WO2022210738A1 - Composition for negative electrode, negative electrode sheet, non-aqueous secondary battery, and method for manufacturing negative electrode sheet and non-aqueous secondary battery - Google Patents
Composition for negative electrode, negative electrode sheet, non-aqueous secondary battery, and method for manufacturing negative electrode sheet and non-aqueous secondary battery Download PDFInfo
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- WO2022210738A1 WO2022210738A1 PCT/JP2022/015556 JP2022015556W WO2022210738A1 WO 2022210738 A1 WO2022210738 A1 WO 2022210738A1 JP 2022015556 W JP2022015556 W JP 2022015556W WO 2022210738 A1 WO2022210738 A1 WO 2022210738A1
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- negative electrode
- water
- soluble polymer
- secondary battery
- mass
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- C08L33/00—Compositions of homopolymers or 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 of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
- C08L33/04—Homopolymers or copolymers of esters
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L33/00—Compositions of homopolymers or 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 of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
- C08L33/24—Homopolymers or copolymers of amides or imides
- C08L33/26—Homopolymers or copolymers of acrylamide or methacrylamide
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
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- 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
- H01M4/36—Selection of substances as active materials, active masses, active liquids
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- 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
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
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- 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
Definitions
- the present invention relates to a negative electrode composition, a negative electrode sheet, a non-aqueous secondary battery, a method for manufacturing a negative electrode sheet, and a method for manufacturing a non-aqueous secondary battery.
- Secondary batteries typified by lithium-ion secondary batteries, are used as power sources for portable electronic devices such as personal computers, video cameras, and mobile phones. Recently, against the background of the global environmental issue of reducing carbon dioxide emissions, it is becoming popular as a power source for transportation equipment such as automobiles, and as a power storage application such as nighttime power and power generated by natural energy generation.
- the electrodes (positive electrode and negative electrode) of the lithium ion secondary battery have an electrode active material layer (positive electrode active material layer and negative electrode active material layer), and this electrode active material layer can absorb or release lithium ions during charging and discharging.
- electrons are also transported between the electrode active material particles or between the electrode active material particles and the current collector, it is required to ensure electron conductivity.
- the binding between the electrode active material particles or between the electrode active material particles and the current collector is important for the efficiency of this electron conduction, and the electrode active material layer usually contains a binder.
- silicon oxide As a negative electrode active material, studies on using silicon oxide as a negative electrode active material have been actively conducted.
- the theoretical capacity of silicon oxide is remarkably higher than that of graphite, etc., making it possible to increase the energy density of batteries.
- silicon oxide When silicon oxide is used as the negative electrode active material, it absorbs a large amount of lithium ions and expands greatly during charging, and the shrinkage width of silicon oxide during discharging is correspondingly increased. Therefore, in a lithium-ion battery using silicon oxide as a negative electrode active material, the volume of the negative electrode active material changes greatly during charging and discharging, and the battery performance tends to deteriorate due to repeated charging and discharging. In other words, there are restrictions on improving the cycle life.
- Patent Document 1 discloses a negative electrode active material containing 20% by mass or more of silicon particles having a median diameter of 0.1 to 2 ⁇ m, a (meth)acrylamide skeleton-containing monomer and sulfonic acid.
- a lithium ion battery negative electrode comprising poly(meth)acrylamide, which is a radical copolymer of a monomer group containing a group-substituted unsaturated hydrocarbon group-containing monomer and exhibits a specific high viscosity in an aqueous solution of a specific concentration, and water A slurry is described. According to the technique described in Patent Document 1, it is said that a lithium ion secondary battery having excellent cycle life (cycle characteristics) can be obtained using this negative electrode slurry.
- Electrodes for lithium-ion secondary batteries are usually formed by applying an electrode-forming composition (slurry) onto a current collector and drying it. Therefore, a slurry for electrode formation is prepared by dispersing an electrode active material and a binder in a liquid medium.
- a slurry for electrode formation is prepared by dispersing an electrode active material and a binder in a liquid medium.
- the present invention relates to a negative electrode composition using carbon-coated silicon oxide as a negative electrode active material, which is used to form a negative electrode active material layer of a nonaqueous secondary battery.
- An object of the present invention is to provide a negative electrode composition capable of sufficiently extending the cycle life while achieving high capacity and low resistance.
- a further object of the present invention is to provide a negative electrode sheet and a non-aqueous secondary battery using the negative electrode composition.
- a further object of the present invention is to provide a method for manufacturing the negative electrode sheet and the non-aqueous secondary battery.
- the present inventors have extensively studied a binder to be combined with carbon-coated silicon oxide from the viewpoint of the polymer structure that constitutes the binder.
- the weight-average molecular weight is suppressed to 300,000 or less, and the interaction with the active material or the interaction between polymers is expected.
- the above technical problems can be solved at a high level by including a specific amount or more of a water-soluble polymer in the binder in which the content of the component having an acid group is suppressed to 5% by mass or less. rice field.
- the present invention has been completed through further studies based on these findings.
- the binder contains 5% by mass or more of a water-soluble polymer
- the composition for a negative electrode wherein the water-soluble polymer has a weight average molecular weight of 300,000 or less, and the component having an acid group accounts for 5% by mass or less of the water-soluble polymer.
- R 1 represents a hydrogen atom or a methyl group
- L 1 represents a single bond or a linking group
- R 2 represents a substituent. * indicates a binding site for incorporation into the water-soluble polymer.
- R3 represents a hydrogen atom or a methyl group
- R4 and R5 represent a hydrogen atom or a substituent. * indicates a binding site for incorporation into the water-soluble polymer.
- ⁇ 4> The negative electrode composition according to any one of ⁇ 1> to ⁇ 3>, wherein the content of the water-soluble polymer is 2 parts by mass or more with respect to 100 parts by mass of the carbon-coated silicon oxide. .
- ⁇ 5> The negative electrode composition according to ⁇ 3>, wherein the water-soluble polymer contains two or more constituents represented by the general formula (1) or (2).
- ⁇ 6> The negative electrode composition according to any one of ⁇ 1> to ⁇ 5>, wherein the acid group is a carboxy group or a salt thereof.
- ⁇ 7> The negative electrode composition according to any one of ⁇ 1> to ⁇ 6>, which is a negative electrode slurry containing a dispersion medium.
- ⁇ 9> It has a positive electrode active material layer, a separator, and a negative electrode active material layer in this order, and the negative electrode active material layer is a layer composed of the negative electrode composition according to any one of ⁇ 1> to ⁇ 7>.
- non-aqueous secondary battery A method for producing a negative electrode sheet, comprising forming a film using the negative electrode composition according to any one of ⁇ 1> to ⁇ 7>.
- ⁇ 11> A method for producing a non-aqueous secondary battery, comprising incorporating the negative electrode sheet obtained by the production method according to ⁇ 10> into a negative electrode of the non-aqueous secondary battery.
- water-soluble polymer means a polymer that dissolves in 1 L of water at 25° C. in an amount of 7 g or more (a polymer whose solubility at 25° C. is 7 [g/1 L-H 2 O] or more).
- a numerical range represented by "to” means a range including the numerical values before and after "to” as lower and upper limits.
- the expression of a compound is used to mean the compound itself, its salts, and its ions. It also includes derivatives in which a part of the structure is changed, such as by introducing a substituent, to the extent that the desired effect is achieved.
- substituents when a substituent has a dissociable hydrogen atom (a group in which a hydrogen atom is dissociated by the action of a base), this substituent includes ions or salts.
- the carboxy group when a compound has a carboxy group, the carboxy group may exist as an anion by dissociating a hydrogen atom, and the anion may form a salt with a counterion (cation).
- Counterions are not particularly limited, and examples thereof include alkali metal ions such as lithium ions, sodium ions and potassium ions.
- substituents, linking groups, etc. hereinafter referred to as substituents, etc. for which substitution or unsubstitution is not specified are intended to mean that the group may have an appropriate substituent.
- non-aqueous secondary battery is meant to include non-aqueous electrolyte secondary batteries and all-solid secondary batteries.
- non-aqueous electrolyte means an electrolyte that does not substantially contain water.
- the "non-aqueous electrolyte” may contain a small amount of water as long as the effects of the present invention are not impaired.
- the "non-aqueous electrolyte” has a water concentration of 200 ppm (by mass) or less, preferably 100 ppm or less, more preferably 20 ppm or less. It is practically difficult to make the non-aqueous electrolyte completely anhydrous, and usually contains 1 ppm or more of water.
- the "solid content” used when describing the content or content ratio means components other than the dispersion medium described below.
- the negative electrode composition and the negative electrode sheet of the present invention provide excellent cycle characteristics to a non-aqueous secondary battery using carbon-coated silicon oxide as a negative electrode active material by forming a negative electrode active material layer using them. can do. Therefore, the non-aqueous secondary battery of the present invention has high capacity, low resistance, and excellent cycle characteristics. According to the method for producing a negative electrode sheet of the present invention, the negative electrode sheet of the present invention can be obtained. Moreover, according to the manufacturing method of the non-aqueous secondary battery of the present invention, the non-aqueous secondary battery of the present invention can be obtained.
- FIG. 1 is a vertical cross-sectional view schematically showing the basic lamination structure of a non-aqueous electrolyte secondary battery.
- the negative electrode composition of the present invention contains a binder containing a water-soluble polymer and a negative electrode active material containing carbon-coated silicon oxide.
- the water-soluble polymer has a weight-average molecular weight of 300,000 or less, and the content of the component having an acid group in the water-soluble polymer is 5% by mass or less. This water-soluble polymer is contained in the binder in an amount of 5% by mass or more.
- the binder contains a certain amount or more of a polymer that has a relatively small weight average molecular weight of 300,000 or less, and the amount of acid groups is limited to suppress the increase in apparent molecular weight. Therefore, it is presumed that one of the reasons for this is that the water-soluble polymer is firmly attached to the negative electrode active material (carbon-coated silicon oxide) by, for example, fitting into the voids of the carbon coating layer (causing an anchor effect). be done.
- the negative electrode composition of the present invention can be prepared by mixing a binder containing a water-soluble polymer, a negative electrode active material containing carbon-coated silicon oxide, and, if necessary, a dispersion medium, a conductive aid, and the like. .
- the binder used in the present invention contains 5% by mass or more of the water-soluble polymer described above based on the total amount of the binder.
- the water-soluble polymer used in the present invention may be either a chain polymerized polymer or a stepwise polymerized polymer, preferably a chain polymerized polymer. There are no particular restrictions on the bond form of the chain polymer, and it may be random or block.
- the water-soluble polymer preferably contains, for example, a component represented by the following general formula (1) or (2) as a component having no acid group.
- R 1 represents a hydrogen atom or a methyl group
- L 1 represents a single bond or a linking group (divalent)
- R 2 represents a substituent. * indicates a binding site for incorporation into a water-soluble polymer.
- R3 represents a hydrogen atom or a methyl group
- R4 and R5 represent a hydrogen atom or a substituent. * indicates a binding site for incorporation into a water-soluble polymer.
- the linking group that can be used as L1 is not particularly limited as long as it does not have an acid group.
- the chemical formula weight of this linking group is preferably 14-1000, more preferably 14-500, even more preferably 26-250.
- Linking groups that can be used as L 1 include, for example, alkylene groups, —O—, carbonyl groups, imino groups, and combinations thereof. As a combination of these, a connecting group formed by combining 2 to 6 groups selected from an alkylene group, —O—, a carbonyl group and an imino group is preferable, and a connecting group formed by combining 2 or 3 groups is more preferable.
- the alkylene group that can be used as L 1 may be either linear or branched, and the number of carbon atoms in the alkylene group is preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, and can be 1 to 4. Most preferably, it is a methylene group, an ethylene group, an ethylethylene group or a propylene group.
- the chemical formula weight of L 1 is preferably 14-200, more preferably 14-150, even more preferably 14-80.
- R 2 is not particularly limited as long as it is a substituent having no acid group.
- the chemical formula weight of R 2 is preferably 15-200, more preferably 15-150, even more preferably 15-100.
- R 2 include a hydroxy group, an alkyloxy group, an alkyl group, an amide group and a sulfonamide group, preferably a hydroxy group or an alkyloxy group.
- the alkyl group in the alkyloxy group may be linear, branched or cyclic.
- the number of carbon atoms in the alkyl group is preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, particularly preferably 1 to 4, and is any one of a methyl group, an ethyl group and an isopropyl group. is most preferred.
- the alkyl group has the same definition as the alkyl group in the above alkyloxy group, and the preferred range is also the same.
- Substituents that can be used as R 4 and R 5 are not particularly limited as long as they are substituents that do not have an acid group.
- the chemical formula weight of each of R 4 and R 5 is preferably 15-200, more preferably 15-150, even more preferably 15-60.
- Alkyl groups are preferred as substituents that can be taken as R 4 and R 5 .
- the alkyl group has the same definition as the alkyl group in the alkyloxy group that can be used as R 2 above, and the preferred range is also the same. It is also preferred that the alkyl groups that can be used as R 4 and R 5 further have substituents.
- substituents include hydroxy groups, alkylcarbonyl groups, amide groups, and urethane bond-containing groups (--NH--CO--O--R b (R b represents an alkyl group).
- a hydroxy group is preferable as a substituent of the alkyl group that can be used as R 4 and R 5 .
- the alkyl group in the alkylcarbonyl group has the same meaning as the alkyl group in the alkyloxy group that can be used as R 2 above, and the preferred range is also the same.
- the alkyl group represented by R b has the same definition as the alkyl group in the alkyloxy group that can be used as R 2 above, and the preferred range is also the same.
- Both R 4 and R 5 are preferably a hydrogen atom, or one is a hydrogen atom and the other is a hydroxyalkyl group.
- the water-soluble polymer used in the present invention may contain one type of component having no acid group alone, or may contain two or more types in combination.
- the ratio of the component represented by the general formula (1) or (2) in the water-soluble polymer (the ratio of the component represented by the general formula (1) in the water-soluble polymer and the above The total ratio of the constituent components represented by the general formula (2)) is preferably 30% by mass or more, more preferably 50% by mass or more, still more preferably 70% by mass or more, and particularly 90% by mass or more. Preferably, it is most preferably 95% by mass or more. From the viewpoint of improving the cycle characteristics of the secondary battery, the water-soluble polymer used in the present invention preferably contains two or more constituents represented by general formula (1) or (2).
- constituents are not particularly limited. Examples include components derived from vinyl monomers such as styrene, maleimide, N-vinylacetamide, vinyl esters and vinyl ethers.
- the "acid group" of the component having an acid group that the water-soluble polymer may have means a group having a dissociative proton or a salt thereof.
- Salt forms include, for example, alkali metal salts (eg, lithium salts, sodium salts, potassium salts, etc.).
- the component having the acid group is not particularly limited, and the component usually contains 1 to 3 acid groups, preferably 1 or 2 groups, and more preferably 1 group.
- the water-soluble polymer contains a component having an acid group, it preferably contains, for example, a component represented by the following general formula (3).
- R6 represents a hydrogen atom or an acid group.
- R7 represents a hydrogen atom or a methyl group, L2 represents a single bond or a linking group ( divalent ), and R8 represents an acid group. * indicates a binding site for incorporation into a water-soluble polymer.
- the linking group that can be used as L 2 is not particularly limited, and examples thereof include an alkylene group, an arylene group, a carbonyl group, an ether bond (--O--), an imino group, or a linking group in which two or more of these are combined.
- the alkylene group that can be used as L 2 may be either linear or branched, and the number of carbon atoms in the alkylene group is preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, and can be 1 to 4. Particularly preferred are methylene, ethylene, propylene and dimethylethylene groups.
- the number of carbon atoms in the arylene group that can be taken as L 2 is preferably 6-30, more preferably 6-20, still more preferably 6-15, and particularly preferably 6-10.
- Specific examples of arylene groups include phenylene groups and naphthylene groups.
- linking group combining two or more types is a linking group combining at least two types of an alkylene group, an arylene group, a carbonyl group, an ether bond (-O-) and an imino group, and a combination of 2 to 10 types. is preferable, a linking group in which 2 to 7 types are combined is more preferable, and a linking group in which 2 to 4 types are combined is even more preferable.
- Specific examples of the above-mentioned "linking group combining two or more types” include, for example, "carbonyl group-imino group-alkylene group” and "carbonyl group-ether bond-alkylene group”.
- the proportion of the component having an acid group in the water-soluble polymer is 5% by mass or less, preferably 4% by mass or less, more preferably 3% by mass or less, further preferably 2% by mass or less, and 1% by mass or less. is particularly preferred, and it is most preferred that the water-soluble polymer does not have constituents with acid groups.
- the weight average molecular weight of the water-soluble polymer used in the present invention is 300,000 or less, preferably 290,000 or less, more preferably 280,000 or less, and even more preferably 270,000 or less.
- the weight average molecular weight of the water-soluble polymer is preferably 10,000 or more, more preferably 40,000 or more, still more preferably 100,000 or more, particularly preferably 140,000 or more, and most preferably 170,000 or more.
- the weight average molecular weight of a polymer is a value obtained by measuring by the method described in the Examples section below.
- the content of the water-soluble polymer in the binder used in the present invention is 5% by mass or more, preferably 10% by mass or more, more preferably 20% by mass or more, from the viewpoint of improving the cycle characteristics of the secondary battery.
- the binder used in the present invention may consist of the above water-soluble polymer.
- the content of the water-soluble polymer in the negative electrode composition is preferably 2 parts by mass or more, and 4 parts by mass with respect to 100 parts by mass of carbon-coated silicon oxide. Part or more is more preferable, and 8 parts by mass or more is even more preferable.
- the content of the water-soluble polymer in the negative electrode composition is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and 20 parts by mass or less with respect to 100 parts by mass of carbon-coated silicon oxide. More preferred.
- the binder used in the present invention can contain polymers other than the above water-soluble polymers.
- Such polymers include, for example, water-insoluble polymers, water-soluble polymers having a weight-average molecular weight exceeding 300,000, and water-soluble polymers containing constituents having acid groups exceeding 5% by weight. Specific examples of such polymers include polymer B described in Table 1 below, but polymer B is not limited to "polymer B described in Table 1 below".
- the negative electrode active material used in the present invention includes carbon-coated silicon oxide (SiOx (0 ⁇ x ⁇ 1.5)). Carbon-coated silicon oxide can reversibly store and release lithium ions.
- the silicon oxide may be coated with carbon over the entire surface, or may have a portion not coated with carbon. Even if the entire surface of silicon oxide is carbon-coated, the carbon-coated layer itself has a large number of voids.
- the proportion of carbon atoms in the carbon-coated silicon oxide (the total of the carbon coating layer and silicon oxide) is not particularly limited, and is preferably 0.5 to 5% by mass, more preferably 1 to 3% by mass.
- Carbon-coated silicon oxide may be a commercially available product. For example, referring to JP-A-2019-204686, silicon oxide can be prepared by carbon-coating.
- the negative electrode active material used in the present invention may contain a negative electrode active material other than carbon-coated silicon oxide.
- negative electrode active materials other than carbon-coated silicon oxide are referred to as "other negative electrode active materials.”
- Other negative electrode active materials are preferably those capable of reversibly intercalating and deintercalating lithium ions.
- the material is not particularly limited as long as it has the above properties, and examples thereof include carbonaceous materials, metal oxides, metal composite oxides, lithium alloys, negative electrode active materials capable of forming an alloy with lithium, and the like.
- the lithium alloy is not particularly limited as long as it is an alloy normally used as a negative electrode active material for secondary batteries, and examples thereof include lithium aluminum alloys.
- the negative electrode active material capable of forming an alloy with lithium is not particularly limited as long as it is commonly used as a negative electrode active material for secondary batteries.
- active materials include negative electrode active materials having tin atoms and metals such as Al and In.
- negative electrode active materials containing tin atoms include Sn, SnO, SnO 2 , SnS, SnS 2 , active materials containing silicon atoms and tin atoms, and the like.
- composite oxides with lithium oxide such as Li 2 SnO 2 .
- carbonaceous materials are preferably used as other negative electrode active materials from the viewpoint of reliability.
- carbonaceous materials used as negative electrode active materials are materials that are substantially made of carbon.
- carbon black such as petroleum pitch, graphite (natural graphite, artificial graphite such as vapor growth graphite, etc.), and carbonaceous materials obtained by baking various synthetic resins such as PAN (polyacrylonitrile) resin or furfuryl alcohol resin Materials can be mentioned.
- various carbon fibers such as PAN-based carbon fiber, cellulose-based carbon fiber, pitch-based carbon fiber, vapor growth carbon fiber, dehydrated PVA (polyvinyl alcohol)-based carbon fiber, lignin carbon fiber, vitreous carbon fiber and activated carbon fiber. , mesophase microspheres, graphite whiskers and tabular graphite.
- metal oxides and metal composite oxides applied as negative electrode active materials are not particularly limited as long as they are oxides capable of intercalating and deintercalating lithium.
- Chalcogenite which is a reaction product with an element belonging to Group 16 of the Norms Table, is also preferred.
- amorphous as used herein means a broad scattering band having an apex in the region of 20° to 40° in terms of 2 ⁇ value in an X-ray diffraction method using CuK ⁇ rays, and a crystalline diffraction line.
- amorphous oxides of metalloid elements and the above chalcogenides are more preferable, elements of groups 13 (IIIB) to 15 (VB) of the periodic table, Particularly preferred are oxides of Al, Ga, Si, Sn, Ge, Pb, Sb and Bi, or a combination of two or more thereof (excluding oxides containing Si), or chalcogenides.
- Specific examples of preferred amorphous oxides and chalcogenides include Ga 2 O 3 , GeO, PbO, PbO 2 , Pb 2 O 3 , Pb 2 O 4 , Pb 3 O 4 , Sb 2 O 3 and Sb 2 .
- the metal (composite) oxide and the chalcogenide preferably contain at least one of titanium and lithium as a constituent component from the viewpoint of high current density charge/discharge characteristics.
- lithium-containing metal composite oxides include composite oxides of lithium oxide and the above metal (composite) oxides or chalcogenides, more specifically Li 2 SnO 2 . mentioned.
- Other negative electrode active materials preferably contain titanium atoms. More specifically, TiNb 2 O 7 (niobium titanate [NTO]) and Li 4 Ti 5 O 12 (lithium titanate [LTO]) have small volume fluctuations when absorbing and desorbing lithium ions, and are therefore suitable for rapid charging. It is preferable in that it has excellent discharge characteristics, suppresses deterioration of the electrode, and can improve the life of the lithium ion secondary battery.
- NTO niobium titanate
- Li 4 Ti 5 O 12 lithium titanate [LTO]
- the shape of the carbon-coated silicon oxide and other negative electrode active materials is not particularly limited, but is preferably particulate.
- the volume-based median diameter D50 of carbon-coated silicon oxide and other negative electrode active materials is preferably 0.1 to 60 ⁇ m.
- a conventional pulverizer or classifier is used to obtain a predetermined particle size.
- a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a whirling jet mill, a sieve, or the like is preferably used.
- wet pulverization can also be performed in which water or an organic solvent such as methanol is allowed to coexist.
- Classification is preferably carried out in order to obtain a desired particle size.
- the classification method is not particularly limited, and a sieve, an air classifier, or the like can be used as desired. Both dry and wet classification can be used.
- the median diameter D50 of carbon-coated silicon oxide is also preferably 0.1 to 30 ⁇ m, more preferably 0.5 to 20 ⁇ m, and particularly preferably 2 to 8 ⁇ m.
- the median diameter D50 can be determined by a laser diffraction method, for example, using SALD-2300 (trade name) manufactured by Shimadzu Corporation.
- the mass ratio (carbon-coated silicon oxide/graphite) is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more.
- the upper limit of the mass ratio of carbon-coated silicon oxide to graphite is not particularly limited, 4 or less is practical.
- the content of carbon-coated silicon oxide in the negative electrode active material is not particularly limited, and can be, for example, 10 to 90% by mass, preferably 10 to 50% by mass, more preferably 15 to 40% by mass.
- the mass (mg) (basis weight) of carbon-coated silicon oxide and other negative electrode active materials per unit area (cm 2 ) of the negative electrode active material layer is not particularly limited. do not have. It can be determined appropriately according to the designed battery capacity.
