black, vapor phase carbon fiber, or the like as the conductive auxiliary agent. Specific examples of the vapor phase carbon fiber include VGCF (registered trademark) -H (Showa Denko KK).
電極スラリーは、導電助剤として、カーボンブラック、気相法炭素繊維等を含んでもよい。気相法炭素繊維の具体例としては、VGCF(登録商標)-H(昭和電工(株))が挙げられる。 <3-3. Conductive aid>
The electrode slurry may contain carbon black, vapor phase carbon fiber, or the like as the conductive auxiliary agent. Specific examples of the vapor phase carbon fiber include VGCF (registered trademark) -H (Showa Denko KK).
<3-4.水性媒体>
電極スラリーの水性媒体は、水を含む。電極スラリーの水性媒体は、親水性の溶媒を含んでもよい。親水性の溶媒としては、メタノール、エタノール及びN-メチルピロリドン等が挙げられる。水性媒体中の水の含有率は80質量%以上であることが好ましく、90質量%以上であることがより好ましく、95質量%以上であることがさらに好ましい。水性媒体は、電極バインダー組成物に含まれる媒体と同じでもよい。 <3-4. Aqueous medium>
The aqueous medium of the electrode slurry contains water. The aqueous medium of the electrode slurry may contain a hydrophilic solvent. Examples of the hydrophilic solvent include methanol, ethanol, N-methylpyrrolidone and the like. The content of water in the aqueous medium is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more. The aqueous medium may be the same as the medium contained in the electrode binder composition.
電極スラリーの水性媒体は、水を含む。電極スラリーの水性媒体は、親水性の溶媒を含んでもよい。親水性の溶媒としては、メタノール、エタノール及びN-メチルピロリドン等が挙げられる。水性媒体中の水の含有率は80質量%以上であることが好ましく、90質量%以上であることがより好ましく、95質量%以上であることがさらに好ましい。水性媒体は、電極バインダー組成物に含まれる媒体と同じでもよい。 <3-4. Aqueous medium>
The aqueous medium of the electrode slurry contains water. The aqueous medium of the electrode slurry may contain a hydrophilic solvent. Examples of the hydrophilic solvent include methanol, ethanol, N-methylpyrrolidone and the like. The content of water in the aqueous medium is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more. The aqueous medium may be the same as the medium contained in the electrode binder composition.
<4.電極>
本実施形態の電極は、集電体と、集電体の表面に形成された電極活物質層とを有する。電極活物質層は、電極活物質、及び本実施形態の電極バインダーを含む。電極の形状としては、例えば、積層体や捲回体が挙げられるが、特に限定されない。集電体は、厚さ0.001~0.5mmのシート状の金属であることが好ましい。金属としては、鉄、銅、アルミニウム、ニッケル、ステンレス等が挙げられる。非水系二次電池がリチウムイオン二次電池の場合、正極の集電体の材料としてはアルミニウム、負極の集電体の材料としては銅が好ましい。 <4. Electrode>
The electrode of the present embodiment has a current collector and an electrode active material layer formed on the surface of the current collector. The electrode active material layer contains the electrode active material and the electrode binder of the present embodiment. Examples of the shape of the electrode include a laminated body and a wound body, but the shape is not particularly limited. The current collector is preferably a sheet-shaped metal having a thickness of 0.001 to 0.5 mm. Examples of the metal include iron, copper, aluminum, nickel, stainless steel and the like. When the non-aqueous secondary battery is a lithium ion secondary battery, aluminum is preferable as the material of the positive electrode current collector, and copper is preferable as the material of the negative electrode current collector.
本実施形態の電極は、集電体と、集電体の表面に形成された電極活物質層とを有する。電極活物質層は、電極活物質、及び本実施形態の電極バインダーを含む。電極の形状としては、例えば、積層体や捲回体が挙げられるが、特に限定されない。集電体は、厚さ0.001~0.5mmのシート状の金属であることが好ましい。金属としては、鉄、銅、アルミニウム、ニッケル、ステンレス等が挙げられる。非水系二次電池がリチウムイオン二次電池の場合、正極の集電体の材料としてはアルミニウム、負極の集電体の材料としては銅が好ましい。 <4. Electrode>
The electrode of the present embodiment has a current collector and an electrode active material layer formed on the surface of the current collector. The electrode active material layer contains the electrode active material and the electrode binder of the present embodiment. Examples of the shape of the electrode include a laminated body and a wound body, but the shape is not particularly limited. The current collector is preferably a sheet-shaped metal having a thickness of 0.001 to 0.5 mm. Examples of the metal include iron, copper, aluminum, nickel, stainless steel and the like. When the non-aqueous secondary battery is a lithium ion secondary battery, aluminum is preferable as the material of the positive electrode current collector, and copper is preferable as the material of the negative electrode current collector.
本実施形態の電極は、例えば、電極スラリーを集電体上に塗布し、乾燥させることにより製造できるが、この方法に限られない。
The electrode of the present embodiment can be manufactured, for example, by applying an electrode slurry on a current collector and drying it, but the method is not limited to this method.
電極スラリーを集電体上に塗布する方法としては、例えば、リバースロール法、ダイレクトロール法、ドクターブレード法、ナイフ法、エクストルージョン法、カーテン法、グラビア法、バー法、ディップ法およびスクイーズ法等が挙げられる。これらの中でも、ドクターブレード法、ナイフ法、またはエクストルージョン法が好ましく、ドクターブレードを用いて塗布することがより好ましい。電極スラリーの粘性等の諸物性及び乾燥性に対して好適であり、良好な表面状態の塗布膜を得られるためである。
Examples of the method for applying the electrode slurry onto the current collector include a reverse roll method, a direct roll method, a doctor blade method, a knife method, an extrusion method, a curtain method, a gravure method, a bar method, a dip method and a squeeze method. Can be mentioned. Among these, the doctor blade method, the knife method, or the extrusion method is preferable, and it is more preferable to apply using the doctor blade. This is because it is suitable for various physical properties such as viscosity of the electrode slurry and drying property, and a coating film having a good surface condition can be obtained.
電極スラリーは、集電体の片面にのみ塗布してもよいし、両面に塗布してもよい。電極スラリーを集電体の両面に塗布する場合は、片面ずつ塗布してもよく、両面同時に塗布してもよい。また、電極スラリーは、集電体の表面に連続して塗布してもよいし、間欠的に塗布してもよい。電極スラリーの塗布量、塗布範囲は、電池の大きさなどに応じて、適宜決定できる。乾燥後の電極活物質層の目付量は、4~20mg/cm2であることが好ましく、6~16mg/cm2であることがより好ましい。
The electrode slurry may be applied to only one side of the current collector or may be applied to both sides. When the electrode slurry is applied to both sides of the current collector, it may be applied to each side or both sides at the same time. Further, the electrode slurry may be continuously applied to the surface of the current collector, or may be applied intermittently. The coating amount and coating range of the electrode slurry can be appropriately determined according to the size of the battery and the like. The basis weight of the electrode active material layer after drying is preferably 4 to 20 mg / cm 2 , and more preferably 6 to 16 mg / cm 2 .
集電体に塗布された電極スラリーを乾燥することにより電極シートが得られる。乾燥方法は、特に限定されないが、例えば、熱風、真空、(遠)赤外線、電子線、マイクロ波および低温風を単独あるいは組み合わせて用いることができる。乾燥温度は、40℃以上180℃以下であることが好ましく、乾燥時間は、1分以上30分以下であることが好ましい。
An electrode sheet can be obtained by drying the electrode slurry applied to the current collector. The drying method is not particularly limited, and for example, hot air, vacuum, (far) infrared rays, electron beams, microwaves, and low temperature air can be used alone or in combination. The drying temperature is preferably 40 ° C. or higher and 180 ° C. or lower, and the drying time is preferably 1 minute or longer and 30 minutes or lower.
電極シートはそのまま電極として用いてもよいが、電極として適当な大きさや形状にするために切断してもよい。電極シートの切断方法は特に限定されないが、例えば、スリット、レーザー、ワイヤーカット、カッター、トムソン等を用いることができる。
The electrode sheet may be used as it is as an electrode, but it may be cut to obtain an appropriate size and shape as an electrode. The method for cutting the electrode sheet is not particularly limited, but for example, a slit, a laser, a wire cut, a cutter, a Thomson, or the like can be used.
電極シートを切断する前または後に、必要に応じてそれをプレスしてもよい。それによって電極活物質を電極により強固に結着させ、さらに電極を薄くすることによる非水系電池のコンパクト化が可能になる。プレスの方法としては、一般的な方法を用いることができ、特に金型プレス法またはロールプレス法を用いることが好ましい。プレス圧は、特に限定されないが、プレスによる電極活物質へのリチウムイオン等のドープ/脱ドープに影響を及ぼさない範囲である0.5~5t/cm2とすることが好ましい。
It may be pressed as needed before or after cutting the electrode sheet. As a result, the electrode active material is firmly bound to the electrode, and the electrode can be made thinner, so that the non-aqueous battery can be made compact. As a pressing method, a general method can be used, and it is particularly preferable to use a die pressing method or a roll pressing method. The press pressure is not particularly limited, but is preferably 0.5 to 5 t / cm 2 , which is a range that does not affect the doping / dedoping of lithium ions or the like on the electrode active material by the press.
<5.電池>
本実施形態にかかる電池の好ましい一例として、リチウムイオン二次電池について説明するが、電池の構成は以下に説明する構成に限られない。ここで説明する例にかかるリチウムイオン二次電池は、正極、負極、電解液、及び必要に応じてセパレータ等の部品が外装体に収容されている。正極と負極のうち少なくとも一方は、本実施形態にかかる電極バインダーを含む。 <5. Battery>
A lithium ion secondary battery will be described as a preferred example of the battery according to the present embodiment, but the battery configuration is not limited to the configuration described below. In the lithium ion secondary battery according to the example described here, parts such as a positive electrode, a negative electrode, an electrolytic solution, and, if necessary, a separator are housed in an exterior body. At least one of the positive electrode and the negative electrode contains the electrode binder according to the present embodiment.
