Binder for nonaqueous electrolyte batteries, electrode mixture, electrode, and nonaqueous electrolyte battery

Abstract

Provided is a binder for nonaqueous electrolyte batteries, wherein the binder comprises a polymer that contains a segment A having a glass transition temperature of 25°C or less and a segment B having a melting point of 50°C or higher.

Description

Binder for non-aqueous electrolyte battery, electrode mixture, electrode, and non-aqueous electrolyte battery

[0001] The present disclosure relates to a binder for a nonaqueous electrolyte battery, an electrode mixture, an electrode, and a nonaqueous electrolyte battery.

[0002] Patent Document 1 describes a slurry for an electrode mixture for a lithium secondary battery, which contains an electrode active material (A), a binder (B), and fluororubber particles (C).

[0003] Patent Document 2 describes a binder containing a fluorine-containing polymer, wherein the fluorine-containing polymer has polymerization units based on vinylidene fluoride and polymerization units based on a monomer having an amide group (-CO-NRR' (R and R' are the same or different and each represents a hydrogen atom or an alkyl group which may have a substituent)) or an amide bond (-CO-NR"- (R" represents a hydrogen atom, an alkyl group which may have a substituent, or a phenyl group which may have a substituent)), and wherein the binder has a solution viscosity of 10 to 20,000 mPa·s.

[0004] Patent Document 3 discloses a binder for batteries containing a fluorine-containing copolymer, in which the fluorine-containing copolymer contains a repeating unit (a) based on vinylidene fluoride and a repeating unit represented by the general formula (b1): -(CH ２ -CFRf １ )-(wherein, Rf １ is a linear or branched fluorinated alkyl group or fluorinated alkoxy group having 1 to 12 carbon atoms, and when the number of carbon atoms is 2 or more, an oxygen atom may be contained between the carbon atoms. ２ )-(wherein, Rf ２ is a linear or branched fluorinated alkyl group or fluorinated alkoxy group having 1 to 12 carbon atoms, and when the carbon number is 2 or more, an oxygen atom may be contained between the carbon atoms.), and in the fluorine-containing copolymer, the molar ratio of the repeating unit (a) to the repeating unit (b) ((a) / (b)) is 95 / 5 to 5 / 95.

[0005] International Publication No. 2011 / 002097 Japanese Patent Application Laid-Open No. 2013-219016 International Publication No. 2022 / 039260

[0006] An object of the present disclosure is to provide a binder for a non-aqueous electrolyte battery that can form an electrode material layer that is excellent in flexibility and toughness.

[0007] According to the present disclosure, there is provided a binder for a non-aqueous electrolyte battery, which contains a polymer including a segment A having a glass transition temperature of 25°C or less and a segment B having a melting point of 50°C or more.

[0008] According to the present disclosure, it is possible to provide a binder for a nonaqueous electrolyte battery that can form an electrode material layer that is excellent in flexibility and toughness.

[0009] Specific embodiments of the present disclosure will be described in detail below, but the present disclosure is not limited to the following embodiments.

[0010] A wound-type nonaqueous electrolyte battery is manufactured by sandwiching a separator between a positive electrode and a negative electrode and winding them. During winding, bending stress is also applied to the electrode material layer of the electrode, so the binder used to form the electrode material layer is required to have excellent flexibility and the ability to provide an electrode material layer that can withstand bending stress. Therefore, Patent Document 3 proposes a binder that can form an electrode material layer that exhibits sufficient flexibility, which contains a fluorine-containing copolymer containing a repeating unit (a) having a specific structure and a repeating unit (b) having a specific structure in an extremely limited molar ratio.

[0011] The electrode material layer formed using the binder described in Patent Document 3 has sufficient flexibility to prevent cracking even when wound while being tightened. On the other hand, some manufacturing methods for wound batteries involve sandwiching a separator between the positive electrode and the negative electrode, and winding them while applying a certain tension to them. When using such a manufacturing method, not only bending stress but also tension is applied to the electrode material layer. The present inventors have discovered that if the electrode material layer used in such a manufacturing method can be imparted with not only flexibility but also toughness, a battery exhibiting high performance can be manufactured.

[0012] The binder for a nonaqueous electrolyte battery according to the present disclosure was developed in consideration of such current circumstances, and by using the binder for a nonaqueous electrolyte battery according to the present disclosure, an electrode material layer having excellent flexibility and toughness can be formed.

[0013] In the present disclosure, the flexibility and toughness of an electrode material layer can be confirmed, for example, by performing a three-point bending test on an electrode including the electrode material layer. An electrode material layer of an electrode having a small maximum test force measured in the three-point bending test can be said to have excellent flexibility. Furthermore, an electrode material layer of an electrode having a large half-width measured in the three-point bending test can be said to have excellent toughness. The half-width can be determined by plotting a curve using the results of the three-point bending test of the electrode, with the stroke of the autograph on the horizontal axis and the stress on the vertical axis, and measuring the peak width at half the stress peak.

[0014] That is, according to the present disclosure, there is provided a binder for nonaqueous electrolyte batteries (hereinafter, sometimes referred to as a first binder for nonaqueous electrolyte batteries) containing a polymer including a segment A having a glass transition temperature of 25°C or less and a segment B having a melting point of 50°C or more.

[0015] The present disclosure also provides a binder for non-aqueous electrolyte batteries containing a polymer, wherein the polymer has a glass transition temperature and a melting point, contains 2,3,3,3-tetrafluoropropene units, and has a tetrahydrofuran extractable amount at 25°C of 5 mass% or less (hereinafter, may be referred to as a second binder for non-aqueous electrolyte batteries).

[0016] In the present disclosure, the non-aqueous electrolyte refers to a liquid non-aqueous electrolyte, and is distinguished from solid electrolytes such as polymer electrolytes and inorganic solid electrolytes.

[0017] First, the configuration of the first binder for a nonaqueous electrolyte battery will be described in detail.

[0018] 1. First Binder for Non-Aqueous Electrolyte Battery The first binder for non-aqueous electrolyte battery contains a polymer including a segment A and a segment B. As long as the polymer includes the segment A and the segment B, it may also include another segment having a different structure from the segments A and B.

[0019] (Polymer Segment A) Segment A has a glass transition temperature of 25° C. or lower. The glass transition temperature of segment A is preferably 0° C. or lower, more preferably −5° C. or lower, and even more preferably −10° C. or lower. Since the first binder for a nonaqueous electrolyte battery contains a polymer including segment A having a glass transition temperature, it is possible to form an electrode material layer having excellent flexibility.

[0020] The glass transition temperature can be determined by using a differential scanning calorimeter (DSC822e manufactured by Mettler Toledo or X-DSC7000 manufactured by Hitachi High-Tech Science Corporation) to obtain a DSC curve by cooling 10 mg of a sample to −75° C. and then raising the temperature at 20° C. / min, and determining the temperature indicating the intersection point between an extension of the baseline before and after the second-order transition of the DSC curve and a tangent to the inflection point of the DSC curve as the glass transition temperature.

[0021] The heat of fusion of the segment A is preferably less than 5 J / g, more preferably less than 3 J / g, and even more preferably less than 2 J / g, since this can further improve the flexibility of the electrode material layer.

[0022] The heat of fusion can be calculated from the magnitude of the melting peak (ΔH) in the endothermic curve obtained by heating a sample from 30° C. to 220° C. at a rate of 10° C. / min using a differential scanning calorimetry (DSC) device. When a polymer does not show a clear melting peak, the polymer has no heat of fusion, i.e., the heat of fusion of the polymer is 0 J / g.

[0023] Segment A may be a segment that does not exhibit a distinct melting point.

[0024] Segment A preferably contains a fluorine-containing monomer unit because this can improve the electrolyte resistance of the electrode material layer. The fluorine-containing monomer that can constitute Segment A is not particularly limited as long as it is a monomer containing a fluorine atom, and examples thereof include vinylidene fluoride [VdF], trifluoroethylene, tetrafluoroethylene [TFE], hexafluoropropylene, perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether), chlorotrifluoroethylene, hexafluoroisobutene, vinyl fluoride, a monomer that provides a repeating unit represented by general formula (b1) described later, and a monomer that provides a repeating unit represented by general formula (b2) described later.

[0025] The content of the fluorine-containing monomer unit in segment A is preferably 50 mol% or more, more preferably 90 mol% or more, and even more preferably 99 mol% or more, based on all monomer units constituting segment A, and is preferably 100 mol% or less, and may be 100 mol% or less.

[0026] Segment A may further contain a non-fluorine-containing monomer unit. Examples of the non-fluorine-containing monomer include ethylene, propylene, and alkyl vinyl ether. The content of the non-fluorine-containing monomer unit is preferably 0 to 50 mol %, more preferably 0 to 10 mol %, and even more preferably 0 to 1 mol %, relative to all monomer units constituting segment A, and may even be 0 mol %.

[0027] Segment A is a cyano group, a carboxyl group, an alkoxycarbonyl group, I, Br, -CH ２ The segment A may further contain units based on a monomer having a reactive group such as OH or a carbon-carbon double bond. The content of units based on a monomer having a reactive group is preferably 0 to 50 mol %, more preferably 0 to 10 mol %, and even more preferably 0 to 1 mol %, relative to all monomer units constituting the segment A, and may be 0 mol %.

[0028] In the present disclosure, the content of each monomer unit can be measured by an NMR method.

[0029] Segment A preferably contains at least a VdF unit or a TFE unit as a fluorine-containing monomer unit, and more preferably contains at least a VdF unit. By containing a VdF unit in segment A, the glass transition temperature of segment A can be easily adjusted to a desired range, and the flexibility of the electrode material layer can be further improved. Furthermore, by containing a VdF unit in segment A, the solvent solubility of the binder in solvents such as N-methyl-2-pyrrolidone and N,N-dimethylformamide can be improved.

[0030] The content of VdF units in segment A is preferably 99 to 15 mol%, more preferably 94 mol% or less, even more preferably 88 mol% or less, still more preferably 82 mol% or less, particularly preferably 80 mol% or less, more preferably 22 mol% or more, even more preferably 50 mol% or more, still more preferably 60 mol% or more, and particularly preferably 70 mol% or more, based on all monomer units constituting segment A.

[0031] Segment A more preferably contains a VdF unit and at least one repeating unit selected from the group consisting of repeating units represented by any of the following formulas, because this can further improve the flexibility of the electrode material layer and can further improve the solubility of the binder in solvents such as N-methyl-2-pyrrolidone and N,N-dimethylformamide. ２-CF [-CF ３ ]- General formula (b1): -CH ２ -CFRf １ - (wherein, Rf １ is a linear or branched fluorinated alkyl or fluorinated alkoxy group having 1 to 12 carbon atoms, and when the number of carbon atoms is 2 or more, it may contain an oxygen atom between carbon atoms.) General formula (b2): -CHF-CHRf ２ - (wherein, Rf ２ is a linear or branched fluorinated alkyl or fluorinated alkoxy group having 1 to 12 carbon atoms, and when the number of carbon atoms is 2 or more, it may contain an oxygen atom between carbon atoms.

[0032] The content of at least one unit selected from the group consisting of repeating units represented by any of the above formulas in Segment A is preferably 1 to 85 mol%, more preferably 6 mol% or more, even more preferably 12 mol% or more, still more preferably 18 mol% or more, particularly preferably 20 mol% or more, more preferably 78 mol% or less, even more preferably 50 mol% or less, still more preferably 40 mol% or less, and particularly preferably 30 mol% or less, based on all monomer units constituting Segment A.

[0033] Formula: -CF ２ -CF [-CF ３ ]- is a repeating unit based on hexafluoropropylene. Thus, in one embodiment, segment A contains a VdF unit and a hexafluoropropylene unit.

[0034] General formula (b1): -CH ２ -CFRf １ -, Rf １ is a linear or branched fluorinated alkyl group having 1 to 12 carbon atoms, or a linear or branched fluorinated alkoxy group having 1 to 12 carbon atoms. When the fluorinated alkyl group and the fluorinated alkoxy group each have two or more carbon atoms, they can contain an oxygen atom (—O—) between carbon atoms.

[0035] Rf １ The fluorinated alkyl group of Rf may be a partially fluorinated alkyl group in which some of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms, or may be a perfluorinated alkyl group in which all of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms. １ In the fluorinated alkyl group, a hydrogen atom may be substituted with a substituent other than a fluorine atom, but it is preferred that the fluorinated alkyl group does not contain any substituent other than a fluorine atom.

[0036] Rf １ The fluorinated alkoxy group of Rf may be a partially fluorinated alkoxy group in which some of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms, or may be a perfluorinated alkoxy group in which all of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms. １ In the fluorinated alkoxy group of formula (I), a hydrogen atom may be substituted with a substituent other than a fluorine atom, but it is preferred that the fluorinated alkoxy group does not contain any substituent other than a fluorine atom.

[0037] Rf １ The number of carbon atoms in the group is preferably 1 to 10, more preferably 1 to 6, even more preferably 1 to 4, and particularly preferably 1.

[0038] Rf １ As the compound represented by the general formula: -(Rf １１ ) ｍ -(O) ｐ -(Rf １２ -O) ｎ -Rf １３ (wherein, Rf １１ and Rf １２ are independently a linear or branched fluorinated alkylene group having 1 to 4 carbon atoms, Rf １３ is a linear or branched fluorinated alkyl group having 1 to 4 carbon atoms, p is 0 or 1, m is an integer of 0 to 4, and n is an integer of 0 to 4).