- the content of carbon-coated silicon oxide and other negative electrode active materials in the negative electrode composition is not particularly limited. 15 to 95% by mass is more preferable.
- the negative electrode composition of the present invention can also contain a dispersion medium to form a negative electrode slurry.
- an aqueous medium containing water can be used as the dispersion medium.
- the "aqueous medium containing water” is water or a mixture of water and a water-soluble organic solvent.
- water-soluble organic solvent refers to an organic solvent that mixes with water without causing phase separation, and includes, for example, N-methylpyrrolidone, methanol, ethanol, acetone, tetrahydrofuran, and the like.
- the negative electrode composition of the present invention can also contain a conductive aid.
- a conductive aid there are no particular restrictions on the conductive aid, and any commonly known conductive aid can be used.
- graphites such as natural graphite and artificial graphite, carbon blacks such as acetylene black, ketjen black, and furnace black, amorphous carbon such as needle coke, vapor-grown carbon fiber, or carbon nanotube, which are electronic conductive materials
- Carbon fibers such as carbon fibers such as graphene or fullerene may be used, metal powders such as copper and nickel, metal fibers may be used, and conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, and polyphenylene derivatives may be used.
- a negative electrode active material and a conductive aid when used in combination, among the above conductive aids, Li insertion and release do not occur when the secondary battery is charged and discharged, and do not function as a negative electrode active material. is used as a conductive aid. Therefore, among conductive aids, those that can function as a negative electrode active material in a negative electrode active material layer during charging and discharging of a secondary battery are classified as negative electrode active materials instead of conductive aids. Whether or not it functions as a negative electrode active material when a secondary battery is charged and discharged is not univocally determined by the combination with the negative electrode active material.
- the content of the conductive aid in the negative electrode composition is preferably 10 to 90% by mass, more preferably 30 to 80% by mass, and even more preferably 50 to 70% by mass based on 100% by mass of solid content.
- the shape of the conductive aid is not particularly limited, but it is preferably particulate.
- the median diameter D50 of the conductive aid is not particularly limited, and is preferably 0.01 to 50 ⁇ m, preferably 0.02 to 10.0 ⁇ m, for example.
- the negative electrode composition of the present invention may optionally contain, as components other than the components described above, a lithium salt, an ionic liquid, a thickener, an antifoaming agent, a leveling agent, a dehydrating agent, an antioxidant, and the like. can be done.
- a cross-linking agent for chemically cross-linking the water-soluble polymer such as one that undergoes a cross-linking reaction by radical polymerization, condensation polymerization, or ring-opening polymerization
- a polymerization initiator that generates acid or radicals by heat or light
- the negative electrode sheet of the present invention has a layer (negative electrode active material layer) configured (formed) using the negative electrode composition of the present invention.
- the negative electrode sheet of the present invention only needs to have a negative electrode active material layer. It may be a sheet formed of This negative electrode sheet is usually a sheet having a structure in which a negative electrode active material layer is laminated on a current collector.
- the negative electrode sheet of the present invention may have other layers such as a protective layer (release sheet) and a coat layer.
- the negative electrode sheet of the present invention can be suitably used as a material constituting a negative electrode active material layer of a secondary battery.
- the negative electrode sheet of the present invention can be obtained by forming a negative electrode active material layer using the negative electrode composition of the present invention.
- a current collector or the like is used as a base material, and the composition for a negative electrode of the present invention is applied thereon (may be via another layer) to form a coating film, which is dried to form a base material.
- An electrode sheet having a negative electrode active material layer (coated dry layer) thereon can be obtained.
- Non-aqueous secondary battery of the present invention means all devices in which ions pass between the positive and negative electrodes through an electrolyte due to charging and discharging, and energy is stored and released at the positive and negative electrodes. That is, the term "non-aqueous secondary battery” as used in the present invention includes both batteries and capacitors (for example, lithium ion capacitors). From the viewpoint of energy storage capacity, the non-aqueous secondary battery of the present invention is preferably used for battery applications (not a capacitor).
- the non-aqueous secondary battery of the present invention will be described by taking the form of a non-aqueous electrolyte secondary battery as an example, but the secondary battery of the present invention is not limited to the non-aqueous electrolyte secondary battery. It broadly includes all non-aqueous secondary batteries including solid secondary batteries.
- a non-aqueous electrolyte secondary battery which is a preferred embodiment of the present invention, has a configuration including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode.
- the positive electrode has a positive electrode current collector and a positive electrode active material layer in contact with the positive electrode current collector
- the negative electrode has a negative electrode current collector and a negative electrode active material layer in contact with the negative electrode current collector.
- the negative electrode active material layer is formed using the electrode composition of the present invention.
- FIG. 1 is a schematic cross-sectional view showing a laminated structure of a general non-aqueous electrolyte secondary battery 10 including working electrodes when operated as a battery.
- the non-aqueous electrolyte secondary battery 10 has a laminated structure having, when viewed from the negative electrode side, a negative electrode current collector 1, a negative electrode active material layer 2, a separator 3, a positive electrode active material layer 4, and a positive electrode current collector 5 in this order. is doing.
- the space between the negative electrode active material layer and the positive electrode active material layer is filled with a non-aqueous electrolyte (not shown) and separated by the separator 3 .
- the separator 3 has pores and functions as a positive/negative separator that insulates the positive/negative electrodes while permeating the electrolytic solution and ions under normal battery usage conditions.
- a positive/negative separator that insulates the positive/negative electrodes while permeating the electrolytic solution and ions under normal battery usage conditions.
- a light bulb is employed in the actuation portion 6, which is lit by the discharge.
- the negative electrode current collector 1 and the negative electrode active material layer 2 are collectively referred to as a negative electrode
- the positive electrode active material layer 4 and the positive electrode current collector 5 are collectively referred to as a positive electrode.
- the non-aqueous secondary battery of the present invention comprises a positive electrode active material, a non-aqueous electrolyte, a solid electrolyte material, other members, etc., except that the negative electrode composition of the present invention is used to form a negative electrode active material layer.
- a positive electrode active material a positive electrode active material
- a non-aqueous electrolyte a solid electrolyte material
- other members etc.
- the negative electrode composition of the present invention is used to form a negative electrode active material layer.
- the negative electrode composition of the present invention is used to form a negative electrode active material layer.
- JP-A-2016-201308, JP-A-2005-108835, JP-A-2012-185938, and International Publication No. 2020/067106 can be referred to as appropriate.
- the non-aqueous secondary battery of the present invention can be used, for example, in notebook computers, pen-input computers, mobile computers, e-book players, mobile phones, cordless phone slaves, pagers, handy terminals, mobile facsimiles, mobile copiers, mobile printers, and headphone stereos. , video movies, liquid crystal televisions, handy cleaners, portable CDs, minidiscs, electric shavers, transceivers, electronic notebooks, calculators, portable tape recorders, radios, backup power supplies, memory cards, and other electronic devices.
- the weight average molecular weight (Mw) of the polymer shown in Table 1 below is the weight average molecular weight converted to sodium polyacrylate by gel permeation chromatography (GPC), and is a value measured under the following conditions.
- Measuring instrument HLC-8220GPC (trade name, manufactured by Tosoh Corporation)
- Guard column TSKgel guard column PWXL (trade name, manufactured by Tosoh Corporation)
- Carrier 200 mM sodium nitrate aqueous solution
- Rinse liquid Ultrapure water
- Carrier flow rate Sample pump 1.0 mL/min Reference pump 0.223 mL/min Pump initial pressure: sample pump 4.4 MPa Reference pump 0.8MPa Sample concentration: 0.10% by mass
- Detector RI (refractive index) detector
- composition No. 1 in Table 1 below 30 parts by mass of carbon-coated silicon oxide (SiOC, carbon atom content ratio 1.3% by mass, average primary particle size: 5 ⁇ m, Osaka Titanium Co., Ltd.) in a 60 ml ointment container (manufactured by Umano Kagaku Co., Ltd.), 70 parts by mass of graphite (trade name: mag-d, manufactured by Hitachi Chemical Co., Ltd.), 5 parts by mass of acetylene black (trade name: Denka Black, manufactured by Denka), 5 parts by mass of polymer 1, 22.5 parts by mass of distilled water Parts by mass were added, and dispersed for 10 minutes at 2000 rpm using a foaming mixer (trade name, manufactured by THINKY).
- a negative electrode composition 1 was obtained by adding 27 parts by mass of distilled water to the dispersed liquid and dispersing the mixture at 2000 rpm for 10 minutes using a bubble removing mixer.
- compositions 2 to 19 and c1 to c3 compositions of Nos. 2 to 19 and c1 to c3 in Table 1 below.
- the negative electrode composition was prepared in the same manner as the negative electrode composition 1, except that polymers 2 to 19 and c1 to c3 described in Table 1 below were used instead of the polymer 1. 2-19 and c1-c3 were prepared.
- Lithium foil (thickness 50 ⁇ m, 14.5 mm ⁇ ) and polypropylene separator (thickness 25 ⁇ m, 16.0 mm ⁇ ) were stacked in this order. I let you in.
- the separator was further impregnated with 200 ⁇ L of the electrolytic solution, and the negative electrode sheet was stacked so that the negative electrode active material layer surface was in contact with the separator.
- the 2032 type coin case was crimped to prepare a non-aqueous electrolyte secondary battery 1 (a battery having a laminate consisting of Li foil-separator-negative electrode active material layer-copper foil).
- Cycle characteristics were evaluated by repeating 50 charge/discharge cycles, with one charge/discharge cycle being defined as one charge/discharge cycle. Assuming that the discharge capacity at the first cycle after initialization (initial discharge capacity) is 100%, the discharge capacity retention rate at the 50th cycle (100 ⁇ “50th cycle discharge capacity” / “initial discharge capacity”) was calculated. , was applied to the following evaluation ranks, and the cycle characteristics were evaluated. The results are shown in Table 1 below. In this test, evaluation ranks "1" to "3" are passed. -Evaluation rank of discharge capacity retention rate (cycle characteristics)- 1: 95% or more 2: 90% or more and less than 95% 3: 85% or more and less than 90% 4: less than 85%
- “Acid group content in polymer A (% by mass)” means the content of constituents having acid groups in polymer A.
- Constent 1 (parts by mass)” When the content of SiOC in the negative electrode composition is 100 parts by mass, it means the content of polymer A with respect to 100 parts by mass of SiOC.
- Constent in binder (% by mass) means the content of the water-soluble polymer defined in the present invention in the binder.
- Constent 2 (parts by mass)” When the content of SiOC in the negative electrode composition is 100 parts by mass, it means the content of polymer B with respect to 100 parts by mass of SiOC.
- content of “latex” is content of solid content. All Polymer A's, including those of the Comparative Examples, are water soluble.
- No. Polymer A used in the negative electrode compositions of c1 and c3 contains more than 5% by mass of constituents having acid groups. No. Nos. c1 and c3 produced using the negative electrode compositions. Batteries of c1 and c3 were inferior in cycle characteristics.
- No. Polymer A used in the negative electrode composition of c2 has a content of constituents having an acid group of 5% by mass or less, but a weight average molecular weight of more than 300,000. No. No. c2 produced using the negative electrode composition. The battery of c2 was inferior in cycle characteristics. On the other hand, it can be seen that the batteries (Nos. 1 to 19) produced using the negative electrode compositions (Nos. 1 to 19) of the present invention are excellent in cycle characteristics.
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Abstract
The present invention relates to a composition for a negative electrode comprising a binder and carbon-coated silicon oxide, wherein the binder includes 5% by mass or more of a water-soluble polymer, the water-soluble polymer has a weight average molecular weight of 300,000 or less, and the proportion of an acid group-containing component in the water-soluble polymer is 5% by mass or less, and also to a negative electrode sheet and a non-aqueous secondary battery produced using this composition for a negative electrode, and a method for manufacturing the negative electrode sheet and non-aqueous secondary battery.
Description
本発明は、負極用組成物、負極シート、非水二次電池、負極シートの製造方法、及び非水二次電池の製造方法に関する。
The present invention relates to a negative electrode composition, a negative electrode sheet, a non-aqueous secondary battery, a method for manufacturing a negative electrode sheet, and a method for manufacturing a non-aqueous secondary battery.
リチウムイオン二次電池に代表される二次電池は、パソコン、ビデオカメラ、携帯電話等のポータブル電子機器の動力源として用いられている。最近では、二酸化炭素排出量削減という地球規模の環境課題を背景に、自動車等の輸送機器の動力電源として、また、夜間電力、自然エネルギー発電による電力等の蓄電用途としても普及してきている。
Secondary batteries, typified by lithium-ion secondary batteries, are used as power sources for portable electronic devices such as personal computers, video cameras, and mobile phones. Recently, against the background of the global environmental issue of reducing carbon dioxide emissions, it is becoming popular as a power source for transportation equipment such as automobiles, and as a power storage application such as nighttime power and power generated by natural energy generation.
リチウムイオン二次電池の電極（正極及び負極）は電極活物質層（正極活物質層及び負極活物質層）を有し、この電極活物質層は、充放電時にリチウムイオンを吸蔵ないし放出可能な電極活物質粒子を含む。また、電極活物質粒子間、ないし電極活物質粒子と集電体との間では電子輸送も行われるため、電子伝導性を確保することが要求される。この電子伝導の効率化には電極活物質粒子間、ないし電極活物質粒子と集電体との間の結着性が重要であり、電極活物質層は通常、バインダーを有している。
The electrodes (positive electrode and negative electrode) of the lithium ion secondary battery have an electrode active material layer (positive electrode active material layer and negative electrode active material layer), and this electrode active material layer can absorb or release lithium ions during charging and discharging. Contains electrode active material particles. In addition, since electrons are also transported between the electrode active material particles or between the electrode active material particles and the current collector, it is required to ensure electron conductivity. The binding between the electrode active material particles or between the electrode active material particles and the current collector is important for the efficiency of this electron conduction, and the electrode active material layer usually contains a binder.
リチウムイオン二次電池の高容量化を実現するために、負極活物質として酸化ケイ素を用いる検討が盛んに行われている。酸化ケイ素の理論容量は黒鉛等に比べて格段に高く、電池の高エネルギー密度化が可能となる。
負極活物質として酸化ケイ素を用いると、充電時にはリチウムイオンを多量に吸蔵して大きく膨張し、その分、放電時における酸化ケイ素の収縮幅も大きくなる。したがって、負極活物質として酸化ケイ素を用いたリチウムイオン電池は充放電時の負極活物質の体積変化が大きく、充放電の繰り返しにより電池性能が低下しやすい。つまり、サイクル寿命の向上には制約がある。
このような問題に対処した技術として、例えば特許文献１には、メジアン径が０．１～２μｍであるシリコン粒子を２０質量％以上含む負極活物質と、（メタ）アクリルアミド骨格含有モノマー及びスルホン酸基置換不飽和炭化水素基含有モノマーを含むモノマー群のラジカル共重合物であり、特定濃度の水溶液状態で特定の高粘度を示すポリ（メタ）アクリルアミドと、水とを含む、リチウムイオン電池負極用スラリーが記載されている。特許文献１記載の技術によれば、この負極用スラリーを用いて、サイクル寿命（サイクル特性）に優れたリチウムイオン二次電池が得られるとされる。 In order to increase the capacity of lithium-ion secondary batteries, studies on using silicon oxide as a negative electrode active material have been actively conducted. The theoretical capacity of silicon oxide is remarkably higher than that of graphite, etc., making it possible to increase the energy density of batteries.
When silicon oxide is used as the negative electrode active material, it absorbs a large amount of lithium ions and expands greatly during charging, and the shrinkage width of silicon oxide during discharging is correspondingly increased. Therefore, in a lithium-ion battery using silicon oxide as a negative electrode active material, the volume of the negative electrode active material changes greatly during charging and discharging, and the battery performance tends to deteriorate due to repeated charging and discharging. In other words, there are restrictions on improving the cycle life.
As a technique for dealing with such problems, for example,Patent Document 1 discloses a negative electrode active material containing 20% by mass or more of silicon particles having a median diameter of 0.1 to 2 μm, a (meth)acrylamide skeleton-containing monomer and sulfonic acid. A lithium ion battery negative electrode comprising poly(meth)acrylamide, which is a radical copolymer of a monomer group containing a group-substituted unsaturated hydrocarbon group-containing monomer and exhibits a specific high viscosity in an aqueous solution of a specific concentration, and water A slurry is described. According to the technique described in Patent Document 1, it is said that a lithium ion secondary battery having excellent cycle life (cycle characteristics) can be obtained using this negative electrode slurry.
負極活物質として酸化ケイ素を用いると、充電時にはリチウムイオンを多量に吸蔵して大きく膨張し、その分、放電時における酸化ケイ素の収縮幅も大きくなる。したがって、負極活物質として酸化ケイ素を用いたリチウムイオン電池は充放電時の負極活物質の体積変化が大きく、充放電の繰り返しにより電池性能が低下しやすい。つまり、サイクル寿命の向上には制約がある。
このような問題に対処した技術として、例えば特許文献１には、メジアン径が０．１～２μｍであるシリコン粒子を２０質量％以上含む負極活物質と、（メタ）アクリルアミド骨格含有モノマー及びスルホン酸基置換不飽和炭化水素基含有モノマーを含むモノマー群のラジカル共重合物であり、特定濃度の水溶液状態で特定の高粘度を示すポリ（メタ）アクリルアミドと、水とを含む、リチウムイオン電池負極用スラリーが記載されている。特許文献１記載の技術によれば、この負極用スラリーを用いて、サイクル寿命（サイクル特性）に優れたリチウムイオン二次電池が得られるとされる。 In order to increase the capacity of lithium-ion secondary batteries, studies on using silicon oxide as a negative electrode active material have been actively conducted. The theoretical capacity of silicon oxide is remarkably higher than that of graphite, etc., making it possible to increase the energy density of batteries.
When silicon oxide is used as the negative electrode active material, it absorbs a large amount of lithium ions and expands greatly during charging, and the shrinkage width of silicon oxide during discharging is correspondingly increased. Therefore, in a lithium-ion battery using silicon oxide as a negative electrode active material, the volume of the negative electrode active material changes greatly during charging and discharging, and the battery performance tends to deteriorate due to repeated charging and discharging. In other words, there are restrictions on improving the cycle life.
As a technique for dealing with such problems, for example,
また、酸化ケイ素をカーボンコートして負極活物質として用いることが提案されている。カーボンコートにより酸化ケイ素粒子の導電性を高めることができ、酸化ケイ素と電解質との副反応も抑えることができるとされる。それゆえ、カーボンコートされた酸化ケイ素は、次世代リチウムイオン二次電池の負極活物質として期待されている。例えば、特許文献２には、カーボンコートした酸化ケイ素と、アルゴンイオンレーザーラマンスペクトルにおける１５８０ｃｍ－１のピーク強度に対する１３６０ｃｍ－１のピーク強度比であるＲ値が０．２～１．５である黒鉛と、バインダーと、カーボンブラックと、水とを含有するリチウムイオン電池負極用スラリーが記載されている。特許文献２記載の技術によれば、この負極用スラリーを用いて形成した負極合材層にリチウムイオンをドープして用いることにより、サイクル寿命に優れたリチウムイオン二次電池が得られるとされる。
It has also been proposed to coat silicon oxide with carbon and use it as a negative electrode active material. It is said that the carbon coating can increase the conductivity of the silicon oxide particles and suppress the side reaction between the silicon oxide and the electrolyte. Therefore, carbon-coated silicon oxide is expected as a negative electrode active material for next-generation lithium-ion secondary batteries. For example, in Patent Document 2, carbon-coated silicon oxide and graphite having an R value, which is the ratio of the peak intensity at 1360 cm −1 to the peak intensity at 1580 cm −1 in the argon ion laser Raman spectrum, is 0.2 to 1.5. , a binder, carbon black, and water for a lithium ion battery negative electrode. According to the technique described in Patent Document 2, a lithium ion secondary battery having an excellent cycle life can be obtained by doping lithium ions into a negative electrode mixture layer formed using this negative electrode slurry. .
リチウムイオン二次電池の電極は通常、電極形成用の組成物（スラリー）を集電体上に塗布し、乾燥して形成される。したがって、電極形成のためのスラリーは、電極活物質とバインダーとを液媒体中に分散して調製される。近年の環境問題への関心の高まりを背景に、液媒体として水系のものが求められるようになっており、例えば、上記の特許文献１及び２に記載されるように、水系スラリーに適した種々の水溶性バインダーが開発されている。
Electrodes for lithium-ion secondary batteries are usually formed by applying an electrode-forming composition (slurry) onto a current collector and drying it. Therefore, a slurry for electrode formation is prepared by dispersing an electrode active material and a binder in a liquid medium. Against the backdrop of increasing interest in environmental issues in recent years, there has been a demand for aqueous media as liquid media. of water-soluble binders have been developed.
本発明は、負極活物質としてカーボンコートされた酸化ケイ素を用いた負極用組成物であって、非水二次電池の負極活物質層の形成に用いることにより、得られる非水二次電池の高容量と低抵抗を実現しながら、サイクル寿命も十分に長期化することができる負極用組成物を提供することを課題とする。更に、本発明は、上記負極用組成物を用いた負極シート及び非水二次電池を提供することを課題とする。更に本発明は、上記負極シート及び非水二次電池の製造方法を提供することを課題とする。
The present invention relates to a negative electrode composition using carbon-coated silicon oxide as a negative electrode active material, which is used to form a negative electrode active material layer of a nonaqueous secondary battery. An object of the present invention is to provide a negative electrode composition capable of sufficiently extending the cycle life while achieving high capacity and low resistance. A further object of the present invention is to provide a negative electrode sheet and a non-aqueous secondary battery using the negative electrode composition. A further object of the present invention is to provide a method for manufacturing the negative electrode sheet and the non-aqueous secondary battery.
本発明者らは上記課題に鑑み、カーボンコートされた酸化ケイ素と組合せるバインダーについて、バインダーを構成するポリマー構造の観点から鋭意検討を重ねた。その結果、バインダーの機械強度を考慮して通常はポリマーを高分子量化するところ、逆に重量平均分子量を３０万以下に抑え、また、活物質との相互作用ないしポリマー間の相互作用などが期待される酸基を有する構成成分についてもその含有量を５質量％以下の少量に抑えた水溶性ポリマーを、バインダー中に特定量以上含ませることにより、上記技術課題を高いレベルで解決できることを見出した。本発明はこれらの知見に基づき更に検討を重ね、完成されるに至ったものである。
In view of the above problems, the present inventors have extensively studied a binder to be combined with carbon-coated silicon oxide from the viewpoint of the polymer structure that constitutes the binder. As a result, the weight-average molecular weight is suppressed to 300,000 or less, and the interaction with the active material or the interaction between polymers is expected. It has been found that the above technical problems can be solved at a high level by including a specific amount or more of a water-soluble polymer in the binder in which the content of the component having an acid group is suppressed to 5% by mass or less. rice field. The present invention has been completed through further studies based on these findings.