本実施形態にかかる電池の好ましい一例として、リチウムイオン二次電池について説明するが、電池の構成は以下に説明する構成に限られない。ここで説明する例にかかるリチウムイオン二次電池は、正極、負極、電解液、及び必要に応じてセパレータ等の部品が外装体に収容されている。正極と負極のうち少なくとも一方は、本実施形態にかかる電極バインダーを含む。 <5. Battery>
A lithium ion secondary battery will be described as a preferred example of the battery according to the present embodiment, but the battery configuration is not limited to the configuration described below. In the lithium ion secondary battery according to the example described here, parts such as a positive electrode, a negative electrode, an electrolytic solution, and, if necessary, a separator are housed in an exterior body. At least one of the positive electrode and the negative electrode contains the electrode binder according to the present embodiment.
<5-1.電解液>
電解液としては、イオン伝導性を有する非水系の液体を使用する。電解液としては、電解質を有機溶媒に溶解させた溶液、イオン液体等が挙げられるが、製造コストが低く、内部抵抗の低い電池が得られるため、前者が好ましい。 <5-1. Electrolyte>
As the electrolytic solution, a non-aqueous liquid having ionic conductivity is used. Examples of the electrolytic solution include a solution in which an electrolyte is dissolved in an organic solvent, an ionic liquid, and the like, but the former is preferable because a battery having a low manufacturing cost and a low internal resistance can be obtained.
電解液としては、イオン伝導性を有する非水系の液体を使用する。電解液としては、電解質を有機溶媒に溶解させた溶液、イオン液体等が挙げられるが、製造コストが低く、内部抵抗の低い電池が得られるため、前者が好ましい。 <5-1. Electrolyte>
As the electrolytic solution, a non-aqueous liquid having ionic conductivity is used. Examples of the electrolytic solution include a solution in which an electrolyte is dissolved in an organic solvent, an ionic liquid, and the like, but the former is preferable because a battery having a low manufacturing cost and a low internal resistance can be obtained.
電解質としては、アルカリ金属塩を用いることができ、電極活物質の種類等に応じ適宜選択できる。電解質としては、例えば、LiClO4、LiBF6、LiPF6、LiCF3SO3、LiCF3CO2、LiAsF6、LiSbF6、LiB10Cl10、LiAlCl4、LiCl、LiBr、LiB(C2H5)4、CF3SO3Li、CH3SO3Li、LiCF3SO3、LiC4F9SO3、Li(CF3SO2)2N、脂肪族カルボン酸リチウム等が挙げられる。また、電解質として、その他のアルカリ金属塩を用いることもできる。
As the electrolyte, an alkali metal salt can be used and can be appropriately selected depending on the type of the electrode active material and the like. As the electrolyte, for example, LiClO 4, LiBF 6, LiPF 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiB 10 Cl 10, LiAlCl 4, LiCl, LiBr, LiB (C 2 H 5) 4 , CF 3 SO 3 Li, CH 3 SO 3 Li, LiCF 3 SO 3 , LiC 4 F 9 SO 3 , Li (CF 3 SO 2 ) 2 N, lithium aliphatic carboxylate and the like can be mentioned. Further, other alkali metal salts can also be used as the electrolyte.
電解質を溶解する有機溶媒としては、特に限定されないが、例えば、エチレンカーボネート(EC)、プロピレンカーボネート(PC)、ジエチルカーボネート(DEC)、メチルエチルカーボネート(MEC)、ジメチルカーボネート(DMC)、フルオロエチレンカーボネート(FEC)、ビニレンカーボネート(VC)等の炭酸エステル化合物;アセトニトリル等のニトリル化合物;酢酸エチル、酢酸プロピル、プロピオン酸メチル、プロピオン酸エチル、プロピオン酸プロピルなどのカルボン酸エステルが挙げられる。これらの有機溶媒は、1種単独で使用してもよいし、2種以上を組み合わせて使用してもよい。
The organic solvent that dissolves the electrolyte is not particularly limited, and is, for example, ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), dimethyl carbonate (DMC), and fluoroethylene carbonate. Carbonic acid ester compounds such as (FEC) and vinylene carbonate (VC); nitrile compounds such as acetonitrile; carboxylic acid esters such as ethyl acetate, propyl acetate, methyl propionate, ethyl propionate and propyl propionate. These organic solvents may be used alone or in combination of two or more.
<5-2.外装体>
外装体としては、金属やアルミラミネート材などを適宜使用できる。電池の形状は、コイン型、ボタン型、シート型、円筒型、角型、扁平型等、いずれの形状であってもよい。 <5-2. Exterior>
As the exterior body, a metal, an aluminum laminated material, or the like can be appropriately used. The shape of the battery may be any shape such as a coin type, a button type, a sheet type, a cylindrical type, a square type, and a flat type.
外装体としては、金属やアルミラミネート材などを適宜使用できる。電池の形状は、コイン型、ボタン型、シート型、円筒型、角型、扁平型等、いずれの形状であってもよい。 <5-2. Exterior>
As the exterior body, a metal, an aluminum laminated material, or the like can be appropriately used. The shape of the battery may be any shape such as a coin type, a button type, a sheet type, a cylindrical type, a square type, and a flat type.
以下に、リチウムイオン二次電池の負極バインダー、負極スラリー、負極、リチウムイオン二次電池についての実施例および比較例を示して本発明をさらに詳細に説明する。なお、本発明はこれらに実施例によって限定されるものではない。
Hereinafter, the present invention will be described in more detail by showing examples and comparative examples of a negative electrode binder, a negative electrode slurry, a negative electrode, and a lithium ion secondary battery of a lithium ion secondary battery. The present invention is not limited to these examples.
<1.負極バインダー(重合体(P))の作製>
実施例1~7及び比較例1~8で用いた単量体の構成を表2に示した。単量体の構成以外は実施例1~7及び比較例1~8における負極バインダーの製造方法は同様である。単量体及び試薬の詳細は以下の通りである。単量体が溶液として用いられる場合、表中の単量体の使用量は、溶媒を含まないその単量体自体の量を示す。 <1. Preparation of Negative Electrode Binder (Polymer (P))>
The composition of the monomers used in Examples 1 to 7 and Comparative Examples 1 to 8 is shown in Table 2. Except for the composition of the monomer, the methods for producing the negative electrode binder in Examples 1 to 7 and Comparative Examples 1 to 8 are the same. Details of the monomers and reagents are as follows. When the monomer is used as a solution, the amount of the monomer used in the table indicates the amount of the monomer itself without solvent.
実施例1~7及び比較例1~8で用いた単量体の構成を表2に示した。単量体の構成以外は実施例1~7及び比較例1~8における負極バインダーの製造方法は同様である。単量体及び試薬の詳細は以下の通りである。単量体が溶液として用いられる場合、表中の単量体の使用量は、溶媒を含まないその単量体自体の量を示す。 <1. Preparation of Negative Electrode Binder (Polymer (P))>
The composition of the monomers used in Examples 1 to 7 and Comparative Examples 1 to 8 is shown in Table 2. Except for the composition of the monomer, the methods for producing the negative electrode binder in Examples 1 to 7 and Comparative Examples 1 to 8 are the same. Details of the monomers and reagents are as follows. When the monomer is used as a solution, the amount of the monomer used in the table indicates the amount of the monomer itself without solvent.
単量体(A-1):N-ビニルアセトアミド(NVA)(昭和電工(株)製)
単量体(B-1):アクリル酸ナトリウム(AaNa)(28.5質量%水溶液)
単量体(C-1):アクリル酸ベンジル
単量体(C-2):アクリル酸フェノキシエチル
単量体(C-3):メトキシポリエチレングリコールメタクリレート(EVONIK INDUSTRIES製;VISIOMER(登録商標)MPEG2005 MA W)(式(2)中のR3=CH3、R4=H、R6=CH3、n=45、m=0、m+n=45)の50.0質量%水溶液
単量体(D-1):スチレン
重合開始剤:2,2’-アゾビス(2-メチルプロピオンアミジン)2塩酸塩(和光純薬工業社製;V-50)及び過硫酸アンモニウム(和光純薬工業社製) Monomer (A-1): N-vinylacetamide (NVA) (manufactured by Showa Denko KK)
Monomer (B-1): Sodium acrylate (AaNa) (28.5% by mass aqueous solution)
Monomer (C-1): benzyl acrylate Monomer (C-2): Phenoxyethyl acrylate Monomer (C-3): methoxypolyethylene glycol methacrylate (manufactured by EVONIK INDUSTRIES; VISIOMER® MPEG2005 MA W) (R 3 = CH 3 , R 4 = H, R 6 = CH 3 , n = 45, m = 0, m + n = 45 in formula (2)) 50.0 mass% aqueous solution monomer (D) -1): Styrene polymerization initiator: 2,2'-azobis (2-methylpropionamidine) dihydrochloride (manufactured by Wako Pure Chemical Industries, Ltd .; V-50) and ammonium persulfate (manufactured by Wako Pure Chemical Industries, Ltd.)