[0039] Rf １１ and Rf １２The fluorinated alkylene group of Rf may be a partially fluorinated alkylene group in which some of the hydrogen atoms bonded to the carbon atoms are substituted with fluorine atoms, or may be a perfluorinated alkylene group in which all of the hydrogen atoms bonded to the carbon atoms are substituted with fluorine atoms. １１ and Rf １２ The fluorinated alkylene group Rf may have a hydrogen atom substituted with a substituent other than a fluorine atom, but preferably does not contain any substituent other than a fluorine atom. １１ and Rf １２ may be the same or different in each occurrence.

[0040] Rf １１ Examples of the fluorinated alkylene group include -CHF-, -CF ２ -, -CH ２ -CF ２ -, -CHF-CF ２ -, -CF ２ -CF ２ -, -CF(CF ３ ) -, -CH ２ -CF ２ -CF ２ -, -CHF-CF ２ -CF ２ -, -CF ２ -CF ２ -CF ２ -, -CF(CF ３ )-CF ２ -, -CF ２ -CF (CF ３ ) -, -C(CF ３ ) ２ -, -CH ２ -CF ２ -CF ２ -CF ２ -, -CHF-CF ２ -CF ２ -CF ２ -, -CF ２ -CF ２ -CF ２ -CF ２ -, -CH(CF ３ )-CF ２ -CF ２ -, -CF(CF ３ )-CF ２-CF ２ -, -C(CF ３ ) ２ -CF ２ Among these, a perfluorinated alkylene group having 1 or 2 carbon atoms is preferred, and —CF ２ - is more preferable.

[0041] Rf １２ Examples of the fluorinated alkylene group include -CHF-, -CF ２ -, -CH ２ -CF ２ -, -CHF-CF ２ -, -CF ２ -CF ２ -, -CF(CF ３ ) -, -CH ２ -CF ２ -CF ２ -, -CHF-CF ２ -CF ２ -, -CF ２ -CF ２ -CF ２ -, -CF(CF ３ )-CF ２ -, -CF ２ -CF (CF ３ ) -, -C(CF ３ ) ２ -, -CH ２ -CF ２ -CF ２ -CF ２ -, -CHF-CF ２ -CF ２ -CF ２ -, -CF ２ -CF ２ -CF ２ -CF ２ -, -CH(CF ３ )-CF ２ -CF ２ -, -CF(CF ３ )-CF ２ -CF ２ -, -C(CF ３ ) ２ -CF ２ Among them, a perfluorinated alkylene group having 1 to 3 carbon atoms is preferred, and —CF ２ -, -CF ２ CF ２-, -CF ２ -CF ２ -CF ２ -, -CF(CF ３ )-CF ２ -or-CF ２ -CF (CF ３ )- is more preferred.

[0042] Rf １３ The fluorinated alkyl group of Rf may be a partially fluorinated alkyl group in which some of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms, or a perfluorinated alkyl group in which all of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms. １３ In the fluorinated alkyl group, a hydrogen atom may be substituted with a substituent other than a fluorine atom, but it is preferable that the fluorinated alkyl group does not contain a substituent other than a fluorine atom (for example, a reactive functional group such as —CN, —I, or —Br).

[0043] Rf １３ Examples of the fluorinated alkyl group include —CH ２ F, -CHF ２ , -CF ３ , -CH ２ -CH ２ F, -CH ２ -CHF ２ , -CH ２ -CF ３ , -CHF-CH ２ F, -CHF-CHF ２ , -CHF-CF ３ , -CF ２ -CH ２ F, -CF ２ -CHF ２ , -CF ２ -CF ３ , -CH ２ -CF ２ -CH ２ F, -CHF-CF ２ -CH ２ F, -CF ２ -CF ２ -CH ２ F, -CF(CF ３ )-CH ２ F, -CH ２ -CF ２ -CHF２ , -CHF-CF ２ -CHF ２ , -CF ２ -CF ２ -CHF ２ , -CF(CF ３ )-CHF ２ , -CH ２ -CF ２ -CF ３ , -CHF-CF ２ -CF ３ , -CF ２ -CF ２ -CF ３ , -CF(CF ３ )-CF ３ , -CH ２ -CF ２ -CF ２ -CF ３ , -CHF-CF ２ -CF ２ -CF ３ , -CF ２ -CF ２ -CF ２ -CF ３ , -CH(CF ３ )-CF ２ -CF ３ , -CF(CF ３ )-CF ２ -CF ３ , -C(CF ３ ) ２ -CF ３ etc. are listed, among which, -CF ３ , -CHF-CF ３ , -CF ２ -CHF ２ , -CF ２ -CF ３ , -CF ２ -CF ２ -CF ３ , -CF(CF ３ )-CF ３ , -CF ２ -CF ２ -CF ２ -CF ３ , -CH(CF ３ )-CF ２ -CF ３ or -CF(CF ３ )-CF２ -CF ３ is preferred.

[0044] As p, 0 is preferred.

[0045] m is preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0. When p is 0, m is also preferably 0.

[0046] n is preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0.

[0047] The repeating unit represented by formula (b1) is, for example, —CH ２ -CF [-CF ３ ]-, -CH ２ -CF [-CF ２ CF ３ ]-, -CH ２ -CF [-CF ２ CF ２ CF ３ ]-, -CH ２ -CF [-CF ２ CF ２ CF ２ CF ３ ]-, -CH ２ -CF [-CF ２ -O-CF(CF ３ )-CF ２ -O-CHF-CF ３ ]-, -CH ２ -CF [-CF ２ -O-CF(CF ３ )-CF ２ -O-CF ２ -CF ３ ]-, -CH ２ -CF [-CF ２ -O-CF(CF ３ )-CF ２ -O-CF(CF ３ )-CF ３ ]-, -CH ２ -CF [-CF ２ -O-CF(CF ３ )-CF ２ —O—CH(CF ３ )-CF ２ -CF３ ]-, -CH ２ -CF [-CF ２ -O-CF(CF ３ )-CF ２ -O-CF(CF ３ )-CF ２ -CF ３ ]-, -CH ２ -CF[-OCF ２ OCF ３ ]-, -CH ２ -CF[-OCF ２ CF ２ CF ２ OCF ３ ]-, -CH ２ -CF [-CF ２ OCF ２ OCF ３ ]-, -CH ２ -CF [-CF ２ OCF ２ CF ２ CF ２ OCF ３ ]−, or −CH ２ -CF[-O-CF ２ -CF ３ ]- is preferred, and -CH ２ -CF [-CF ３ ]−, or −CH ２ -CF [-CF ２ -O-CF(CF ３ )-CF ２ -O-CHF-CF ３ ]-, is more preferred.

[0048] General formula (b2): -CHF-CHRf ２ -, Rf ２ is a linear or branched fluorinated alkyl group having 1 to 12 carbon atoms, or a linear or branched fluorinated alkoxy group having 1 to 12 carbon atoms. When the fluorinated alkyl group and the fluorinated alkoxy group each have two or more carbon atoms, they can contain an oxygen atom (—O—) between carbon atoms.

[0049] Rf ２The fluorinated alkyl group of Rf may be a partially fluorinated alkyl group in which some of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms, or may be a perfluorinated alkyl group in which all of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms. ２ In the fluorinated alkyl group, a hydrogen atom may be substituted with a substituent other than a fluorine atom, but it is preferred that the fluorinated alkyl group does not contain any substituent other than a fluorine atom.

[0050] Rf ２ The fluorinated alkoxy group of Rf may be a partially fluorinated alkoxy group in which some of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms, or may be a perfluorinated alkoxy group in which all of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms. ２ In the fluorinated alkoxy group of formula (I), a hydrogen atom may be substituted with a substituent other than a fluorine atom, but it is preferred that the fluorinated alkoxy group does not contain any substituent other than a fluorine atom.

[0051] Rf ２ The number of carbon atoms in the group is preferably 1 to 10, more preferably 1 to 6, even more preferably 1 to 4, and particularly preferably 1.

[0052] Rf ２ As the compound represented by the general formula: -(Rf ２１ ) ｍ -(O) ｐ -(Rf ２２ -O) ｎ -Rf ２３ (wherein, Rf ２１ and Rf ２２ are independently a linear or branched fluorinated alkylene group having 1 to 4 carbon atoms, Rf ２３ is a linear or branched fluorinated alkyl group having 1 to 4 carbon atoms, p is 0 or 1, m is an integer of 0 to 4, and n is an integer of 0 to 4.

[0053] Rf ２１ and Rf ２２The fluorinated alkylene group of Rf may be a partially fluorinated alkylene group in which some of the hydrogen atoms bonded to the carbon atoms are substituted with fluorine atoms, or may be a perfluorinated alkylene group in which all of the hydrogen atoms bonded to the carbon atoms are substituted with fluorine atoms. ２１ and Rf ２２ The fluorinated alkylene group Rf may have a hydrogen atom substituted with a substituent other than a fluorine atom, but preferably does not contain any substituent other than a fluorine atom. ２１ and Rf ２２ may be the same or different in each occurrence.

[0054] Rf ２１ Examples of the fluorinated alkylene group include -CHF-, -CF ２ -, -CH ２ -CF ２ -, -CHF-CF ２ -, -CF ２ -CF ２ -, -CF(CF ３ ) -, -CH ２ -CF ２ -CF ２ -, -CHF-CF ２ -CF ２ -, -CF ２ -CF ２ -CF ２ -, -CF(CF ３ )-CF ２ -, -CF ２ -CF (CF ３ ) -, -C(CF ３ ) ２ -, -CH ２ -CF ２ -CF ２ -CF ２ -, -CHF-CF ２ -CF ２ -CF ２ -, -CF ２ -CF ２ -CF ２ -CF ２ -, -CH(CF ３ )-CF ２ -CF ２ -, -CF(CF ３ )-CF ２-CF ２ -, -C(CF ３ ) ２ -CF ２ Among these, a perfluorinated alkylene group having 1 or 2 carbon atoms is preferred, and —CF ２ - is more preferable.

[0055] Rf ２２ Examples of the fluorinated alkylene group include -CHF-, -CF ２ -, -CH ２ -CF ２ -, -CHF-CF ２ -, -CF ２ -CF ２ -, -CF(CF ３ ) -, -CH ２ -CF ２ -CF ２ -, -CHF-CF ２ -CF ２ -, -CF ２ -CF ２ -CF ２ -, -CF(CF ３ )-CF ２ -, -CF ２ -CF (CF ３ ) -, -C(CF ３ ) ２ -, -CH ２ -CF ２ -CF ２ -CF ２ -, -CHF-CF ２ -CF ２ -CF ２ -, -CF ２ -CF ２ -CF ２ -CF ２ -, -CH(CF ３ )-CF ２ -CF ２ -, -CF(CF ３ )-CF ２ -CF ２ -, -C(CF ３ ) ２ -CF ２ Among them, a perfluorinated alkylene group having 1 to 3 carbon atoms is preferred, and —CF ２ -, -CF ２ CF ２-, -CF ２ -CF ２ -CF ２ -, -CF(CF ３ )-CF ２ -or-CF ２ -CF (CF ３ )- is more preferred.

[0056] Rf ２３ The fluorinated alkyl group of Rf may be a partially fluorinated alkyl group in which some of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms, or a perfluorinated alkyl group in which all of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms. ２３ In the fluorinated alkyl group, a hydrogen atom may be substituted with a substituent other than a fluorine atom, but it is preferable that the fluorinated alkyl group does not contain a substituent other than a fluorine atom (for example, a reactive functional group such as —CN, —I, or —Br).

[0057] Rf ２３ Examples of the fluorinated alkyl group include —CH ２ F, -CHF ２ , -CF ３ , -CH ２ -CH ２ F, -CH ２ -CHF ２ , -CH ２ -CF ３ , -CHF-CH ２ F, -CHF-CHF ２ , -CHF-CF ３ , -CF ２ -CH ２ F, -CF ２ -CHF ２ , -CF ２ -CF ３ , -CH ２ -CF ２ -CH ２ F, -CHF-CF ２ -CH ２ F, -CF ２ -CF ２ -CH ２ F, -CF(CF ３ )-CH ２ F, -CH ２ -CF ２ -CHF２ , -CHF-CF ２ -CHF ２ , -CF ２ -CF ２ -CHF ２ , -CF(CF ３ )-CHF ２ , -CH ２ -CF ２ -CF ３ , -CHF-CF ２ -CF ３ , -CF ２ -CF ２ -CF ３ , -CF(CF ３ )-CF ３ , -CH ２ -CF ２ -CF ２ -CF ３ , -CHF-CF ２ -CF ２ -CF ３ , -CF ２ -CF ２ -CF ２ -CF ３ , -CH(CF ３ )-CF ２ -CF ３ , -CF(CF ３ )-CF ２ -CF ３ , -C(CF ３ ) ２ -CF ３ etc. are included. Among them, -CF ３ , -CHF-CF ３ , -CF ２ -CHF ２ , -CF ２ -CF ３ , -CF ２ -CF ２ -CF ３ , -CF(CF ３ )-CF ３ , -CF ２ -CF ２ -CF ２ -CF ３ , -CH(CF ３ )-CF ２ -CF ３ or -CF(CF ３ )-CF２ -CF ３ is preferred.

[0058] As p, 0 is preferred.

[0059] m is preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0. When p is 0, m is also preferably 0.

[0060] n is preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0.