すなわち、上記の課題は以下の手段により解決された。
＜１＞
バインダーとカーボンコートされた酸化ケイ素とを含有する負極用組成物であって、
上記バインダー中、水溶性ポリマーを５質量％以上含み、
上記水溶性ポリマーは重量平均分子量が３０万以下であり、上記水溶性ポリマー中に占める酸基を有する構成成分の割合が５質量％以下である、負極用組成物。
＜２＞
上記水溶性ポリマーが連鎖重合ポリマーである、＜１＞に記載の負極用組成物。
＜３＞
上記水溶性ポリマーが、酸基を有しない構成成分として下記一般式（１）又は（２）で表される構成成分を含む、＜１＞又は＜２＞に記載の負極用組成物。
一般式（１）中、Ｒ１は水素原子又はメチル基を示し、Ｌ１は単結合又は連結基を示し、Ｒ２は置換基を示す。＊は上記水溶性ポリマー中に組み込まれるための結合部位を示す。
一般式（２）中、Ｒ３は水素原子又はメチル基を示し、Ｒ４及びＲ５は水素原子又は置換基を示す。＊は上記水溶性ポリマー中に組み込まれるための結合部位を示す。
＜４＞
上記水溶性ポリマーの含有量が、上記のカーボンコートされた酸化ケイ素１００質量部に対して、２質量部以上である、＜１＞～＜３＞のいずれか１つに記載の負極用組成物。
＜５＞
上記水溶性ポリマーが、上記一般式（１）又は（２）で表される２種以上の構成成分を含む、＜３＞に記載の負極用組成物。
＜６＞
上記酸基がカルボキシ基又はその塩である、＜１＞～＜５＞のいずれか１つに記載の負極用組成物。
＜７＞
分散媒体を含む負極用スラリーである、＜１＞～＜６＞のいずれか１つに記載の負極用組成物。
＜８＞
＜１＞～＜７＞のいずれか１つに記載の負極用組成物で構成した層を有する負極シート。
＜９＞
正極活物質層とセパレータと負極活物質層とをこの順で有し、上記負極活物質層が＜１＞～＜７＞のいずれか１つに記載の負極用組成物で構成した層である、非水二次電池。
＜１０＞
＜１＞～＜７＞のいずれか１つに記載の負極用組成物を用いて成膜することを含む、負極シートの製造方法。
＜１１＞
＜１０＞に記載の製造方法により得られた負極シートを非水二次電池の負極に組み込むことを含む、非水二次電池の製造方法。 That is, the above problems have been solved by the following means.
<1>
A negative electrode composition containing a binder and carbon-coated silicon oxide,
The binder contains 5% by mass or more of a water-soluble polymer,
The composition for a negative electrode, wherein the water-soluble polymer has a weight average molecular weight of 300,000 or less, and the component having an acid group accounts for 5% by mass or less of the water-soluble polymer.
<2>
The negative electrode composition according to <1>, wherein the water-soluble polymer is a chain polymer.
<3>
The negative electrode composition according to <1> or <2>, wherein the water-soluble polymer contains a component represented by the following general formula (1) or (2) as a component having no acid group.
In general formula (1), R 1 represents a hydrogen atom or a methyl group, L 1 represents a single bond or a linking group, and R 2 represents a substituent. * indicates a binding site for incorporation into the water-soluble polymer.
In general formula ( 2 ), R3 represents a hydrogen atom or a methyl group, and R4 and R5 represent a hydrogen atom or a substituent. * indicates a binding site for incorporation into the water-soluble polymer.
<4>
The negative electrode composition according to any one of <1> to <3>, wherein the content of the water-soluble polymer is 2 parts by mass or more with respect to 100 parts by mass of the carbon-coated silicon oxide. .
<5>
The negative electrode composition according to <3>, wherein the water-soluble polymer contains two or more constituents represented by the general formula (1) or (2).
<6>
The negative electrode composition according to any one of <1> to <5>, wherein the acid group is a carboxy group or a salt thereof.
<7>
The negative electrode composition according to any one of <1> to <6>, which is a negative electrode slurry containing a dispersion medium.
<8>
A negative electrode sheet having a layer composed of the negative electrode composition according to any one of <1> to <7>.
<9>
It has a positive electrode active material layer, a separator, and a negative electrode active material layer in this order, and the negative electrode active material layer is a layer composed of the negative electrode composition according to any one of <1> to <7>. , non-aqueous secondary battery.
<10>
A method for producing a negative electrode sheet, comprising forming a film using the negative electrode composition according to any one of <1> to <7>.
<11>
A method for producing a non-aqueous secondary battery, comprising incorporating the negative electrode sheet obtained by the production method according to <10> into a negative electrode of the non-aqueous secondary battery.
＜１＞
バインダーとカーボンコートされた酸化ケイ素とを含有する負極用組成物であって、
上記バインダー中、水溶性ポリマーを５質量％以上含み、
上記水溶性ポリマーは重量平均分子量が３０万以下であり、上記水溶性ポリマー中に占める酸基を有する構成成分の割合が５質量％以下である、負極用組成物。
＜２＞
上記水溶性ポリマーが連鎖重合ポリマーである、＜１＞に記載の負極用組成物。
＜３＞
上記水溶性ポリマーが、酸基を有しない構成成分として下記一般式（１）又は（２）で表される構成成分を含む、＜１＞又は＜２＞に記載の負極用組成物。
一般式（２）中、Ｒ３は水素原子又はメチル基を示し、Ｒ４及びＲ５は水素原子又は置換基を示す。＊は上記水溶性ポリマー中に組み込まれるための結合部位を示す。
＜４＞
上記水溶性ポリマーの含有量が、上記のカーボンコートされた酸化ケイ素１００質量部に対して、２質量部以上である、＜１＞～＜３＞のいずれか１つに記載の負極用組成物。
＜５＞
上記水溶性ポリマーが、上記一般式（１）又は（２）で表される２種以上の構成成分を含む、＜３＞に記載の負極用組成物。
＜６＞
上記酸基がカルボキシ基又はその塩である、＜１＞～＜５＞のいずれか１つに記載の負極用組成物。
＜７＞
分散媒体を含む負極用スラリーである、＜１＞～＜６＞のいずれか１つに記載の負極用組成物。
＜８＞
＜１＞～＜７＞のいずれか１つに記載の負極用組成物で構成した層を有する負極シート。
＜９＞
正極活物質層とセパレータと負極活物質層とをこの順で有し、上記負極活物質層が＜１＞～＜７＞のいずれか１つに記載の負極用組成物で構成した層である、非水二次電池。
＜１０＞
＜１＞～＜７＞のいずれか１つに記載の負極用組成物を用いて成膜することを含む、負極シートの製造方法。
＜１１＞
＜１０＞に記載の製造方法により得られた負極シートを非水二次電池の負極に組み込むことを含む、非水二次電池の製造方法。 That is, the above problems have been solved by the following means.
<1>
A negative electrode composition containing a binder and carbon-coated silicon oxide,
The binder contains 5% by mass or more of a water-soluble polymer,
The composition for a negative electrode, wherein the water-soluble polymer has a weight average molecular weight of 300,000 or less, and the component having an acid group accounts for 5% by mass or less of the water-soluble polymer.
<2>
The negative electrode composition according to <1>, wherein the water-soluble polymer is a chain polymer.
<3>
The negative electrode composition according to <1> or <2>, wherein the water-soluble polymer contains a component represented by the following general formula (1) or (2) as a component having no acid group.
In general formula ( 2 ), R3 represents a hydrogen atom or a methyl group, and R4 and R5 represent a hydrogen atom or a substituent. * indicates a binding site for incorporation into the water-soluble polymer.
<4>
The negative electrode composition according to any one of <1> to <3>, wherein the content of the water-soluble polymer is 2 parts by mass or more with respect to 100 parts by mass of the carbon-coated silicon oxide. .
<5>
The negative electrode composition according to <3>, wherein the water-soluble polymer contains two or more constituents represented by the general formula (1) or (2).
<6>
The negative electrode composition according to any one of <1> to <5>, wherein the acid group is a carboxy group or a salt thereof.
<7>
The negative electrode composition according to any one of <1> to <6>, which is a negative electrode slurry containing a dispersion medium.
<8>
A negative electrode sheet having a layer composed of the negative electrode composition according to any one of <1> to <7>.
<9>
It has a positive electrode active material layer, a separator, and a negative electrode active material layer in this order, and the negative electrode active material layer is a layer composed of the negative electrode composition according to any one of <1> to <7>. , non-aqueous secondary battery.
<10>
A method for producing a negative electrode sheet, comprising forming a film using the negative electrode composition according to any one of <1> to <7>.
<11>
A method for producing a non-aqueous secondary battery, comprising incorporating the negative electrode sheet obtained by the production method according to <10> into a negative electrode of the non-aqueous secondary battery.
本明細書において、「水溶性ポリマー」とは２５℃の水１Ｌに７ｇ以上溶解するポリマー（２５℃における溶解度が７［ｇ／１Ｌ－Ｈ２Ｏ］以上のポリマー）を意味する。
本明細書において、「～」を用いて表される数値範囲は、「～」の前後に記載される数値を下限値及び上限値として含む範囲を意味する。
本明細書において化合物の表示（例えば、化合物と末尾に付して呼ぶとき）については、この化合物そのもののほか、その塩、そのイオンを含む意味に用いる。また、所望の効果を奏する範囲で、置換基を導入する等構造の一部を変化させた誘導体を含む意味である。
本明細書において置換基が解離性の水素原子（水素原子が塩基の作用により解離する基）を有する場合、この置換基にはイオンないし塩の形態が含まれる。
例えば、化合物がカルボキシ基を有する場合、このカルボキシ基は、水素原子が解離してアニオンとして存在していてもよく、このアニオンは、対イオン（カチオン）と塩を形成していてもよい。対イオンに特に制限はなく、例えば、リチウムイオン、ナトリウムイオン及びカリウムイオンなどのアルカリ金属イオンが挙げられる。
本明細書において置換又は無置換を明記していない置換基、連結基等（以下、置換基等という。）については、その基に適宜の置換基を有していてもよい意味である。よって、本明細書において、単に、「～基」（例えば「アルキル基」）と記載されている場合であっても、この「～基」（例えば「アルキル基」）は、置換基を有しない態様（例えば「無置換アルキル基」）に加えて、更に置換基を有する態様（例えば「置換アルキル基」）も包含する。これは置換又は無置換を明記していない化合物についても同義である。
本明細書において、特定の符号で示された置換基等が複数あるとき、又は複数の置換基等を同時若しくは択一的に規定するときには、それぞれの置換基等は互いに同一でも異なっていてもよいことを意味する。また、特に断らない場合であっても、複数の置換基等が隣接するときにはそれらが互いに連結したり縮環したりして環を形成していてもよい意味である。
本明細書において、ポリマーが同一表示の（同一の一般式で表示された）複数の構成成分を有する場合は、各構成成分は互いに同一でも異なっていてもよい。
本明細書において「非水二次電池」とは、非水電解液二次電池と全固体二次電池とを含む意味である。本明細書において「非水電解液」とは、水を実質的に含まない電解液を意味する。すなわち、「非水電解液」は本発明の効果を妨げない範囲で微量の水を含んでいてもよい。本発明において「非水電解液」は、水の濃度が２００ｐｐｍ（質量基準）以下であり、１００ｐｐｍ以下が好ましく２０ｐｐｍ以下がより好ましい。なお、非水電解液を完全に無水とすることは現実的に困難であり、通常は水が１ｐｐｍ以上含まれる。
本明細書において、含有量又は含有割合を記載する場合に使用する「固形分」とは、後述する分散媒体以外の成分を意味する。 As used herein, the term “water-soluble polymer” means a polymer that dissolves in 1 L of water at 25° C. in an amount of 7 g or more (a polymer whose solubility at 25° C. is 7 [g/1 L-H 2 O] or more).
In this specification, a numerical range represented by "to" means a range including the numerical values before and after "to" as lower and upper limits.
In the present specification, the expression of a compound (for example, when it is called with a compound at the end) is used to mean the compound itself, its salts, and its ions. It also includes derivatives in which a part of the structure is changed, such as by introducing a substituent, to the extent that the desired effect is achieved.
In the present specification, when a substituent has a dissociable hydrogen atom (a group in which a hydrogen atom is dissociated by the action of a base), this substituent includes ions or salts.
For example, when a compound has a carboxy group, the carboxy group may exist as an anion by dissociating a hydrogen atom, and the anion may form a salt with a counterion (cation). Counterions are not particularly limited, and examples thereof include alkali metal ions such as lithium ions, sodium ions and potassium ions.
In the present specification, substituents, linking groups, etc. (hereinafter referred to as substituents, etc.) for which substitution or unsubstitution is not specified are intended to mean that the group may have an appropriate substituent. Therefore, in this specification, even when simply described as "- group" (eg, "alkyl group"), this "- group" (eg, "alkyl group") does not have a substituent In addition to embodiments (eg, "unsubstituted alkyl group"), embodiments having further substituents (eg, "substituted alkyl group") are also included. This also applies to compounds that are not specified as substituted or unsubstituted.
In this specification, when there are multiple substituents or the like indicated by a specific symbol, or when multiple substituents or the like are defined simultaneously or alternatively, the respective substituents or the like may be the same or different from each other. means good. Further, even if not otherwise specified, when a plurality of substituents and the like are adjacent to each other, they may be connected to each other or condensed to form a ring.
In this specification, when a polymer has a plurality of constituents with the same designation (indicated by the same general formula), each constituent may be the same or different.
As used herein, the term “non-aqueous secondary battery” is meant to include non-aqueous electrolyte secondary batteries and all-solid secondary batteries. As used herein, the term "non-aqueous electrolyte" means an electrolyte that does not substantially contain water. That is, the "non-aqueous electrolyte" may contain a small amount of water as long as the effects of the present invention are not impaired. In the present invention, the "non-aqueous electrolyte" has a water concentration of 200 ppm (by mass) or less, preferably 100 ppm or less, more preferably 20 ppm or less. It is practically difficult to make the non-aqueous electrolyte completely anhydrous, and usually contains 1 ppm or more of water.
In this specification, the "solid content" used when describing the content or content ratio means components other than the dispersion medium described below.
本明細書において、「～」を用いて表される数値範囲は、「～」の前後に記載される数値を下限値及び上限値として含む範囲を意味する。
本明細書において化合物の表示（例えば、化合物と末尾に付して呼ぶとき）については、この化合物そのもののほか、その塩、そのイオンを含む意味に用いる。また、所望の効果を奏する範囲で、置換基を導入する等構造の一部を変化させた誘導体を含む意味である。
本明細書において置換基が解離性の水素原子（水素原子が塩基の作用により解離する基）を有する場合、この置換基にはイオンないし塩の形態が含まれる。
例えば、化合物がカルボキシ基を有する場合、このカルボキシ基は、水素原子が解離してアニオンとして存在していてもよく、このアニオンは、対イオン（カチオン）と塩を形成していてもよい。対イオンに特に制限はなく、例えば、リチウムイオン、ナトリウムイオン及びカリウムイオンなどのアルカリ金属イオンが挙げられる。
本明細書において置換又は無置換を明記していない置換基、連結基等（以下、置換基等という。）については、その基に適宜の置換基を有していてもよい意味である。よって、本明細書において、単に、「～基」（例えば「アルキル基」）と記載されている場合であっても、この「～基」（例えば「アルキル基」）は、置換基を有しない態様（例えば「無置換アルキル基」）に加えて、更に置換基を有する態様（例えば「置換アルキル基」）も包含する。これは置換又は無置換を明記していない化合物についても同義である。
本明細書において、特定の符号で示された置換基等が複数あるとき、又は複数の置換基等を同時若しくは択一的に規定するときには、それぞれの置換基等は互いに同一でも異なっていてもよいことを意味する。また、特に断らない場合であっても、複数の置換基等が隣接するときにはそれらが互いに連結したり縮環したりして環を形成していてもよい意味である。
本明細書において、ポリマーが同一表示の（同一の一般式で表示された）複数の構成成分を有する場合は、各構成成分は互いに同一でも異なっていてもよい。
本明細書において「非水二次電池」とは、非水電解液二次電池と全固体二次電池とを含む意味である。本明細書において「非水電解液」とは、水を実質的に含まない電解液を意味する。すなわち、「非水電解液」は本発明の効果を妨げない範囲で微量の水を含んでいてもよい。本発明において「非水電解液」は、水の濃度が２００ｐｐｍ（質量基準）以下であり、１００ｐｐｍ以下が好ましく２０ｐｐｍ以下がより好ましい。なお、非水電解液を完全に無水とすることは現実的に困難であり、通常は水が１ｐｐｍ以上含まれる。
本明細書において、含有量又は含有割合を記載する場合に使用する「固形分」とは、後述する分散媒体以外の成分を意味する。 As used herein, the term “water-soluble polymer” means a polymer that dissolves in 1 L of water at 25° C. in an amount of 7 g or more (a polymer whose solubility at 25° C. is 7 [g/1 L-H 2 O] or more).
In this specification, a numerical range represented by "to" means a range including the numerical values before and after "to" as lower and upper limits.
In the present specification, the expression of a compound (for example, when it is called with a compound at the end) is used to mean the compound itself, its salts, and its ions. It also includes derivatives in which a part of the structure is changed, such as by introducing a substituent, to the extent that the desired effect is achieved.
In the present specification, when a substituent has a dissociable hydrogen atom (a group in which a hydrogen atom is dissociated by the action of a base), this substituent includes ions or salts.
For example, when a compound has a carboxy group, the carboxy group may exist as an anion by dissociating a hydrogen atom, and the anion may form a salt with a counterion (cation). Counterions are not particularly limited, and examples thereof include alkali metal ions such as lithium ions, sodium ions and potassium ions.
In the present specification, substituents, linking groups, etc. (hereinafter referred to as substituents, etc.) for which substitution or unsubstitution is not specified are intended to mean that the group may have an appropriate substituent. Therefore, in this specification, even when simply described as "- group" (eg, "alkyl group"), this "- group" (eg, "alkyl group") does not have a substituent In addition to embodiments (eg, "unsubstituted alkyl group"), embodiments having further substituents (eg, "substituted alkyl group") are also included. This also applies to compounds that are not specified as substituted or unsubstituted.
In this specification, when there are multiple substituents or the like indicated by a specific symbol, or when multiple substituents or the like are defined simultaneously or alternatively, the respective substituents or the like may be the same or different from each other. means good. Further, even if not otherwise specified, when a plurality of substituents and the like are adjacent to each other, they may be connected to each other or condensed to form a ring.
In this specification, when a polymer has a plurality of constituents with the same designation (indicated by the same general formula), each constituent may be the same or different.
As used herein, the term “non-aqueous secondary battery” is meant to include non-aqueous electrolyte secondary batteries and all-solid secondary batteries. As used herein, the term "non-aqueous electrolyte" means an electrolyte that does not substantially contain water. That is, the "non-aqueous electrolyte" may contain a small amount of water as long as the effects of the present invention are not impaired. In the present invention, the "non-aqueous electrolyte" has a water concentration of 200 ppm (by mass) or less, preferably 100 ppm or less, more preferably 20 ppm or less. It is practically difficult to make the non-aqueous electrolyte completely anhydrous, and usually contains 1 ppm or more of water.
In this specification, the "solid content" used when describing the content or content ratio means components other than the dispersion medium described below.
本発明の負極用組成物及び負極シートは、これらを用いて負極活物質層を形成することにより、カーボンコートされた酸化ケイ素を負極活物質とする非水二次電池に優れたサイクル特性を付与することができる。したがって、本発明の非水二次電池は高容量かつ低抵抗で、更にサイクル特性に優れるものである。
本発明の負極シートの製造方法によれば、本発明の上記負極シートを得ることができる。また本発明の非水二次電池の製造方法によれば、本発明の上記非水二次電池を得ることができる。 The negative electrode composition and the negative electrode sheet of the present invention provide excellent cycle characteristics to a non-aqueous secondary battery using carbon-coated silicon oxide as a negative electrode active material by forming a negative electrode active material layer using them. can do. Therefore, the non-aqueous secondary battery of the present invention has high capacity, low resistance, and excellent cycle characteristics.
According to the method for producing a negative electrode sheet of the present invention, the negative electrode sheet of the present invention can be obtained. Moreover, according to the manufacturing method of the non-aqueous secondary battery of the present invention, the non-aqueous secondary battery of the present invention can be obtained.
本発明の負極シートの製造方法によれば、本発明の上記負極シートを得ることができる。また本発明の非水二次電池の製造方法によれば、本発明の上記非水二次電池を得ることができる。 The negative electrode composition and the negative electrode sheet of the present invention provide excellent cycle characteristics to a non-aqueous secondary battery using carbon-coated silicon oxide as a negative electrode active material by forming a negative electrode active material layer using them. can do. Therefore, the non-aqueous secondary battery of the present invention has high capacity, low resistance, and excellent cycle characteristics.
According to the method for producing a negative electrode sheet of the present invention, the negative electrode sheet of the present invention can be obtained. Moreover, according to the manufacturing method of the non-aqueous secondary battery of the present invention, the non-aqueous secondary battery of the present invention can be obtained.
［負極用組成物］
本発明の負極用組成物は、水溶性ポリマーを含むバインダーと、カーボンコートされた酸化ケイ素を含む負極活物質とを含有する。
上記水溶性ポリマーは、重量平均分子量３０万以下のポリマーであり、酸基を有する構成成分の水溶性ポリマー中に占める含有量の割合は５質量％以下である。この水溶性ポリマーはバインダー中に５質量％以上含まれている。
本発明の負極用組成物を用いて作製した負極活物質層を二次電池に組み込むことにより、得られる二次電池のサイクル寿命を効果的に高めることができる。この理由はまだ定かではないが、重量平均分子量３０万以下と比較的分子量が小さく、また酸基の量が制限されて見かけの分子量の増大も抑えられたポリマーがバインダー中に一定量以上含まれることにより、このポリマーがカーボンコート層の空隙に嵌るなどして（アンカー効果を生じて）水溶性ポリマーが負極活物質（カーボンコートされた酸化ケイ素）に強固に結着することが一因と推定される。
本発明の負極用組成物は、水溶性ポリマーを含むバインダーと、カーボンコートされた酸化珪素を含む負極活物質と、必要に応じて分散媒体及び導電助剤等を混合して調製することができる。 [Negative electrode composition]
The negative electrode composition of the present invention contains a binder containing a water-soluble polymer and a negative electrode active material containing carbon-coated silicon oxide.
The water-soluble polymer has a weight-average molecular weight of 300,000 or less, and the content of the component having an acid group in the water-soluble polymer is 5% by mass or less. This water-soluble polymer is contained in the binder in an amount of 5% by mass or more.
By incorporating the negative electrode active material layer produced using the negative electrode composition of the present invention into the secondary battery, the cycle life of the obtained secondary battery can be effectively increased. The reason for this is not yet clear, but the binder contains a certain amount or more of a polymer that has a relatively small weight average molecular weight of 300,000 or less, and the amount of acid groups is limited to suppress the increase in apparent molecular weight. Therefore, it is presumed that one of the reasons for this is that the water-soluble polymer is firmly attached to the negative electrode active material (carbon-coated silicon oxide) by, for example, fitting into the voids of the carbon coating layer (causing an anchor effect). be done.
The negative electrode composition of the present invention can be prepared by mixing a binder containing a water-soluble polymer, a negative electrode active material containing carbon-coated silicon oxide, and, if necessary, a dispersion medium, a conductive aid, and the like. .
本発明の負極用組成物は、水溶性ポリマーを含むバインダーと、カーボンコートされた酸化ケイ素を含む負極活物質とを含有する。
上記水溶性ポリマーは、重量平均分子量３０万以下のポリマーであり、酸基を有する構成成分の水溶性ポリマー中に占める含有量の割合は５質量％以下である。この水溶性ポリマーはバインダー中に５質量％以上含まれている。
本発明の負極用組成物を用いて作製した負極活物質層を二次電池に組み込むことにより、得られる二次電池のサイクル寿命を効果的に高めることができる。この理由はまだ定かではないが、重量平均分子量３０万以下と比較的分子量が小さく、また酸基の量が制限されて見かけの分子量の増大も抑えられたポリマーがバインダー中に一定量以上含まれることにより、このポリマーがカーボンコート層の空隙に嵌るなどして（アンカー効果を生じて）水溶性ポリマーが負極活物質（カーボンコートされた酸化ケイ素）に強固に結着することが一因と推定される。
本発明の負極用組成物は、水溶性ポリマーを含むバインダーと、カーボンコートされた酸化珪素を含む負極活物質と、必要に応じて分散媒体及び導電助剤等を混合して調製することができる。 [Negative electrode composition]
The negative electrode composition of the present invention contains a binder containing a water-soluble polymer and a negative electrode active material containing carbon-coated silicon oxide.
The water-soluble polymer has a weight-average molecular weight of 300,000 or less, and the content of the component having an acid group in the water-soluble polymer is 5% by mass or less. This water-soluble polymer is contained in the binder in an amount of 5% by mass or more.