単量体(B-1):アクリル酸ナトリウム(AaNa)(28.5質量%水溶液)
単量体(C-1):アクリル酸ベンジル
単量体(C-2):アクリル酸フェノキシエチル
単量体(C-3):メトキシポリエチレングリコールメタクリレート(EVONIK INDUSTRIES製;VISIOMER(登録商標)MPEG2005 MA W)(式(2)中のR3=CH3、R4=H、R6=CH3、n=45、m=0、m+n=45)の50.0質量%水溶液
単量体(D-1):スチレン
重合開始剤:2,2’-アゾビス(2-メチルプロピオンアミジン)2塩酸塩(和光純薬工業社製;V-50)及び過硫酸アンモニウム(和光純薬工業社製) Monomer (A-1): N-vinylacetamide (NVA) (manufactured by Showa Denko KK)
Monomer (B-1): Sodium acrylate (AaNa) (28.5% by mass aqueous solution)
Monomer (C-1): benzyl acrylate Monomer (C-2): Phenoxyethyl acrylate Monomer (C-3): methoxypolyethylene glycol methacrylate (manufactured by EVONIK INDUSTRIES; VISIOMER® MPEG2005 MA W) (R 3 = CH 3 , R 4 = H, R 6 = CH 3 , n = 45, m = 0, m + n = 45 in formula (2)) 50.0 mass% aqueous solution monomer (D) -1): Styrene polymerization initiator: 2,2'-azobis (2-methylpropionamidine) dihydrochloride (manufactured by Wako Pure Chemical Industries, Ltd .; V-50) and ammonium persulfate (manufactured by Wako Pure Chemical Industries, Ltd.)
冷却管、温度計、攪拌機、滴下ロートが組みつけられたセパラブルフラスコに、表2に示される組成の単量体を合計で100質量部と、2,2’-アゾビス(2-メチルプロピオンアミジン)2塩酸塩を0.2質量部と、過硫酸アンモニウムを0.05質量部と、水693質量部とを30℃で仕込んだ。これを、80℃に昇温し、4時間重合を行った。
In a separable flask equipped with a cooling tube, a thermometer, a stirrer, and a dropping funnel, a total of 100 parts by mass of the monomers having the composition shown in Table 2 and 2,2'-azobis (2-methylpropionamidine) were added. ) 0.2 parts by mass of 2 hydrochloride, 0.05 part by mass of ammonium persulfate, and 693 parts by mass of water were charged at 30 ° C. This was heated to 80 ° C. and polymerized for 4 hours.
その後、負極バインダー(重合体(P))の含有率が10.0質量%となるように水を加えて(単量体(B-1)に含まれる水を考慮して水の添加量を調節する)、負極バインダー組成物Q1~Q7、及びCQ1~CQ8を調製した。以下の説明において、「重合体P1~P7、及びCP1~CP8の各々」を「重合体(P)」、及び「負極バインダー組成物Q1~Q7、及びCQ1~CQ8の各々」を「負極バインダー組成物(Q)」とすることもある。
After that, water was added so that the content of the negative electrode binder (polymer (P)) was 10.0% by mass (the amount of water added was adjusted in consideration of the water contained in the monomer (B-1)). (Adjust), negative electrode binder compositions Q1 to Q7, and CQ1 to CQ8 were prepared. In the following description, "each of the polymers P1 to P7 and CP1 to CP8" is referred to as "polymer (P)", and "each of the negative electrode binder compositions Q1 to Q7 and CQ1 to CQ8" is referred to as "negative electrode binder composition". It may be called "thing (Q)".
負極バインダー組成物(Q)を、23℃で24時間静置後状態を目視にて観察したところ、上澄み及び沈殿は生じておらず、濁っており、分散状態が維持されていることが確認された。
When the negative electrode binder composition (Q) was allowed to stand at 23 ° C. for 24 hours and then visually observed, it was confirmed that no supernatant and no precipitate were formed, the mixture was turbid, and the dispersed state was maintained. rice field.
<2.負極バインダー組成物についての各種測定>
重合体(P)及び負極バインダー組成物(Q)について以下の測定を行った。測定結果は表2に示したとおりである。 <2. Various measurements on the negative electrode binder composition>
The following measurements were performed on the polymer (P) and the negative electrode binder composition (Q). The measurement results are shown in Table 2.
重合体(P)及び負極バインダー組成物(Q)について以下の測定を行った。測定結果は表2に示したとおりである。 <2. Various measurements on the negative electrode binder composition>
The following measurements were performed on the polymer (P) and the negative electrode binder composition (Q). The measurement results are shown in Table 2.
<2-1.重合体(P)の重量平均分子量>
重合体(P)の重量平均分子量を、ゲルパーミエーションクロマトグラフィー(GPC)を用いて以下の条件で測定した。 <2-1. Weight average molecular weight of polymer (P)>
The weight average molecular weight of the polymer (P) was measured by gel permeation chromatography (GPC) under the following conditions.
重合体(P)の重量平均分子量を、ゲルパーミエーションクロマトグラフィー(GPC)を用いて以下の条件で測定した。 <2-1. Weight average molecular weight of polymer (P)>
The weight average molecular weight of the polymer (P) was measured by gel permeation chromatography (GPC) under the following conditions.
GPC装置:GPC‐101(昭和電工(株)製))
溶媒:0.1M NaNO3水溶液
サンプルカラム:Shodex Column Ohpak SB-806 HQ(8.0mmI.D. x 300mm) ×2
リファレンスカラム:Shodex Column Ohpak SB-800 RL(8.0mmI.D. x 300mm) ×2
カラム温度:40℃
サンプル濃度:0.1質量%
検出器:RI-71S(株式会社島津製作所製)
ポンプ:DU-H2000(株式会社島津製作所製)
圧力:1.3MPa
流量:1ml/min
分子量スタンダード:プルラン(P‐5、P-10、P‐20、P-50、P‐100、P-200、P-400、P-800、P-1300、P-2500(昭和電工(株)製)) GPC device: GPC-101 (manufactured by Showa Denko KK))
Solvent: 0.1M NaNO 3 aqueous solution Sample column: Shodex Volume Ohpak SB-806 HQ (8.0 mm ID x 300 mm) x 2
Reference column: Shodex Colon Ohpak SB-800 RL (8.0 mm ID x 300 mm) x 2
Column temperature: 40 ° C
Sample concentration: 0.1% by mass
Detector: RI-71S (manufactured by Shimadzu Corporation)
Pump: DU-H2000 (manufactured by Shimadzu Corporation)
Pressure: 1.3MPa
Flow rate: 1 ml / min
Molecular weight standard: Pullulan (P-5, P-10, P-20, P-50, P-100, P-200, P-400, P-800, P-1300, P-2500 (Showa Denko KK) Made))
溶媒:0.1M NaNO3水溶液
サンプルカラム:Shodex Column Ohpak SB-806 HQ(8.0mmI.D. x 300mm) ×2
リファレンスカラム:Shodex Column Ohpak SB-800 RL(8.0mmI.D. x 300mm) ×2
カラム温度:40℃
サンプル濃度:0.1質量%
検出器:RI-71S(株式会社島津製作所製)
ポンプ:DU-H2000(株式会社島津製作所製)
圧力:1.3MPa
流量:1ml/min
分子量スタンダード:プルラン(P‐5、P-10、P‐20、P-50、P‐100、P-200、P-400、P-800、P-1300、P-2500(昭和電工(株)製)) GPC device: GPC-101 (manufactured by Showa Denko KK))
Solvent: 0.1M NaNO 3 aqueous solution Sample column: Shodex Volume Ohpak SB-806 HQ (8.0 mm ID x 300 mm) x 2
Reference column: Shodex Colon Ohpak SB-800 RL (8.0 mm ID x 300 mm) x 2
Column temperature: 40 ° C
Sample concentration: 0.1% by mass
Detector: RI-71S (manufactured by Shimadzu Corporation)
Pump: DU-H2000 (manufactured by Shimadzu Corporation)
Pressure: 1.3MPa
Flow rate: 1 ml / min
Molecular weight standard: Pullulan (P-5, P-10, P-20, P-50, P-100, P-200, P-400, P-800, P-1300, P-2500 (Showa Denko KK) Made))
<2-2.重合体(P)の水への溶解性>
実施例1~7及び比較例1~8で作製した負極バインダー組成物(Q)に水を加え、重合体(P)の濃度が3.0質量%(水100gに対して重合体(P)3.09g)の混合液を作製した。実施例1~7及び比較例3~8にかかる混合液については、濁っており、不溶分が確認できたが、比較例1及び2については透明な水溶液であった。このことから、実施例1~7及び比較例3~8にかかる共重合体(P)の23℃の水への溶解度は3.09g/100g未満であり、比較例1及び2にかかる共重合体(P)の23℃の水への溶解度は3.09g/100g以上であることがわかった。 <2-2. Solubility of polymer (P) in water>
Water was added to the negative electrode binder compositions (Q) prepared in Examples 1 to 7 and Comparative Examples 1 to 8, and the concentration of the polymer (P) was 3.0% by mass (the polymer (P) with respect to 100 g of water). A mixed solution of 3.09 g) was prepared. The mixed solutions of Examples 1 to 7 and Comparative Examples 3 to 8 were turbid and insoluble components could be confirmed, but Comparative Examples 1 and 2 were transparent aqueous solutions. From this, the solubility of the copolymer (P) according to Examples 1 to 7 and Comparative Examples 3 to 8 in water at 23 ° C. is less than 3.09 g / 100 g, and the copolymer weight according to Comparative Examples 1 and 2. It was found that the solubility of the coalescence (P) in water at 23 ° C. was 3.09 g / 100 g or more.