[0061] Examples of the repeating unit represented by general formula (b2) include: -CHF-CH[-CF ３ ]-, -CHF-CH[-CF ２ CF ３ ]-, -CHF-CH[-CF ２ CF ２ CF ３ ]-, or -CHF-CH[-CF ２ CF ２ CF ２ CF ３ ]-, is preferred, and -CHF-CH[-CF ３ ] - is more preferred.

[0062] In particular, it is preferable that segment A contains VdF units and 2,3,3,3-tetrafluoropropene units. By containing VdF units and 2,3,3,3-tetrafluoropropene units in segment A, the flexibility of the electrode material layer can be further improved and an electrode mixture with excellent viscosity stability can be obtained. In addition, the solubility of the binder in solvents such as N-methyl-2-pyrrolidone and N,N-dimethylformamide can be improved.

[0063] The content of 2,3,3,3-tetrafluoropropene units in segment A is preferably 1 to 85 mol %, more preferably 6 mol % or more, even more preferably 12 mol % or more, still more preferably 18 mol % or more, particularly preferably 20 mol % or more, more preferably 78 mol % or less, even more preferably 50 mol % or less, still more preferably 40 mol % or less, and particularly preferably 30 mol % or less, based on all monomer units constituting segment A.

[0064] In one embodiment, segment A can be formed by a 2,3,3,3-tetrafluoropropene / VdF copolymer or a 2,3,3,3-tetrafluoropropene / VdF / TFE copolymer.

[0065] In the 2,3,3,3-tetrafluoropropene / VdF copolymer, the composition (mol %) of 2,3,3,3-tetrafluoropropene units / VdF units is preferably (18 to 40) / (82 to 60), more preferably (20 to 30) / (80 to 70).

[0066] In the 2,3,3,3-tetrafluoropropene / VdF / TFE copolymer, the composition (mol %) of 2,3,3,3-tetrafluoropropene units / VdF units / TFE units is preferably (18 to 40) / (81 to 25) / (1 to 35), more preferably (20 to 40) / (75 to 30) / (5 to 30).

[0067] In one embodiment, segment A contains 2,3,3,3-tetrafluoropropene units and VdF units, and the content of monomer units other than 2,3,3,3-tetrafluoropropene units and VdF units is preferably 0 to 10 mol %, more preferably 0 to 2 mol %, even more preferably 0 to 1 mol %, still more preferably 0 to 0.1 mol %, and particularly preferably 0 mol %, based on all monomer units constituting segment A. The content of 2,3,3,3-tetrafluoropropene units and the content of VdF units may be within the ranges described above.

[0068] (Polymer Segment B) Segment B has a melting point of 50° C. or higher. The melting point of segment B is preferably 90° C. or higher, more preferably 140° C. or higher, and preferably 240° C. or lower, more preferably 220° C. or lower, and even more preferably 200° C. or lower. The first binder for nonaqueous electrolyte batteries contains a polymer including segment B having a melting point in addition to segment A having a glass transition temperature, and therefore can form an electrode material layer that is excellent in flexibility and toughness.

[0069] The melting point can be determined by using a differential scanning calorimetry (DSC) device to raise the temperature of a sample from 30° C. to 220° C. at a rate of 10° C. / min, and measuring the temperature at the peak of the endothermic curve obtained.

[0070] Generally, the melting point of segment B is the same as the melting point of the first polymer, so the melting point of segment B in the first polymer can be determined by measuring the melting point of the first polymer.

[0071] The heat of fusion of segment B is preferably 5 J / g or more, more preferably 10 J / g or more, even more preferably 30 J / g or more, still more preferably 35 J / g or more, and is preferably 90 J / g or less, more preferably 60 J / g or less, and even more preferably 55 J / g or less, because this can further improve the flexibility and toughness of the electrode material layer.

[0072] The heat of fusion can be calculated from the magnitude of the melting peak (ΔH) of the endothermic curve obtained by heating a sample from 30° C. to 220° C. at a rate of 10° C. / min using a differential scanning calorimetry (DSC) device.

[0073] Segment B preferably contains a fluorine-containing monomer unit because this can improve the oxidation resistance and electrolyte resistance of the electrode material layer. The fluorine-containing monomer that can constitute Segment B is not particularly limited as long as it is a monomer containing a fluorine atom, and examples thereof include vinylidene fluoride [VdF], trifluoroethylene, tetrafluoroethylene [TFE], hexafluoropropylene, perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether), chlorotrifluoroethylene, hexafluoroisobutene, and vinyl fluoride.

[0074] The content of the fluorine-containing monomer unit in segment B is preferably 50 mol % or more, more preferably 90 mol % or more, even more preferably 99 mol % or more, and preferably 100 mol % or less, based on all monomer units constituting segment B.

[0075] Segment B may further contain a non-fluorine-containing monomer unit. Examples of the non-fluorine-containing monomer include ethylene, propylene, and alkyl vinyl ether. The content of the non-fluorine-containing monomer unit is preferably 0 to 50 mol %, more preferably 0 to 10 mol %, and even more preferably 0 to 1 mol %, relative to all monomer units constituting segment B, and may even be 0 mol %.

[0076] Segment B may further contain units based on a monomer having a polar group such as a carbonyl group-containing group, an epoxy group, a hydroxy group, a sulfonic acid group, a sulfate group, a phosphate group, an amino group, an amide group, or an alkoxy group.

[0077] Examples of monomers having a polar group include hydroxyalkyl (meth)acrylates such as hydroxyethyl acrylate and 2-hydroxypropyl acrylate; unsaturated monobasic acids such as (meth)acrylic acid, crotonic acid, vinylacetic acid (3-butenoic acid), 3-pentenoic acid, 4-pentenoic acid, 3-hexenoic acid, and 4-heptenoic acid; unsaturated dibasic acids such as maleic acid, maleic anhydride, citraconic acid, and citraconic anhydride; alkylidene malonic acid esters such as dimethyl methylidene malonate; and vinyl carboxyalkyl ethers such as vinyl carboxymethyl ether and vinyl carboxyethyl ether. carboxyalkyl (meth)acrylates such as 2-carboxyethyl acrylate and 2-carboxyethyl methacrylate; (meth)acryloyloxyalkyl dicarboxylic acid esters such as acryloyloxyethyl succinate, methacryloyloxyethyl succinate, acryloyloxyethyl phthalate, acryloyloxypropyl succinate and methacryloyloxyethyl phthalate; monoesters of unsaturated dibasic acids such as maleic acid monomethyl ester, maleic acid monoethyl ester, citraconic acid monomethyl ester and citraconic acid monoethyl ester; and the like.

[0078] Segment B preferably contains at least a VdF unit as a fluorine-containing monomer unit. By containing a VdF unit in segment B, the melting point of segment B can be easily adjusted within a desired range, the toughness of the electrode material layer can be further improved, and an electrode material layer with excellent electrolyte resistance can be formed. Furthermore, by containing a VdF unit in segment B, the solvent solubility of the binder in solvents such as N-methyl-2-pyrrolidone and N,N-dimethylformamide can be improved.

[0079] Segment B may contain, in addition to VdF units, other monomer units other than VdF units. The other monomers may be either fluorine-containing or non-fluorine-containing monomers, and are preferably fluorine-containing monomers (excluding trifluoroethylene) or non-fluorine-containing monomers.

[0080] Examples of fluorine-containing monomers that can form segment B together with VdF include TFE, hexafluoropropylene, perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether), chlorotrifluoroethylene, hexafluoroisobutene, and vinyl fluoride.

[0081] Examples of the fluorine-free monomer that can constitute the segment B together with VdF include ethylene and propylene.

[0082] In addition to the VdF unit, segment B may further contain a unit based on a monomer unit having a polar group such as a carbonyl group-containing group, an epoxy group, a hydroxy group, a sulfonic acid group, a sulfate group, a phosphate group, an amino group, an amide group, or an alkoxy group. Examples of the monomer having a polar group are as already mentioned.

[0083] Among other monomers that can constitute segment B together with VdF, at least one selected from the group consisting of TFE, hexafluoropropylene, 2,3,3,3-tetrafluoropropene, and (meth)acrylic acid is preferred.

[0084] The content of VdF units in segment B can further improve the toughness and electrolyte resistance of the electrode material layer and further improve the solvent solubility of the binder in solvents such as N-methyl-2-pyrrolidone and N,N-dimethylformamide, and therefore, is preferably 97 mol % or more, more preferably more than 99 mol %, and even more preferably 99.5 mol % or more and 100 mol % or less, based on the total monomer units constituting segment B.

[0085] The content of other monomer units than VdF units in segment B can further improve the toughness and electrolyte resistance of the electrode material layer and further improve the solvent solubility of the binder in solvents such as N-methyl-2-pyrrolidone and N,N-dimethylformamide. Therefore, the content of other monomer units than VdF units is preferably 3 mol % or less, more preferably less than 1 mol %, and even more preferably 0.5 mol % or less, relative to all monomer units constituting segment B, and may be 0 mol % or more.

[0086] In one embodiment, segment B can be formed from a VdF homopolymer containing only VdF units, or a copolymer containing VdF units and at least one other monomer unit selected from the group consisting of TFE units, hexafluoropropylene units, 2,3,3,3-tetrafluoropropene units, and (meth)acrylic acid units.

[0087] In a copolymer containing VdF units and other monomer units, the composition (mol %) of VdF units / other monomer units is preferably (97.0 to 99.9) / (3.0 to 0.1).

[0088] The polymer contained in the first binder for a nonaqueous electrolyte battery may contain another segment C having a different structure from the segments A and B, as long as the polymer contains the segments A and B.

[0089] The polymer contained in the first binder for nonaqueous electrolyte batteries may be a block copolymer containing a chain structure represented by any of the following general formulas: General formula: A-B General formula: A-B-A General formula: B-A-B General formula: A-B-C General formula: B-A-C (wherein A represents segment A, B represents segment B, and C represents segment C).

[0090] The polymer contained in the first binder for nonaqueous electrolyte batteries preferably contains a chain structure represented by general formula (1) or general formula (2), because it can form an electrode material layer with even greater flexibility and toughness and is easy to manufacture. General formula (1): A-B-A General formula (2): B-A-B (wherein A represents segment A and B represents segment B).

[0091] As for the polymer contained in the first binder for nonaqueous electrolyte batteries, the mass ratio (A / B) of segment A to segment B is preferably 40 / 60 to 95 / 5, more preferably 50 / 50 or more, even more preferably 60 / 40 or more, and more preferably 90 / 10 or less, from the viewpoint of a balance between excellent flexibility and excellent toughness.

[0092] The number average molecular weight (polystyrene equivalent) of the polymer contained in the first binder for nonaqueous electrolyte batteries is preferably 20,000 to 1,500,000, more preferably 40,000 or more, even more preferably 70,000 or more, particularly preferably 140,000 or more, more preferably 1,400,000 or less, even more preferably 1,200,000 or less, and particularly preferably 1,100,000 or less. The number average molecular weight can be measured by gel permeation chromatography (GPC) using dimethylformamide as a solvent.

[0093] The weight average molecular weight (polystyrene equivalent) of the polymer contained in the first binder for nonaqueous electrolyte batteries is preferably 50,000 to 3,000,000, more preferably 80,000 or more, even more preferably 100,000 or more, still more preferably 200,000 or more, particularly preferably 500,000 or more, more preferably 2,400,000 or less, even more preferably 2,200,000 or less, and particularly preferably 2,000,000 or less. The weight average molecular weight can be measured by gel permeation chromatography (GPC) using dimethylformamide as a solvent.

[0094] The polymer contained in the first binder for nonaqueous electrolyte batteries can be produced by, for example, the following production methods: (1) a method of preparing a polymer that forms segment B by polymerizing a monomer that can form segment B in the presence of a bromine compound or an iodine compound as a chain transfer agent, and preparing a polymer that forms segment A by polymerizing a monomer that can form segment A in the presence of the polymer that forms segment B; or (2) a method of preparing a polymer that forms segment A by polymerizing a monomer that can form segment A in the presence of a bromine compound or an iodine compound as a chain transfer agent, and preparing a polymer that forms segment B by polymerizing a monomer that can form segment B in the presence of the polymer that forms segment A.

[0095] When method (1) is used, a polymer is obtained in which segment A is bonded to both ends of a polymer chain forming segment B, i.e., a polymer containing a chain structure represented by general formula (1): A-B-A.

[0096] Furthermore, when method (2) is used, a polymer is obtained in which segment B is bonded to both ends of a polymer chain forming segment A, i.e., a polymer containing a chain structure represented by general formula (2): B-A-B.

[0097] In the methods (1) and (2), a bromine compound or an iodine compound is used as a chain transfer agent. By using a bromine compound or an iodine compound, an iodine atom or a bromine atom is introduced into the end of a polymer chain forming one segment, and functions as a binding site for another segment.

[0098] The polymerization method using a bromine compound or an iodine compound includes, for example, a method of emulsion polymerization in an aqueous medium under pressure in the presence of a bromine compound or an iodine compound in a substantially oxygen-free state (iodine transfer polymerization method). ８ I ｘ Br ｙ (wherein x and y are each an integer of 0 to 2 and satisfy 1≦x+y≦2; R ８ is a saturated or unsaturated fluorohydrocarbon group or chlorofluorohydrocarbon group having 1 to 16 carbon atoms, or a hydrocarbon group having 1 to 3 carbon atoms, which may contain an oxygen atom).