By incorporating the negative electrode active material layer produced using the negative electrode composition of the present invention into the secondary battery, the cycle life of the obtained secondary battery can be effectively increased. The reason for this is not yet clear, but the binder contains a certain amount or more of a polymer that has a relatively small weight average molecular weight of 300,000 or less, and the amount of acid groups is limited to suppress the increase in apparent molecular weight. Therefore, it is presumed that one of the reasons for this is that the water-soluble polymer is firmly attached to the negative electrode active material (carbon-coated silicon oxide) by, for example, fitting into the voids of the carbon coating layer (causing an anchor effect). be done.
The negative electrode composition of the present invention can be prepared by mixing a binder containing a water-soluble polymer, a negative electrode active material containing carbon-coated silicon oxide, and, if necessary, a dispersion medium, a conductive aid, and the like. .
（バインダー）
本発明に用いられるバインダーは、バインダー全量に対し、上述の水溶性ポリマー５質量％以上を含む。
本発明に用いられる水溶性ポリマーは、連鎖重合ポリマー及び逐次重合ポリマーのいずれでもよく、連鎖重合ポリマーが好ましい。連鎖重合ポリマーの結合形態は特に制限されず、ランダムでもブロックでもよい。 (binder)
The binder used in the present invention contains 5% by mass or more of the water-soluble polymer described above based on the total amount of the binder.
The water-soluble polymer used in the present invention may be either a chain polymerized polymer or a stepwise polymerized polymer, preferably a chain polymerized polymer. There are no particular restrictions on the bond form of the chain polymer, and it may be random or block.
本発明に用いられるバインダーは、バインダー全量に対し、上述の水溶性ポリマー５質量％以上を含む。
本発明に用いられる水溶性ポリマーは、連鎖重合ポリマー及び逐次重合ポリマーのいずれでもよく、連鎖重合ポリマーが好ましい。連鎖重合ポリマーの結合形態は特に制限されず、ランダムでもブロックでもよい。 (binder)
The binder used in the present invention contains 5% by mass or more of the water-soluble polymer described above based on the total amount of the binder.
The water-soluble polymer used in the present invention may be either a chain polymerized polymer or a stepwise polymerized polymer, preferably a chain polymerized polymer. There are no particular restrictions on the bond form of the chain polymer, and it may be random or block.
上記水溶性ポリマーを構成する主要な構成成分である、酸基を有しない構成成分は特に制限されない。上記水溶性ポリマーは、酸基を有しない構成成分として、例えば、下記一般式（１）又は（２）で表される構成成分を含むことが好ましい。
There are no particular restrictions on the component that does not have an acid group, which is the main component that constitutes the water-soluble polymer. The water-soluble polymer preferably contains, for example, a component represented by the following general formula (1) or (2) as a component having no acid group.
一般式（１）中、Ｒ１は水素原子又はメチル基を示し、Ｌ１は単結合又は連結基（２価）を示し、Ｒ２は置換基を示す。＊は水溶性ポリマー中に組み込まれるための結合部位を示す。
一般式（２）中、Ｒ３は水素原子又はメチル基を示し、Ｒ４及びＲ５は水素原子又は置換基を示す。＊は水溶性ポリマー中に組み込まれるための結合部位を示す。 In general formula (1), R 1 represents a hydrogen atom or a methyl group, L 1 represents a single bond or a linking group (divalent), and R 2 represents a substituent. * indicates a binding site for incorporation into a water-soluble polymer.
In general formula ( 2 ), R3 represents a hydrogen atom or a methyl group, and R4 and R5 represent a hydrogen atom or a substituent. * indicates a binding site for incorporation into a water-soluble polymer.
一般式（２）中、Ｒ３は水素原子又はメチル基を示し、Ｒ４及びＲ５は水素原子又は置換基を示す。＊は水溶性ポリマー中に組み込まれるための結合部位を示す。 In general formula (1), R 1 represents a hydrogen atom or a methyl group, L 1 represents a single bond or a linking group (divalent), and R 2 represents a substituent. * indicates a binding site for incorporation into a water-soluble polymer.
In general formula ( 2 ), R3 represents a hydrogen atom or a methyl group, and R4 and R5 represent a hydrogen atom or a substituent. * indicates a binding site for incorporation into a water-soluble polymer.
Ｌ１として採り得る連結基は、酸基を有しなければ特に制限されない。この連結基の化学式量は１４～１０００が好ましく、１４～５００がより好ましく、２６～２５０が更に好ましい。
Ｌ１として採り得る連結基として、例えば、アルキレン基、－Ｏ－、カルボニル基、及びイミノ基、並びにこれらの組合せが挙げられる。これらの組合せとしては、アルキレン基、－Ｏ－、カルボニル基及びイミノ基の２～６個を組合せてなる連結基が好ましく、２又は３個を組合せてなる連結基がより好ましい。
Ｌ１として具体的には－Ｃ（＝Ｏ）－Ｏ－、－Ｏ－Ｃ（＝Ｏ）－、－ＮＨ－Ｃ（＝Ｏ）－Ｏ－、－Ｏ－Ｃ（＝Ｏ）－ＮＨ－、－ＮＨ－Ｃ（＝Ｏ）－ＮＨ－、及びアルキレン基のいずれかが好ましく、アルキレン基であることがより好ましい。
Ｌ１として採り得るアルキレン基は直鎖及び分岐のいずれでもよく、アルキレン基の炭素数は１～１０が好ましく、１～８がより好ましく、１～６が更に好ましく、１～４とすることが特に好ましく、メチレン基、エチレン基、エチルエチレン基及びプロピレン基のいずれかであることが最も好ましい。
Ｌ１の化学式量は１４～２００が好ましく、１４～１５０がより好ましく、１４～８０が更に好ましい。 The linking group that can be used as L1 is not particularly limited as long as it does not have an acid group. The chemical formula weight of this linking group is preferably 14-1000, more preferably 14-500, even more preferably 26-250.
Linking groups that can be used as L 1 include, for example, alkylene groups, —O—, carbonyl groups, imino groups, and combinations thereof. As a combination of these, a connecting group formed by combining 2 to 6 groups selected from an alkylene group, —O—, a carbonyl group and an imino group is preferable, and a connecting group formed by combining 2 or 3 groups is more preferable.
L 1 specifically includes -C(=O)-O-, -OC(=O)-, -NH-C(=O)-O-, -OC(=O)-NH- , -NH-C(=O)-NH-, and an alkylene group, more preferably an alkylene group.
The alkylene group that can be used as L 1 may be either linear or branched, and the number of carbon atoms in the alkylene group is preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, and can be 1 to 4. Most preferably, it is a methylene group, an ethylene group, an ethylethylene group or a propylene group.
The chemical formula weight of L 1 is preferably 14-200, more preferably 14-150, even more preferably 14-80.
Ｌ１として採り得る連結基として、例えば、アルキレン基、－Ｏ－、カルボニル基、及びイミノ基、並びにこれらの組合せが挙げられる。これらの組合せとしては、アルキレン基、－Ｏ－、カルボニル基及びイミノ基の２～６個を組合せてなる連結基が好ましく、２又は３個を組合せてなる連結基がより好ましい。
Ｌ１として具体的には－Ｃ（＝Ｏ）－Ｏ－、－Ｏ－Ｃ（＝Ｏ）－、－ＮＨ－Ｃ（＝Ｏ）－Ｏ－、－Ｏ－Ｃ（＝Ｏ）－ＮＨ－、－ＮＨ－Ｃ（＝Ｏ）－ＮＨ－、及びアルキレン基のいずれかが好ましく、アルキレン基であることがより好ましい。
Ｌ１として採り得るアルキレン基は直鎖及び分岐のいずれでもよく、アルキレン基の炭素数は１～１０が好ましく、１～８がより好ましく、１～６が更に好ましく、１～４とすることが特に好ましく、メチレン基、エチレン基、エチルエチレン基及びプロピレン基のいずれかであることが最も好ましい。
Ｌ１の化学式量は１４～２００が好ましく、１４～１５０がより好ましく、１４～８０が更に好ましい。 The linking group that can be used as L1 is not particularly limited as long as it does not have an acid group. The chemical formula weight of this linking group is preferably 14-1000, more preferably 14-500, even more preferably 26-250.
Linking groups that can be used as L 1 include, for example, alkylene groups, —O—, carbonyl groups, imino groups, and combinations thereof. As a combination of these, a connecting group formed by combining 2 to 6 groups selected from an alkylene group, —O—, a carbonyl group and an imino group is preferable, and a connecting group formed by combining 2 or 3 groups is more preferable.
L 1 specifically includes -C(=O)-O-, -OC(=O)-, -NH-C(=O)-O-, -OC(=O)-NH- , -NH-C(=O)-NH-, and an alkylene group, more preferably an alkylene group.
The alkylene group that can be used as L 1 may be either linear or branched, and the number of carbon atoms in the alkylene group is preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, and can be 1 to 4. Most preferably, it is a methylene group, an ethylene group, an ethylethylene group or a propylene group.
The chemical formula weight of L 1 is preferably 14-200, more preferably 14-150, even more preferably 14-80.
Ｒ２は、酸基を有しない置換基であれば特に制限されない。Ｒ２の化学式量は１５～２００が好ましく、１５～１５０がより好ましく、１５～１００が更に好ましい。Ｒ２としては、例えば、ヒドロキシ基、アルキルオキシ基、アルキル基、アミド基及びスルホンアミド基が挙げられ、ヒドロキシ基又はアルキルオキシ基であることが好ましい。
アルキルオキシ基中のアルキル基は直鎖、分岐及び環状のいずれでもよい。このアルキル基の炭素数は１～１０が好ましく、１～８がより好ましく、１～６が更に好ましく、１～４とすることが特に好ましく、メチル基、エチル基及びイソプロピル基のいずれかであることが最も好ましい。
アルキル基は、上記アルキルオキシ基中のアルキル基と同義であり、好ましい範囲も同じである。 R 2 is not particularly limited as long as it is a substituent having no acid group. The chemical formula weight of R 2 is preferably 15-200, more preferably 15-150, even more preferably 15-100. Examples of R 2 include a hydroxy group, an alkyloxy group, an alkyl group, an amide group and a sulfonamide group, preferably a hydroxy group or an alkyloxy group.
The alkyl group in the alkyloxy group may be linear, branched or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, particularly preferably 1 to 4, and is any one of a methyl group, an ethyl group and an isopropyl group. is most preferred.
The alkyl group has the same definition as the alkyl group in the above alkyloxy group, and the preferred range is also the same.
アルキルオキシ基中のアルキル基は直鎖、分岐及び環状のいずれでもよい。このアルキル基の炭素数は１～１０が好ましく、１～８がより好ましく、１～６が更に好ましく、１～４とすることが特に好ましく、メチル基、エチル基及びイソプロピル基のいずれかであることが最も好ましい。
アルキル基は、上記アルキルオキシ基中のアルキル基と同義であり、好ましい範囲も同じである。 R 2 is not particularly limited as long as it is a substituent having no acid group. The chemical formula weight of R 2 is preferably 15-200, more preferably 15-150, even more preferably 15-100. Examples of R 2 include a hydroxy group, an alkyloxy group, an alkyl group, an amide group and a sulfonamide group, preferably a hydroxy group or an alkyloxy group.
The alkyl group in the alkyloxy group may be linear, branched or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, particularly preferably 1 to 4, and is any one of a methyl group, an ethyl group and an isopropyl group. is most preferred.
The alkyl group has the same definition as the alkyl group in the above alkyloxy group, and the preferred range is also the same.
Ｒ４及びＲ５として採り得る置換基は、酸基を有しない置換基であれば特に制限されない。Ｒ４及びＲ５の各化学式量は１５～２００が好ましく、１５～１５０がより好ましく、１５～６０が更に好ましい。Ｒ４及びＲ５として採り得る置換基としては、アルキル基が好ましい。
アルキル基は、上記Ｒ２として採り得るアルキルオキシ基中のアルキル基と同義であり、好ましい範囲も同じである。また、Ｒ４及びＲ５として採り得るアルキル基は更に置換基を有することも好ましい。
このような置換基として、例えば、ヒドロキシ基、アルキルカルボニル基、アミド基、並びにウレタン結合含有基（－ＮＨ－ＣＯ－Ｏ－Ｒｂ（Ｒｂはアルキル基を示す。）が挙げられる。なかでもＲ４及びＲ５として採り得るアルキル基の置換基としては、ヒドロキシ基であることが好ましい。
アルキルカルボニル基中のアルキル基は、上記Ｒ２として採り得るアルキルオキシ基中のアルキル基と同義であり、好ましい範囲も同じである。Ｒｂで示されるアルキル基は、上記Ｒ２として採り得るアルキルオキシ基中のアルキル基と同義であり、好ましい範囲も同じである。
Ｒ４及びＲ５は、いずれも水素原子であるか、または、いずれか一方が水素原子であり他方がヒドロキシアルキル基である、ことが好ましい。 Substituents that can be used as R 4 and R 5 are not particularly limited as long as they are substituents that do not have an acid group. The chemical formula weight of each of R 4 and R 5 is preferably 15-200, more preferably 15-150, even more preferably 15-60. Alkyl groups are preferred as substituents that can be taken as R 4 and R 5 .
The alkyl group has the same definition as the alkyl group in the alkyloxy group that can be used as R 2 above, and the preferred range is also the same. It is also preferred that the alkyl groups that can be used as R 4 and R 5 further have substituents.
Examples of such substituents include hydroxy groups, alkylcarbonyl groups, amide groups, and urethane bond-containing groups (--NH--CO--O--R b (R b represents an alkyl group). A hydroxy group is preferable as a substituent of the alkyl group that can be used as R 4 and R 5 .
The alkyl group in the alkylcarbonyl group has the same meaning as the alkyl group in the alkyloxy group that can be used as R 2 above, and the preferred range is also the same. The alkyl group represented by R b has the same definition as the alkyl group in the alkyloxy group that can be used as R 2 above, and the preferred range is also the same.
Both R 4 and R 5 are preferably a hydrogen atom, or one is a hydrogen atom and the other is a hydroxyalkyl group.
アルキル基は、上記Ｒ２として採り得るアルキルオキシ基中のアルキル基と同義であり、好ましい範囲も同じである。また、Ｒ４及びＲ５として採り得るアルキル基は更に置換基を有することも好ましい。
このような置換基として、例えば、ヒドロキシ基、アルキルカルボニル基、アミド基、並びにウレタン結合含有基（－ＮＨ－ＣＯ－Ｏ－Ｒｂ（Ｒｂはアルキル基を示す。）が挙げられる。なかでもＲ４及びＲ５として採り得るアルキル基の置換基としては、ヒドロキシ基であることが好ましい。
アルキルカルボニル基中のアルキル基は、上記Ｒ２として採り得るアルキルオキシ基中のアルキル基と同義であり、好ましい範囲も同じである。Ｒｂで示されるアルキル基は、上記Ｒ２として採り得るアルキルオキシ基中のアルキル基と同義であり、好ましい範囲も同じである。
Ｒ４及びＲ５は、いずれも水素原子であるか、または、いずれか一方が水素原子であり他方がヒドロキシアルキル基である、ことが好ましい。 Substituents that can be used as R 4 and R 5 are not particularly limited as long as they are substituents that do not have an acid group. The chemical formula weight of each of R 4 and R 5 is preferably 15-200, more preferably 15-150, even more preferably 15-60. Alkyl groups are preferred as substituents that can be taken as R 4 and R 5 .
The alkyl group has the same definition as the alkyl group in the alkyloxy group that can be used as R 2 above, and the preferred range is also the same. It is also preferred that the alkyl groups that can be used as R 4 and R 5 further have substituents.
Examples of such substituents include hydroxy groups, alkylcarbonyl groups, amide groups, and urethane bond-containing groups (--NH--CO--O--R b (R b represents an alkyl group). A hydroxy group is preferable as a substituent of the alkyl group that can be used as R 4 and R 5 .
The alkyl group in the alkylcarbonyl group has the same meaning as the alkyl group in the alkyloxy group that can be used as R 2 above, and the preferred range is also the same. The alkyl group represented by R b has the same definition as the alkyl group in the alkyloxy group that can be used as R 2 above, and the preferred range is also the same.
Both R 4 and R 5 are preferably a hydrogen atom, or one is a hydrogen atom and the other is a hydroxyalkyl group.
本発明に用いられる水溶性ポリマーは、酸基を有しない構成成分を１種単独で含んでも良く、２種以上を組合せて含んでもよい。上記水溶性ポリマー中に占める、上記一般式（１）又は（２）で表される構成成分の割合（上記水溶性ポリマー中に占める上記一般式（１）で表される構成成分の割合と上記一般式（２）で表される構成成分の割合の合計）は、３０質量％以上が好ましく、５０質量％以上がより好ましく、７０質量％以上が更に好ましく、９０質量％以上とすることが特に好ましく、９５質量％以上とすることが最も好ましい。
二次電池のサイクル特性向上の観点から、本発明に用いられる水溶性ポリマーは、一般式（１）又は（２）で表される２種以上の構成成分を含むことが好ましく、一般式（１）又は（２）で表される２～６種の構成成分を含むことがより好ましく、一般式（１）又は（２）で表される２～４種の構成成分を含むことが更に好ましい。なお、一般式（１）又は（２）で表される２種以上の構成成分を含む形態としては、一般式（１）で表される構成成分を２種以上含み、一般式（２）で表される構成成分を含まない形態、一般式（２）で表される構成成分を２種以上含み、一般式（１）で表される構成成分を含まない形態、及び一般式（１）で表される構成成分と一般式（２）で表される構成成分の両方を含む形態が挙げられる。 The water-soluble polymer used in the present invention may contain one type of component having no acid group alone, or may contain two or more types in combination. The ratio of the component represented by the general formula (1) or (2) in the water-soluble polymer (the ratio of the component represented by the general formula (1) in the water-soluble polymer and the above The total ratio of the constituent components represented by the general formula (2)) is preferably 30% by mass or more, more preferably 50% by mass or more, still more preferably 70% by mass or more, and particularly 90% by mass or more. Preferably, it is most preferably 95% by mass or more.
From the viewpoint of improving the cycle characteristics of the secondary battery, the water-soluble polymer used in the present invention preferably contains two or more constituents represented by general formula (1) or (2). ) or (2), and more preferably 2 to 4 components represented by general formula (1) or (2). In addition, as a form containing two or more constituent components represented by general formula (1) or (2), two or more constituent components represented by general formula (1) are included, and general formula (2) A form that does not contain the constituents represented by the general formula (2), a form that contains two or more constituents represented by the general formula (2), and a form that does not contain the constituents represented by the general formula (1), and in the general formula (1) Examples include a form containing both the component represented by formula (2) and the component represented by formula (2).
二次電池のサイクル特性向上の観点から、本発明に用いられる水溶性ポリマーは、一般式（１）又は（２）で表される２種以上の構成成分を含むことが好ましく、一般式（１）又は（２）で表される２～６種の構成成分を含むことがより好ましく、一般式（１）又は（２）で表される２～４種の構成成分を含むことが更に好ましい。なお、一般式（１）又は（２）で表される２種以上の構成成分を含む形態としては、一般式（１）で表される構成成分を２種以上含み、一般式（２）で表される構成成分を含まない形態、一般式（２）で表される構成成分を２種以上含み、一般式（１）で表される構成成分を含まない形態、及び一般式（１）で表される構成成分と一般式（２）で表される構成成分の両方を含む形態が挙げられる。 The water-soluble polymer used in the present invention may contain one type of component having no acid group alone, or may contain two or more types in combination. The ratio of the component represented by the general formula (1) or (2) in the water-soluble polymer (the ratio of the component represented by the general formula (1) in the water-soluble polymer and the above The total ratio of the constituent components represented by the general formula (2)) is preferably 30% by mass or more, more preferably 50% by mass or more, still more preferably 70% by mass or more, and particularly 90% by mass or more. Preferably, it is most preferably 95% by mass or more.
From the viewpoint of improving the cycle characteristics of the secondary battery, the water-soluble polymer used in the present invention preferably contains two or more constituents represented by general formula (1) or (2). ) or (2), and more preferably 2 to 4 components represented by general formula (1) or (2). In addition, as a form containing two or more constituent components represented by general formula (1) or (2), two or more constituent components represented by general formula (1) are included, and general formula (2) A form that does not contain the constituents represented by the general formula (2), a form that contains two or more constituents represented by the general formula (2), and a form that does not contain the constituents represented by the general formula (1), and in the general formula (1) Examples include a form containing both the component represented by formula (2) and the component represented by formula (2).
上記一般式（１）で表される構成成分の好ましい具体例を以下に示すが、本発明がこれらの形態に限定されるものではない。
Preferable specific examples of the component represented by the general formula (1) are shown below, but the present invention is not limited to these forms.
上記一般式（２）で表される構成成分の好ましい具体例を以下に示すが、本発明がこれらの形態に限定されるものではない。
Preferable specific examples of the constituent represented by the general formula (2) are shown below, but the present invention is not limited to these forms.
上記水溶性ポリマーが、酸基を有しない構成成分として上記一般式（１）又は（２）で表される構成成分以外の構成成分を含む場合、このような構成成分は特に制限されない。例えば、スチレン、マレイミド、Ｎ－ビニルアセトアミド、ビニルエステル及びビニルエーテル等のビニルモノマー由来の構成成分を挙げることができる。
When the water-soluble polymer contains constituents other than the constituents represented by the general formula (1) or (2) as constituents having no acid group, such constituents are not particularly limited. Examples include components derived from vinyl monomers such as styrene, maleimide, N-vinylacetamide, vinyl esters and vinyl ethers.
上記水溶性ポリマーが有し得る酸基を有する構成成分の「酸基」は、解離性のプロトンを有する基又はその塩を意味する。例えば、カルボキシ基、スルホ基、リン酸基（－ＯＰ（＝Ｏ）（ＯＨ）２）、ホスホン酸基（－Ｐ（＝Ｏ）（ＯＨ）２）又はこれらの塩が挙げられ、カルボキシ基及びスルホ基又はこれらの塩が好ましく、カルボキシ基又はその塩がより好ましい。塩の形態は、例えば、アルカリ金属塩（例えばリチウム塩、ナトリウム塩及びカリウム塩など）が挙げられる。
The "acid group" of the component having an acid group that the water-soluble polymer may have means a group having a dissociative proton or a salt thereof. Examples thereof include a carboxy group, a sulfo group, a phosphate group (--OP(=O)(OH) 2 ), a phosphonic acid group (--P(=O)(OH) 2 ) or salts thereof, and a carboxy group and A sulfo group or a salt thereof is preferred, and a carboxy group or a salt thereof is more preferred. Salt forms include, for example, alkali metal salts (eg, lithium salts, sodium salts, potassium salts, etc.).
上記酸基を有する構成成分は特に制限されず、この構成成分中には酸基が通常１～３個含まれ、好ましくは１又は２個含まれ、より好ましくは１個含まれる。上記水溶性ポリマーが酸基を有する構成成分を含む場合、例えば、下記一般式（３）で表される構成成分を含むことが好ましい。
The component having the acid group is not particularly limited, and the component usually contains 1 to 3 acid groups, preferably 1 or 2 groups, and more preferably 1 group. When the water-soluble polymer contains a component having an acid group, it preferably contains, for example, a component represented by the following general formula (3).
式中、Ｒ６は水素原子又は酸基を示す。Ｒ７は水素原子又はメチル基を示し、Ｌ２は単結合又は連結基（２価）を示し、Ｒ８は酸基を示す。＊は水溶性ポリマー中に組み込まれるための結合部位を示す。
In the formula, R6 represents a hydrogen atom or an acid group. R7 represents a hydrogen atom or a methyl group, L2 represents a single bond or a linking group ( divalent ), and R8 represents an acid group. * indicates a binding site for incorporation into a water-soluble polymer.
Ｌ２として採り得る連結基は特に制限されず、例えば、アルキレン基、アリーレン基、カルボニル基、エーテル結合（－Ｏ－）若しくはイミノ基又はこれらの２種以上を組合せた連結基が挙げられる。
The linking group that can be used as L 2 is not particularly limited, and examples thereof include an alkylene group, an arylene group, a carbonyl group, an ether bond (--O--), an imino group, or a linking group in which two or more of these are combined.