実施例1~7及び比較例1~8で作製した負極バインダー組成物(Q)に水を加え、重合体(P)の濃度が3.0質量%(水100gに対して重合体(P)3.09g)の混合液を作製した。実施例1~7及び比較例3~8にかかる混合液については、濁っており、不溶分が確認できたが、比較例1及び2については透明な水溶液であった。このことから、実施例1~7及び比較例3~8にかかる共重合体(P)の23℃の水への溶解度は3.09g/100g未満であり、比較例1及び2にかかる共重合体(P)の23℃の水への溶解度は3.09g/100g以上であることがわかった。 <2-2. Solubility of polymer (P) in water>
Water was added to the negative electrode binder compositions (Q) prepared in Examples 1 to 7 and Comparative Examples 1 to 8, and the concentration of the polymer (P) was 3.0% by mass (the polymer (P) with respect to 100 g of water). A mixed solution of 3.09 g) was prepared. The mixed solutions of Examples 1 to 7 and Comparative Examples 3 to 8 were turbid and insoluble components could be confirmed, but Comparative Examples 1 and 2 were transparent aqueous solutions. From this, the solubility of the copolymer (P) according to Examples 1 to 7 and Comparative Examples 3 to 8 in water at 23 ° C. is less than 3.09 g / 100 g, and the copolymer weight according to Comparative Examples 1 and 2. It was found that the solubility of the coalescence (P) in water at 23 ° C. was 3.09 g / 100 g or more.
次に、比較例1及び2で作製した負極バインダー組成物(Q)に水を加え、これらの比較例それぞれについて重合体(P)の濃度が5.0質量%(水100gに対して重合体(P)5.26g)、及び10.0質量%(水100gに対して重合体(P)11.1g)の混合液を作製した。比較例1及び2ともに、いずれの混合液も透明な水溶液であった。このことから、比較例1及び2にかかる共重合体(P)の23℃の水への溶解度は11.1g/100g以上であることがわかった。
Next, water was added to the negative electrode binder compositions (Q) prepared in Comparative Examples 1 and 2, and the concentration of the polymer (P) in each of these Comparative Examples was 5.0% by mass (polymer with respect to 100 g of water). A mixed solution of (P) 5.26 g) and 10.0% by mass (11.1 g of the polymer (P) with respect to 100 g of water) was prepared. In both Comparative Examples 1 and 2, both of the mixed solutions were transparent aqueous solutions. From this, it was found that the solubility of the copolymer (P) according to Comparative Examples 1 and 2 in water at 23 ° C. was 11.1 g / 100 g or more.
<2-3.粘度>
負極バインダー組成物(Q)の粘度を、ブルックフィールド型粘度計(東機産業製)により、液温23℃、回転数10rpm、No.5、No.6及びNo.7のうちいずれかのローターを用いて測定した。なお、ローターは、それぞれのサンプルの粘度に応じて選択する。 <2-3. Viscosity>
The viscosity of the negative electrode binder composition (Q) was measured by a Brookfield type viscometer (manufactured by Toki Sangyo) at a liquid temperature of 23 ° C., a rotation speed of 10 rpm, and No. 5, No. 6 and No. It was measured using any of the rotors of 7. The rotor is selected according to the viscosity of each sample.
負極バインダー組成物(Q)の粘度を、ブルックフィールド型粘度計(東機産業製)により、液温23℃、回転数10rpm、No.5、No.6及びNo.7のうちいずれかのローターを用いて測定した。なお、ローターは、それぞれのサンプルの粘度に応じて選択する。 <2-3. Viscosity>
The viscosity of the negative electrode binder composition (Q) was measured by a Brookfield type viscometer (manufactured by Toki Sangyo) at a liquid temperature of 23 ° C., a rotation speed of 10 rpm, and No. 5, No. 6 and No. It was measured using any of the rotors of 7. The rotor is selected according to the viscosity of each sample.
各実施例及び比較例にかかる負極バインダー組成物(Q)の粘度は、重合体(P)を10質量%含む水溶液または水分散液の23℃における粘度となる。
The viscosity of the negative electrode binder composition (Q) according to each Example and Comparative Example is the viscosity of an aqueous solution or an aqueous dispersion containing 10% by mass of the polymer (P) at 23 ° C.
<2-4.pH>
電極バインダー組成物(Q)のpHを、液温23℃の状態でpHメーター(東亜ディーケーケー製)を用いて計測した。 <2-4. pH>
The pH of the electrode binder composition (Q) was measured using a pH meter (manufactured by DKK-TOA Corporation) at a liquid temperature of 23 ° C.
電極バインダー組成物(Q)のpHを、液温23℃の状態でpHメーター(東亜ディーケーケー製)を用いて計測した。 <2-4. pH>
The pH of the electrode binder composition (Q) was measured using a pH meter (manufactured by DKK-TOA Corporation) at a liquid temperature of 23 ° C.
<3.負極スラリーの作製>
黒鉛としてSCMG(登録商標)-XRs(昭和電工(株)製)を76.8質量部と、一酸化ケイ素(SiO)(Sigma-Aldrich製)を19.2質量部と、VGCF(登録商標)-H(昭和電工(株))を1質量部と、バインダー組成物(Q)を30質量部(重合体(P)を3質量部、水を27質量部含む)と、及び水を20質量部と、を混合した。混合は、攪拌式混合装置(自転公転撹拌ミキサー)を用いて2000回転/分で4分間混練することにより行われた。得られた混合物に、さらに水を53質量部加え、上記混合装置で、さらに2000回転/分で4分間混合し、負極スラリーを調製した。 <3. Preparation of negative electrode slurry>
As graphite, SCMG (registered trademark) -XRs (manufactured by Showa Denko KK) is 76.8 parts by mass, silicon monoxide (SiO) (manufactured by Sigma-Aldrich) is 19.2 parts by mass, and VGCF (registered trademark). -H (Showa Denko KK) by 1 part by mass, binder composition (Q) by 30 parts by mass (including polymer (P) by 3 parts by mass, water by 27 parts by mass), and water by 20 parts by mass. And the parts were mixed. Mixing was carried out by kneading at 2000 rpm for 4 minutes using a stirring type mixing device (rotational revolution stirring mixer). To the obtained mixture, 53 parts by mass of water was further added, and the mixture was further mixed at 2000 rpm for 4 minutes with the above mixing device to prepare a negative electrode slurry.
黒鉛としてSCMG(登録商標)-XRs(昭和電工(株)製)を76.8質量部と、一酸化ケイ素(SiO)(Sigma-Aldrich製)を19.2質量部と、VGCF(登録商標)-H(昭和電工(株))を1質量部と、バインダー組成物(Q)を30質量部(重合体(P)を3質量部、水を27質量部含む)と、及び水を20質量部と、を混合した。混合は、攪拌式混合装置(自転公転撹拌ミキサー)を用いて2000回転/分で4分間混練することにより行われた。得られた混合物に、さらに水を53質量部加え、上記混合装置で、さらに2000回転/分で4分間混合し、負極スラリーを調製した。 <3. Preparation of negative electrode slurry>
As graphite, SCMG (registered trademark) -XRs (manufactured by Showa Denko KK) is 76.8 parts by mass, silicon monoxide (SiO) (manufactured by Sigma-Aldrich) is 19.2 parts by mass, and VGCF (registered trademark). -H (Showa Denko KK) by 1 part by mass, binder composition (Q) by 30 parts by mass (including polymer (P) by 3 parts by mass, water by 27 parts by mass), and water by 20 parts by mass. And the parts were mixed. Mixing was carried out by kneading at 2000 rpm for 4 minutes using a stirring type mixing device (rotational revolution stirring mixer). To the obtained mixture, 53 parts by mass of water was further added, and the mixture was further mixed at 2000 rpm for 4 minutes with the above mixing device to prepare a negative electrode slurry.
<4.負極スラリーの外観評価>
上記の電池作製にあたって調整した負極スラリーを目視して外観を確認し、凝集物のサイズをマイクロメーターで測定した。負極スラリー10g中に最長寸法1mm以上の凝集物ある場合を×、ない場合を○とした。 <4. Appearance evaluation of negative electrode slurry>
The appearance of the negative electrode slurry prepared in the above-mentioned battery production was visually confirmed, and the size of the agglomerates was measured with a micrometer. The case where 10 g of the negative electrode slurry contained agglomerates having a maximum dimension of 1 mm or more was evaluated as x, and the case where there was no agglomerate was evaluated as ◯.
上記の電池作製にあたって調整した負極スラリーを目視して外観を確認し、凝集物のサイズをマイクロメーターで測定した。負極スラリー10g中に最長寸法1mm以上の凝集物ある場合を×、ない場合を○とした。 <4. Appearance evaluation of negative electrode slurry>
The appearance of the negative electrode slurry prepared in the above-mentioned battery production was visually confirmed, and the size of the agglomerates was measured with a micrometer. The case where 10 g of the negative electrode slurry contained agglomerates having a maximum dimension of 1 mm or more was evaluated as x, and the case where there was no agglomerate was evaluated as ◯.
<5.負極及び電池の作製>
<5-1.負極の作製>
調製した負極スラリーを、厚さ10μmの銅箔(集電体)の片面に、乾燥後の目付量が8mg/cm2となるようにドクターブレードを用いて塗布した。負極スラリーが塗布された銅箔を、60℃で10分乾燥後、さらに100℃で5分乾燥して負極活物質層が形成された負極シートを作製した。この負極シートを、金型プレスを用いてプレス圧1t/cm2でプレスした。プレスされた負極シートを22mm×22mmに切り出し、導電タブを取り付けて負極を作製した。 <5. Fabrication of negative electrode and battery>
<5-1. Fabrication of negative electrode >
The prepared negative electrode slurry was applied to one side of a copper foil (current collector) having a thickness of 10 μm using a doctor blade so that the basis weight after drying was 8 mg / cm 2. The copper foil coated with the negative electrode slurry was dried at 60 ° C. for 10 minutes and then dried at 100 ° C. for 5 minutes to prepare a negative electrode sheet on which a negative electrode active material layer was formed. This negative electrode sheet was pressed at a press pressure of 1 t / cm 2 using a die press. The pressed negative electrode sheet was cut out to a size of 22 mm × 22 mm, and a conductive tab was attached to prepare a negative electrode.