[0099] Examples of iodine compounds include 1,3-diiodoperfluoropropane, 2-iodoperfluoropropane, 1,3-diiodo-2-chloroperfluoropropane, 1,4-diiodoperfluorobutane, 1,5-diiodo-2,4-dichloroperfluoropentane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane, 1,12-diiodoperfluorododecane, 1,16-diiodoperfluorohexadecane, diiodomethane, 1,2-diiodoethane, 1,3-diiodo-n-propane, CF ２ Br ２ , BrCF ２ CF ２ Br, CF ３ CFBrCF ２ Br, CFClBr ２ , BrCF ２ CFClBr, CFBrClCFClBr, BrCF ２ CF ２ CF ２ Br, BrCF ２ CFBrOCF ３ , 1-bromo-2-iodoperfluoroethane, 1-bromo-3-iodoperfluoropropane, 1-bromo-4-iodoperfluorobutane, 2-bromo-3-iodoperfluorobutane, 3-bromo-4-iodoperfluorobutene-1, 2-bromo-4-iodoperfluorobutene-1, monoiodomonobromo-substituted benzene, diiodomonobromo-substituted benzene, and (2-iodoethyl) and (2-bromoethyl) substituted benzenes, and these compounds may be used alone or in combination with each other.

[0100] Among these, it is preferable to use 1,4-diiodoperfluorobutane, 1,6-diiodoperfluorohexane, and 2-iodoperfluoropropane in terms of polymerization reactivity, crosslinking reactivity, availability, and the like.

[0101] In the above-mentioned production method, the polymerization of the monomer is preferably carried out by emulsion polymerization. In one embodiment, the polymerization of the monomer is carried out in the presence of a polymerization initiator, a surfactant, and a solvent.

[0102] The polymerization initiator may be an oil-soluble radical polymerization initiator or a water-soluble radical initiator.

[0103] The oil-soluble radical polymerization initiator may be a known oil-soluble peroxide, for example, dialkyl peroxycarbonates such as diisopropyl peroxydicarbonate and disec-butyl peroxydicarbonate, peroxyesters such as t-butyl peroxyisobutyrate and t-butyl peroxypivalate, and dialkyl peroxides such as di-t-butyl peroxide, as well as di(ω-hydro-dodecafluoroheptanoyl) peroxide, di(ω-hydro-tetradecafluorooctanoyl) peroxide, di(ω-hydro-hexadecafluorononanoyl) peroxide, di(perfluorobutyryl) peroxide, di(perfluparyl) peroxide, di(perfluorohexanoyl) peroxide, di(perfluoroheptanoyl) peroxide, di(perfluorooctanoyl) peroxide, di(perfluorononanoyl) peroxide, di(ω-chloro- Representative examples include di[perfluoro(or fluorochloro)acyl]peroxides such as di(hexafluorobutyryl)peroxide, di(ω-chlorodecafluorohexanoyl)peroxide, di(ω-chlorotetradecafluorooctanoyl)peroxide, ω-hydro-dodecafluoroheptanoyl-ω-hydrohexadecafluorononanoyl-peroxide, ω-chloro-hexafluorobutyryl-ω-chloro-decafluorohexanoyl-peroxide, ω-hydrododecafluoroheptanoyl-perfluorobutyryl-peroxide, di(dichloropentafluorobutanoyl)peroxide, di(trichlorooctafluorohexanoyl)peroxide, di(tetrachloroundecafluorooctanoyl)peroxide, di(pentachlorotetradecafluorodecanoyl)peroxide, and di(undecachlorodotriacontafluorodocosanoyl)peroxide.

[0104] The water-soluble radical polymerization initiator may be a known water-soluble peroxide, such as ammonium salts, potassium salts, or sodium salts of persulfuric acid, perborate, perchloric acid, perphosphoric acid, or percarbonate, t-butyl permaleate, or t-butyl hydroperoxide. A reducing agent such as a sulfite may also be contained, and the amount used may be 0.1 to 20 times the amount of the peroxide.

[0105] The amount of polymerization initiator to be added is not particularly limited, but may be added all at once, stepwise, or continuously at the beginning of polymerization in an amount (for example, several ppm relative to water concentration) that does not significantly decrease the polymerization rate. The upper limit is within the range in which the heat of polymerization reaction can be removed from the equipment.

[0106] The surfactant may be a nonionic surfactant, an anionic surfactant, a cationic surfactant, etc. The amount added (relative to the solvent) is preferably 10 ppm by mass to 20% by mass, more preferably 10 ppm by mass to 10% by mass, still more preferably 10 to 5000 ppm by mass, and particularly preferably 50 to 5000 ppm by mass.

[0107] Furthermore, a polymerizable emulsifier may be used as the surfactant. The polymerizable emulsifier is not particularly limited as long as it is a compound having at least one unsaturated bond and at least one hydrophilic group. For example, ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COONH ４ , C.H. ２ =CFCF ２ CF (CF ３ ) OCF ２ CF ２ COONH ４ , C.F. ２ = CFOCF ２ CF (CF ３ ) OCF (CF ３ ) COONH ４ The amount added (relative to the solvent) is preferably 10 to 5000 ppm by mass, and more preferably 50 to 5000 ppm by mass.

[0108] The solvent is preferably one that does not have chain transfer properties, and examples of the solvent include water, a mixture of water and a water-soluble organic solvent, and a mixture of water and a water-insoluble organic solvent.

[0109] In the polymerization of the monomer, the polymerization temperature, polymerization pressure, and polymerization time vary depending on the type of solvent and polymerization initiator, but may be -15 to 150°C, atmospheric pressure to 6.5 MPa, and 1 to 24 hours. When an oil-soluble radical polymerization initiator is used as the polymerization initiator, the polymerization temperature is preferably 30 to 95°C. When a water-soluble radical polymerization initiator is used as the polymerization initiator, the polymerization temperature is preferably 0 to 100°C, and more preferably 10 to 95°C.

[0110] When the polymerization of the monomer is carried out by emulsion polymerization, an aqueous dispersion containing the polymer is obtained. In the above-mentioned production method, the polymer in the aqueous dispersion is coagulated, washed with water, dehydrated, and dried to obtain a polymer powder. The coagulation can be carried out by adding an inorganic salt such as aluminum sulfate or an inorganic acid to the dispersion, by applying mechanical shear force to the dispersion, or by freezing the dispersion.

[0111] The polymer contained in the first binder for nonaqueous electrolyte batteries can also be produced by using at least 2,3,3,3-tetrafluoropropene as a monomer according to the methods described in Japanese Patent Laid-Open No. 53-3495 and Japanese Patent Publication No. 61-49327.

[0112] 2. Second Binder for Non-Aqueous Electrolyte Battery The second binder for non-aqueous electrolyte batteries of the present disclosure contains a polymer having a glass transition temperature and a melting point, which contains 2,3,3,3-tetrafluoropropene units and has a tetrahydrofuran extractable amount at 25°C of 5 mass% or less.

[0113] The glass transition temperature of the polymer contained in the second binder for nonaqueous electrolyte batteries is preferably 25° C. or lower, more preferably 0° C. or lower, even more preferably −5° C. or lower, and even more preferably −10° C. or lower, and although there is no lower limit, it may be −40° C. or higher. Since the second binder for nonaqueous electrolyte batteries contains a polymer having a glass transition temperature, it can form an electrode material layer having excellent flexibility.

[0114] The glass transition temperature can be determined by using a differential scanning calorimeter (DSC822e manufactured by Mettler Toledo or X-DSC7000 manufactured by Hitachi High-Tech Science Corporation) to obtain a DSC curve by cooling 10 mg of a sample to −75° C. and then raising the temperature at 20° C. / min, and determining the temperature indicating the intersection point between an extension of the baseline before and after the second-order transition of the DSC curve and a tangent to the inflection point of the DSC curve as the glass transition temperature.

[0115] The melting point of the polymer contained in the second binder for nonaqueous electrolyte batteries is preferably 50° C. or higher, more preferably 90° C. or higher, even more preferably 140° C. or higher, and preferably 240° C. or lower, more preferably 220° C. or lower, and even more preferably 200° C. or lower. The second binder for nonaqueous electrolyte batteries has a glass transition temperature and contains a polymer having a melting point, and therefore, an electrode material layer having excellent flexibility and toughness can be formed.

[0116] The melting point can be determined by using a differential scanning calorimetry (DSC) device to raise the temperature of a sample from 30° C. to 220° C. at a rate of 10° C. / min, and measuring the temperature at the peak of the endothermic curve obtained.

[0117] The tetrahydrofuran extractable amount of the polymer contained in the second binder for nonaqueous electrolyte batteries is 5% by mass or less, preferably 4% by mass or less, and more preferably 3% by mass or less. Since the second binder for nonaqueous electrolyte batteries contains a polymer having a tetrahydrofuran extractable amount within the above numerical range, an electrode material layer having excellent flexibility and toughness can be formed. The lower limit of the tetrahydrofuran extractable amount is not particularly limited, but may be 1% by mass or more or 2% by mass or more.

[0118] The amount of tetrahydrofuran extractables can be measured by a method in which a polymer is immersed in tetrahydrofuran at 25° C. for 24 hours, and the filtered solution is dried and solidified.

[0119] The polymer contained in the second binder for nonaqueous electrolyte batteries contains 2,3,3,3-tetrafluoropropene units. Because the second binder for nonaqueous electrolyte batteries contains 2,3,3,3-tetrafluoropropene units, it is possible to impart solvent solubility to the binder in solvents such as N-methyl-2-pyrrolidone and N,N-dimethylformamide, thereby forming an electrode material layer that is excellent in flexibility and toughness, and furthermore, it is possible to obtain an electrode mixture that is excellent in viscosity stability, and to form an electrode material layer that is excellent in electrolyte resistance.

[0120] The polymer contained in the second binder for nonaqueous electrolyte batteries preferably contains a fluorine-containing monomer unit (excluding 2,3,3,3-tetrafluoropropene units). By introducing the fluorine-containing monomer unit into the polymer, the glass transition temperature and melting point of the polymer can be easily adjusted, an electrode material layer having even more excellent flexibility and toughness can be formed, and an electrode mixture having even more excellent viscosity stability can be obtained, allowing the formation of an electrode material layer having even more excellent electrolyte resistance.

[0121] The fluorine-containing monomer that can constitute the polymer contained in the second binder for nonaqueous electrolyte batteries is not particularly limited as long as it is a monomer other than 2,3,3,3-tetrafluoropropene and contains a fluorine atom, and examples thereof include vinylidene fluoride [VdF], trifluoroethylene, tetrafluoroethylene [TFE], hexafluoropropylene, perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether), chlorotrifluoroethylene, hexafluoroisobutene, and vinyl fluoride.

[0122] The fluorine-containing monomer capable of constituting the polymer contained in the second binder for nonaqueous electrolyte batteries is preferably at least one selected from the group consisting of VdF, TFE, hexafluoropropylene, perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether), and chlorotrifluoroethylene, more preferably at least one selected from the group consisting of VdF and TFE, and even more preferably VdF.

[0123] When the polymer contained in the second binder for nonaqueous electrolyte batteries contains a VdF unit as a fluorine-containing monomer unit, the solvent solubility of the binder in solvents such as N-methyl-2-pyrrolidone and N,N-dimethylformamide is further improved, and by using the second binder for nonaqueous electrolyte batteries, an electrode material layer having even more excellent flexibility and toughness can be formed. Furthermore, an electrode mixture having even more excellent viscosity stability can be obtained, and an electrode material layer having even more excellent electrolyte resistance can be formed.

[0124] The content of 2,3,3,3-tetrafluoropropene units in the polymer contained in the second binder for nonaqueous electrolyte batteries is preferably 1 to 65 mol %, more preferably 5 mol % or more, even more preferably 9 mol % or more, still more preferably 12 mol % or more, particularly preferably 14 mol % or more, more preferably 62 mol % or less, even more preferably 40 mol % or less, still more preferably 32 mol % or less, and particularly preferably 24 mol % or less, based on all monomer units constituting the polymer.

[0125] The content of the fluorine-containing monomer unit in the polymer contained in the second binder for nonaqueous electrolyte batteries is preferably 99 to 35 mol %, more preferably 95 mol % or less, even more preferably 91 mol % or less, still more preferably 88 mol % or less, particularly preferably 86 mol % or less, more preferably 38 mol % or more, even more preferably 60 mol % or more, still more preferably 68 mol % or more, and particularly preferably 76 mol % or more, based on all monomer units constituting the polymer.

[0126] The content of VdF units in the polymer contained in the second binder for nonaqueous electrolyte batteries is preferably 99 to 35 mol %, more preferably 95 mol % or less, even more preferably 91 mol % or less, still more preferably 88 mol % or less, particularly preferably 86 mol % or less, more preferably 38 mol % or more, even more preferably 60 mol % or more, still more preferably 68 mol % or more, and particularly preferably 76 mol % or more, based on all monomer units constituting the polymer.

[0127] The polymer contained in the second binder for nonaqueous electrolyte batteries may further contain a non-fluorine-containing monomer unit. Examples of the non-fluorine-containing monomer include ethylene, propylene, and alkyl vinyl ether. The content of the non-fluorine-containing monomer unit is preferably 0 to 40 mol %, more preferably 0 to 8 mol %, and even more preferably 0 to 1 mol %, based on the total monomer units constituting the polymer.