Ｌ２として採り得るアルキレン基は直鎖及び分岐のいずれでもよく、アルキレン基の炭素数は１～１０が好ましく、１～８がより好ましく、１～６が更に好ましく、１～４とすることが特に好ましく、メチレン基、エチレン基、プロピレン基及びジメチルエチレン基のいずれかであることが最も好ましい。
The alkylene group that can be used as L 2 may be either linear or branched, and the number of carbon atoms in the alkylene group is preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, and can be 1 to 4. Particularly preferred are methylene, ethylene, propylene and dimethylethylene groups.
Ｌ２として採り得るアリーレン基の炭素数は、６～３０が好ましく、６～２０がより好ましく、６～１５が更に好ましく、６～１０が特に好ましい。アリーレン基の具体例として、フェニレン基及びナフチレン基が挙げられる。
The number of carbon atoms in the arylene group that can be taken as L 2 is preferably 6-30, more preferably 6-20, still more preferably 6-15, and particularly preferably 6-10. Specific examples of arylene groups include phenylene groups and naphthylene groups.
上記「２種以上を組合せた連結基」は、アルキレン基、アリーレン基、カルボニル基、エーテル結合（－Ｏ－）及びイミノ基の少なくとも２種を組み合わせた連結基であり、２～１０種を組み合わせた連結基が好ましく、２～７種を組み合わせた連結基がより好ましく、２～４種を組み合わせた連結基が更に好ましい。
上記「２種以上を組合せた連結基」の具体例としては、例えば、「カルボニル基－イミノ基－アルキレン基」及び「カルボニル基－エーテル結合－アルキレン基」が挙げられる。 The above-mentioned "linking group combining two or more types" is a linking group combining at least two types of an alkylene group, an arylene group, a carbonyl group, an ether bond (-O-) and an imino group, and a combination of 2 to 10 types. is preferable, a linking group in which 2 to 7 types are combined is more preferable, and a linking group in which 2 to 4 types are combined is even more preferable.
Specific examples of the above-mentioned "linking group combining two or more types" include, for example, "carbonyl group-imino group-alkylene group" and "carbonyl group-ether bond-alkylene group".
上記「２種以上を組合せた連結基」の具体例としては、例えば、「カルボニル基－イミノ基－アルキレン基」及び「カルボニル基－エーテル結合－アルキレン基」が挙げられる。 The above-mentioned "linking group combining two or more types" is a linking group combining at least two types of an alkylene group, an arylene group, a carbonyl group, an ether bond (-O-) and an imino group, and a combination of 2 to 10 types. is preferable, a linking group in which 2 to 7 types are combined is more preferable, and a linking group in which 2 to 4 types are combined is even more preferable.
Specific examples of the above-mentioned "linking group combining two or more types" include, for example, "carbonyl group-imino group-alkylene group" and "carbonyl group-ether bond-alkylene group".
酸基を有する構成成分の、水溶性ポリマー中に占める割合は５質量％以下であり、４質量％以下が好ましく、３質量％以下がより好ましく、２質量％以下が更に好ましく、１質量％以下が特に好ましく、水溶性ポリマーは酸基を有する構成成分を有しないことが最も好ましい。
The proportion of the component having an acid group in the water-soluble polymer is 5% by mass or less, preferably 4% by mass or less, more preferably 3% by mass or less, further preferably 2% by mass or less, and 1% by mass or less. is particularly preferred, and it is most preferred that the water-soluble polymer does not have constituents with acid groups.
上記一般式（３）で表される構成成分の好ましい具体例を以下に示すが、本発明がこれらの形態に限定されるものではない。
Preferable specific examples of the component represented by the general formula (3) are shown below, but the present invention is not limited to these forms.
本発明に用いられる水溶性ポリマーの重量平均分子量は３０万以下であり、２９万以下が好ましく、２８万以下がより好ましく、２７万以下が更に好ましい。一方、水溶性ポリマーの重量平均分子量は１万以上が好ましく、４万以上がより好ましく、１０万以上が更に好ましく、１４万以上が特に好ましく、１７万以上が最も好ましい。
本明細書において、ポリマーの重量平均分子量は、後記実施例の項に記載の方法により測定して得られる値である。 The weight average molecular weight of the water-soluble polymer used in the present invention is 300,000 or less, preferably 290,000 or less, more preferably 280,000 or less, and even more preferably 270,000 or less. On the other hand, the weight average molecular weight of the water-soluble polymer is preferably 10,000 or more, more preferably 40,000 or more, still more preferably 100,000 or more, particularly preferably 140,000 or more, and most preferably 170,000 or more.
In the present specification, the weight average molecular weight of a polymer is a value obtained by measuring by the method described in the Examples section below.
本明細書において、ポリマーの重量平均分子量は、後記実施例の項に記載の方法により測定して得られる値である。 The weight average molecular weight of the water-soluble polymer used in the present invention is 300,000 or less, preferably 290,000 or less, more preferably 280,000 or less, and even more preferably 270,000 or less. On the other hand, the weight average molecular weight of the water-soluble polymer is preferably 10,000 or more, more preferably 40,000 or more, still more preferably 100,000 or more, particularly preferably 140,000 or more, and most preferably 170,000 or more.
In the present specification, the weight average molecular weight of a polymer is a value obtained by measuring by the method described in the Examples section below.
本発明に用いられるバインダー中、上記水溶性ポリマーの含有量は５質量％以上であり、二次電池のサイクル特性向上の観点から、１０質量％以上が好ましく、２０質量％以上がより好ましい。本発明に用いられるバインダーは上記水溶性ポリマーからなるものであってもよい。
The content of the water-soluble polymer in the binder used in the present invention is 5% by mass or more, preferably 10% by mass or more, more preferably 20% by mass or more, from the viewpoint of improving the cycle characteristics of the secondary battery. The binder used in the present invention may consist of the above water-soluble polymer.
また、二次電池のサイクル特性向上の観点から、負極用組成物中、上記水溶性ポリマーの含有量は、カーボンコートされた酸化ケイ素１００質量部に対して、２質量部以上が好ましく、４質量部以上がより好ましく、８質量部以上が更に好ましい。一方、負極用組成物中、上記水溶性ポリマーの含有量は、カーボンコートされた酸化ケイ素１００質量部に対して、３０質量部以下が好ましく、２５質量部以下がより好ましく、２０質量部以下が更に好ましい。
In addition, from the viewpoint of improving the cycle characteristics of the secondary battery, the content of the water-soluble polymer in the negative electrode composition is preferably 2 parts by mass or more, and 4 parts by mass with respect to 100 parts by mass of carbon-coated silicon oxide. Part or more is more preferable, and 8 parts by mass or more is even more preferable. On the other hand, the content of the water-soluble polymer in the negative electrode composition is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and 20 parts by mass or less with respect to 100 parts by mass of carbon-coated silicon oxide. More preferred.
本発明に用いられるバインダーは、上記水溶性ポリマー以外のポリマーを含むことができる。このようなポリマーとしては、例えば、非水溶性ポリマー、３０万を越える重量平均分子量を有する水溶性ポリマー、及び酸基を有する構成成分の含有量が５質量％を越える水溶性ポリマーが挙げられる。このようなポリマーの具体例として、例えば、後記表１記載のポリマーＢが挙げられるが、ポリマーＢは「後記表１記載のポリマーＢ」に制限されない。
The binder used in the present invention can contain polymers other than the above water-soluble polymers. Such polymers include, for example, water-insoluble polymers, water-soluble polymers having a weight-average molecular weight exceeding 300,000, and water-soluble polymers containing constituents having acid groups exceeding 5% by weight. Specific examples of such polymers include polymer B described in Table 1 below, but polymer B is not limited to "polymer B described in Table 1 below".
（負極活物質）
本発明に用いられる負極活物質は、カーボンコートされた酸化ケイ素（ＳｉＯｘ（０＜ｘ≦１．５））を含む。カーボンコートされた酸化ケイ素は、可逆的にリチウムイオンを吸蔵及び放出できる。
酸化ケイ素は表面全体がカーボンコートされていてもよく、カーボンコートされていない部分があってもよい。なお、酸化ケイ素は表面全体がカーボンコートされていても、カーボンコート層自体が多数の空隙を有している状態にある。
カーボンコートされた酸化ケイ素中（カーボンコート層と酸化ケイ素の合計中）の炭素原子の割合は特に制限されず、例えば、０．５～５質量％が好ましく、１～３質量％がより好ましい。
カーボンコートされた酸化ケイ素は市販品を用いても良く、例えば特開２０１９－２０４６８６号公報を参照して、酸化ケイ素をカーボンコートすることにより調製することもできる。 (Negative electrode active material)
The negative electrode active material used in the present invention includes carbon-coated silicon oxide (SiOx (0<x≦1.5)). Carbon-coated silicon oxide can reversibly store and release lithium ions.
The silicon oxide may be coated with carbon over the entire surface, or may have a portion not coated with carbon. Even if the entire surface of silicon oxide is carbon-coated, the carbon-coated layer itself has a large number of voids.
The proportion of carbon atoms in the carbon-coated silicon oxide (the total of the carbon coating layer and silicon oxide) is not particularly limited, and is preferably 0.5 to 5% by mass, more preferably 1 to 3% by mass.
Carbon-coated silicon oxide may be a commercially available product. For example, referring to JP-A-2019-204686, silicon oxide can be prepared by carbon-coating.
本発明に用いられる負極活物質は、カーボンコートされた酸化ケイ素（ＳｉＯｘ（０＜ｘ≦１．５））を含む。カーボンコートされた酸化ケイ素は、可逆的にリチウムイオンを吸蔵及び放出できる。
酸化ケイ素は表面全体がカーボンコートされていてもよく、カーボンコートされていない部分があってもよい。なお、酸化ケイ素は表面全体がカーボンコートされていても、カーボンコート層自体が多数の空隙を有している状態にある。
カーボンコートされた酸化ケイ素中（カーボンコート層と酸化ケイ素の合計中）の炭素原子の割合は特に制限されず、例えば、０．５～５質量％が好ましく、１～３質量％がより好ましい。
カーボンコートされた酸化ケイ素は市販品を用いても良く、例えば特開２０１９－２０４６８６号公報を参照して、酸化ケイ素をカーボンコートすることにより調製することもできる。 (Negative electrode active material)
The negative electrode active material used in the present invention includes carbon-coated silicon oxide (SiOx (0<x≦1.5)). Carbon-coated silicon oxide can reversibly store and release lithium ions.
The silicon oxide may be coated with carbon over the entire surface, or may have a portion not coated with carbon. Even if the entire surface of silicon oxide is carbon-coated, the carbon-coated layer itself has a large number of voids.
The proportion of carbon atoms in the carbon-coated silicon oxide (the total of the carbon coating layer and silicon oxide) is not particularly limited, and is preferably 0.5 to 5% by mass, more preferably 1 to 3% by mass.
Carbon-coated silicon oxide may be a commercially available product. For example, referring to JP-A-2019-204686, silicon oxide can be prepared by carbon-coating.
本発明に用いられる負極活物質は、カーボンコートされた酸化ケイ素以外の負極活物質を含んでいてもよい。以下、本発明に用いられる負極活物質の説明において、カーボンコートされた酸化ケイ素以外の負極活物質を「その他の負極活物質」と称する。
その他の負極活物質は、可逆的にリチウムイオンを吸蔵及び放出できるものが好ましい。その材料は、上記特性を有するものであれば、特に制限はなく、炭素質材料、金属酸化物、金属複合酸化物、リチウム合金、リチウムと合金形成可能な負極活物質等が挙げられる。
リチウム合金としては、二次電池の負極活物質として通常用いられる合金であれば特に制限されず、例えば、リチウムアルミニウム合金が挙げられる。
リチウムと合金形成可能な負極活物質は、二次電池の負極活物質として通常用いられるものであれば特に制限されない。このような活物質として、スズ原子を有する負極活物質、Ａｌ及びＩｎ等の各金属が挙げられる。
スズ原子を有する負極活物質としては、例えば、Ｓｎ、ＳｎＯ、ＳｎＯ２、ＳｎＳ、ＳｎＳ２、更には上記ケイ素原子及びスズ原子を含有する活物質等が挙げられる。また、酸化リチウムとの複合酸化物、例えば、Ｌｉ２ＳｎＯ２も包含される。
これらの中でも、その他の負極活物質としては、炭素質材料が信頼性の点から好ましく用いられる。 The negative electrode active material used in the present invention may contain a negative electrode active material other than carbon-coated silicon oxide. Hereinafter, in the description of the negative electrode active material used in the present invention, negative electrode active materials other than carbon-coated silicon oxide are referred to as "other negative electrode active materials."
Other negative electrode active materials are preferably those capable of reversibly intercalating and deintercalating lithium ions. The material is not particularly limited as long as it has the above properties, and examples thereof include carbonaceous materials, metal oxides, metal composite oxides, lithium alloys, negative electrode active materials capable of forming an alloy with lithium, and the like.
The lithium alloy is not particularly limited as long as it is an alloy normally used as a negative electrode active material for secondary batteries, and examples thereof include lithium aluminum alloys.
The negative electrode active material capable of forming an alloy with lithium is not particularly limited as long as it is commonly used as a negative electrode active material for secondary batteries. Examples of such active materials include negative electrode active materials having tin atoms and metals such as Al and In.
Examples of negative electrode active materials containing tin atoms include Sn, SnO, SnO 2 , SnS, SnS 2 , active materials containing silicon atoms and tin atoms, and the like. Also included are composite oxides with lithium oxide, such as Li 2 SnO 2 .
Among these, carbonaceous materials are preferably used as other negative electrode active materials from the viewpoint of reliability.
その他の負極活物質は、可逆的にリチウムイオンを吸蔵及び放出できるものが好ましい。その材料は、上記特性を有するものであれば、特に制限はなく、炭素質材料、金属酸化物、金属複合酸化物、リチウム合金、リチウムと合金形成可能な負極活物質等が挙げられる。
リチウム合金としては、二次電池の負極活物質として通常用いられる合金であれば特に制限されず、例えば、リチウムアルミニウム合金が挙げられる。
リチウムと合金形成可能な負極活物質は、二次電池の負極活物質として通常用いられるものであれば特に制限されない。このような活物質として、スズ原子を有する負極活物質、Ａｌ及びＩｎ等の各金属が挙げられる。
スズ原子を有する負極活物質としては、例えば、Ｓｎ、ＳｎＯ、ＳｎＯ２、ＳｎＳ、ＳｎＳ２、更には上記ケイ素原子及びスズ原子を含有する活物質等が挙げられる。また、酸化リチウムとの複合酸化物、例えば、Ｌｉ２ＳｎＯ２も包含される。
これらの中でも、その他の負極活物質としては、炭素質材料が信頼性の点から好ましく用いられる。 The negative electrode active material used in the present invention may contain a negative electrode active material other than carbon-coated silicon oxide. Hereinafter, in the description of the negative electrode active material used in the present invention, negative electrode active materials other than carbon-coated silicon oxide are referred to as "other negative electrode active materials."
Other negative electrode active materials are preferably those capable of reversibly intercalating and deintercalating lithium ions. The material is not particularly limited as long as it has the above properties, and examples thereof include carbonaceous materials, metal oxides, metal composite oxides, lithium alloys, negative electrode active materials capable of forming an alloy with lithium, and the like.
The lithium alloy is not particularly limited as long as it is an alloy normally used as a negative electrode active material for secondary batteries, and examples thereof include lithium aluminum alloys.
The negative electrode active material capable of forming an alloy with lithium is not particularly limited as long as it is commonly used as a negative electrode active material for secondary batteries. Examples of such active materials include negative electrode active materials having tin atoms and metals such as Al and In.
Examples of negative electrode active materials containing tin atoms include Sn, SnO, SnO 2 , SnS, SnS 2 , active materials containing silicon atoms and tin atoms, and the like. Also included are composite oxides with lithium oxide, such as Li 2 SnO 2 .
Among these, carbonaceous materials are preferably used as other negative electrode active materials from the viewpoint of reliability.
その他の負極活物質として用いられる炭素質材料とは、実質的に炭素からなる材料である。例えば、石油ピッチ等のカーボンブラック、黒鉛（天然黒鉛、気相成長黒鉛等の人造黒鉛等）、及びＰＡＮ（ポリアクリロニトリル）系の樹脂若しくはフルフリルアルコール樹脂等の各種の合成樹脂を焼成した炭素質材料を挙げることができる。更に、ＰＡＮ系炭素繊維、セルロース系炭素繊維、ピッチ系炭素繊維、気相成長炭素繊維、脱水ＰＶＡ（ポリビニルアルコール）系炭素繊維、リグニン炭素繊維、ガラス状炭素繊維及び活性炭素繊維等の各種炭素繊維類、メソフェーズ微小球体、グラファイトウィスカー並びに平板状の黒鉛等を挙げることもできる。
Other carbonaceous materials used as negative electrode active materials are materials that are substantially made of carbon. For example, carbon black such as petroleum pitch, graphite (natural graphite, artificial graphite such as vapor growth graphite, etc.), and carbonaceous materials obtained by baking various synthetic resins such as PAN (polyacrylonitrile) resin or furfuryl alcohol resin Materials can be mentioned. Furthermore, various carbon fibers such as PAN-based carbon fiber, cellulose-based carbon fiber, pitch-based carbon fiber, vapor growth carbon fiber, dehydrated PVA (polyvinyl alcohol)-based carbon fiber, lignin carbon fiber, vitreous carbon fiber and activated carbon fiber. , mesophase microspheres, graphite whiskers and tabular graphite.
その他の負極活物質として適用される金属酸化物及び金属複合酸化物としては、リチウムを吸蔵及び放出可能な酸化物であれば特に制限されず、非晶質酸化物が好ましく、更に金属元素と周期律表第１６族の元素との反応生成物であるカルコゲナイトも好ましく挙げられる。ここでいう非晶質とは、ＣｕＫα線を用いたＸ線回折法で、２θ値で２０°～４０°の領域に頂点を有するブロードな散乱帯を有するものを意味し、結晶性の回折線を有してもよい。
上記非晶質酸化物及びカルコゲナイドからなる化合物群の中でも、半金属元素の非晶質酸化物、及び上記カルコゲナイドがより好ましく、周期律表第１３（ＩＩＩＢ）族～１５（ＶＢ）族の元素、Ａｌ、Ｇａ、Ｓｉ、Ｓｎ、Ｇｅ、Ｐｂ、Ｓｂ及びＢｉの１種単独若しくはそれらの２種以上の組み合わせからなる酸化物（ただし、Ｓｉを含む酸化物は除く）、又はカルコゲナイドが特に好ましい。好ましい非晶質酸化物及びカルコゲナイドの具体例としては、例えば、Ｇａ２Ｏ３、ＧｅＯ、ＰｂＯ、ＰｂＯ２、Ｐｂ２Ｏ３、Ｐｂ２Ｏ４、Ｐｂ３Ｏ４、Ｓｂ２Ｏ３、Ｓｂ２Ｏ４、Ｓｂ２Ｏ８Ｂｉ２Ｏ３、Ｓｂ２Ｏ５、Ｂｉ２Ｏ３、Ｂｉ２Ｏ４、ＧｅＳ、ＰｂＳ、ＰｂＳ２、Ｓｂ２Ｓ３及びＳｂ２Ｓ５が好ましく挙げられる。 Other metal oxides and metal composite oxides applied as negative electrode active materials are not particularly limited as long as they are oxides capable of intercalating and deintercalating lithium. Chalcogenite, which is a reaction product with an element belonging to Group 16 of the Norms Table, is also preferred. The term “amorphous” as used herein means a broad scattering band having an apex in the region of 20° to 40° in terms of 2θ value in an X-ray diffraction method using CuKα rays, and a crystalline diffraction line. may have
Among the compound group consisting of the above amorphous oxides and chalcogenides, amorphous oxides of metalloid elements and the above chalcogenides are more preferable, elements of groups 13 (IIIB) to 15 (VB) of the periodic table, Particularly preferred are oxides of Al, Ga, Si, Sn, Ge, Pb, Sb and Bi, or a combination of two or more thereof (excluding oxides containing Si), or chalcogenides. Specific examples of preferred amorphous oxides and chalcogenides include Ga 2 O 3 , GeO, PbO, PbO 2 , Pb 2 O 3 , Pb 2 O 4 , Pb 3 O 4 , Sb 2 O 3 and Sb 2 . O4 , Sb2O8Bi2O3 , Sb2O5 , Bi2O3 , Bi2O4 , GeS , PbS , PbS2 , Sb2S3 and Sb2S5 are preferred .
上記非晶質酸化物及びカルコゲナイドからなる化合物群の中でも、半金属元素の非晶質酸化物、及び上記カルコゲナイドがより好ましく、周期律表第１３（ＩＩＩＢ）族～１５（ＶＢ）族の元素、Ａｌ、Ｇａ、Ｓｉ、Ｓｎ、Ｇｅ、Ｐｂ、Ｓｂ及びＢｉの１種単独若しくはそれらの２種以上の組み合わせからなる酸化物（ただし、Ｓｉを含む酸化物は除く）、又はカルコゲナイドが特に好ましい。好ましい非晶質酸化物及びカルコゲナイドの具体例としては、例えば、Ｇａ２Ｏ３、ＧｅＯ、ＰｂＯ、ＰｂＯ２、Ｐｂ２Ｏ３、Ｐｂ２Ｏ４、Ｐｂ３Ｏ４、Ｓｂ２Ｏ３、Ｓｂ２Ｏ４、Ｓｂ２Ｏ８Ｂｉ２Ｏ３、Ｓｂ２Ｏ５、Ｂｉ２Ｏ３、Ｂｉ２Ｏ４、ＧｅＳ、ＰｂＳ、ＰｂＳ２、Ｓｂ２Ｓ３及びＳｂ２Ｓ５が好ましく挙げられる。 Other metal oxides and metal composite oxides applied as negative electrode active materials are not particularly limited as long as they are oxides capable of intercalating and deintercalating lithium. Chalcogenite, which is a reaction product with an element belonging to Group 16 of the Norms Table, is also preferred. The term “amorphous” as used herein means a broad scattering band having an apex in the region of 20° to 40° in terms of 2θ value in an X-ray diffraction method using CuKα rays, and a crystalline diffraction line. may have
Among the compound group consisting of the above amorphous oxides and chalcogenides, amorphous oxides of metalloid elements and the above chalcogenides are more preferable, elements of groups 13 (IIIB) to 15 (VB) of the periodic table, Particularly preferred are oxides of Al, Ga, Si, Sn, Ge, Pb, Sb and Bi, or a combination of two or more thereof (excluding oxides containing Si), or chalcogenides. Specific examples of preferred amorphous oxides and chalcogenides include Ga 2 O 3 , GeO, PbO, PbO 2 , Pb 2 O 3 , Pb 2 O 4 , Pb 3 O 4 , Sb 2 O 3 and Sb 2 . O4 , Sb2O8Bi2O3 , Sb2O5 , Bi2O3 , Bi2O4 , GeS , PbS , PbS2 , Sb2S3 and Sb2S5 are preferred .
金属（複合）酸化物及び上記カルコゲナイドは、構成成分として、チタン及びリチウムの少なくとも一方を含有していることが、高電流密度充放電特性の観点で好ましい。リチウムを含有する金属複合酸化物（リチウム複合金属酸化物）としては、例えば、酸化リチウムと上記金属（複合）酸化物若しくは上記カルコゲナイドとの複合酸化物、より具体的には、Ｌｉ２ＳｎＯ２が挙げられる。
The metal (composite) oxide and the chalcogenide preferably contain at least one of titanium and lithium as a constituent component from the viewpoint of high current density charge/discharge characteristics. Examples of lithium-containing metal composite oxides (lithium composite metal oxides) include composite oxides of lithium oxide and the above metal (composite) oxides or chalcogenides, more specifically Li 2 SnO 2 . mentioned.