<5-1.負極の作製>
調製した負極スラリーを、厚さ10μmの銅箔(集電体)の片面に、乾燥後の目付量が8mg/cm2となるようにドクターブレードを用いて塗布した。負極スラリーが塗布された銅箔を、60℃で10分乾燥後、さらに100℃で5分乾燥して負極活物質層が形成された負極シートを作製した。この負極シートを、金型プレスを用いてプレス圧1t/cm2でプレスした。プレスされた負極シートを22mm×22mmに切り出し、導電タブを取り付けて負極を作製した。 <5. Fabrication of negative electrode and battery>
<5-1. Fabrication of negative electrode >
The prepared negative electrode slurry was applied to one side of a copper foil (current collector) having a thickness of 10 μm using a doctor blade so that the basis weight after drying was 8 mg / cm 2. The copper foil coated with the negative electrode slurry was dried at 60 ° C. for 10 minutes and then dried at 100 ° C. for 5 minutes to prepare a negative electrode sheet on which a negative electrode active material layer was formed. This negative electrode sheet was pressed at a press pressure of 1 t / cm 2 using a die press. The pressed negative electrode sheet was cut out to a size of 22 mm × 22 mm, and a conductive tab was attached to prepare a negative electrode.
<5-2.正極の作製>
LiNi1/3Mn1/3Co1/3O2を90質量部、アセチレンブラックを5質量部、及びポリフッ化ビニリデン5質量部を混合し、その後、N-メチルピロリドン100質量部を混合して正極スラリーを調製した(固形分中のLiNi1/3Mn1/3Co1/3O2の割合は0.90)。 <5-2. Fabrication of positive electrode>
90 parts by mass of LiNi 1/3 Mn 1/3 Co 1/3 O 2 , 5 parts by mass of acetylene black, and 5 parts by mass of polyvinylidene fluoride are mixed, and then 100 parts by mass of N-methylpyrrolidone is mixed. A positive electrode slurry was prepared ( the ratio of LiNi 1/3 Mn 1/3 Co 1/3 O 2 in the solid content was 0.90).
LiNi1/3Mn1/3Co1/3O2を90質量部、アセチレンブラックを5質量部、及びポリフッ化ビニリデン5質量部を混合し、その後、N-メチルピロリドン100質量部を混合して正極スラリーを調製した(固形分中のLiNi1/3Mn1/3Co1/3O2の割合は0.90)。 <5-2. Fabrication of positive electrode>
90 parts by mass of LiNi 1/3 Mn 1/3 Co 1/3 O 2 , 5 parts by mass of acetylene black, and 5 parts by mass of polyvinylidene fluoride are mixed, and then 100 parts by mass of N-methylpyrrolidone is mixed. A positive electrode slurry was prepared ( the ratio of LiNi 1/3 Mn 1/3 Co 1/3 O 2 in the solid content was 0.90).
調製した正極スラリーを、ドクターブレード法により厚さ20μmのアルミニウム箔(集電体)の片面に、乾燥後の目付量が22.5mg/cm2(22.5×10-3g/cm2)となるようにドクターブレードを用いて塗布した。正極スラリーが塗布されたアルミニウム箔を、120℃で5分乾燥後、ロールプレスによりプレスして、厚さ100μmの正極活物質層が形成された正極シートを作製した。得られた正極シートを20mm×20mm(2.0cm×2.0cm)に切り出し、導電タブを取り付けて正極を作製した。
The prepared positive electrode slurry was placed on one side of an aluminum foil (current collector) having a thickness of 20 μm by the doctor blade method, and the basis weight after drying was 22.5 mg / cm 2 (22.5 × 10 -3 g / cm 2 ). It was applied using a doctor blade so as to be. The aluminum foil coated with the positive electrode slurry was dried at 120 ° C. for 5 minutes and then pressed by a roll press to prepare a positive electrode sheet on which a positive electrode active material layer having a thickness of 100 μm was formed. The obtained positive electrode sheet was cut into 20 mm × 20 mm (2.0 cm × 2.0 cm), and a conductive tab was attached to prepare a positive electrode.
作製した正極の理論容量は、正極スラリーの乾燥後の目付量(22.5×10-3g/cm2)×正極スラリーの塗布面積(2.0cm×2.0cm)×LiNi1/3Mn1/3Co1/3O2の正極活物質としての容量(160mAh/g)×固形分中のLiNi1/3Mn1/3Co1/3O2の割合(0.90)で求められ、算出される値は、13mAhである。
The theoretical capacity of the prepared positive electrode is the amount of the positive electrode slurry after drying (22.5 × 10 -3 g / cm 2 ) × the coating area of the positive electrode slurry (2.0 cm × 2.0 cm) × LiNi 1/3 Mn. 1/3 Co 1/3 O 2 capacity as positive electrode active material (160 mAh / g) x LiNi 1/3 Mn 1/3 Co 1/3 O 2 ratio (0.90) in solid content , The calculated value is 13 mAh.
<5-3.電解液の調製>
エチレンカーボネート(EC)とエチルメチルカーボネート(EMC)とフルオロエチレンカーボネート(FEC)とを体積比30:60:10で混合した混合溶媒を調整した。この混合溶媒に、LiPF6を1.0mol/Lの濃度になるように、ビニレンカーボネート(VC)を1.0質量%の濃度になるように溶解して、電解液を調製した。 <5-3. Preparation of electrolyte>
A mixed solvent was prepared by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and fluoroethylene carbonate (FEC) at a volume ratio of 30:60:10. An electrolytic solution was prepared by dissolving LiPF 6 in this mixed solvent at a concentration of 1.0 mol / L and vinylene carbonate (VC) at a concentration of 1.0% by mass.
エチレンカーボネート(EC)とエチルメチルカーボネート(EMC)とフルオロエチレンカーボネート(FEC)とを体積比30:60:10で混合した混合溶媒を調整した。この混合溶媒に、LiPF6を1.0mol/Lの濃度になるように、ビニレンカーボネート(VC)を1.0質量%の濃度になるように溶解して、電解液を調製した。 <5-3. Preparation of electrolyte>
A mixed solvent was prepared by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and fluoroethylene carbonate (FEC) at a volume ratio of 30:60:10. An electrolytic solution was prepared by dissolving LiPF 6 in this mixed solvent at a concentration of 1.0 mol / L and vinylene carbonate (VC) at a concentration of 1.0% by mass.
<5-4.電池の組み立て>
ポリオレフィン多孔性フィルムからなるセパレータを介して、正極と負極とを、それぞれの活物質層が互いに対向するように配して、アルミラミネート外装体(電池パック)の中に収納した。この外装体の中に電解液を注入し、真空ヒートシーラーでパッキングし、ラミネート型電池を得た。 <5-4. Battery assembly>
The positive electrode and the negative electrode were arranged so that the active material layers faced each other via a separator made of a polyolefin porous film, and were housed in an aluminum laminated exterior body (battery pack). An electrolytic solution was injected into this exterior body and packed with a vacuum heat sealer to obtain a laminated battery.
ポリオレフィン多孔性フィルムからなるセパレータを介して、正極と負極とを、それぞれの活物質層が互いに対向するように配して、アルミラミネート外装体(電池パック)の中に収納した。この外装体の中に電解液を注入し、真空ヒートシーラーでパッキングし、ラミネート型電池を得た。 <5-4. Battery assembly>
The positive electrode and the negative electrode were arranged so that the active material layers faced each other via a separator made of a polyolefin porous film, and were housed in an aluminum laminated exterior body (battery pack). An electrolytic solution was injected into this exterior body and packed with a vacuum heat sealer to obtain a laminated battery.
<6.負極及び電池の評価>
各実施例及び比較例の負極及び電池の評価をした。評価方法は以下の通りで、評価結果は表2に示した通りである。 <6. Evaluation of negative electrode and battery>
The negative electrodes and batteries of each Example and Comparative Example were evaluated. The evaluation method is as follows, and the evaluation results are as shown in Table 2.
各実施例及び比較例の負極及び電池の評価をした。評価方法は以下の通りで、評価結果は表2に示した通りである。 <6. Evaluation of negative electrode and battery>
The negative electrodes and batteries of each Example and Comparative Example were evaluated. The evaluation method is as follows, and the evaluation results are as shown in Table 2.
<6-1.負極のクラックの数>
負極シートの表面を目視して外観を確認し、5cm×20cmの長方形の範囲におけるクラックの数を数えた。 <6-1. Number of cracks in the negative electrode>
The appearance was visually confirmed by visually observing the surface of the negative electrode sheet, and the number of cracks in a rectangular area of 5 cm × 20 cm was counted.
負極シートの表面を目視して外観を確認し、5cm×20cmの長方形の範囲におけるクラックの数を数えた。 <6-1. Number of cracks in the negative electrode>
The appearance was visually confirmed by visually observing the surface of the negative electrode sheet, and the number of cracks in a rectangular area of 5 cm × 20 cm was counted.
<6-2.負極活物質層の剥離強度>
プレス工程後の負極シートを用いて、全工程において23℃、相対湿度50質量%雰囲気で行った。試験機はテンシロン(登録商標、(株)エー・アンド・デイ製)を用いた。負極シートを幅25mm、長さ70mmで切り出し、試験片とした。試験片上の負極活物質層と、幅50mm、長さ200mmSUS板とを両面テープ(NITTOTAPE(登録商標) No5、日東電工(株)製)を用いて、試験片の中心とSUS板の中心とが一致するように貼り合わせた。なお、両面テープは試験片の全範囲をカバーするように貼り合わせた。貼り合わせは2kgローラを試験片全体にわたって1往復させることにより行った。 <6-2. Peeling strength of negative electrode active material layer>
Using the negative electrode sheet after the pressing step, the whole step was carried out in an atmosphere of 23 ° C. and a relative humidity of 50% by mass. The testing machine used was Tencilon (registered trademark, manufactured by A & D Co., Ltd.). The negative electrode sheet was cut out with a width of 25 mm and a length of 70 mm to obtain a test piece. Using double-sided tape (NITTO TAPE (registered trademark) No. 5, manufactured by Nitto Denko Corporation) with the negative electrode active material layer on the test piece and a SUS plate with a width of 50 mm and a length of 200 mm, the center of the test piece and the center of the SUS plate can be aligned. They were pasted together so that they would match. The double-sided tape was attached so as to cover the entire range of the test piece. The bonding was performed by reciprocating a 2 kg roller once over the entire test piece.