[0128] The polymer contained in the second binder for a nonaqueous electrolyte battery contains a cyano group, a carboxyl group, an alkoxycarbonyl group, I, Br, —CH ２ The polymer may further contain units based on a monomer having a reactive group such as OH or a carbon-carbon double bond. The content of units based on a monomer having a reactive group is preferably 0 to 10 mol %, more preferably 0 to 2 mol %, and even more preferably 0 to 1 mol %, based on all monomer units constituting the polymer, and may be 0 mol %.

[0129] The polymer contained in the second binder for nonaqueous electrolyte batteries may further contain units based on a monomer having a polar group such as a carbonyl group-containing group, an epoxy group, a hydroxy group, a sulfonic acid group, a sulfate group, a phosphate group, an amino group, an amide group, or an alkoxy group.

[0130] Examples of monomers having a polar group include hydroxyalkyl (meth)acrylates such as hydroxyethyl acrylate and 2-hydroxypropyl acrylate; unsaturated monobasic acids such as (meth)acrylic acid, crotonic acid, vinylacetic acid (3-butenoic acid), 3-pentenoic acid, 4-pentenoic acid, 3-hexenoic acid, and 4-heptenoic acid; unsaturated dibasic acids such as maleic acid, maleic anhydride, citraconic acid, and citraconic anhydride; alkylidene malonic acid esters such as dimethyl methylidene malonate; and vinyl carboxyalkyl ethers such as vinyl carboxymethyl ether and vinyl carboxyethyl ether. carboxyalkyl (meth)acrylates such as 2-carboxyethyl acrylate and 2-carboxyethyl methacrylate; (meth)acryloyloxyalkyl dicarboxylic acid esters such as acryloyloxyethyl succinate, methacryloyloxyethyl succinate, acryloyloxyethyl phthalate, acryloyloxypropyl succinate and methacryloyloxyethyl phthalate; monoesters of unsaturated dibasic acids such as maleic acid monomethyl ester, maleic acid monoethyl ester, citraconic acid monomethyl ester and citraconic acid monoethyl ester; and the like.

[0131] The content of units based on monomers having a polar group is preferably 0 to 10 mol %, more preferably 0 to 2 mol %, and even more preferably 0 to 1 mol %, relative to all monomer units constituting the polymer, and may be 0 mol %.

[0132] In one embodiment, the polymer contained in the second binder for nonaqueous electrolyte batteries contains 2,3,3,3-tetrafluoropropene units and fluorine-containing monomer units (excluding 2,3,3,3-tetrafluoropropene units), and the content of monomer units other than 2,3,3,3-tetrafluoropropene units and fluorine-containing monomer units is preferably 0 to 10 mol %, more preferably 0 to 2 mol %, even more preferably 0 to 1 mol %, still more preferably 0 to 0.1 mol %, and particularly preferably 0 mol %, based on all monomer units constituting the polymer. The content of 2,3,3,3-tetrafluoropropene units and the content of fluorine-containing monomer units may be within the ranges described above.

[0133] In one embodiment, the polymer contained in the second binder for nonaqueous electrolyte batteries contains 2,3,3,3-tetrafluoropropene units and VdF units, and the content of monomer units other than 2,3,3,3-tetrafluoropropene units and VdF units is preferably 0 to 10 mol %, more preferably 0 to 2 mol %, even more preferably 0 to 1 mol %, still more preferably 0 to 0.1 mol %, and particularly preferably 0 mol %, based on all monomer units constituting the polymer. The content of 2,3,3,3-tetrafluoropropene units and the content of VdF units may be within the ranges described above.

[0134] The number average molecular weight (polystyrene equivalent) of the polymer contained in the second binder for nonaqueous electrolyte batteries is preferably 20,000 to 1,500,000, more preferably 40,000 or more, even more preferably 70,000 or more, particularly preferably 140,000 or more, more preferably 1,400,000 or less, even more preferably 1,200,000 or less, and particularly preferably 1,100,000 or less. The number average molecular weight can be measured by gel permeation chromatography (GPC) using dimethylformamide as a solvent.

[0135] The weight average molecular weight (polystyrene equivalent) of the polymer contained in the second binder for nonaqueous electrolyte batteries is preferably 50,000 to 3,000,000, more preferably 80,000 or more, even more preferably 100,000 or more, still more preferably 200,000 or more, particularly preferably 500,000 or more, more preferably 2,400,000 or less, even more preferably 2,200,000 or less, and particularly preferably 2,000,000 or less. The weight average molecular weight can be measured by gel permeation chromatography (GPC) using dimethylformamide as a solvent.

[0136] The heat of fusion of the polymer contained in the second binder for nonaqueous electrolyte batteries is preferably 1 J / g or more, more preferably 3 J / g or more, even more preferably 5 J / g or more, still more preferably 8 J / g or more, and is preferably 40 J / g or less, more preferably 30 J / g or less, and even more preferably 20 J / g or less.

[0137] In one embodiment, the polymer contained in the second binder for a nonaqueous electrolyte battery includes two or more segments. By configuring the polymer with two or more segments, it is possible to easily impart a glass transition temperature and a melting point to the polymer, and it is also possible to easily adjust the glass transition temperature and the melting point of the polymer, thereby further improving the flexibility and toughness of the electrode material layer.

[0138] When the polymer contained in the second binder for a nonaqueous electrolyte battery contains two or more segments, the configuration of each segment can be similar to the configuration of each segment of the polymer contained in the first binder for a nonaqueous electrolyte battery. That is, the polymer contained in the second binder for a nonaqueous electrolyte battery can contain Segment A and Segment B, like the polymer contained in the first binder for a nonaqueous electrolyte battery, and can have a configuration similar to that of the polymer contained in the first binder for a nonaqueous electrolyte battery.

[0139] The polymer contained in the second binder for a nonaqueous electrolyte battery can be produced, for example, by the method described above as the method for producing the polymer contained in the first binder for a nonaqueous electrolyte battery.

[0140] The first binder for nonaqueous electrolyte batteries and the second binder for nonaqueous electrolyte batteries (hereinafter sometimes simply referred to as "binders for nonaqueous electrolyte batteries") may contain a polymer other than the above-mentioned polymers. Examples of the other polymers include fluoropolymers, polymethacrylates, polymethyl methacrylates, polyacrylonitriles, polyimides, polyamides, polyamide-imides, polycarbonates, styrene rubbers, butadiene rubbers, styrene-butadiene rubbers, and polyacrylic acids.

[0141] The binder for nonaqueous electrolyte batteries of the present disclosure can be suitably used as a material for forming batteries such as secondary batteries and capacitors.

[0142] The present disclosure also relates to the use of a binder containing a polymer including a segment A having a glass transition temperature of 25° C. or less and a segment B having a melting point of 50° C. or more for forming a nonaqueous electrolyte battery. The binder can be particularly suitably used for forming an electrode material layer of a nonaqueous electrolyte battery.

[0143] The present disclosure also relates to use of a binder for forming a nonaqueous electrolyte battery, the binder containing a polymer having a glass transition temperature and a melting point, containing 2,3,3,3-tetrafluoropropene units, and having a tetrahydrofuran extractable amount of 5 mass% or less at 25° C. The binder can be particularly suitably used for forming an electrode material layer of a nonaqueous electrolyte battery.

[0144] The battery may be a primary battery, a storage battery (secondary battery), or a storage element. Non-aqueous electrolyte batteries include all non-aqueous electrolyte batteries equipped with an electrolyte and a power generation element. Examples of non-aqueous electrolyte batteries include lithium ion primary batteries, lithium ion secondary batteries, sodium ion secondary batteries, nickel-metal hydride batteries, lithium ion capacitors, and electric double layer capacitors.

[0145] The binder for nonaqueous electrolyte batteries of the present disclosure can form an electrode material layer that is excellent in flexibility and toughness, and is therefore suitable as a binder for use in electrodes of batteries such as secondary batteries, capacitors, etc. The binder for nonaqueous electrolyte batteries of the present disclosure can also be used as a binder for separator coatings of secondary batteries.

[0146] The binder for a nonaqueous electrolyte battery of the present disclosure may be a binder for a nonaqueous electrolyte secondary battery. In the present disclosure, the binder for a nonaqueous electrolyte secondary battery includes a binder used in a positive electrode, a negative electrode, and a separator of a nonaqueous electrolyte secondary battery. The nonaqueous electrolyte secondary battery is preferably a lithium ion secondary battery.

[0147] 3. Electrode Mix The electrode mix for a nonaqueous electrolyte battery of the present disclosure contains the above-described binder for a nonaqueous electrolyte battery, a powder electrode material, and water or a nonaqueous solvent. The electrode mix of the present disclosure may be an electrode mix for a nonaqueous electrolyte secondary battery, or may be an electrode mix for a lithium-ion secondary battery. Because the electrode mix of the present disclosure contains the above-described binder for a nonaqueous electrolyte battery, it can form an electrode material layer that is excellent in flexibility and toughness.

[0148] The electrode mixture may be a positive electrode mixture used in producing a positive electrode, or a negative electrode mixture used in producing a negative electrode. The electrode material layer formed from the electrode mixture of the present disclosure may be a positive electrode material layer or a negative electrode material layer, as long as it contains the above-mentioned battery binder and powder electrode material.

[0149] The powder electrode material is a powder electrode material used in batteries and preferably contains an electrode active material. Electrode active materials are divided into positive electrode active materials and negative electrode active materials. In the case of lithium-ion secondary batteries, the positive electrode active material is not particularly limited as long as it is capable of electrochemically absorbing and desorbing lithium ions, but lithium composite oxides are preferred, and lithium transition metal composite oxides are more preferred. Lithium-containing transition metal phosphate compounds are also preferred as the positive electrode active material. It is also preferred that the positive electrode active material be a substance containing lithium and at least one transition metal, such as a lithium transition metal composite oxide or a lithium-containing transition metal phosphate compound.

[0150] The transition metal of the lithium transition metal composite oxide is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc., and a specific example of the lithium transition metal composite oxide is LiCoO ２ Lithium-cobalt composite oxides such as LiNiO ２ Lithium-nickel composite oxides such as LiMnO ２ , LiMn ２ O ４ , Li ２ MnO ３ and lithium-manganese composite oxides in which a part of the transition metal atoms that constitute the main part of these lithium transition metal composite oxides has been substituted with other metals such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, etc. Examples of the above-mentioned substituted oxides include lithium-nickel-manganese composite oxide, lithium-nickel-cobalt-aluminum composite oxide, lithium-nickel-cobalt-manganese composite oxide, lithium-manganese-aluminum composite oxide, and lithium-titanium composite oxide, and more specifically, LiNi ０．５ Mn ０．５ O ２ , LiNi ０．８５ Co ０．１０ Al ０．０５ O ２ , LiNi ０．３３ Co ０．３３ Mn ０．３３ O ２ , LiNi ０．５ Mn ０．３ Co ０．２ O２ , LiNi ０．６ Mn ０．２ Co ０．２ O ２ , LiNi ０．８ Mn ０．１ Co ０．１ O ２ , LiNi ０．９ Mn ０．０５ Co ０．０５ O ２ , LiMn １．８ Al ０．２ O ４ , LiMn １．５ Ni ０．５ O ４ , Li ４ Ti ５ O １２ , LiNi ０．８２ Co ０．１５ Al ０．０３ O ２ etc.

[0151] The transition metal of the lithium-containing transition metal phosphate compound is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu, or the like. Specific examples of the lithium-containing transition metal phosphate compound include LiFePO ４ , Li ３ Fe ２ (P.O. ４ ) ３ , LiFeP ２ O ７ Iron phosphates such as LiCoPO ４ and lithium transition metal phosphate compounds in which a part of the transition metal atoms constituting the main component of these compounds is substituted with another metal such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, or Si.

[0152] In particular, from the viewpoint of high voltage, high energy density, charge / discharge cycle characteristics, etc., LiCoO ２ , LiNiO ２ , LiMn ２ O ４ , LiNi ０．８２ Co ０．１５ Al ０．０３ O ２ , LiNi ０．３３ Mn ０．３３Co ０．３３ O ２ , LiNi ０．５ Mn ０．３ Co ０．２ O ２ , LiNi ０．６ Mn ０．２ Co ０．２ O ２ , LiNi ０．８ Mn ０．１ Co ０．１ O ２ , LiNi ０．９ Mn ０．０５ Co ０．０５ O ２ , LiFePO ４ is preferred.

[0153] As the lithium transition metal composite oxide, a lithium-nickel composite oxide is preferred, and the lithium transition metal composite oxide is represented by the general formula (7): ｙ Ni １－ｘ M ｘ O ２ (wherein x is 0.01≦x≦0.5, y is 0.9≦y≦1.2, and M represents a metal atom (excluding Li and Ni).) Such lithium transition metal composite oxides with a high nickel content are useful for increasing the capacity of secondary batteries.

[0154] In the general formula (7), x is a coefficient satisfying 0.01≦x≦0.5, and since a secondary battery with an even higher capacity can be obtained, it is preferable that 0.05≦x≦0.4, and more preferably 0.10≦x≦0.3.

[0155] In general formula (7), examples of the metal atom of M include V, Ti, Cr, Mn, Fe, Co, Cu, Al, Zn, Mg, Ga, Zr, Si, etc. Preferred metal atoms of M are transition metals such as V, Ti, Cr, Mn, Fe, Co, and Cu, or combinations of the above transition metals with other metals such as Al, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Mg, Ga, Zr, and Si.