その他の負極活物質はチタン原子を含有することも好ましい。より具体的にはＴｉＮｂ２Ｏ７（チタン酸ニオブ酸化物［ＮＴＯ］）、Ｌｉ４Ｔｉ５Ｏ１２（チタン酸リチウム［ＬＴＯ］）がリチウムイオンの吸蔵放出時の体積変動が小さいことから急速充放電特性に優れ、電極の劣化が抑制され、リチウムイオン二次電池の寿命向上が可能となる点で好ましい。
Other negative electrode active materials preferably contain titanium atoms. More specifically, TiNb 2 O 7 (niobium titanate [NTO]) and Li 4 Ti 5 O 12 (lithium titanate [LTO]) have small volume fluctuations when absorbing and desorbing lithium ions, and are therefore suitable for rapid charging. It is preferable in that it has excellent discharge characteristics, suppresses deterioration of the electrode, and can improve the life of the lithium ion secondary battery.
カーボンコートされた酸化珪素及びその他の負極活物質の形状は特に制限されないが粒子状が好ましい。カーボンコートされた酸化珪素及びその他の負極活物質の体積基準のメジアン径Ｄ５０は、０．１～６０μｍが好ましい。所定の粒子径にするには、通常の粉砕機若しくは分級機が用いられる。例えば、乳鉢、ボールミル、サンドミル、振動ボールミル、衛星ボールミル、遊星ボールミル、旋回気流型ジェットミル若しくは篩等が好適に用いられる。粉砕時には水、あるいはメタノール等の有機溶媒を共存させた湿式粉砕も行うことができる。所望の粒子径とするためには分級を行うことが好ましい。分級方法としては、特に限定はなく、篩、風力分級機等を所望により用いることができる。分級は乾式及び湿式ともに用いることができる。
The shape of the carbon-coated silicon oxide and other negative electrode active materials is not particularly limited, but is preferably particulate. The volume-based median diameter D50 of carbon-coated silicon oxide and other negative electrode active materials is preferably 0.1 to 60 μm. A conventional pulverizer or classifier is used to obtain a predetermined particle size. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a whirling jet mill, a sieve, or the like is preferably used. At the time of pulverization, wet pulverization can also be performed in which water or an organic solvent such as methanol is allowed to coexist. Classification is preferably carried out in order to obtain a desired particle size. The classification method is not particularly limited, and a sieve, an air classifier, or the like can be used as desired. Both dry and wet classification can be used.
カーボンコートされた酸化珪素のメジアン径Ｄ５０は、０．１～３０μｍであることも好ましく、０．５～２０μｍがより好ましく、２～８μｍが特に好ましい。
上記メジアン径Ｄ５０は、レーザー回折法で求めることができ、例えば、島津製作所製ＳＡＬＤ－２３００（商品名）を用いて求めることができる。 The median diameter D50 of carbon-coated silicon oxide is also preferably 0.1 to 30 μm, more preferably 0.5 to 20 μm, and particularly preferably 2 to 8 μm.
The median diameter D50 can be determined by a laser diffraction method, for example, using SALD-2300 (trade name) manufactured by Shimadzu Corporation.
上記メジアン径Ｄ５０は、レーザー回折法で求めることができ、例えば、島津製作所製ＳＡＬＤ－２３００（商品名）を用いて求めることができる。 The median diameter D50 of carbon-coated silicon oxide is also preferably 0.1 to 30 μm, more preferably 0.5 to 20 μm, and particularly preferably 2 to 8 μm.
The median diameter D50 can be determined by a laser diffraction method, for example, using SALD-2300 (trade name) manufactured by Shimadzu Corporation.
カーボンコートされた酸化ケイ素をその他の負極活物質と組合せて用いる場合、カーボンコートされた酸化ケイ素と炭素質材料の組み合わせが好ましく、カーボンコートされた酸化ケイ素と黒鉛の組み合わせが特に好ましい。カーボンコートされた酸化ケイ素と黒鉛を組み合わせる際の質量比（カーボンコートされた酸化ケイ素／黒鉛）は０．１以上が好ましく、０．２以上がより好ましく、０．３以上が更に好ましい。黒鉛に対するカーボンコートされた酸化ケイ素の質量比の上限値に特に制限はないが、４以下が実際的である。
負極活物質中のカーボンコートされた酸化ケイ素の含有量は特に制限されず、例えば１０～９０質量％とすることができ、１０～５０質量％が好ましく、１５～４０質量％がより好ましい。
負極活物質層を形成する場合、負極活物質層の単位面積（ｃｍ２）当たりのカーボンコートされた酸化ケイ素及びその他の負極活物質の質量（ｍｇ）（目付量）は特に限定されるものではない。設計された電池容量に応じて、適宜に決めることができる。 When carbon-coated silicon oxide is used in combination with other negative electrode active materials, a combination of carbon-coated silicon oxide and a carbonaceous material is preferred, and a combination of carbon-coated silicon oxide and graphite is particularly preferred. When carbon-coated silicon oxide and graphite are combined, the mass ratio (carbon-coated silicon oxide/graphite) is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more. Although the upper limit of the mass ratio of carbon-coated silicon oxide to graphite is not particularly limited, 4 or less is practical.
The content of carbon-coated silicon oxide in the negative electrode active material is not particularly limited, and can be, for example, 10 to 90% by mass, preferably 10 to 50% by mass, more preferably 15 to 40% by mass.
When forming the negative electrode active material layer, the mass (mg) (basis weight) of carbon-coated silicon oxide and other negative electrode active materials per unit area (cm 2 ) of the negative electrode active material layer is not particularly limited. do not have. It can be determined appropriately according to the designed battery capacity.
負極活物質中のカーボンコートされた酸化ケイ素の含有量は特に制限されず、例えば１０～９０質量％とすることができ、１０～５０質量％が好ましく、１５～４０質量％がより好ましい。
負極活物質層を形成する場合、負極活物質層の単位面積（ｃｍ２）当たりのカーボンコートされた酸化ケイ素及びその他の負極活物質の質量（ｍｇ）（目付量）は特に限定されるものではない。設計された電池容量に応じて、適宜に決めることができる。 When carbon-coated silicon oxide is used in combination with other negative electrode active materials, a combination of carbon-coated silicon oxide and a carbonaceous material is preferred, and a combination of carbon-coated silicon oxide and graphite is particularly preferred. When carbon-coated silicon oxide and graphite are combined, the mass ratio (carbon-coated silicon oxide/graphite) is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more. Although the upper limit of the mass ratio of carbon-coated silicon oxide to graphite is not particularly limited, 4 or less is practical.
The content of carbon-coated silicon oxide in the negative electrode active material is not particularly limited, and can be, for example, 10 to 90% by mass, preferably 10 to 50% by mass, more preferably 15 to 40% by mass.
When forming the negative electrode active material layer, the mass (mg) (basis weight) of carbon-coated silicon oxide and other negative electrode active materials per unit area (cm 2 ) of the negative electrode active material layer is not particularly limited. do not have. It can be determined appropriately according to the designed battery capacity.
カーボンコートされた酸化ケイ素及びその他の負極活物質の、負極用組成物中における含有量は、特に限定されず、固形分１００質量％において、合計で、１０～９８質量％であることが好ましく、１５～９５質量％がより好ましい。
The content of carbon-coated silicon oxide and other negative electrode active materials in the negative electrode composition is not particularly limited. 15 to 95% by mass is more preferable.
（分散媒体）
本発明の負極用組成物は、分散媒体を含有して、負極用スラリーとすることもできる。
本発明の負極用組成物を用いて非水電解液二次電池を作製する場合、分散媒体としては水を含む水性媒体を用いることができる。「水を含む水性媒体」とは、水、又は、水と水溶性有機溶媒との混合液である。また、「水溶性有機溶媒」とは、水と混合したときに相分離せずに混じり合う有機溶媒であり、例えばＮ－メチルピロリドン、メタノール、エタノール、アセトン、テトラヒドロフラン等が挙げられる。 (dispersion medium)
The negative electrode composition of the present invention can also contain a dispersion medium to form a negative electrode slurry.
When a non-aqueous electrolyte secondary battery is produced using the negative electrode composition of the present invention, an aqueous medium containing water can be used as the dispersion medium. The "aqueous medium containing water" is water or a mixture of water and a water-soluble organic solvent. The term "water-soluble organic solvent" refers to an organic solvent that mixes with water without causing phase separation, and includes, for example, N-methylpyrrolidone, methanol, ethanol, acetone, tetrahydrofuran, and the like.
本発明の負極用組成物は、分散媒体を含有して、負極用スラリーとすることもできる。
本発明の負極用組成物を用いて非水電解液二次電池を作製する場合、分散媒体としては水を含む水性媒体を用いることができる。「水を含む水性媒体」とは、水、又は、水と水溶性有機溶媒との混合液である。また、「水溶性有機溶媒」とは、水と混合したときに相分離せずに混じり合う有機溶媒であり、例えばＮ－メチルピロリドン、メタノール、エタノール、アセトン、テトラヒドロフラン等が挙げられる。 (dispersion medium)
The negative electrode composition of the present invention can also contain a dispersion medium to form a negative electrode slurry.
When a non-aqueous electrolyte secondary battery is produced using the negative electrode composition of the present invention, an aqueous medium containing water can be used as the dispersion medium. The "aqueous medium containing water" is water or a mixture of water and a water-soluble organic solvent. The term "water-soluble organic solvent" refers to an organic solvent that mixes with water without causing phase separation, and includes, for example, N-methylpyrrolidone, methanol, ethanol, acetone, tetrahydrofuran, and the like.
（導電助剤）
本発明の負極用組成物は、導電助剤を含有することもできる。
導電助剤としては、特に制限はなく、一般的な導電助剤として知られているものを用いることができる。例えば、電子伝導性材料である、天然黒鉛、人造黒鉛等の黒鉛類、アセチレンブラック、ケッチェンブラック、ファーネスブラック等のカーボンブラック類、ニードルコークス等の無定形炭素、気相成長炭素繊維若しくはカーボンナノチューブ等の炭素繊維類、グラフェン若しくはフラーレン等の炭素質材料であってもよいし、銅、ニッケル等の金属粉、金属繊維でもよく、ポリアニリン、ポリピロール、ポリチオフェン、ポリアセチレン、ポリフェニレン誘導体等導電性高分子を用いてもよい。
本発明において、負極活物質と導電助剤とを併用する場合、上記の導電助剤のうち、二次電池を充放電した際にＬｉの挿入と放出が起きず、負極活物質として機能しないものを導電助剤とする。したがって、導電助剤の中でも、二次電池を充放電した際に負極活物質層中において負極活物質として機能しうるものは、導電助剤ではなく負極活物質に分類する。二次電池を充放電した際に負極活物質として機能するか否かは、一義的ではなく、負極活物質との組み合わせにより決定される。 (Conductivity aid)
The negative electrode composition of the present invention can also contain a conductive aid.
There are no particular restrictions on the conductive aid, and any commonly known conductive aid can be used. For example, graphites such as natural graphite and artificial graphite, carbon blacks such as acetylene black, ketjen black, and furnace black, amorphous carbon such as needle coke, vapor-grown carbon fiber, or carbon nanotube, which are electronic conductive materials Carbon fibers such as carbon fibers such as graphene or fullerene may be used, metal powders such as copper and nickel, metal fibers may be used, and conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, and polyphenylene derivatives may be used.
In the present invention, when a negative electrode active material and a conductive aid are used in combination, among the above conductive aids, Li insertion and release do not occur when the secondary battery is charged and discharged, and do not function as a negative electrode active material. is used as a conductive aid. Therefore, among conductive aids, those that can function as a negative electrode active material in a negative electrode active material layer during charging and discharging of a secondary battery are classified as negative electrode active materials instead of conductive aids. Whether or not it functions as a negative electrode active material when a secondary battery is charged and discharged is not univocally determined by the combination with the negative electrode active material.
本発明の負極用組成物は、導電助剤を含有することもできる。
導電助剤としては、特に制限はなく、一般的な導電助剤として知られているものを用いることができる。例えば、電子伝導性材料である、天然黒鉛、人造黒鉛等の黒鉛類、アセチレンブラック、ケッチェンブラック、ファーネスブラック等のカーボンブラック類、ニードルコークス等の無定形炭素、気相成長炭素繊維若しくはカーボンナノチューブ等の炭素繊維類、グラフェン若しくはフラーレン等の炭素質材料であってもよいし、銅、ニッケル等の金属粉、金属繊維でもよく、ポリアニリン、ポリピロール、ポリチオフェン、ポリアセチレン、ポリフェニレン誘導体等導電性高分子を用いてもよい。
本発明において、負極活物質と導電助剤とを併用する場合、上記の導電助剤のうち、二次電池を充放電した際にＬｉの挿入と放出が起きず、負極活物質として機能しないものを導電助剤とする。したがって、導電助剤の中でも、二次電池を充放電した際に負極活物質層中において負極活物質として機能しうるものは、導電助剤ではなく負極活物質に分類する。二次電池を充放電した際に負極活物質として機能するか否かは、一義的ではなく、負極活物質との組み合わせにより決定される。 (Conductivity aid)
The negative electrode composition of the present invention can also contain a conductive aid.
There are no particular restrictions on the conductive aid, and any commonly known conductive aid can be used. For example, graphites such as natural graphite and artificial graphite, carbon blacks such as acetylene black, ketjen black, and furnace black, amorphous carbon such as needle coke, vapor-grown carbon fiber, or carbon nanotube, which are electronic conductive materials Carbon fibers such as carbon fibers such as graphene or fullerene may be used, metal powders such as copper and nickel, metal fibers may be used, and conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, and polyphenylene derivatives may be used.
In the present invention, when a negative electrode active material and a conductive aid are used in combination, among the above conductive aids, Li insertion and release do not occur when the secondary battery is charged and discharged, and do not function as a negative electrode active material. is used as a conductive aid. Therefore, among conductive aids, those that can function as a negative electrode active material in a negative electrode active material layer during charging and discharging of a secondary battery are classified as negative electrode active materials instead of conductive aids. Whether or not it functions as a negative electrode active material when a secondary battery is charged and discharged is not univocally determined by the combination with the negative electrode active material.
導電助剤は、１種を用いてもよいし、２種以上を用いてもよい。
導電助剤の、負極用組成物中の含有量は、固形分１００質量％において、１０～９０質量％が好ましく、３０～８０質量％がより好ましく、５０～７０質量％が更に好ましい。 1 type may be used for a conductive support agent, and 2 or more types may be used for it.
The content of the conductive aid in the negative electrode composition is preferably 10 to 90% by mass, more preferably 30 to 80% by mass, and even more preferably 50 to 70% by mass based on 100% by mass of solid content.
導電助剤の、負極用組成物中の含有量は、固形分１００質量％において、１０～９０質量％が好ましく、３０～８０質量％がより好ましく、５０～７０質量％が更に好ましい。 1 type may be used for a conductive support agent, and 2 or more types may be used for it.
The content of the conductive aid in the negative electrode composition is preferably 10 to 90% by mass, more preferably 30 to 80% by mass, and even more preferably 50 to 70% by mass based on 100% by mass of solid content.
導電助剤の形状は、特に制限されないが、粒子状が好ましい。導電助剤のメジアン径Ｄ５０は、特に限定されず、例えば、０．０１～５０μｍが好ましく、０．０２～１０．０μｍが好ましい。
The shape of the conductive aid is not particularly limited, but it is preferably particulate. The median diameter D50 of the conductive aid is not particularly limited, and is preferably 0.01 to 50 μm, preferably 0.02 to 10.0 μm, for example.
（他の添加剤）
本発明の負極用組成物は、上記各成分以外の他の成分として、所望により、リチウム塩、イオン液体、増粘剤、消泡剤、レベリング剤、脱水剤、酸化防止剤等を含有することができる。また、上記水溶性ポリマーを化学架橋するための、架橋剤（ラジカル重合、縮合重合又は開環重合により架橋反応するもの等）、更には重合開始剤（酸又はラジカルを熱又は光によって発生させるもの等）を含有していてもよい。
上記導電助剤及び他の添加剤に関し、例えば、国際公開第２０１９／２０３３３４号、特開２０１５－４６３８９号公報等を参照することができる。 (other additives)
The negative electrode composition of the present invention may optionally contain, as components other than the components described above, a lithium salt, an ionic liquid, a thickener, an antifoaming agent, a leveling agent, a dehydrating agent, an antioxidant, and the like. can be done. In addition, a cross-linking agent for chemically cross-linking the water-soluble polymer (such as one that undergoes a cross-linking reaction by radical polymerization, condensation polymerization, or ring-opening polymerization), and a polymerization initiator (that generates acid or radicals by heat or light) etc.).
Regarding the conductive aid and other additives, for example, International Publication No. WO 2019/203334, JP-A-2015-46389, etc. can be referred to.
本発明の負極用組成物は、上記各成分以外の他の成分として、所望により、リチウム塩、イオン液体、増粘剤、消泡剤、レベリング剤、脱水剤、酸化防止剤等を含有することができる。また、上記水溶性ポリマーを化学架橋するための、架橋剤（ラジカル重合、縮合重合又は開環重合により架橋反応するもの等）、更には重合開始剤（酸又はラジカルを熱又は光によって発生させるもの等）を含有していてもよい。
上記導電助剤及び他の添加剤に関し、例えば、国際公開第２０１９／２０３３３４号、特開２０１５－４６３８９号公報等を参照することができる。 (other additives)
The negative electrode composition of the present invention may optionally contain, as components other than the components described above, a lithium salt, an ionic liquid, a thickener, an antifoaming agent, a leveling agent, a dehydrating agent, an antioxidant, and the like. can be done. In addition, a cross-linking agent for chemically cross-linking the water-soluble polymer (such as one that undergoes a cross-linking reaction by radical polymerization, condensation polymerization, or ring-opening polymerization), and a polymerization initiator (that generates acid or radicals by heat or light) etc.).
Regarding the conductive aid and other additives, for example, International Publication No. WO 2019/203334, JP-A-2015-46389, etc. can be referred to.
［負極シート］
本発明の負極シートは、本発明の負極用組成物を用いて構成（形成）された層（負極活物質層）を有する。本発明の負極シートは、負極活物質層を有すればよく、負極活物質層が基材（集電体）上に形成されているシートでも、基材を有さず、負極活物質層だけで形成されているシートであってもよい。この負極シートは、通常、集電体上に負極活物質層を積層した構成のシートである。本発明の負極シートは保護層（剥離シート）、コート層等の他の層を有してもよい。
本発明の負極シートは、二次電池の負極活物質層を構成する材料として好適に用いることができる。 [Negative electrode sheet]
The negative electrode sheet of the present invention has a layer (negative electrode active material layer) configured (formed) using the negative electrode composition of the present invention. The negative electrode sheet of the present invention only needs to have a negative electrode active material layer. It may be a sheet formed of This negative electrode sheet is usually a sheet having a structure in which a negative electrode active material layer is laminated on a current collector. The negative electrode sheet of the present invention may have other layers such as a protective layer (release sheet) and a coat layer.
The negative electrode sheet of the present invention can be suitably used as a material constituting a negative electrode active material layer of a secondary battery.
本発明の負極シートは、本発明の負極用組成物を用いて構成（形成）された層（負極活物質層）を有する。本発明の負極シートは、負極活物質層を有すればよく、負極活物質層が基材（集電体）上に形成されているシートでも、基材を有さず、負極活物質層だけで形成されているシートであってもよい。この負極シートは、通常、集電体上に負極活物質層を積層した構成のシートである。本発明の負極シートは保護層（剥離シート）、コート層等の他の層を有してもよい。
本発明の負極シートは、二次電池の負極活物質層を構成する材料として好適に用いることができる。 [Negative electrode sheet]
The negative electrode sheet of the present invention has a layer (negative electrode active material layer) configured (formed) using the negative electrode composition of the present invention. The negative electrode sheet of the present invention only needs to have a negative electrode active material layer. It may be a sheet formed of This negative electrode sheet is usually a sheet having a structure in which a negative electrode active material layer is laminated on a current collector. The negative electrode sheet of the present invention may have other layers such as a protective layer (release sheet) and a coat layer.
The negative electrode sheet of the present invention can be suitably used as a material constituting a negative electrode active material layer of a secondary battery.
［負極シートの製造方法］
本発明の負極シートは、本発明の負極用組成物を用いて負極活物質層を形成することにより得ることができる。例えば、集電体等を基材として、その上（他の層を介していてもよい）に本発明の負極用組成物を塗布して塗膜を形成し、これを乾燥して、基材上に負極活物質層（塗布乾燥層）を有する電極シートを得ることができる。 [Manufacturing method of negative electrode sheet]
The negative electrode sheet of the present invention can be obtained by forming a negative electrode active material layer using the negative electrode composition of the present invention. For example, a current collector or the like is used as a base material, and the composition for a negative electrode of the present invention is applied thereon (may be via another layer) to form a coating film, which is dried to form a base material. An electrode sheet having a negative electrode active material layer (coated dry layer) thereon can be obtained.
本発明の負極シートは、本発明の負極用組成物を用いて負極活物質層を形成することにより得ることができる。例えば、集電体等を基材として、その上（他の層を介していてもよい）に本発明の負極用組成物を塗布して塗膜を形成し、これを乾燥して、基材上に負極活物質層（塗布乾燥層）を有する電極シートを得ることができる。 [Manufacturing method of negative electrode sheet]
The negative electrode sheet of the present invention can be obtained by forming a negative electrode active material layer using the negative electrode composition of the present invention. For example, a current collector or the like is used as a base material, and the composition for a negative electrode of the present invention is applied thereon (may be via another layer) to form a coating film, which is dried to form a base material. An electrode sheet having a negative electrode active material layer (coated dry layer) thereon can be obtained.
［非水二次電池］
本発明の非水二次電池は、充放電により電解質を介して正負極間をイオンが通過し、正負極においてエネルギーを貯蔵、放出するデバイス全般を意味する。すなわち、本発明において非水二次電池という場合、電池とキャパシタ（例えば、リチウムイオンキャパシタ）の両方を包含する意味である。エネルギー貯蔵量の観点から、本発明の非水二次電池は電池用途に用いること（キャパシタでないこと）が好ましい。 [Non-aqueous secondary battery]
The non-aqueous secondary battery of the present invention means all devices in which ions pass between the positive and negative electrodes through an electrolyte due to charging and discharging, and energy is stored and released at the positive and negative electrodes. That is, the term "non-aqueous secondary battery" as used in the present invention includes both batteries and capacitors (for example, lithium ion capacitors). From the viewpoint of energy storage capacity, the non-aqueous secondary battery of the present invention is preferably used for battery applications (not a capacitor).
本発明の非水二次電池は、充放電により電解質を介して正負極間をイオンが通過し、正負極においてエネルギーを貯蔵、放出するデバイス全般を意味する。すなわち、本発明において非水二次電池という場合、電池とキャパシタ（例えば、リチウムイオンキャパシタ）の両方を包含する意味である。エネルギー貯蔵量の観点から、本発明の非水二次電池は電池用途に用いること（キャパシタでないこと）が好ましい。 [Non-aqueous secondary battery]
The non-aqueous secondary battery of the present invention means all devices in which ions pass between the positive and negative electrodes through an electrolyte due to charging and discharging, and energy is stored and released at the positive and negative electrodes. That is, the term "non-aqueous secondary battery" as used in the present invention includes both batteries and capacitors (for example, lithium ion capacitors). From the viewpoint of energy storage capacity, the non-aqueous secondary battery of the present invention is preferably used for battery applications (not a capacitor).
本発明の非水二次電池について、非水電解液二次電池の形態を例にして説明するが、本発明の二次電池は非水電解液二次電池に限定されるものではなく、全固体二次電池を含む非水二次電池全般を広く包含するものである。
本発明の好ましい一実施形態である非水電解液二次電池は、正極と、負極と、正極と負極との間に配されたセパレータとを含む構成を有する。正極は、正極集電体と、この正極集電体に接する正極活物質層とを有し、負極は、負極集電体と、この負極集電体に接する負極活物質層とを有する。本発明の非水電解液二次電池は、上記負極活物質層が、本発明の電極用組成物を用いて構成されている。 The non-aqueous secondary battery of the present invention will be described by taking the form of a non-aqueous electrolyte secondary battery as an example, but the secondary battery of the present invention is not limited to the non-aqueous electrolyte secondary battery. It broadly includes all non-aqueous secondary batteries including solid secondary batteries.