プレス工程後の負極シートを用いて、全工程において23℃、相対湿度50質量%雰囲気で行った。試験機はテンシロン(登録商標、(株)エー・アンド・デイ製)を用いた。負極シートを幅25mm、長さ70mmで切り出し、試験片とした。試験片上の負極活物質層と、幅50mm、長さ200mmSUS板とを両面テープ(NITTOTAPE(登録商標) No5、日東電工(株)製)を用いて、試験片の中心とSUS板の中心とが一致するように貼り合わせた。なお、両面テープは試験片の全範囲をカバーするように貼り合わせた。貼り合わせは2kgローラを試験片全体にわたって1往復させることにより行った。 <6-2. Peeling strength of negative electrode active material layer>
Using the negative electrode sheet after the pressing step, the whole step was carried out in an atmosphere of 23 ° C. and a relative humidity of 50% by mass. The testing machine used was Tencilon (registered trademark, manufactured by A & D Co., Ltd.). The negative electrode sheet was cut out with a width of 25 mm and a length of 70 mm to obtain a test piece. Using double-sided tape (NITTO TAPE (registered trademark) No. 5, manufactured by Nitto Denko Corporation) with the negative electrode active material layer on the test piece and a SUS plate with a width of 50 mm and a length of 200 mm, the center of the test piece and the center of the SUS plate can be aligned. They were pasted together so that they would match. The double-sided tape was attached so as to cover the entire range of the test piece. The bonding was performed by reciprocating a 2 kg roller once over the entire test piece.
試験片とSUS板とを貼り合わせた状態で10分放置した後、負極活物質から銅箔を、試験片の一端から長さ方向に20mm剥がし、180°折り返し、剥がした銅箔の部分を試験機の上側のチャックで掴んだ。さらに、銅箔を剥がした方のSUS板の一端を下側チャックで掴んだ。その状態で、試験片から銅箔を100±10mm/minの速度で引き剥がし、剥離長さ(mm)-剥離力(mN)のグラフを得た。得られたグラフにおいて剥離長さ10~45mmにおける剥離力の平均値(mN)を算出し、剥離力の平均値を試験片の幅25mmで割った数値を負極活物質層の剥離強度(mN/mm)とした。なお、いずれの実施例及び比較例においても、試験中、両面テープとSUS板の間での剥離、及び両面テープと負極活物質層との間での界面剥離は起こらなかった。
After leaving the test piece and the SUS plate bonded together for 10 minutes, peel the copper foil from the negative electrode active material by 20 mm in the length direction from one end of the test piece, fold it back 180 °, and test the peeled copper foil part. I grabbed it with the chuck on the upper side of the machine. Further, one end of the SUS plate from which the copper foil was peeled off was grasped by the lower chuck. In that state, the copper foil was peeled off from the test piece at a speed of 100 ± 10 mm / min, and a graph of peeling length (mm) -peeling force (mN) was obtained. In the obtained graph, the average value (mN) of the peeling force at the peeling length of 10 to 45 mm was calculated, and the value obtained by dividing the average value of the peeling force by the width of the test piece of 25 mm was the peeling strength (mN / mN /) of the negative electrode active material layer. mm). In each of the Examples and Comparative Examples, peeling between the double-sided tape and the SUS plate and interfacial peeling between the double-sided tape and the negative electrode active material layer did not occur during the test.
<6-3.電池の初期効率>
電池の初期効率の測定を、25℃の条件下、以下の手順で行った。まず、4.2Vになるまで0.2Cの電流で充電し(CC充電)、次に、電流0.05Cになるまで4.2Vの電圧で充電した(CV充電)。30分放置後、電圧2.75Vになるまで0.2Cの電流で放電(CC放電)した。CC充電、CV充電、及びCC放電の一連の操作を1サイクルとして、5サイクル繰り返した。nサイクル目のCC充電及びCV充電における電流の時間積分値の和をnサイクル目の充電容量(mAh)、nサイクル目のCC放電における電流の時間積分値をnサイクル目の放電容量(mAh)とする。4サイクル目及び5サイクル目の放電容量の平均値を初期放電容量とし、以下の計算式[1]で初期効率を算出した。正極理論容量は、正極の作製の説明において求めた値である。 <6-3. Battery initial efficiency>
The initial efficiency of the battery was measured under the condition of 25 ° C. according to the following procedure. First, it was charged with a current of 0.2 C until it reached 4.2 V (CC charging), and then it was charged with a voltage of 4.2 V until it reached a current of 0.05 C (CV charging). After leaving it for 30 minutes, it was discharged (CC discharge) with a current of 0.2 C until the voltage reached 2.75 V. A series of operations of CC charging, CV charging, and CC discharging were set as one cycle, and 5 cycles were repeated. The sum of the time integral values of the currents in the nth cycle CC charge and CV charge is the charge capacity (mAh) in the nth cycle, and the time integral value of the current in the CC discharge in the nth cycle is the discharge capacity (mAh) in the nth cycle. And. The average value of the discharge capacities in the 4th cycle and the 5th cycle was used as the initial discharge capacity, and the initial efficiency was calculated by the following formula [1]. The positive electrode theoretical capacity is a value obtained in the description of manufacturing the positive electrode.
電池の初期効率の測定を、25℃の条件下、以下の手順で行った。まず、4.2Vになるまで0.2Cの電流で充電し(CC充電)、次に、電流0.05Cになるまで4.2Vの電圧で充電した(CV充電)。30分放置後、電圧2.75Vになるまで0.2Cの電流で放電(CC放電)した。CC充電、CV充電、及びCC放電の一連の操作を1サイクルとして、5サイクル繰り返した。nサイクル目のCC充電及びCV充電における電流の時間積分値の和をnサイクル目の充電容量(mAh)、nサイクル目のCC放電における電流の時間積分値をnサイクル目の放電容量(mAh)とする。4サイクル目及び5サイクル目の放電容量の平均値を初期放電容量とし、以下の計算式[1]で初期効率を算出した。正極理論容量は、正極の作製の説明において求めた値である。 <6-3. Battery initial efficiency>
The initial efficiency of the battery was measured under the condition of 25 ° C. according to the following procedure. First, it was charged with a current of 0.2 C until it reached 4.2 V (CC charging), and then it was charged with a voltage of 4.2 V until it reached a current of 0.05 C (CV charging). After leaving it for 30 minutes, it was discharged (CC discharge) with a current of 0.2 C until the voltage reached 2.75 V. A series of operations of CC charging, CV charging, and CC discharging were set as one cycle, and 5 cycles were repeated. The sum of the time integral values of the currents in the nth cycle CC charge and CV charge is the charge capacity (mAh) in the nth cycle, and the time integral value of the current in the CC discharge in the nth cycle is the discharge capacity (mAh) in the nth cycle. And. The average value of the discharge capacities in the 4th cycle and the 5th cycle was used as the initial discharge capacity, and the initial efficiency was calculated by the following formula [1]. The positive electrode theoretical capacity is a value obtained in the description of manufacturing the positive electrode.
初期効率(%)={初期放電容量/13mAh(正極理論容量)}×100 [1]
Initial efficiency (%) = {initial discharge capacity / 13 mAh (theoretical positive electrode capacity)} x 100 [1]
<6-4.負極膨れ>
負極の電極膨れの測定は以下の手順で行った。まず、電池の組み立て前にマイクロメーター((株)ミツトヨ製 MDH-25MB)を使用して、負極の厚みを5点測定し、その平均値を初期厚み(μm)とした。次に電池を組み立て、上記の初期効率の測定後、上記と同様にCC充電、CV充電を行い満充電した。その後、電池を解体し、負極を取り出し、乾燥せずに負極の厚みを5点測定し、その平均値を解体時厚み(μm)とした。以下の計算式[2]で負極膨れを算出した。 <6-4. Negative electrode swelling>
The electrode swelling of the negative electrode was measured by the following procedure. First, before assembling the battery, the thickness of the negative electrode was measured at 5 points using a micrometer (MDH-25MB manufactured by Mitutoyo Co., Ltd.), and the average value was taken as the initial thickness (μm). Next, the battery was assembled, and after the above initial efficiency was measured, CC charging and CV charging were performed in the same manner as described above to fully charge the battery. Then, the battery was disassembled, the negative electrode was taken out, the thickness of the negative electrode was measured at 5 points without drying, and the average value was taken as the dismantling thickness (μm). The negative electrode swelling was calculated by the following formula [2].
負極の電極膨れの測定は以下の手順で行った。まず、電池の組み立て前にマイクロメーター((株)ミツトヨ製 MDH-25MB)を使用して、負極の厚みを5点測定し、その平均値を初期厚み(μm)とした。次に電池を組み立て、上記の初期効率の測定後、上記と同様にCC充電、CV充電を行い満充電した。その後、電池を解体し、負極を取り出し、乾燥せずに負極の厚みを5点測定し、その平均値を解体時厚み(μm)とした。以下の計算式[2]で負極膨れを算出した。 <6-4. Negative electrode swelling>
The electrode swelling of the negative electrode was measured by the following procedure. First, before assembling the battery, the thickness of the negative electrode was measured at 5 points using a micrometer (MDH-25MB manufactured by Mitutoyo Co., Ltd.), and the average value was taken as the initial thickness (μm). Next, the battery was assembled, and after the above initial efficiency was measured, CC charging and CV charging were performed in the same manner as described above to fully charge the battery. Then, the battery was disassembled, the negative electrode was taken out, the thickness of the negative electrode was measured at 5 points without drying, and the average value was taken as the dismantling thickness (μm). The negative electrode swelling was calculated by the following formula [2].