[0156] Lithium transition metal composite oxides with a high nickel content include LiNi ０．８０ Co ０．１５ Al０．０５ O ２ , LiNi ０．８２ Co ０．１５ Al ０．０３ O ２ , LiNi ０．３３ Mn ０．３３ Co ０．３３ O ２ , LiNi ０．５ Mn ０．３ Co ０．２ O ２ , LiNi ０．６ Mn ０．２ Co ０．２ O ２ , LiNi ０．８ Mn ０．１ Co ０．１ O ２ , and LiNi ０．９０ Mn ０．０５ Co ０．０５ O ２ At least one selected from the group consisting of LiNi is preferred. ０．８２ Co ０．１５ Al ０．０３ O ２ , LiNi ０．６ Mn ０．２ Co ０．２ O ２ , LiNi ０．８ Mn ０．１ Co ０．１ O ２ , and LiNi ０．９ Mn ０．０５ Co ０．０５ O ２ At least one selected from the group consisting of:

[0157] Furthermore, a substance having a different composition from the substance constituting the main positive electrode active material may be attached to the surface of the positive electrode active material. Examples of the surface-attached substance include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide, sulfates such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate, and carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate.

[0158] These surface-attaching substances can be attached to the surface of the positive electrode active material by, for example, a method of dissolving or suspending the surface-attaching substance precursor in a solvent, adding the substance to the positive electrode active material by impregnation, and drying the solvent; a method of dissolving or suspending the surface-attaching substance precursor in a solvent, adding the substance to the positive electrode active material by impregnation, and then reacting the substance by heating or the like; a method of adding the substance to the positive electrode active material precursor and simultaneously baking the substance; or the like.

[0159] The amount of the surface-attached substance is preferably 0.1 ppm or more, more preferably 1 ppm or more, and even more preferably 10 ppm or more, and preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less, by mass relative to the positive electrode active material. The surface-attached substance can suppress the oxidation reaction of the nonaqueous electrolyte on the surface of the positive electrode active material and improve the battery life, but if the amount of attachment is too small, the effect will not be fully exerted, and if it is too large, the movement of lithium ions into and out of the positive electrode active material will be hindered, which may increase the resistance.

[0160] The particle shape of the positive electrode active material may be a block, polyhedron, sphere, ellipsoid, plate, needle, column, or the like, as conventionally used. Among these, those formed by aggregation of primary particles to form secondary particles, with the secondary particles being spherical or ellipsoidal, are preferred. Typically, electrochemical devices experience expansion and contraction of the active material in the electrode during charging and discharging, which can lead to deterioration, such as destruction of the active material or disconnection of the conductive path, due to stress. Therefore, a material formed by aggregation of primary particles to form secondary particles is preferred over a single-particle active material consisting of only primary particles, as this relieves the stress of expansion and contraction and prevents deterioration. Furthermore, spherical or ellipsoidal particles are preferred over plate-like equiaxially oriented particles because they are less oriented during electrode molding, resulting in less expansion and contraction of the electrode during charging and discharging, and are also more easily mixed uniformly with the conductive agent during electrode fabrication.

[0161] The tap density of the positive electrode active material is usually 1.3 g / cm ３ or more, preferably 1.5 g / cm ３ More preferably, 1.6 g / cm ３ or more, most preferably 1.7 g / cm ３That is all. If the tap density of the positive electrode active material is below the above lower limit, the amount of dispersion medium required when forming the positive electrode material layer increases, and the amounts of conductive agent and binder required also increase, which may restrict the filling rate of the positive electrode active material in the positive electrode material layer and restrict the battery capacity. By using a metal composite oxide powder with a high tap density, a high-density positive electrode material layer can be formed. Generally, the higher the tap density, the more preferable it is, and there is no particular upper limit. However, if it is too high, the diffusion of lithium ions in the positive electrode material layer using the non-aqueous electrolyte as a medium becomes rate-limiting, which may lead to a decrease in load characteristics. Therefore, the tap density is usually set to 3.5 g / cm. ３ Preferably 3.3 g / cm or less ３ The following is the result.

[0162] The tap density of the positive electrode active material is determined by passing it through a sieve with an opening of 300 μm and measuring 20 cm ３ After dropping a sample into the tapping cell to fill the cell volume, tapping is performed 1,000 times with a stroke length of 10 mm using a powder density measuring device (for example, Tap Denser manufactured by Seishin Enterprise Co., Ltd.), and the density obtained from the volume and weight of the sample at that time is defined as the tap density.

[0163] The median diameter d50 of the particles of the positive electrode active material (the secondary particle diameter when primary particles are aggregated to form secondary particles) is usually 0.1 μm or more, preferably 0.5 μm or more, more preferably 1 μm or more, and most preferably 3 μm or more, and usually 20 μm or less, preferably 18 μm or less, more preferably 16 μm or less, and most preferably 15 μm or less. Below the lower limit, a high bulk density product may not be obtained. Above the upper limit, the diffusion of lithium within the particles takes time, resulting in a decrease in battery performance. Also, problems such as streaking may occur when preparing a battery positive electrode, i.e., when the active material, conductive agent, binder, etc. are slurried with a solvent and applied as a thin film. Mixing two or more positive electrode active materials with different median diameters d50 can further improve the filling properties during positive electrode preparation.

[0164] The median diameter d50 in the present disclosure is measured using a known laser diffraction / scattering particle size distribution analyzer. When using a HORIBA LA-920 particle size distribution analyzer, the measurement is performed using a 0.1% by mass aqueous solution of sodium hexametaphosphate as the dispersion medium, and after ultrasonic dispersion for 5 minutes, the measurement is performed with a measurement refractive index set to 1.24.

[0165] When primary particles aggregate to form secondary particles, the average primary particle diameter of the positive electrode active material is typically 0.01 μm or more, preferably 0.05 μm or more, more preferably 0.08 μm or more, and most preferably 0.1 μm or more, and typically 3 μm or less, preferably 2 μm or less, more preferably 1 μm or less, and most preferably 0.6 μm or less. If the average diameter exceeds the upper limit, it is difficult to form spherical secondary particles, which can adversely affect powder packing and significantly reduce the specific surface area, potentially resulting in a decrease in battery performance, such as output characteristics. Conversely, if the average diameter is below the lower limit, problems such as poor charge / discharge reversibility due to underdeveloped crystals can occur. The primary particle diameter is measured by observation using a scanning electron microscope (SEM). Specifically, the average diameter is determined by taking a 10,000x magnification photograph of 50 random primary particles and calculating the longest intercept of a horizontal line at the left and right boundaries of the primary particles.

[0166] The BET specific surface area of ​​the positive electrode active material is 0.1 m ２ / g or more, preferably 0.15m ２ / g or more, more preferably 0.18m ２ / g or more, 4.0m ２ / g or less, preferably 2.5m ２ / g or less, more preferably 1.5m ２ If the BET specific surface area is smaller than this range, the battery performance is likely to deteriorate, whereas if it is larger, it becomes difficult to increase the tap density, which may easily cause problems with the coating properties when forming the positive electrode material layer.

[0167] The BET specific surface area is defined as a value measured by a surface area meter (for example, a fully automatic surface area measuring device manufactured by Ohkura Riken) using a nitrogen-helium mixed gas precisely adjusted so that the relative pressure of nitrogen to atmospheric pressure is 0.3, after which the sample is pre-dried at 150°C for 30 minutes under a nitrogen flow, by a nitrogen adsorption BET single-point method based on a gas flow method.

[0168] As a method for producing a positive electrode active material, a general method for producing an inorganic compound is used. In particular, various methods can be considered for producing a spherical or oval-spherical active material. For example, a transition metal raw material such as a transition metal nitrate or sulfate, and optionally raw materials of other elements, are dissolved or pulverized and dispersed in a solvent such as water, and the pH is adjusted while stirring to produce and recover a spherical precursor, which is then dried as necessary, and then dispersed in a solvent such as LiOH, Li ２ CO ３ , LiNO ３ a method of adding a Li source such as LiOH or LiO, and baking at a high temperature to obtain an active material; a method of dissolving or pulverizing and dispersing transition metal raw materials such as transition metal nitrates, sulfates, hydroxides, and oxides, and, if necessary, raw materials of other elements, in a solvent such as water, and drying and molding the resulting material using a spray dryer or the like to obtain a spherical or oval-spherical precursor, to which LiOH, Li, ２ CO ３ , LiNO ３ and the like, and calcining at high temperature to obtain an active material. Also, a method of adding a transition metal source material such as a transition metal nitrate, sulfate, hydroxide, or oxide, and LiOH, Li ２ CO ３ , LiNO ３ and the like, and, if necessary, raw materials of other elements, in a solvent such as water, and then drying and molding the resulting solution using a spray dryer or the like to form a spherical or oval spherical precursor, which is then fired at a high temperature to obtain an active material.

[0169] In the present disclosure, one type of positive electrode active material powder may be used alone, or two or more types having different compositions or different powder properties may be used in any combination and ratio.

[0170] The negative electrode active material is not particularly limited as long as it can electrochemically absorb and release lithium ions, and examples thereof include carbonaceous materials, metal oxides such as tin oxide and silicon oxide, metal composite oxides, lithium alone, lithium alloys such as lithium-aluminum alloys, metals capable of forming alloys with lithium such as Sn and Si, etc. These may be used alone or in any combination and ratio of two or more.

[0171] The metal composite oxide is not particularly limited as long as it is capable of absorbing and releasing lithium, but it is preferable that the metal composite oxide contains titanium and / or lithium as a constituent component from the viewpoint of high current density charge / discharge characteristics.

[0172] Examples of carbonaceous materials include: (1) natural graphite, (2) artificial carbonaceous substances and artificial graphitic substances; carbonaceous substances (for example, natural graphite, coal-based coke, petroleum-based coke, coal-based pitch, petroleum-based pitch, or oxidized versions of these pitches, needle coke, pitch coke, and carbon materials obtained by partially graphitizing these pitches, furnace black, acetylene black, pitch-based carbon fiber, and other organic pyrolysis products; carbonizable organic substances (for example, coal tar pitch ranging from soft pitch to hard pitch, coal-based heavy oils such as carbonized liquefied oil, atmospheric residue, vacuum residue, straight-run heavy oils, cracked petroleum heavy oils such as ethylene tar produced as a by-product during the thermal decomposition of crude oil, naphtha, etc.); aromatic hydrocarbons such as acenaphthylene, decacyclene, anthracene, and phenanthrene; N-ring compounds such as phenazine and acridine; S-ring compounds such as thiophene and bithiophene; biphenyl, terphenyl; carbonaceous materials obtained by heat-treating at least once in the range of 400 to 3200°C any of the following: polyphenylenes such as phenylenes, polyvinyl chloride, polyvinyl alcohol, polyvinyl butyral, insolubilized products thereof, nitrogen-containing organic polymers such as polyacrylonitrile and polypyrrole, sulfur-containing organic polymers such as polythiophenes and polystyrene, natural polymers such as cellulose, lignin, mannan, polygalacturonic acid, chitosan, and polysaccharides represented by saccharose, thermoplastic resins such as polyphenylene sulfide and polyphenylene oxide, and thermosetting resins such as furfuryl alcohol resin, phenol-formaldehyde resin, and imide resin), and charcoals thereof, or solutions of carbonizable organic substances dissolved in low-molecular organic solvents such as benzene, toluene, xylene, quinoline, and n-hexane, and charcoals thereof; (3) a carbonaceous material in which the negative electrode layer is made of carbonaceous matter having at least two or more different types of crystallinity and / or has an interface where carbonaceous matter of the different crystallinity contacts, and (4) a carbonaceous material in which the negative electrode layer is made of carbonaceous matter having at least two or more different types of orientation and / or has an interface where carbonaceous matter of the different orientations contacts, is preferred because it has a good balance between initial irreversible capacity and high current density charge / discharge characteristics.

[0173] The content of the electrode active material (positive electrode active material or negative electrode active material) is preferably 40 mass % or more in the electrode mixture in order to increase the capacity of the resulting electrode.

[0174] The powder electrode material may further contain a conductive agent, such as carbon blacks such as acetylene black and ketjen black, carbon materials such as graphite, carbon fiber, carbon nanotubes, carbon nanohorns, and graphene.

[0175] The ratio of the powder electrode material (active material and conductive agent) to the above-mentioned battery binder in the electrode mixture is usually about 80:20 to 99.5:0.5 by mass, and is determined taking into consideration the retention of the powder components, adhesion to the current collector, and conductivity of the electrode.

[0176] With the blending ratio as described above, the battery binder cannot completely fill the voids between the powder components in the electrode material layer formed on the current collector. However, when water or a non-aqueous solvent that well dissolves or disperses the battery binder is used as the solvent, the battery binder is uniformly dispersed in the electrode material layer after drying, forming a mesh-like structure and well holding the powder components, which is preferable.

[0177] The electrode mixture of the present disclosure contains water or a non-aqueous solvent. Examples of the non-aqueous solvent include nitrogen-containing organic solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and dimethylformamide; ketone-based solvents such as acetone, methyl ethyl ketone, cyclohexanone, and methyl isobutyl ketone; ester-based solvents such as ethyl acetate and butyl acetate; ether-based solvents such as dioxane; and mixtures thereof.

[0178] In particular, the electrode mixture of the present disclosure preferably contains a non-aqueous solvent, preferably contains at least one selected from the group consisting of N-methyl-2-pyrrolidone and N,N-dimethylacetamide, and more preferably contains N-methyl-2-pyrrolidone, in view of excellent stability and coatability of the electrode mixture.