A non-aqueous electrolyte secondary battery, which is a preferred embodiment of the present invention, has a configuration including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode. The positive electrode has a positive electrode current collector and a positive electrode active material layer in contact with the positive electrode current collector, and the negative electrode has a negative electrode current collector and a negative electrode active material layer in contact with the negative electrode current collector. In the non-aqueous electrolyte secondary battery of the present invention, the negative electrode active material layer is formed using the electrode composition of the present invention.
本発明の好ましい一実施形態である非水電解液二次電池は、正極と、負極と、正極と負極との間に配されたセパレータとを含む構成を有する。正極は、正極集電体と、この正極集電体に接する正極活物質層とを有し、負極は、負極集電体と、この負極集電体に接する負極活物質層とを有する。本発明の非水電解液二次電池は、上記負極活物質層が、本発明の電極用組成物を用いて構成されている。 The non-aqueous secondary battery of the present invention will be described by taking the form of a non-aqueous electrolyte secondary battery as an example, but the secondary battery of the present invention is not limited to the non-aqueous electrolyte secondary battery. It broadly includes all non-aqueous secondary batteries including solid secondary batteries.
A non-aqueous electrolyte secondary battery, which is a preferred embodiment of the present invention, has a configuration including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode. The positive electrode has a positive electrode current collector and a positive electrode active material layer in contact with the positive electrode current collector, and the negative electrode has a negative electrode current collector and a negative electrode active material layer in contact with the negative electrode current collector. In the non-aqueous electrolyte secondary battery of the present invention, the negative electrode active material layer is formed using the electrode composition of the present invention.
図１は、一般的な非水電解液二次電池１０の積層構造を、電池として作動させる際の作動電極も含めて、模式化して示す断面図である。非水電解液二次電池１０は、負極側からみて、負極集電体１、負極活物質層２、セパレータ３、正極活物質層４、正極集電体５を、この順に有する積層構造を有している。負極活物質層と正極活物質層との間は非水電解液（図示せず）で満たされ、かつセパレータ３で分断されている。セパレータ３は空孔を有し、通常の電池の使用状態では電解液及びイオンを透過しながら正負極間を絶縁する正負極分離膜として機能する。このような構造により、例えばリチウムイオン二次電池であれば、充電時には外部回路を通って負極側に電子（ｅ－）が供給され、同時に電解液を介して正極からリチウムイオン（Ｌｉ＋）が移動してきて負極に蓄積される。一方、放電時には、負極に蓄積されたリチウムイオン（Ｌｉ＋）が電解液を介して正極側に戻され、作動部位６には電子が供給される。図示した例では、作動部位６に電球を採用しており、放電によりこれが点灯するようにされている。
本発明において、負極集電体１と負極活物質層２とを合わせて負極と称し、正極活物質層４と正極集電体５とを合わせて正極と称している。 FIG. 1 is a schematic cross-sectional view showing a laminated structure of a general non-aqueous electrolytesecondary battery 10 including working electrodes when operated as a battery. The non-aqueous electrolyte secondary battery 10 has a laminated structure having, when viewed from the negative electrode side, a negative electrode current collector 1, a negative electrode active material layer 2, a separator 3, a positive electrode active material layer 4, and a positive electrode current collector 5 in this order. is doing. The space between the negative electrode active material layer and the positive electrode active material layer is filled with a non-aqueous electrolyte (not shown) and separated by the separator 3 . The separator 3 has pores and functions as a positive/negative separator that insulates the positive/negative electrodes while permeating the electrolytic solution and ions under normal battery usage conditions. With such a structure, for example, in the case of a lithium ion secondary battery, during charging, electrons (e − ) are supplied to the negative electrode side through an external circuit, and at the same time lithium ions (Li + ) are released from the positive electrode through the electrolyte. It moves and accumulates at the negative electrode. On the other hand, during discharge, the lithium ions (Li + ) accumulated in the negative electrode are returned to the positive electrode side through the electrolyte, and electrons are supplied to the operating portion 6 . In the illustrated example, a light bulb is employed in the actuation portion 6, which is lit by the discharge.
In the present invention, the negative electrodecurrent collector 1 and the negative electrode active material layer 2 are collectively referred to as a negative electrode, and the positive electrode active material layer 4 and the positive electrode current collector 5 are collectively referred to as a positive electrode.
本発明において、負極集電体１と負極活物質層２とを合わせて負極と称し、正極活物質層４と正極集電体５とを合わせて正極と称している。 FIG. 1 is a schematic cross-sectional view showing a laminated structure of a general non-aqueous electrolyte
In the present invention, the negative electrode
本発明の非水二次電池は、本発明の負極用組成物を用いて負極活物質層を形成すること以外は、正極活物質材料、非水電解液、固体電解質材料、その他の各部材等は特に制限されない。これらの材料及び部材等は、通常の非水二次電池に用いられるものを適宜に適用することができる。また、本発明の非水二次電池の作製方法についても、本発明の負極用組成物を用いて負極活物質層を形成すること以外は、通常の方法を適宜に採用することができる。例えば、特開２０１６－２０１３０８号公報、特開２００５－１０８８３５号公報、特開２０１２－１８５９３８号公報及び国際公開第２０２０／０６７１０６号等を適宜に参照することができる。
The non-aqueous secondary battery of the present invention comprises a positive electrode active material, a non-aqueous electrolyte, a solid electrolyte material, other members, etc., except that the negative electrode composition of the present invention is used to form a negative electrode active material layer. is not particularly limited. As these materials, members, and the like, those used in ordinary non-aqueous secondary batteries can be appropriately applied. As for the method for producing the non-aqueous secondary battery of the present invention, a normal method can be appropriately adopted, except that the negative electrode composition of the present invention is used to form the negative electrode active material layer. For example, JP-A-2016-201308, JP-A-2005-108835, JP-A-2012-185938, and International Publication No. 2020/067106 can be referred to as appropriate.
本発明の非水二次電池は、例えば、ノートパソコン、ペン入力パソコン、モバイルパソコン、電子ブックプレーヤー、携帯電話、コードレスフォン子機、ページャー、ハンディーターミナル、携帯ファックス、携帯コピー、携帯プリンター、ヘッドフォンステレオ、ビデオムービー、液晶テレビ、ハンディークリーナー、ポータブルＣＤ、ミニディスク、電気シェーバー、トランシーバー、電子手帳、電卓、携帯テープレコーダー、ラジオ、バックアップ電源、メモリーカード等の電子機器に搭載することができる。また、民生用として、自動車、電動車両、モーター、照明器具、玩具、ゲーム機器、ロードコンディショナー、時計、ストロボ、カメラ、医療機器（ペースメーカー、補聴器、肩もみ機等）等に搭載することができる。また、太陽電池と組み合わせることもできる。
The non-aqueous secondary battery of the present invention can be used, for example, in notebook computers, pen-input computers, mobile computers, e-book players, mobile phones, cordless phone slaves, pagers, handy terminals, mobile facsimiles, mobile copiers, mobile printers, and headphone stereos. , video movies, liquid crystal televisions, handy cleaners, portable CDs, minidiscs, electric shavers, transceivers, electronic notebooks, calculators, portable tape recorders, radios, backup power supplies, memory cards, and other electronic devices. In addition, for consumer use, it can be installed in automobiles, electric vehicles, motors, lighting equipment, toys, game devices, road conditioners, watches, strobes, cameras, medical devices (pacemakers, hearing aids, shoulder massagers, etc.). It can also be combined with a solar cell.
実施例に基づき本発明について更に詳細に説明する。なお、本発明は本発明で規定すること以外は、これらの実施例により限定して解釈されるものではない。
The present invention will be described in more detail based on examples. It should be noted that the present invention is not to be construed as being limited by these examples, except as defined by the present invention.
［ポリマーＡの合成］
＜ポリマー１（後記表１のＮｏ．１のポリマー）の合成＞
以下のようにして、後記表１に記載するポリマー１を合成した。
５００ｍＬセパラブルフラスコにイオン交換水を１０８．１ｇ入れ、窒素雰囲気下７５℃で撹拌しながら、２－ヒドロキシエチルアクリレートを１７．５ｇ、Ｎ－（２－ヒドロキシエチル）アクリルアミドを５２．５ｇ、イオン交換水を２４．９ｇ含む混合液と、及び２，２’－アゾビス［Ｎ－（２－カルボキシエチル）－２－メチルプロピオンアミジン］４水和物を１．２６ｇ、イオン交換水を３３．３ｇ含む混合液とを同時に１時間かけて滴下した。滴下終了後、７５℃で２時間撹拌し、固形分２９．８質量％のポリマー溶液を得た。 [Synthesis of polymer A]
<Synthesis of polymer 1 (No. 1 polymer in Table 1 below)>
Polymer 1 shown in Table 1 below was synthesized in the following manner.
108.1 g of ion-exchanged water was placed in a 500 mL separable flask, and while stirring at 75° C. under a nitrogen atmosphere, 17.5 g of 2-hydroxyethyl acrylate, 52.5 g of N-(2-hydroxyethyl)acrylamide, and ion-exchanged A mixture containing 24.9 g of water, 1.26 g of 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine] tetrahydrate, and 33.3 g of ion-exchanged water and the mixed liquid were simultaneously added dropwise over 1 hour. After completion of the dropwise addition, the mixture was stirred at 75° C. for 2 hours to obtain a polymer solution having a solid content of 29.8% by mass.
＜ポリマー１（後記表１のＮｏ．１のポリマー）の合成＞
以下のようにして、後記表１に記載するポリマー１を合成した。
５００ｍＬセパラブルフラスコにイオン交換水を１０８．１ｇ入れ、窒素雰囲気下７５℃で撹拌しながら、２－ヒドロキシエチルアクリレートを１７．５ｇ、Ｎ－（２－ヒドロキシエチル）アクリルアミドを５２．５ｇ、イオン交換水を２４．９ｇ含む混合液と、及び２，２’－アゾビス［Ｎ－（２－カルボキシエチル）－２－メチルプロピオンアミジン］４水和物を１．２６ｇ、イオン交換水を３３．３ｇ含む混合液とを同時に１時間かけて滴下した。滴下終了後、７５℃で２時間撹拌し、固形分２９．８質量％のポリマー溶液を得た。 [Synthesis of polymer A]
<Synthesis of polymer 1 (No. 1 polymer in Table 1 below)>
108.1 g of ion-exchanged water was placed in a 500 mL separable flask, and while stirring at 75° C. under a nitrogen atmosphere, 17.5 g of 2-hydroxyethyl acrylate, 52.5 g of N-(2-hydroxyethyl)acrylamide, and ion-exchanged A mixture containing 24.9 g of water, 1.26 g of 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine] tetrahydrate, and 33.3 g of ion-exchanged water and the mixed liquid were simultaneously added dropwise over 1 hour. After completion of the dropwise addition, the mixture was stirred at 75° C. for 2 hours to obtain a polymer solution having a solid content of 29.8% by mass.
＜ポリマー２～１９及びｃ１～ｃ３の合成（後記表１のＮｏ．２～１９及びｃ１～ｃ３のポリマーの合成＞
上記ポリマー１の合成において、構成成分を導くモノマーとして後記表１記載のモノマーを後記表１の質量比で用いたこと以外は、上記ポリマー１と同様にして、ポリマー２～１９及びｃ１～ｃ３を合成した。 <Synthesis ofpolymers 2 to 19 and c1 to c3 (synthesis of polymers Nos. 2 to 19 and c1 to c3 in Table 1 below>
In the synthesis ofPolymer 1, Polymers 2 to 19 and c1 to c3 were prepared in the same manner as Polymer 1, except that the monomers shown in Table 1 below were used as monomers leading to the constituent components at the mass ratios shown in Table 1 below. Synthesized.
上記ポリマー１の合成において、構成成分を導くモノマーとして後記表１記載のモノマーを後記表１の質量比で用いたこと以外は、上記ポリマー１と同様にして、ポリマー２～１９及びｃ１～ｃ３を合成した。 <Synthesis of
In the synthesis of
（重量平均分子量の測定）
後記表１記載のポリマーの重量平均分子量（Ｍｗ）は、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）によるポリアクリル酸ナトリウム換算の重量平均分子量であり、下記条件で測定した値である。
測定器：ＨＬＣ－８２２０ＧＰＣ（商品名、東ソー社製）
カラム：ＴＯＳＯＨ ＴＳＫｇｅｌ ５０００ＰＷＸＬ（商品名、東ソー社製）、ＴＯＳＯＨ ＴＳＫｇｅｌ Ｇ４０００ＰＷＸＬ（商品名、東ソー社製）、ＴＯＳＯＨ ＴＳＫｇｅｌ Ｇ２５００ＰＷＸＬ（商品名、東ソー社製）をつなげた。
ガードカラム：ＴＳＫｇｅｌ ｇｕａｒｄｃｏｌｕｍｎ ＰＷＸＬ（商品名、東ソー社製）
キャリア：２００ｍＭ 硝酸ナトリウム水溶液
リンス液：超純水
キャリア流量：サンプルポンプ １．０ｍＬ／ｍｉｎ
リファレンスポンプ ０．２２３ｍＬ／ｍｉｎ
ポンプ初期圧力：サンプルポンプ ４．４ＭＰａ
リファレンスポンプ ０．８ＭＰａ
試料濃度：０．１０質量％
カラム温度：４０℃
検出器温度：４０℃
収集時間：４５分間（ランタイム ４７．０分間）
検出器：ＲＩ（屈折率）検出器 (Measurement of weight average molecular weight)
The weight average molecular weight (Mw) of the polymer shown in Table 1 below is the weight average molecular weight converted to sodium polyacrylate by gel permeation chromatography (GPC), and is a value measured under the following conditions.
Measuring instrument: HLC-8220GPC (trade name, manufactured by Tosoh Corporation)
Columns: TOSOH TSKgel 5000PWXL (trade name, manufactured by Tosoh Corporation), TOSOH TSKgel G4000PWXL (trade name, manufactured by Tosoh Corporation), and TOSOH TSKgel G2500PWXL (trade name, manufactured by Tosoh Corporation) were connected.
Guard column: TSKgel guard column PWXL (trade name, manufactured by Tosoh Corporation)
Carrier: 200 mM sodium nitrate aqueous solution Rinse liquid: Ultrapure water Carrier flow rate: Sample pump 1.0 mL/min
Reference pump 0.223 mL/min
Pump initial pressure: sample pump 4.4 MPa
Reference pump 0.8MPa
Sample concentration: 0.10% by mass
Column temperature: 40°C
Detector temperature: 40°C
Acquisition time: 45 minutes (runtime 47.0 minutes)
Detector: RI (refractive index) detector
後記表１記載のポリマーの重量平均分子量（Ｍｗ）は、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）によるポリアクリル酸ナトリウム換算の重量平均分子量であり、下記条件で測定した値である。
測定器：ＨＬＣ－８２２０ＧＰＣ（商品名、東ソー社製）
カラム：ＴＯＳＯＨ ＴＳＫｇｅｌ ５０００ＰＷＸＬ（商品名、東ソー社製）、ＴＯＳＯＨ ＴＳＫｇｅｌ Ｇ４０００ＰＷＸＬ（商品名、東ソー社製）、ＴＯＳＯＨ ＴＳＫｇｅｌ Ｇ２５００ＰＷＸＬ（商品名、東ソー社製）をつなげた。
ガードカラム：ＴＳＫｇｅｌ ｇｕａｒｄｃｏｌｕｍｎ ＰＷＸＬ（商品名、東ソー社製）
キャリア：２００ｍＭ 硝酸ナトリウム水溶液
リンス液：超純水
キャリア流量：サンプルポンプ １．０ｍＬ／ｍｉｎ
リファレンスポンプ ０．２２３ｍＬ／ｍｉｎ
ポンプ初期圧力：サンプルポンプ ４．４ＭＰａ
リファレンスポンプ ０．８ＭＰａ
試料濃度：０．１０質量％
カラム温度：４０℃
検出器温度：４０℃
収集時間：４５分間（ランタイム ４７．０分間）
検出器：ＲＩ（屈折率）検出器 (Measurement of weight average molecular weight)
The weight average molecular weight (Mw) of the polymer shown in Table 1 below is the weight average molecular weight converted to sodium polyacrylate by gel permeation chromatography (GPC), and is a value measured under the following conditions.
Measuring instrument: HLC-8220GPC (trade name, manufactured by Tosoh Corporation)
Columns: TOSOH TSKgel 5000PWXL (trade name, manufactured by Tosoh Corporation), TOSOH TSKgel G4000PWXL (trade name, manufactured by Tosoh Corporation), and TOSOH TSKgel G2500PWXL (trade name, manufactured by Tosoh Corporation) were connected.
Guard column: TSKgel guard column PWXL (trade name, manufactured by Tosoh Corporation)
Carrier: 200 mM sodium nitrate aqueous solution Rinse liquid: Ultrapure water Carrier flow rate: Sample pump 1.0 mL/min
Reference pump 0.223 mL/min
Pump initial pressure: sample pump 4.4 MPa
Reference pump 0.8MPa
Sample concentration: 0.10% by mass
Column temperature: 40°C
Detector temperature: 40°C
Acquisition time: 45 minutes (runtime 47.0 minutes)
Detector: RI (refractive index) detector
［負極用組成物１（後記表１のＮｏ．１の組成物）の調製］
６０ｍｌの軟膏容器（馬野化学社製）にカーボンコートされた酸化ケイ素（ＳｉＯＣ、炭素原子の含有量の割合１．３質量％、平均一次粒子径：５μｍ、大阪チタニウム社製）を３０質量部、黒鉛（商品名：ｍａｇ－ｄ、日立化成社製）を７０質量部、アセチレンブラック（商品名：デンカブラック、デンカ社製）を５質量部、ポリマー１を５質量部、蒸留水を２２．５質量部加え、泡取り練太郎（商品名、ＴＨＩＮＫＹ社製）を用いて２０００ｒｐｍで１０分間分散した。分散した液に蒸留水を２７質量部加え、泡取り練太郎を用いて２０００ｒｐｍで１０分間分散することにより、負極用組成物１を得た。 [Preparation of negative electrode composition 1 (composition No. 1 in Table 1 below)]
30 parts by mass of carbon-coated silicon oxide (SiOC, carbon atom content ratio 1.3% by mass, average primary particle size: 5 μm, Osaka Titanium Co., Ltd.) in a 60 ml ointment container (manufactured by Umano Kagaku Co., Ltd.), 70 parts by mass of graphite (trade name: mag-d, manufactured by Hitachi Chemical Co., Ltd.), 5 parts by mass of acetylene black (trade name: Denka Black, manufactured by Denka), 5 parts by mass ofpolymer 1, 22.5 parts by mass of distilled water Parts by mass were added, and dispersed for 10 minutes at 2000 rpm using a foaming mixer (trade name, manufactured by THINKY). A negative electrode composition 1 was obtained by adding 27 parts by mass of distilled water to the dispersed liquid and dispersing the mixture at 2000 rpm for 10 minutes using a bubble removing mixer.
６０ｍｌの軟膏容器（馬野化学社製）にカーボンコートされた酸化ケイ素（ＳｉＯＣ、炭素原子の含有量の割合１．３質量％、平均一次粒子径：５μｍ、大阪チタニウム社製）を３０質量部、黒鉛（商品名：ｍａｇ－ｄ、日立化成社製）を７０質量部、アセチレンブラック（商品名：デンカブラック、デンカ社製）を５質量部、ポリマー１を５質量部、蒸留水を２２．５質量部加え、泡取り練太郎（商品名、ＴＨＩＮＫＹ社製）を用いて２０００ｒｐｍで１０分間分散した。分散した液に蒸留水を２７質量部加え、泡取り練太郎を用いて２０００ｒｐｍで１０分間分散することにより、負極用組成物１を得た。 [Preparation of negative electrode composition 1 (composition No. 1 in Table 1 below)]
30 parts by mass of carbon-coated silicon oxide (SiOC, carbon atom content ratio 1.3% by mass, average primary particle size: 5 μm, Osaka Titanium Co., Ltd.) in a 60 ml ointment container (manufactured by Umano Kagaku Co., Ltd.), 70 parts by mass of graphite (trade name: mag-d, manufactured by Hitachi Chemical Co., Ltd.), 5 parts by mass of acetylene black (trade name: Denka Black, manufactured by Denka), 5 parts by mass of
［負極用組成物２～１９及びｃ１～ｃ３（後記表１のＮｏ．２～１９及びｃ１～ｃ３の組成物）の調製］
上記負極用組成物１の調製において、ポリマー１に代えて後記表１記載のポリマー２～１９及びｃ１～ｃ３を用いたこと以外は、上記負極用組成物１と同様にして、負極用組成物２～１９及びｃ１～ｃ３を調製した。 [Preparation ofnegative electrode compositions 2 to 19 and c1 to c3 (compositions of Nos. 2 to 19 and c1 to c3 in Table 1 below)]
In the preparation of thenegative electrode composition 1, the negative electrode composition was prepared in the same manner as the negative electrode composition 1, except that polymers 2 to 19 and c1 to c3 described in Table 1 below were used instead of the polymer 1. 2-19 and c1-c3 were prepared.
上記負極用組成物１の調製において、ポリマー１に代えて後記表１記載のポリマー２～１９及びｃ１～ｃ３を用いたこと以外は、上記負極用組成物１と同様にして、負極用組成物２～１９及びｃ１～ｃ３を調製した。 [Preparation of
In the preparation of the
［非水電解液二次電池（２０３２型コイン電池）１（後記表１のＮｏ．１の電池）の作製］
得られた負極用組成物１を厚み２０μｍの銅箔上にアプリケーターにより塗布し、８０℃で１時間乾燥させた。その後、プレス機を用いて加圧した後に１５０℃の真空で６時間乾燥し、負極活物質層の厚さが２５μｍの負極シートを得た。
上記負極シートから直径１３．０ｍｍの円板を切り出し、負極の形成に用いた。
リチウム箔（厚み５０μｍ、１４．５ｍｍφ）、ポリプロピレン製セパレータ（厚み２５μｍ、１６．０ｍｍφ）の順番に重ね１Ｍ ＬｉＰＦ６のエチレンカーボネート／エチルメチルカーボネート（体積比１対２）電解液 ２００μＬをセパレータに浸み込ませた。セパレータに、更に電解液を２００μＬ浸み込ませて、負極シートを負極活物質層面がセパレータに接するようにして重ねた。その後、２０３２型コインケースをかしめ、非水電解液二次電池１（Ｌｉ箔－セパレータ－負極活物質層－銅箔からなる積層体を具備する電池）を作製した。 [Preparation of non-aqueous electrolyte secondary battery (2032 type coin battery) 1 (No. 1 battery in Table 1 below)]
Thenegative electrode composition 1 thus obtained was applied onto a copper foil having a thickness of 20 μm with an applicator and dried at 80° C. for 1 hour. Then, after pressing with a press, the sheet was dried in vacuum at 150° C. for 6 hours to obtain a negative electrode sheet having a negative electrode active material layer with a thickness of 25 μm.
A disc with a diameter of 13.0 mm was cut out from the above negative electrode sheet and used to form a negative electrode.
Lithium foil (thickness 50 μm, 14.5 mmφ) and polypropylene separator (thickness 25 μm, 16.0 mmφ ) were stacked in this order. I let you in. The separator was further impregnated with 200 μL of the electrolytic solution, and the negative electrode sheet was stacked so that the negative electrode active material layer surface was in contact with the separator. After that, the 2032 type coin case was crimped to prepare a non-aqueous electrolyte secondary battery 1 (a battery having a laminate consisting of Li foil-separator-negative electrode active material layer-copper foil).
得られた負極用組成物１を厚み２０μｍの銅箔上にアプリケーターにより塗布し、８０℃で１時間乾燥させた。その後、プレス機を用いて加圧した後に１５０℃の真空で６時間乾燥し、負極活物質層の厚さが２５μｍの負極シートを得た。
上記負極シートから直径１３．０ｍｍの円板を切り出し、負極の形成に用いた。
リチウム箔（厚み５０μｍ、１４．５ｍｍφ）、ポリプロピレン製セパレータ（厚み２５μｍ、１６．０ｍｍφ）の順番に重ね１Ｍ ＬｉＰＦ６のエチレンカーボネート／エチルメチルカーボネート（体積比１対２）電解液 ２００μＬをセパレータに浸み込ませた。セパレータに、更に電解液を２００μＬ浸み込ませて、負極シートを負極活物質層面がセパレータに接するようにして重ねた。その後、２０３２型コインケースをかしめ、非水電解液二次電池１（Ｌｉ箔－セパレータ－負極活物質層－銅箔からなる積層体を具備する電池）を作製した。 [Preparation of non-aqueous electrolyte secondary battery (2032 type coin battery) 1 (No. 1 battery in Table 1 below)]
The
A disc with a diameter of 13.0 mm was cut out from the above negative electrode sheet and used to form a negative electrode.