負極膨れ(%)={1-(解体時厚み/初期厚み)}×100 [2]
Negative electrode swelling (%) = {1- (thickness at the time of dismantling / initial thickness)} x 100 [2]
<6-5.電池の放電容量維持率(100サイクル)>
電池の放電容量維持率の測定(電池の充放電サイクル試験)は、25℃の条件下、以下の手順で行った。まず、電圧4.2Vになるまで1Cの電流で充電し(CC充電)、次に、電流0.05Cになるまで4.2Vの電圧で充電した(CV充電)。30分放置後、電圧2.75Vになるまで1Cの電流で放電した(CC放電)。CC充電、CV充電、及びCC放電の一連の操作を1サイクルとする。nサイクル目のCC充電及びCV充電における電流の時間積分値の和をnサイクル目の充電容量(mAh)、nサイクル目のCC放電における電流の時間積分値をnサイクル目の放電容量(mAh)とする。電池のnサイクル目の放電容量維持率は、1サイクル目の放電容量に対するnサイクル目の放電容量の割合(%)である。本実施例及び比較例では、100サイクル目の放電容量維持率を評価した。 <6-5. Battery discharge capacity retention rate (100 cycles)>
The measurement of the battery discharge capacity retention rate (battery charge / discharge cycle test) was performed under the condition of 25 ° C. according to the following procedure. First, it was charged with a current of 1 C until the voltage reached 4.2 V (CC charging), and then charged with a voltage of 4.2 V until the current reached 0.05 C (CV charging). After leaving it for 30 minutes, it was discharged with a current of 1 C until the voltage reached 2.75 V (CC discharge). A series of operations of CC charging, CV charging, and CC discharging is regarded as one cycle. The sum of the time integral values of the currents in the nth cycle CC charge and CV charge is the charge capacity (mAh) in the nth cycle, and the time integral value of the current in the CC discharge in the nth cycle is the discharge capacity (mAh) in the nth cycle. And. The discharge capacity retention rate in the nth cycle of the battery is the ratio (%) of the discharge capacity in the nth cycle to the discharge capacity in the first cycle. In this example and the comparative example, the discharge capacity retention rate at the 100th cycle was evaluated.
電池の放電容量維持率の測定(電池の充放電サイクル試験)は、25℃の条件下、以下の手順で行った。まず、電圧4.2Vになるまで1Cの電流で充電し(CC充電)、次に、電流0.05Cになるまで4.2Vの電圧で充電した(CV充電)。30分放置後、電圧2.75Vになるまで1Cの電流で放電した(CC放電)。CC充電、CV充電、及びCC放電の一連の操作を1サイクルとする。nサイクル目のCC充電及びCV充電における電流の時間積分値の和をnサイクル目の充電容量(mAh)、nサイクル目のCC放電における電流の時間積分値をnサイクル目の放電容量(mAh)とする。電池のnサイクル目の放電容量維持率は、1サイクル目の放電容量に対するnサイクル目の放電容量の割合(%)である。本実施例及び比較例では、100サイクル目の放電容量維持率を評価した。 <6-5. Battery discharge capacity retention rate (100 cycles)>
The measurement of the battery discharge capacity retention rate (battery charge / discharge cycle test) was performed under the condition of 25 ° C. according to the following procedure. First, it was charged with a current of 1 C until the voltage reached 4.2 V (CC charging), and then charged with a voltage of 4.2 V until the current reached 0.05 C (CV charging). After leaving it for 30 minutes, it was discharged with a current of 1 C until the voltage reached 2.75 V (CC discharge). A series of operations of CC charging, CV charging, and CC discharging is regarded as one cycle. The sum of the time integral values of the currents in the nth cycle CC charge and CV charge is the charge capacity (mAh) in the nth cycle, and the time integral value of the current in the CC discharge in the nth cycle is the discharge capacity (mAh) in the nth cycle. And. The discharge capacity retention rate in the nth cycle of the battery is the ratio (%) of the discharge capacity in the nth cycle to the discharge capacity in the first cycle. In this example and the comparative example, the discharge capacity retention rate at the 100th cycle was evaluated.
<7.評価結果>
表2からわかるように、実施例1~7で作製された負極バインダー及び負極スラリーは、集電体上に形成された電極活物質層のクラックの発生を抑制しつつ、集電体に対する電極活物質層の剥離強度を大きく向上できていることがわかる。実施例1~7で作製された負極バインダーによれば、負極スラリー中の凝集物の発生を抑制できていることがわかる。 <7. Evaluation result>
As can be seen from Table 2, the negative electrode binders and negative electrode slurries produced in Examples 1 to 7 suppress the generation of cracks in the electrode active material layer formed on the current collector, and the electrode activity with respect to the current collector. It can be seen that the peel strength of the material layer can be greatly improved. According to the negative electrode binders produced in Examples 1 to 7, it can be seen that the generation of agglomerates in the negative electrode slurry can be suppressed.
表2からわかるように、実施例1~7で作製された負極バインダー及び負極スラリーは、集電体上に形成された電極活物質層のクラックの発生を抑制しつつ、集電体に対する電極活物質層の剥離強度を大きく向上できていることがわかる。実施例1~7で作製された負極バインダーによれば、負極スラリー中の凝集物の発生を抑制できていることがわかる。 <7. Evaluation result>
As can be seen from Table 2, the negative electrode binders and negative electrode slurries produced in Examples 1 to 7 suppress the generation of cracks in the electrode active material layer formed on the current collector, and the electrode activity with respect to the current collector. It can be seen that the peel strength of the material layer can be greatly improved. According to the negative electrode binders produced in Examples 1 to 7, it can be seen that the generation of agglomerates in the negative electrode slurry can be suppressed.
実施例1~7で作製された負極は、クラックが少なく、集電体に対する電極活物質層の剥離強度が高いことがわかる。実施例1~7で作製された負極は、リチウムイオン二次電池に組み込んだ場合に、電池の使用に伴う負極膨れが小さいことがわかる。
It can be seen that the negative electrodes produced in Examples 1 to 7 have few cracks and the peel strength of the electrode active material layer with respect to the current collector is high. It can be seen that when the negative electrodes produced in Examples 1 to 7 are incorporated into a lithium ion secondary battery, the swelling of the negative electrode due to the use of the battery is small.
実施例1~7で作製されたリチウムイオン二次電池は、クラックが少なく、集電体に対する電極活物質層の剥離強度が高い負極を備えている。実施例1~7で作製されたリチウムイオン二次電池は、初期効率及び放電容量維持率はともに高く、負極膨れを抑制できている。
The lithium ion secondary batteries produced in Examples 1 to 7 have a negative electrode having few cracks and high peel strength of the electrode active material layer with respect to the current collector. The lithium ion secondary batteries produced in Examples 1 to 7 have high initial efficiency and discharge capacity retention rate, and can suppress swelling of the negative electrode.
比較例1~3の重合体CP1~CP3及び比較例5~8の重合体CP5~CP8はいずれも、ブルックフィールド型粘度計によって、回転数10rpmで測定した液温23℃における10質量%の水分散液の粘度が低い。これらの比較例はそれぞれ、負極にクラックは見られるか、負極活物質層の剥離強度が低かったか、のうち少なくともいずれかに該当した。
The polymers CP1 to CP3 of Comparative Examples 1 to 3 and the polymers CP5 to CP8 of Comparative Examples 5 to 8 are all 10% by mass of water at a liquid temperature of 23 ° C. measured at a rotation speed of 10 rpm by a Brookfield type viscometer. The viscosity of the dispersion is low. Each of these comparative examples corresponded to at least one of whether cracks were found in the negative electrode or the peel strength of the negative electrode active material layer was low.
また、比較例2~3及び比較例5~8で作製した負極はいずれも、リチウムイオン二次電池に組み込んだ場合に、電池の使用に伴う負極膨れが大きかった。さらに、比較例2~3及び比較例5~8で作製したリチウムイオン二次電池は、初期効率及び放電容量維持率が低かった。
Further, when the negative electrodes produced in Comparative Examples 2 to 3 and Comparative Examples 5 to 8 were incorporated into a lithium ion secondary battery, the negative electrode swelling due to the use of the battery was large. Further, the lithium ion secondary batteries produced in Comparative Examples 2 to 3 and Comparative Examples 5 to 8 had low initial efficiency and discharge capacity retention rate.
Claims (15)
- 23℃における水への溶解度が11.1g/100g未満であり、
重量平均分子量は、60万以上750万以下であり、
ブルックフィールド型粘度計によって、回転数10rpmで測定した液温23℃における10質量%の水分散液の粘度が、27000mPa・s以上100000mPa・s以下である重合体(P)を含む非水系二次電池電極用バインダー。 The solubility in water at 23 ° C. is less than 11.1 g / 100 g.
The weight average molecular weight is 600,000 or more and 7.5 million or less.
A non-aqueous secondary containing a polymer (P) having a viscosity of 10% by mass of an aqueous dispersion at a liquid temperature of 23 ° C. measured by a Brookfield viscometer at a rotation speed of 10 rpm of 27,000 mPa · s or more and 100,000 mPa · s or less. Binder for battery electrodes. - 前記粘度は、29000mPa・s以上である請求項1に記載の非水系二次電池電極用バインダー。 The binder for a non-aqueous secondary battery electrode according to claim 1, wherein the viscosity is 29000 mPa · s or more.