[0179] The amount of water or non-aqueous solvent in the electrode mixture is determined in consideration of the coatability onto the current collector, the formability of a thin film after drying, etc. Usually, the ratio of the battery binder to water or non-aqueous solvent is preferably 0.5:99.5 to 20:80 by mass.

[0180] In order to further improve adhesion to the current collector, the electrode mixture may further contain, for example, an acrylic resin such as polyacrylic acid, polymethacrylate, or polymethyl methacrylate, a polyimide, polyamide, or polyamideimide resin, a styrene rubber, a butadiene rubber, or a styrene-butadiene rubber.

[0181] To the electrode mixture, a dispersant such as a resin having a surface active effect, a cationic surfactant, or a nonionic surfactant may be added in order to improve the dispersion stability of the electrode slurry.

[0182] The content of the binder for a nonaqueous electrolyte battery in the electrode mixture is preferably 0.1 to 20 mass %, more preferably 0.2 to 10 mass %, and even more preferably 0.5 to 3 mass %, relative to the mass of the electrode mixture.

[0183] The electrode mixture can be prepared by dispersing and mixing the powder electrode material in a solution or dispersion prepared by dissolving or dispersing a binder for non-aqueous electrolyte batteries in water or a non-aqueous solvent. The resulting electrode mixture is then uniformly applied to a current collector such as a metal foil or a metal mesh, dried, and pressed as necessary to form a thin electrode material layer on the current collector, thereby forming a thin film electrode.

[0184] Alternatively, the binder for nonaqueous electrolyte batteries and the powder of the electrode material may be mixed first, and then water or a nonaqueous solvent may be added to prepare the electrode mixture. Alternatively, the binder for nonaqueous electrolyte batteries and the powder of the electrode material may be heated and melted, and extruded using an extruder to prepare a thin film of the electrode mixture. This thin film may then be attached to a current collector coated with a conductive adhesive or a general-purpose organic solvent to prepare an electrode sheet. Furthermore, a solution or dispersion of the binder for nonaqueous electrolyte batteries and the powder of the electrode material may be applied to a preformed electrode material. Thus, the method of application as a binder for nonaqueous electrolyte batteries is not particularly limited.

[0185] 4. Electrode The electrode of the present disclosure contains the binder for a nonaqueous electrolyte battery described above. The electrode of the present disclosure is preferably an electrode for a nonaqueous electrolyte battery. Because the electrode of the present disclosure contains the binder for a nonaqueous electrolyte battery described above, the electrode does not crack even when a powder electrode material is thickly coated and wound and pressed to increase density, and the powder electrode material does not fall off or peel from the current collector.

[0186] The electrode preferably comprises a current collector and an electrode material layer formed on the current collector, the electrode material layer containing the powder electrode material and the binder for a non-aqueous electrolyte battery. The electrode may be a positive electrode or a negative electrode, but is preferably a positive electrode.

[0187] Examples of the current collectors (positive electrode current collector and negative electrode current collector) include metal foils or metal meshes made of iron, stainless steel, copper, aluminum, nickel, titanium, etc. Among these, aluminum foil is preferred as the positive electrode current collector, and copper foil is preferred as the negative electrode current collector.

[0188] The electrode of the present disclosure can be manufactured by, for example, the method described above. Because the electrode mixture has excellent coatability, by manufacturing the electrode material layer of the electrode of the present disclosure using the electrode mixture, it is possible to easily manufacture an electrode having a smooth, uniform, and thick electrode material layer.

[0189] 5. Nonaqueous Electrolyte Battery The nonaqueous electrolyte battery of the present disclosure includes the above-described electrode. The nonaqueous electrolyte battery of the present disclosure is preferably a nonaqueous electrolyte secondary battery. In one embodiment of the nonaqueous electrolyte battery of the present disclosure, the battery includes a positive electrode in which a positive electrode mixture is supported on a positive electrode current collector, a negative electrode in which a negative electrode mixture is supported on a negative electrode current collector, and an electrolyte. In the nonaqueous electrolyte secondary battery of the present disclosure, at least one of the positive electrode and the negative electrode may be the above-described electrode, and it is preferable that the positive electrode be the above-described electrode. The secondary battery is preferably a lithium-ion secondary battery.

[0190] The nonaqueous electrolyte secondary battery of the present disclosure preferably further comprises a nonaqueous electrolyte solution. The nonaqueous electrolyte solution is not particularly limited, but one or more of known hydrocarbon solvents such as propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyrolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; and fluorine-based solvents such as fluoroethylene carbonate, fluoroether, and fluorinated carbonate can be used. Any conventionally known electrolyte can also be used, and examples thereof include LiClO ４ , LiAsF ６ , LiPF ６ , LiBF ４ , LiCl, LiBr, CH ３ SO ３ Li, CF ３ SO ３ Li, cesium carbonate, etc. can be used.

[0191] A separator may be interposed between the positive electrode and the negative electrode. As the separator, a conventionally known separator may be used, or a separator coated with the above-mentioned battery binder may be used.

[0192] It is also preferable to use the above-mentioned binder for a non-aqueous electrolyte battery in at least one of the positive electrode, negative electrode, and separator of a secondary battery (preferably a lithium ion secondary battery).

[0193] A film for a secondary battery made of the binder for a nonaqueous electrolyte battery described above is also one of the preferred embodiments of the present disclosure.

[0194] A preferred embodiment of the present disclosure is a laminate for a secondary battery having a substrate and a layer made of the binder for a non-aqueous electrolyte battery formed on the substrate. Examples of the substrate include those exemplified as the current collector and known substrates (such as porous membranes) used in separators for secondary batteries.

[0195] The electrode of the present disclosure includes an electrode material layer having excellent flexibility and toughness, and therefore can be suitably used as an electrode for a wound-type nonaqueous electrolyte secondary battery. The nonaqueous electrolyte secondary battery of the present disclosure may be a wound-type nonaqueous electrolyte secondary battery.

[0196] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims.

[0197] <1> According to a first aspect of the present disclosure, there is provided a binder for non-aqueous electrolyte batteries, containing a polymer including segment A having a glass transition temperature of 25°C or less and segment B having a melting point of 50°C or higher. <2> According to a second aspect of the present disclosure, there is provided a binder for non-aqueous electrolyte batteries according to the first aspect, in which segment A has a heat of fusion of less than 5 J / g, and segment B has a heat of fusion of 5 J / g or more. <3> According to a third aspect of the present disclosure, there is provided a binder for non-aqueous electrolyte batteries according to the first or second aspect, in which the polymer contains a chain structure represented by general formula (1) or (2): General formula (1): A-B-A General formula (2): B-A-B (wherein A represents segment A and B represents segment B). <4> According to a fourth aspect of the present disclosure, there is provided a binder for non-aqueous electrolyte batteries according to any of the first to third aspects, in which segment A of the polymer contains a fluorine-containing monomer unit. <5> According to a fifth aspect of the present disclosure, there is provided a binder for non-aqueous electrolyte batteries according to any one of the first to fourth aspects, wherein segment A of the polymer contains a vinylidene fluoride unit. <6> According to a sixth aspect of the present disclosure, there is provided a binder for non-aqueous electrolyte batteries according to any one of the first to fifth aspects, wherein segment A of the polymer contains a vinylidene fluoride unit and at least one repeating unit selected from the group consisting of repeating units represented by any of the following formulas: Formula: -CF ２ -CF [-CF ３ ]- Formula:-CH ２ -CFRf １ - (wherein, Rf １is a linear or branched fluorinated alkyl or fluorinated alkoxy group having 1 to 12 carbon atoms, and when the number of carbon atoms is 2 or more, it may contain an oxygen atom between carbon atoms.) Formula: -CHF-CHRf ２ - (wherein, Rf ２is a linear or branched fluorinated alkyl group or fluorinated alkoxy group having 1 to 12 carbon atoms, and when the number of carbon atoms is 2 or more, an oxygen atom may be contained between the carbon atoms.) <7> According to a seventh aspect of the present disclosure, there is provided a binder for nonaqueous electrolyte batteries according to any of the first to sixth aspects, in which segment A of the polymer contains vinylidene fluoride units and 2,3,3,3-tetrafluoropropene units. <8> According to an eighth aspect of the present disclosure, there is provided a binder for nonaqueous electrolyte batteries according to any of the fifth to seventh aspects, in which the content of vinylidene fluoride units in segment A of the polymer is 99 to 15 mol % based on all monomer units constituting segment A. <9> According to a ninth aspect of the present disclosure, there is provided a binder for nonaqueous electrolyte batteries according to any of the first to eighth aspects, in which segment B of the polymer contains fluorine-containing monomer units. <10> According to a tenth aspect of the present disclosure, there is provided a binder for non-aqueous electrolyte batteries according to any of the first to ninth aspects, wherein segment B of the polymer contains vinylidene fluoride units. <11> According to an eleventh aspect of the present disclosure, there is provided a binder for non-aqueous electrolyte batteries according to the tenth aspect, wherein a content of vinylidene fluoride units in segment B of the polymer is 97 mol % or more based on all monomer units constituting segment B. <12> According to a twelfth aspect of the present disclosure, there is provided a binder for non-aqueous electrolyte batteries according to any of the first to eleventh aspects, wherein segment B of the polymer contains only vinylidene fluoride units, or contains vinylidene fluoride units and at least one monomer unit selected from the group consisting of tetrafluoroethylene units, hexafluoropropylene units, 2,3,3,3-tetrafluoropropene units, and (meth)acrylic acid units. <13> According to a thirteenth aspect of the present disclosure, there is provided the binder for a nonaqueous electrolyte battery according to any one of the first to twelfth aspects, wherein a mass ratio of segment A to segment B in the polymer is 40 / 60 to 95 / 5.<14> According to a fourteenth aspect of the present disclosure, the polymer contains a chain structure represented by general formula (1) or general formula (2), General formula (1): A-B-A General formula (2): B-A-B (wherein A represents segment A and B represents segment B), segment A of the polymer has a glass transition temperature of -10°C or lower, contains vinylidene fluoride units and 2,3,3,3-tetrafluoropropene units, the content of the 2,3,3,3-tetrafluoropropene units in segment A is 18 to 30 mol% based on all monomer units constituting segment A and the content of the vinylidene fluoride units in segment A is 70 to 82 mol% based on all monomer units constituting segment A, and segment B of the polymer has a melting point of 140 to 200°C, A binder for non-aqueous electrolyte batteries according to any one of the first to thirteenth aspects is provided, the binder containing a polymer, the polymer having a glass transition temperature and a melting point, containing 2,3,3,3-tetrafluoropropene units, and having a tetrahydrofuran extractable amount at 25°C of 5 mass% or less. <16> A sixteenth aspect of the present disclosure provides a binder for non-aqueous electrolyte batteries according to the fifteenth aspect, the polymer further containing vinylidene fluoride units. <17> According to a seventeenth aspect of the present disclosure, there is provided the binder for a nonaqueous electrolyte battery according to the fifteenth or sixteenth aspect, wherein the polymer contains two or more segments.<18> According to an eighteenth aspect of the present disclosure, there is provided a binder for a non-aqueous electrolyte battery according to any one of the fifteenth to seventeenth aspects, wherein the glass transition temperature of the polymer is -10°C or lower, the melting point of the polymer is 140 to 200°C, the polymer contains vinylidene fluoride units and 2,3,3,3-tetrafluoropropene units, the content of the 2,3,3,3-tetrafluoropropene units is 9 to 24 mol% based on all monomer units constituting the polymer, and the content of the vinylidene fluoride units is 76 to 91 mol% based on all monomer units constituting the polymer, the tetrahydrofuran extractable amount of the polymer at 25°C is 2 to 4 mass%, and the weight average molecular weight of the polymer is 200,000 to 2,000,000. <19> According to a nineteenth aspect of the present disclosure, there is provided an electrode mixture for a non-aqueous electrolyte battery, containing the binder for a non-aqueous electrolyte battery according to any one of the first to eighteenth aspects. <20> According to a twentieth aspect of the present disclosure, there is provided an electrode mixture for a nonaqueous electrolyte battery according to a nineteenth aspect, further comprising a powder electrode material, and water or a nonaqueous solvent. <21> According to a twenty-first aspect of the present disclosure, there is provided an electrode for a nonaqueous electrolyte battery, comprising an electrode material layer formed from the electrode mixture according to the nineteenth or twentieth aspect. <22> According to a twenty-second aspect of the present disclosure, there is provided a nonaqueous electrolyte battery comprising the electrode according to the twenty-first aspect.

[0198] Next, embodiments of the present disclosure will be described with reference to examples, but the present disclosure is not limited to these examples.

[0199] The values ​​in the examples were measured by the following methods.

[0200] <Polymer Composition> The compositions of the fluorine-containing copolymer and PVdF were measured by solution NMR. Measurement device: Varian VNMRS400 Resonance frequency: 376.04 (Sfrq) Pulse width: 30° (pw=6.8)

[0201] <Content of Polar Group-Containing Monomer Units in PVdF> The content of polar group-containing monomer units (acrylic acid units, maleic acid, etc.) in PVdF was measured by acid-base titration of the carboxyl group. Specifically, approximately 0.5 g of PVdF was dissolved in acetone at a temperature of 70-80°C. 5 ml of water was added dropwise under vigorous stirring to avoid solidification of the PVdF. Titration with a 0.1 N NaOH aqueous solution was performed at a neutral transition of approximately -270 mV until complete neutralization of the acidity. From the measurement results, the amount of substance of the polar group-containing monomer units contained in 1 g of PVdF was determined, and the content of the polar group-containing monomer units was calculated.