Lithium foil (thickness 50 μm, 14.5 mmφ) and polypropylene separator (thickness 25 μm, 16.0 mmφ ) were stacked in this order. I let you in. The separator was further impregnated with 200 μL of the electrolytic solution, and the negative electrode sheet was stacked so that the negative electrode active material layer surface was in contact with the separator. After that, the 2032 type coin case was crimped to prepare a non-aqueous electrolyte secondary battery 1 (a battery having a laminate consisting of Li foil-separator-negative electrode active material layer-copper foil).
［非水電解液二次電池２～１９及びｃ１～ｃ３（後記表１のＮｏ．２～１９及びｃ１～ｃ３の電池）の作製］
上記非水電解液二次電池１の作製において、負極用組成物１に代えて後記表１記載の負極用組成物２～１９及びｃ１～ｃ３を用いたこと以外は、上記非水電解液二次電池１と同様にして、非水電解液二次電池２～１９及びｃ１～ｃ３を作製した。 [Preparation of non-aqueous electrolytesecondary batteries 2 to 19 and c1 to c3 (batteries No. 2 to 19 and c1 to c3 in Table 1 below)]
In the production of the nonaqueous electrolytesecondary battery 1, except that the negative electrode compositions 2 to 19 and c1 to c3 listed in Table 1 below were used instead of the negative electrode composition 1, the nonaqueous electrolyte 2 Non-aqueous electrolyte secondary batteries 2 to 19 and c1 to c3 were produced in the same manner as the secondary battery 1.
上記非水電解液二次電池１の作製において、負極用組成物１に代えて後記表１記載の負極用組成物２～１９及びｃ１～ｃ３を用いたこと以外は、上記非水電解液二次電池１と同様にして、非水電解液二次電池２～１９及びｃ１～ｃ３を作製した。 [Preparation of non-aqueous electrolyte
In the production of the nonaqueous electrolyte
［試験例］ サイクル特性の評価
各コイン電池の放電容量維持率を、充放電評価装置：ＴＯＳＣＡＴ－３０００（商品名、東洋システム社製）により測定した。充電は、Ｃレート０．２Ｃ（５時間で満充電になる速度）で電池電圧が０．０２Ｖに達するまで行った。放電は、Ｃレート０．２Ｃで電池電圧が１．５Ｖに達するまで行った。この充電１回と放電１回を充放電１サイクルとして３サイクル充放電を繰り返して、各コイン電池を初期化した。
初期化後、充電を０．５Ｃで０．０２Ｖに達するまで行った。放電を０．５Ｃで１．５Ｖに達するまで行った。この充電１回と放電１回を充放電１サイクルとして、５０サイクル充放電を繰り返すことでサイクル特性の評価を行った。初期化後１サイクル目の放電容量（初期放電容量）を１００％としたとき、５０サイクル目の放電容量維持率（１００×「５０サイクル目の放電容量」／「初期放電容量」）を算出し、下記評価ランクに当てはめサイクル特性を評価した。結果を後記表１に示す。本試験において、評価ランク「１」～「３」が合格である。
－放電容量維持率（サイクル特性）の評価ランク－
１： ９５％以上
２： ９０％以上、９５％未満
３： ８５％以上、９０％未満
４： ８５％未満 [Test Examples] Evaluation of Cycle Characteristics The discharge capacity retention rate of each coin battery was measured using a charge/discharge evaluation device: TOSCAT-3000 (trade name, manufactured by Toyo System Co., Ltd.). The battery was charged at a C rate of 0.2C (the rate at which the battery is fully charged in 5 hours) until the battery voltage reached 0.02V. Discharge was performed at a C rate of 0.2C until the battery voltage reached 1.5V. Each coin battery was initialized by repeating 3 cycles of charging and discharging, with one charging and one discharging as one cycle of charging and discharging.
After initialization, charging was performed at 0.5C until reaching 0.02V. Discharge was performed at 0.5C until reaching 1.5V. Cycle characteristics were evaluated by repeating 50 charge/discharge cycles, with one charge/discharge cycle being defined as one charge/discharge cycle. Assuming that the discharge capacity at the first cycle after initialization (initial discharge capacity) is 100%, the discharge capacity retention rate at the 50th cycle (100 × “50th cycle discharge capacity” / “initial discharge capacity”) was calculated. , was applied to the following evaluation ranks, and the cycle characteristics were evaluated. The results are shown in Table 1 below. In this test, evaluation ranks "1" to "3" are passed.
-Evaluation rank of discharge capacity retention rate (cycle characteristics)-
1: 95% or more 2: 90% or more and less than 95% 3: 85% or more and less than 90% 4: less than 85%
各コイン電池の放電容量維持率を、充放電評価装置：ＴＯＳＣＡＴ－３０００（商品名、東洋システム社製）により測定した。充電は、Ｃレート０．２Ｃ（５時間で満充電になる速度）で電池電圧が０．０２Ｖに達するまで行った。放電は、Ｃレート０．２Ｃで電池電圧が１．５Ｖに達するまで行った。この充電１回と放電１回を充放電１サイクルとして３サイクル充放電を繰り返して、各コイン電池を初期化した。
初期化後、充電を０．５Ｃで０．０２Ｖに達するまで行った。放電を０．５Ｃで１．５Ｖに達するまで行った。この充電１回と放電１回を充放電１サイクルとして、５０サイクル充放電を繰り返すことでサイクル特性の評価を行った。初期化後１サイクル目の放電容量（初期放電容量）を１００％としたとき、５０サイクル目の放電容量維持率（１００×「５０サイクル目の放電容量」／「初期放電容量」）を算出し、下記評価ランクに当てはめサイクル特性を評価した。結果を後記表１に示す。本試験において、評価ランク「１」～「３」が合格である。
－放電容量維持率（サイクル特性）の評価ランク－
１： ９５％以上
２： ９０％以上、９５％未満
３： ８５％以上、９０％未満
４： ８５％未満 [Test Examples] Evaluation of Cycle Characteristics The discharge capacity retention rate of each coin battery was measured using a charge/discharge evaluation device: TOSCAT-3000 (trade name, manufactured by Toyo System Co., Ltd.). The battery was charged at a C rate of 0.2C (the rate at which the battery is fully charged in 5 hours) until the battery voltage reached 0.02V. Discharge was performed at a C rate of 0.2C until the battery voltage reached 1.5V. Each coin battery was initialized by repeating 3 cycles of charging and discharging, with one charging and one discharging as one cycle of charging and discharging.
After initialization, charging was performed at 0.5C until reaching 0.02V. Discharge was performed at 0.5C until reaching 1.5V. Cycle characteristics were evaluated by repeating 50 charge/discharge cycles, with one charge/discharge cycle being defined as one charge/discharge cycle. Assuming that the discharge capacity at the first cycle after initialization (initial discharge capacity) is 100%, the discharge capacity retention rate at the 50th cycle (100 × “50th cycle discharge capacity” / “initial discharge capacity”) was calculated. , was applied to the following evaluation ranks, and the cycle characteristics were evaluated. The results are shown in Table 1 below. In this test, evaluation ranks "1" to "3" are passed.
-Evaluation rank of discharge capacity retention rate (cycle characteristics)-
1: 95% or more 2: 90% or more and less than 95% 3: 85% or more and less than 90% 4: less than 85%
＜表の注＞
構成成分を導くモノマーの略称について説明する。また、モノマー由来の構成成分の構造を記載する。
（酸基を有しない構成成分）
ＨＥＡ：２－ヒドロキシエチルアクリレート
ＨＥＡＡ：Ｎ－（２－ヒドロキシエチル）アクリルアミド
Ａａｍ：アクリルアミド
ＭＥＡ：２－メトキシエチルアクリレート
<Notes to the table>
The abbreviations of the monomers leading to the constituents are explained. Also, the structures of the constituents derived from the monomers are described.
(Constituent without acid group)
HEA: 2-hydroxyethyl acrylate HEAA: N-(2-hydroxyethyl) acrylamide Aam: acrylamide MEA: 2-methoxyethyl acrylate
構成成分を導くモノマーの略称について説明する。また、モノマー由来の構成成分の構造を記載する。
（酸基を有しない構成成分）
ＨＥＡ：２－ヒドロキシエチルアクリレート
ＨＥＡＡ：Ｎ－（２－ヒドロキシエチル）アクリルアミド
Ａａｍ：アクリルアミド
ＭＥＡ：２－メトキシエチルアクリレート
The abbreviations of the monomers leading to the constituents are explained. Also, the structures of the constituents derived from the monomers are described.
(Constituent without acid group)
HEA: 2-hydroxyethyl acrylate HEAA: N-(2-hydroxyethyl) acrylamide Aam: acrylamide MEA: 2-methoxyethyl acrylate
（酸基を有する構成成分）
ＡＡ：アクリル酸ナトリウム
ＡＭＰＳ：２－アクリルアミド－２－メチルプロパンスルホン酸
(Constituent with acid group)
AA: sodium acrylate AMPS: 2-acrylamido-2-methylpropanesulfonic acid
ＡＡ：アクリル酸ナトリウム
ＡＭＰＳ：２－アクリルアミド－２－メチルプロパンスルホン酸
AA: sodium acrylate AMPS: 2-acrylamido-2-methylpropanesulfonic acid
ラテックス：スチレン／２－エチルヘキシルアクリレート／アクリル酸＝４０／５５／５（質量比）のコポリマーラテックス、Ｍｗ＝１２０万、平均一次粒子径３μｍ（固形分１５質量％）、このラテックスは非水溶性である。
水溶性高酸基ポリマー：上記ポリマー１と同様にして合成したランダムコポリマー（「ＨＥＡＡ／ＨＥＡ／ＡＡ」、ＨＥＡＡ：ＨＥＡ：ＡＡ＝７０：２０：１０（質量比）、Ｍｗ＝１５万）
水溶性高分子量ポリマー：上記ポリマー１と同様にして合成したランダムコポリマー（「ＨＥＡＡ／ＨＥＡ」、ＨＥＡＡ：ＨＥＡ＝５０：５０（質量比）、Ｍｗ＝４０万） Latex: Copolymer latex of styrene/2-ethylhexyl acrylate/acrylic acid = 40/55/5 (mass ratio), Mw = 1.2 million, averageprimary particle size 3 µm (solid content 15% by mass), this latex is water-insoluble. be.
Water-soluble high acid group polymer: random copolymer synthesized in the same manner aspolymer 1 above (“HEAA/HEA/AA”, HEAA:HEA:AA=70:20:10 (mass ratio), Mw=150,000)
Water-soluble high-molecular-weight polymer: random copolymer synthesized in the same manner as polymer 1 (“HEAA/HEA”, HEAA:HEA=50:50 (mass ratio), Mw=400,000)
水溶性高酸基ポリマー：上記ポリマー１と同様にして合成したランダムコポリマー（「ＨＥＡＡ／ＨＥＡ／ＡＡ」、ＨＥＡＡ：ＨＥＡ：ＡＡ＝７０：２０：１０（質量比）、Ｍｗ＝１５万）
水溶性高分子量ポリマー：上記ポリマー１と同様にして合成したランダムコポリマー（「ＨＥＡＡ／ＨＥＡ」、ＨＥＡＡ：ＨＥＡ＝５０：５０（質量比）、Ｍｗ＝４０万） Latex: Copolymer latex of styrene/2-ethylhexyl acrylate/acrylic acid = 40/55/5 (mass ratio), Mw = 1.2 million, average
Water-soluble high acid group polymer: random copolymer synthesized in the same manner as
Water-soluble high-molecular-weight polymer: random copolymer synthesized in the same manner as polymer 1 (“HEAA/HEA”, HEAA:HEA=50:50 (mass ratio), Mw=400,000)
「ポリマーＡ中の酸基含有量（質量％）」：ポリマーＡ中、酸基を有する構成成分の含有量を意味する。
「含有量１（質量部）」：負極用組成物中、ＳｉＯＣの含有量を１００質量部とした場合に、ＳｉＯＣ １００質量部に対するポリマーＡの含有量を意味する。
「バインダー中の含有量（質量％）」：バインダー中、本発明で規定する水溶性ポリマーの含有量を意味する。
「含有量２（質量部）」：負極用組成物中、ＳｉＯＣの含有量を１００質量部とした場合に、ＳｉＯＣ １００質量部に対するポリマーＢの含有量を意味する。なお、「ラテックス」の含有量は固形分の含有量である。
ポリマーＡは、比較例のものを含め、すべて水溶性である。 "Acid group content in polymer A (% by mass)": means the content of constituents having acid groups in polymer A.
"Content 1 (parts by mass)": When the content of SiOC in the negative electrode composition is 100 parts by mass, it means the content of polymer A with respect to 100 parts by mass of SiOC.
"Content in binder (% by mass)": means the content of the water-soluble polymer defined in the present invention in the binder.
"Content 2 (parts by mass)": When the content of SiOC in the negative electrode composition is 100 parts by mass, it means the content of polymer B with respect to 100 parts by mass of SiOC. In addition, content of "latex" is content of solid content.
All Polymer A's, including those of the Comparative Examples, are water soluble.
「含有量１（質量部）」：負極用組成物中、ＳｉＯＣの含有量を１００質量部とした場合に、ＳｉＯＣ １００質量部に対するポリマーＡの含有量を意味する。
「バインダー中の含有量（質量％）」：バインダー中、本発明で規定する水溶性ポリマーの含有量を意味する。
「含有量２（質量部）」：負極用組成物中、ＳｉＯＣの含有量を１００質量部とした場合に、ＳｉＯＣ １００質量部に対するポリマーＢの含有量を意味する。なお、「ラテックス」の含有量は固形分の含有量である。
ポリマーＡは、比較例のものを含め、すべて水溶性である。 "Acid group content in polymer A (% by mass)": means the content of constituents having acid groups in polymer A.
"Content 1 (parts by mass)": When the content of SiOC in the negative electrode composition is 100 parts by mass, it means the content of polymer A with respect to 100 parts by mass of SiOC.
"Content in binder (% by mass)": means the content of the water-soluble polymer defined in the present invention in the binder.
"Content 2 (parts by mass)": When the content of SiOC in the negative electrode composition is 100 parts by mass, it means the content of polymer B with respect to 100 parts by mass of SiOC. In addition, content of "latex" is content of solid content.
All Polymer A's, including those of the Comparative Examples, are water soluble.
Ｎｏ．ｃ１及びｃ３の負極用組成物に用いたポリマーＡは、酸基を有する構成成分の含有量が５質量％を越える。Ｎｏ．ｃ１及びｃ３の負極用組成物を用いて作製されたＮｏ．ｃ１及びｃ３の電池は、サイクル特性に劣っていた。
Ｎｏ．ｃ２の負極用組成物に用いたポリマーＡは、酸基を有する構成成分の含有量が５質量％以下であるが、重量平均分子量が３０万を越えている。Ｎｏ．ｃ２の負極用組成物を用いて作製されたＮｏ．ｃ２の電池は、サイクル特性に劣っていた。
これに対して、本発明の負極用組成物（Ｎｏ．１～１９）を用いて作製した電池（Ｎｏ．１～１９）はサイクル特性に優れていることが分かる。 No. Polymer A used in the negative electrode compositions of c1 and c3 contains more than 5% by mass of constituents having acid groups. No. Nos. c1 and c3 produced using the negative electrode compositions. Batteries of c1 and c3 were inferior in cycle characteristics.
No. Polymer A used in the negative electrode composition of c2 has a content of constituents having an acid group of 5% by mass or less, but a weight average molecular weight of more than 300,000. No. No. c2 produced using the negative electrode composition. The battery of c2 was inferior in cycle characteristics.
On the other hand, it can be seen that the batteries (Nos. 1 to 19) produced using the negative electrode compositions (Nos. 1 to 19) of the present invention are excellent in cycle characteristics.
Ｎｏ．ｃ２の負極用組成物に用いたポリマーＡは、酸基を有する構成成分の含有量が５質量％以下であるが、重量平均分子量が３０万を越えている。Ｎｏ．ｃ２の負極用組成物を用いて作製されたＮｏ．ｃ２の電池は、サイクル特性に劣っていた。
これに対して、本発明の負極用組成物（Ｎｏ．１～１９）を用いて作製した電池（Ｎｏ．１～１９）はサイクル特性に優れていることが分かる。 No. Polymer A used in the negative electrode compositions of c1 and c3 contains more than 5% by mass of constituents having acid groups. No. Nos. c1 and c3 produced using the negative electrode compositions. Batteries of c1 and c3 were inferior in cycle characteristics.
No. Polymer A used in the negative electrode composition of c2 has a content of constituents having an acid group of 5% by mass or less, but a weight average molecular weight of more than 300,000. No. No. c2 produced using the negative electrode composition. The battery of c2 was inferior in cycle characteristics.
On the other hand, it can be seen that the batteries (Nos. 1 to 19) produced using the negative electrode compositions (Nos. 1 to 19) of the present invention are excellent in cycle characteristics.
本発明をその実施態様とともに説明したが、我々は特に指定しない限り我々の発明を説明のどの細部においても限定しようとするものではなく、添付の請求の範囲に示した発明の精神と範囲に反することなく幅広く解釈されるべきであると考える。
While we have described our invention in conjunction with embodiments thereof, we do not intend to limit our invention in any detail to the description unless specified otherwise, which is contrary to the spirit and scope of the invention as set forth in the appended claims. I think it should be interpreted broadly.
本願は、２０２１年３月３１日に日本国で特許出願された特願２０２１－０６０３３３に基づく優先権を主張するものであり、これはここに参照してその内容を本明細書の記載の一部として取り込む。
This application claims priority based on Japanese Patent Application No. 2021-060333 filed in Japan on March 31, 2021, the contents of which are incorporated herein by reference. taken in as a part.
１０ 非水電解液二次電池
１ 負極集電体
２ 負極活物質層
３ セパレータ
４ 正極活物質層
５ 正極集電体
６ 作動部位（電球） REFERENCE SIGNSLIST 10 Nonaqueous electrolyte secondary battery 1 Negative electrode current collector 2 Negative electrode active material layer 3 Separator 4 Positive electrode active material layer 5 Positive electrode current collector 6 Operating part (bulb)
１ 負極集電体
２ 負極活物質層
３ セパレータ
４ 正極活物質層
５ 正極集電体
６ 作動部位（電球） REFERENCE SIGNS
Claims (11)
- バインダーとカーボンコートされた酸化ケイ素とを含有する負極用組成物であって、
前記バインダー中、水溶性ポリマーを５質量％以上含み、
前記水溶性ポリマーは重量平均分子量が３０万以下であり、前記水溶性ポリマー中に占める酸基を有する構成成分の割合が５質量％以下である、負極用組成物。 A negative electrode composition containing a binder and carbon-coated silicon oxide,
The binder contains 5% by mass or more of a water-soluble polymer,
The composition for a negative electrode, wherein the water-soluble polymer has a weight-average molecular weight of 300,000 or less, and a component having an acid group accounts for 5% by mass or less of the water-soluble polymer. - 前記水溶性ポリマーが連鎖重合ポリマーである、請求項１に記載の負極用組成物。 The composition for a negative electrode according to claim 1, wherein the water-soluble polymer is a chain polymerization polymer.
- 前記水溶性ポリマーが、酸基を有しない構成成分として下記一般式（１）又は（２）で表される構成成分を含む、請求項１又は２に記載の負極用組成物。
一般式（２）中、Ｒ３は水素原子又はメチル基を示し、Ｒ４及びＲ５は水素原子又は置換基を示す。＊は前記水溶性ポリマー中に組み込まれるための結合部位を示す。 3. The negative electrode composition according to claim 1, wherein the water-soluble polymer contains a component represented by the following general formula (1) or (2) as a component having no acid group.
In general formula ( 2 ), R3 represents a hydrogen atom or a methyl group, and R4 and R5 represent a hydrogen atom or a substituent. * indicates a binding site for incorporation into the water-soluble polymer. - 前記水溶性ポリマーの含有量が、前記のカーボンコートされた酸化ケイ素１００質量部に対して、２質量部以上である、請求項１～３のいずれか１項に記載の負極用組成物。 The negative electrode composition according to any one of claims 1 to 3, wherein the content of the water-soluble polymer is 2 parts by mass or more with respect to 100 parts by mass of the carbon-coated silicon oxide.
- 前記水溶性ポリマーが、前記一般式（１）又は（２）で表される２種以上の構成成分を含む、請求項３に記載の負極用組成物。 The negative electrode composition according to claim 3, wherein the water-soluble polymer contains two or more constituents represented by the general formula (1) or (2).
- 前記酸基がカルボキシ基又はその塩である、請求項１～５のいずれか１項に記載の負極用組成物。 The composition for a negative electrode according to any one of claims 1 to 5, wherein the acid group is a carboxy group or a salt thereof.
- 分散媒体を含む負極用スラリーである、請求項１～６のいずれか１項に記載の負極用組成物。 The negative electrode composition according to any one of claims 1 to 6, which is a negative electrode slurry containing a dispersion medium.
- 請求項１～７のいずれか１項に記載の負極用組成物で構成した層を有する負極シート。 A negative electrode sheet having a layer composed of the negative electrode composition according to any one of claims 1 to 7.
- 正極活物質層とセパレータと負極活物質層とをこの順で有し、前記負極活物質層が請求項１～７のいずれか１項に記載の負極用組成物で構成した層である、非水二次電池。 It has a positive electrode active material layer, a separator and a negative electrode active material layer in this order, and the negative electrode active material layer is a layer composed of the negative electrode composition according to any one of claims 1 to 7. Water secondary battery.
- 請求項１～７のいずれか１項に記載の負極用組成物を用いて成膜することを含む、負極シートの製造方法。 A method for producing a negative electrode sheet, comprising forming a film using the negative electrode composition according to any one of claims 1 to 7.
- 請求項１０に記載の製造方法により得られた負極シートを非水二次電池の負極に組み込むことを含む、非水二次電池の製造方法。 A method for manufacturing a non-aqueous secondary battery, comprising incorporating the negative electrode sheet obtained by the manufacturing method according to claim 10 into the negative electrode of the non-aqueous secondary battery.
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| JP2013051203A (en) * | 2011-08-04 | 2013-03-14 | Nippon Zeon Co Ltd | Composite particle for electrochemical element electrode, electrochemical element electrode material, electrochemical element electrode, and electrochemical element |
| JP2013084351A (en) * | 2011-10-06 | 2013-05-09 | Nippon Zeon Co Ltd | Composite particle for electrochemical device electrode, electrochemical device electrode material, and electrochemical device electrode |
| JP2013179059A (en) * | 2009-05-11 | 2013-09-09 | Nexeon Ltd | Lithium ion rechargeable battery cells |
| WO2018155609A1 (en) * | 2017-02-23 | 2018-08-30 | 日本電気株式会社 | Lithium-ion secondary cell provided with negative electrode for high energy density cell |
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| JP2013179059A (en) * | 2009-05-11 | 2013-09-09 | Nexeon Ltd | Lithium ion rechargeable battery cells |
| JP2013051203A (en) * | 2011-08-04 | 2013-03-14 | Nippon Zeon Co Ltd | Composite particle for electrochemical element electrode, electrochemical element electrode material, electrochemical element electrode, and electrochemical element |
| JP2013084351A (en) * | 2011-10-06 | 2013-05-09 | Nippon Zeon Co Ltd | Composite particle for electrochemical device electrode, electrochemical device electrode material, and electrochemical device electrode |
| WO2018155609A1 (en) * | 2017-02-23 | 2018-08-30 | 日本電気株式会社 | Lithium-ion secondary cell provided with negative electrode for high energy density cell |
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