- 前記粘度は、70000mPa・s以下である請求項1または2に記載の非水系二次電池電極用バインダー。 The binder for a non-aqueous secondary battery electrode according to claim 1 or 2, wherein the viscosity is 70,000 mPa · s or less.
- 23℃における水への溶解度が5.26g/100g未満である、請求項1~3のいずれか1項に記載の非水系二次電池電極用バインダー。 The binder for a non-aqueous secondary battery electrode according to any one of claims 1 to 3, wherein the solubility in water at 23 ° C. is less than 5.26 g / 100 g.
- 前記重合体(P)の重量平均分子量は500万以下である請求項1~4のいずれか1項に記載の非水系二次電池電極用バインダー。 The binder for a non-aqueous secondary battery electrode according to any one of claims 1 to 4, wherein the polymer (P) has a weight average molecular weight of 5 million or less.
- 前記重合体(P)は、エチレン性不飽和結合を有する単量体の共重合体であって、アニオン性官能基を有する単量体に由来する構造単位と、極性官能基を有さない単量体に由来する構造単位とを含む共重合体である請求項1~5にいずれか1項に記載の非水系二次電池電極用バインダー。 The polymer (P) is a copolymer of a monomer having an ethylenically unsaturated bond, and has a structural unit derived from a monomer having an anionic functional group and a simple polymer having no polar functional group. The binder for a non-aqueous secondary battery electrode according to any one of claims 1 to 5, which is a copolymer containing a structural unit derived from a weight.
- 前記重合体(P)が、
エチレン性不飽和結合及びアミド結合を有する単量体(A)由来の構造単位(a)と、 エチレン性不飽和結合及びアニオン性官能基を有する化合物及びそれらの化合物の塩からなる群から選択される少なくとも1種である単量体(B)由来の構造単位(b)と、 単量体(A)及び単量体(B)以外のエチレン性不飽和結合を有するカルボン酸エステル化合物である単量体(C)由来の構造単位(c)と、
を有する共重合体(cP)である請求項1~6のいずれか1項に記載の非水系二次電池電極用バインダー。 The polymer (P) is
Selected from the group consisting of a structural unit (a) derived from a monomer (A) having an ethylenically unsaturated bond and an amide bond, a compound having an ethylenically unsaturated bond and an anionic functional group, and a salt of those compounds. A carboxylic acid ester compound having an ethylenically unsaturated bond other than the structural unit (b) derived from the monomer (B), which is at least one kind, and the monomer (A) and the monomer (B). The structural unit (c) derived from the metric (C) and
The binder for a non-aqueous secondary battery electrode according to any one of claims 1 to 6, which is a copolymer (cP) having the above. - 前記単量体(A)は、式(1)で表される化合物である請求項7に記載の非水系二次電池電極用バインダー。
- 前記単量体(B)は、(メタ)アクリル酸及びその塩からなる群から選択されるいずれかを含む請求項7または8に記載の非水系二次電池電極用バインダー。 The binder for a non-aqueous secondary battery electrode according to claim 7 or 8, wherein the monomer (B) contains any one selected from the group consisting of (meth) acrylic acid and a salt thereof.
- 前記共重合体(cP)において、構造単位(b)の含有率は50.0質量%以上である請求項7~9のいずれか1項に記載の非水系二次電池電極用バインダー。 The binder for a non-aqueous secondary battery electrode according to any one of claims 7 to 9, wherein the content of the structural unit (b) in the copolymer (cP) is 50.0% by mass or more.
- 請求項1~10のいずれか1項に記載の非水系二次電池電極用バインダーと、水性媒体とを含む非水系二次電池電極用バインダー組成物。 A binder composition for a non-aqueous secondary battery electrode, which comprises the binder for a non-aqueous secondary battery electrode according to any one of claims 1 to 10 and an aqueous medium.
- 水性媒体100gに対する前記重合体(P)の含有量は、前記重合体(P)の23℃の水への前記溶解度よりも多く、水性媒体中に前記重合体(P)が分散している請求項11に記載の非水系二次電池電極用バインダー組成物。 The content of the polymer (P) in 100 g of the aqueous medium is higher than the solubility of the polymer (P) in water at 23 ° C., and the polymer (P) is dispersed in the aqueous medium. Item 12. The binder composition for a non-aqueous secondary battery electrode according to Item 11.
- 前記非水系二次電池は、リチウムイオン二次電池である請求項11または12に記載の非水系二次電池電極用バインダー組成物。 The binder composition for a non-aqueous secondary battery electrode according to claim 11 or 12, wherein the non-aqueous secondary battery is a lithium ion secondary battery.
- 請求項1~10のいずれか1項に記載の非水系二次電池電極用バインダーと、電極活物質と、水性媒体とを含む非水系二次電池電極用スラリー。 A slurry for a non-aqueous secondary battery electrode containing the binder for a non-aqueous secondary battery electrode according to any one of claims 1 to 10, an electrode active material, and an aqueous medium.
- 集電体と、
前記集電体表面に形成された請求項1~10のいずれか1項に記載の非水系二次電池電極用バインダー及び電極活物質を含む電極活物質層と
を有する非水系二次電池電極。 With the current collector,
A non-aqueous secondary battery electrode having the binder for a non-aqueous secondary battery electrode according to any one of claims 1 to 10 formed on the surface of the current collector and an electrode active material layer containing the electrode active material.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2022528828A JPWO2021246376A1 (en) | 2020-06-05 | 2021-05-31 |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2020-098515 | 2020-06-05 | ||
JP2020098515 | 2020-06-05 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2021246376A1 true WO2021246376A1 (en) | 2021-12-09 |
Family
ID=78830283
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2021/020727 WO2021246376A1 (en) | 2020-06-05 | 2021-05-31 | Binder for non-aqueous secondary battery electrode and slurry for non-aqueous secondary battery electrode |
Country Status (3)
Country | Link |
---|---|
JP (1) | JPWO2021246376A1 (en) |
TW (1) | TW202211521A (en) |
WO (1) | WO2021246376A1 (en) |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2015162384A (en) * | 2014-02-27 | 2015-09-07 | 日本ゼオン株式会社 | Binder composition for lithium ion secondary battery positive electrodes, slurry composition for lithium ion secondary battery positive electrodes, positive electrode for lithium ion secondary batteries, and lithium ion secondary battery |
WO2016158939A1 (en) * | 2015-03-30 | 2016-10-06 | 東亞合成株式会社 | Composition for electrode mixture layer of nonaqueous electrolyte secondary battery, production method for said composition, and use of said composition |
JP2018160397A (en) * | 2017-03-23 | 2018-10-11 | 三洋化成工業株式会社 | Battery electrode binder |
WO2020012941A1 (en) * | 2018-07-10 | 2020-01-16 | Jsr株式会社 | Power storage device composition, power storage device electrode slurry, power storage device electrode, and power storage device |
-
2021
- 2021-05-31 WO PCT/JP2021/020727 patent/WO2021246376A1/en active Application Filing
- 2021-05-31 JP JP2022528828A patent/JPWO2021246376A1/ja active Pending
- 2021-06-03 TW TW110120184A patent/TW202211521A/en unknown
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2015162384A (en) * | 2014-02-27 | 2015-09-07 | 日本ゼオン株式会社 | Binder composition for lithium ion secondary battery positive electrodes, slurry composition for lithium ion secondary battery positive electrodes, positive electrode for lithium ion secondary batteries, and lithium ion secondary battery |
WO2016158939A1 (en) * | 2015-03-30 | 2016-10-06 | 東亞合成株式会社 | Composition for electrode mixture layer of nonaqueous electrolyte secondary battery, production method for said composition, and use of said composition |
JP2018160397A (en) * | 2017-03-23 | 2018-10-11 | 三洋化成工業株式会社 | Battery electrode binder |
WO2020012941A1 (en) * | 2018-07-10 | 2020-01-16 | Jsr株式会社 | Power storage device composition, power storage device electrode slurry, power storage device electrode, and power storage device |
Also Published As
Publication number | Publication date |
---|---|
JPWO2021246376A1 (en) | 2021-12-09 |
TW202211521A (en) | 2022-03-16 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP7338749B2 (en) | Copolymer for binder for non-aqueous battery electrode, slurry for non-aqueous battery electrode, non-aqueous battery electrode, and non-aqueous battery | |
JP6890736B1 (en) | Copolymer for electrode binder and lithium ion secondary battery | |
JP7415924B2 (en) | Copolymer for binder for non-aqueous battery electrodes and slurry for manufacturing non-aqueous battery electrodes | |
JP7416239B2 (en) | Binder for non-aqueous secondary battery electrodes and slurry for non-aqueous secondary battery electrodes | |
JP7272272B2 (en) | Method for producing slurry for non-aqueous battery electrode | |
WO2021246376A1 (en) | Binder for non-aqueous secondary battery electrode and slurry for non-aqueous secondary battery electrode | |
JP6868751B1 (en) | Non-aqueous secondary battery Electrodes, electrode slurries, and non-aqueous secondary batteries | |
WO2022250080A1 (en) | Nonaqueous secondary battery electrode binder, and nonaqueous secondary battery electrode | |
JP2023164051A (en) | Binder for nonaqueous secondary battery electrode and nonaqueous secondary battery electrode | |
WO2021131278A1 (en) | Nonaqueous secondary battery electrode, electrode slurry, and nonaqueous secondary battery | |
JP2023176321A (en) | Method for manufacturing nonaqueous secondary battery electrode slurry and method for manufacturing nonaqueous secondary battery electrode |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 21817592 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 2022528828 Country of ref document: JP Kind code of ref document: A |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 21817592 Country of ref document: EP Kind code of ref document: A1 |