[0202] <Weight-average molecular weight> The weight-average molecular weight of PVdF was measured by gel permeation chromatography (GPC). It was calculated from data measured using Tosoh AS-8010, CO-8020, a column (three GMHHR-H columns connected in series) and Shimadzu RID-10A, with dimethylformamide (DMF) as the solvent at a flow rate of 1.0 ml / min (reference: polystyrene). The weight-average molecular weight of the fluorinated copolymer was calculated based on the results measured by the GPC method, with standard polystyrene as the standard. GPC apparatus: TOSOH HLC-8320GPC Columns: One SuperAW-H, three SuperAWM-H Developing solvent: Dimethylformamide [DMF] Sample concentration: 0.05% by mass Measurement temperature: 40°C

[0203] <Storage Modulus (E′)> The storage modulus is a value measured by dynamic viscoelasticity measurement at 30° C. or 60° C., and was measured using a dynamic viscoelasticity analyzer DVA220 manufactured by IT Measurement & Control Co., Ltd., using a test piece having a length of 30 mm, a width of 5 mm, and a thickness of 50 to 100 μm, under the following conditions: tensile mode, grip width of 20 mm, measurement temperature from −30° C. to 160° C., temperature rise rate of 2° C. / min, and frequency of 1 Hz.

[0204] The test pieces used for the measurements were prepared by dissolving PVdF in N-methyl-2-pyrrolidone (NMP) to a concentration of 10 to 20% by mass, casting the solution onto a glass plate, drying it at 100°C for 12 hours, and further drying it under vacuum at 100°C for 12 hours, and cutting the resulting film having a thickness of 50 to 100 μm into a length of 30 mm and a width of 5 mm.

[0205] <Melting Point> Using a differential scanning calorimetry (DSC) device, the temperature of a sample was raised from 30° C. to 220° C. at a rate of 10° C. / min, and the temperature at the peak of the endothermic curve was determined as the melting point.

[0206] <Glass Transition Temperature (Tg)> A DSC curve was obtained by heating 10 mg of a sample at a rate of 20°C / min using a differential scanning calorimeter (DSC822e manufactured by Mettler Toledo or X-DSC7000 manufactured by Hitachi High-Tech Science Corporation), and the glass transition temperature was determined as the temperature at the intersection of an extension of the baseline before and after the second-order transition of the DSC curve and a tangent to the inflection point of the DSC curve.

[0207] <Heat of Fusion> Using a differential scanning calorimeter (DSC822e manufactured by Mettler Toledo or X-DSC7000 manufactured by Hitachi High-Tech Science Corporation), the temperature of the sample was raised from 30°C to 220°C at a rate of 10°C / min, and the heat of fusion was calculated from the magnitude of the melting peak (ΔH) of the obtained endothermic curve.

[0208] <THF Extraction Amount> 9 g of tetrahydrofuran (THF) was added to 1 g of the polymer obtained in each Example, and the mixture was stirred using a stirrer at 25° C. After 24 hours, the solid content was filtered, the solution was evaporated to dryness, and the weight of the dried product was measured to calculate the extraction amount (the ratio (% by mass) of the weight of the dried product to the weight (1 g) of the polymer).

[0209] <Viscosity Change Rate of Positive Electrode Mix> Using a Brookfield DV2T type viscometer, the viscosity of the positive electrode mix was measured 10 minutes after the start of measurement under conditions of 25°C, spindle LV-04 (64), and a rotation speed of 6 rpm. The viscosity change rate (X24) was calculated using the following formula from the viscosity (η0) of the positive electrode mix measured immediately after preparation and the viscosity (η24) 24 hours after preparation of the mix under conditions of a storage temperature of 50°C. Xn = η24 / η0 × 100 [%]

[0210] <Peel strength between positive electrode material layer of positive electrode and positive electrode current collector> A 1.2 cm × 7.0 cm test piece was prepared by cutting out a positive electrode having a positive electrode material layer on one side. The positive electrode material layer side of the test piece was fixed to a movable jig with double-sided tape, and the tape was attached to the surface of the positive electrode current collector. The stress (N / cm) when the tape was pulled at a 90-degree angle at a speed of 100 mm / min was measured using an autograph. A 1 N load cell was used for the autograph.

[0211] <Maximum Test Force> The bending strength (3-point bending test) was measured according to a method in accordance with ASTM D790. A positive electrode having a positive electrode material layer on both sides or a negative electrode having a negative electrode material layer on both sides was cut into a size of 15 mm x 20 mm to prepare a test specimen. A three-point bending test was performed by placing the test specimen between points 1 and 2, spaced 10 mm apart, and pressing the center of the test specimen (point 3) with a probe in the thickness direction at a constant speed. The force applied to the third point was measured while moving at a speed of 5 mm / min in the thickness direction. The maximum bending force or maximum bending strength is the maximum value of the force applied to the specimen according to the moving distance of the probe.

[0212] <Full Width at Half Maximum> The bending strength (3-point bending test) was measured according to a method in accordance with ASTM D790. A positive electrode having a positive electrode material layer on both sides or a negative electrode having a negative electrode material layer on both sides was cut into a size of 15 mm x 20 mm to prepare a test specimen. A three-point bending test was performed by placing the test specimen between points 1 and 2, spaced 10 mm apart, and pressing the center of the test specimen (point 3) with a probe in the thickness direction at a constant speed. The force applied to the third point was measured while moving at a speed of 5 mm / min in the thickness direction. The maximum bending strength (maximum bending force or maximum bending strength) is the maximum force applied to the test specimen depending on the distance traveled by the probe. Next, the test force at half the maximum bending strength is calculated, and the half-width is the distance from the stroke at which the test force reaches half the maximum bending strength as the test force increases after the start of the test to the stroke at which the test force reaches half the maximum bending strength as the test force decreases after reaching the maximum test force. That is, a curve is drawn with the stroke on the autograph as the horizontal axis and the stress as the vertical axis, and the half-width can be determined as the peak width at half the stress peak.

[0213] The following polymers were used in the examples and comparative examples.

[0214] PVdF A: VdF homopolymer, weight average molecular weight 900,000, storage modulus at 30°C 1,740 MPa, storage modulus at 60°C 1,140 MPa, melting point 171°C. B: VdF homopolymer, weight average molecular weight 1,800,000, storage modulus at 30°C 1,820 MPa, storage modulus at 60°C 1,180 MPa, melting point 171°C. C: PVdF containing acrylic acid units, content of acrylic acid units 1.0 mol%, weight average molecular weight 1,100,000, storage modulus at 30°C 1,280 MPa, storage modulus at 60°C 720 MPa, melting point 161°C. D: PVdF containing maleic acid units, content of maleic acid units 0.5 mol%, weight average molecular weight 900,000, storage modulus at 30°C 1,260 MPa, storage modulus at 60°C 760 MPa, melting point 167°C. E: PVdF containing CTFE units, CTFE unit content: 2.4 mol%, weight average molecular weight: 800,000, storage modulus at 30°C: 1,250 MPa, storage modulus at 60°C: 880 MPa, melting point: 168°C. F: PVdF containing HFP units and acrylic acid units, VdF / HFP=97.5 / 2.5 (mol%), acrylic acid unit content: 1.0 mol%, weight average molecular weight: 1,110,000, storage modulus at 30°C: 1,080 MPa, storage modulus at 60°C: 750 MPa, melting point: 150°C.

[0215] Production Example 1 Fluorine-containing copolymer a (Production of B-A-B block polymer (wherein A represents segment A and B represents segment B)) (Step 1) 4000 ml of pure water, CH ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COONH ４ 0.8001 g of 50% aqueous solution, C ５ F １１ COONH ４24.021 g of a 50% aqueous solution was added and purged with nitrogen, then slightly pressurized with VdF. The temperature was adjusted to 80 ° C. while stirring at 400 rpm. VdF was injected up to 1.64 MPa, and a mixed monomer solution of VdF and 2,3,3,3-tetrafluoropropylene (R1234yf) with a molar ratio of 77.2 / 22.8 was further injected up to 2.001 MPa. 0.16 g of ammonium persulfate dissolved in 4 ml of pure water was injected with nitrogen to start polymerization. When the mixed monomer solution reached 24 g, 1.009 g of 1,4-diiodoperfluorobutane was added. When the pressure dropped to 1.98 MPa, the mixed monomer solution was increased to 2.01 MPa, and this was repeated until 1020 g was charged. The gas in the autoclave was released to 0.05 MPa, and then heat treatment was carried out for 3 hours. A 10 g sample of the dispersion in the autoclave was taken and dried to obtain a polymer having a molar ratio of VdF / R1234yf=77.6 / 22.4, a glass transition temperature of −12.5° C., and no heat of fusion.

[0216] (Step 2) After the heat treatment in step 1, the autoclave was maintained at 80°C, and the pressure was increased to 2.003 MPa with VdF. A solution of 0.08 g of ammonium persulfate in 4 ml of pure water was then added with nitrogen to start polymerization. When the pressure dropped to 1.98 MPa, the pressure was increased to 2.01 MPa with VdF. This process was repeated until 180 g had been added. The gas in the autoclave was released and cooled, and 5,270 g of dispersion was recovered. The solid content of the dispersion was 23.83% by mass.

[0217] Aluminum sulfate was added to this dispersion to cause coagulation, followed by drying, yielding 1,250 g of polymer. The resulting block polymer had a molar ratio of VdF / R1234yf = 82.0 / 18.0, and the content of segment B calculated from the composition was 17.2 mass%. The weight-average molecular weight Mw was 1,266,000, the glass transition temperature was -12.9°C, the melting point was 160.3°C, and the heat of fusion was 8.2 mJ / mg. The THF extractable amount was 3 mass%.

[0218] Production Example 2 Fluorine-containing copolymer b (production of B-A-B block polymer (in the formula, A represents segment A, and B represents segment B)) The same procedure as in Production Example 1 was followed, except that the amount of monomer mixture charged in step 1 was changed from 1020 g to 900 g, and the amount of VdF charged in step 2 was changed from 180 g to 300 g, and 5236 g of a dispersion was recovered. The solids content of the dispersion was 24.10 mass%.

[0219] Aluminum sulfate was added to this dispersion to cause coagulation, followed by drying, yielding 1,257 g of polymer. The resulting block polymer had a molar ratio of VdF / R1234yf = 84.2 / 15.8, and the content of segment B calculated from the composition was 28.1 mass%. The weight-average molecular weight Mw was 1,206,000, the glass transition temperature was -11.0 °C, the melting point was 161.1 °C, and the heat of fusion was 11.0 mJ / mg. The THF extractable amount was 3 mass%.

[0220] Production Example 3 Fluorine-containing copolymer c (production of B-A-B block polymer (in the formula, A represents segment A, and B represents segment B)) The same procedure as in Production Example 1 was followed, except that the amount of monomer mixture charged in step 1 was changed from 1020 g to 780 g, and the amount of VdF charged in step 2 was changed from 180 g to 420 g, and 5252 g of a dispersion was recovered. The solids content of the dispersion was 23.74 wt %.

[0221] Aluminum sulfate was added to this dispersion to cause coagulation, followed by drying, yielding 1,250 g of polymer. The resulting block polymer had a molar ratio of VdF / R1234yf = 85.9 / 14.1, and the content of segment B calculated from the composition was 36.0 mass%. The weight-average molecular weight Mw was 1,290,000, the glass transition temperature was -11.2 ° C, the melting point was 161.4 ° C, and the heat of fusion was 17.1 mJ / mg. The THF extractable amount was 3 mass%.

[0222] Production Example 4 Fluorine-containing copolymer d (Production of A-B-A block polymer (wherein A represents segment A and B represents segment B)) (Step 1) 4000 ml of pure water, CH ２ =CFCF ２ OCF (CF ３ )CF２ OCF (CF ３ ) COONH ４ 0.8003 g of 50% aqueous solution, C ５ F １１ COONH ４ 24.014 g of a 50% aqueous solution was added and purged with nitrogen. The mixture was slightly pressurized with VdF, and the temperature was adjusted to 80°C while stirring at 400 rpm. VdF was then injected up to 2.00 MPa. A solution of 0.16 g of ammonium persulfate in 4 ml of pure water was injected with nitrogen to start polymerization. When the pressure reached 24 g of VdF, 1.009 g of 1,4-diiodoperfluorobutane was added. When the pressure dropped to 1.98 MPa, the pressure was increased to 2.01 MPa with VdF. This process was repeated until 300 g was added. The gas in the autoclave was released to 0.05 MPa, and then heat treatment was performed for 3 hours. 10 g of the dispersion in the autoclave was sampled and dried to obtain a polymer. The glass transition temperature was not observed, the melting point was 161.1°C, and the heat of fusion was 44.8 mJ / mg.

[0223] (Step 2) After the heat treatment in step 1, the autoclave was maintained at 80 ° C., and a mixed monomer solution of VdF and R1234yf in a molar ratio of 77.5 / 22.5 was added to the autoclave at 1.64 MPa and 2.001 MPa, respectively. 0.08 g of ammonium persulfate dissolved in 4 ml of pure water was added under pressure with nitrogen to start polymerization. When the pressure dropped to 1.98 MPa, the mixed monomer solution was added and the pressure was increased to 2.01 MPa. This process was repeated until 900 g had been added. The gas in the autoclave was released and cooled, and 5271 g of dispersion was recovered. The solid content of the dispersion was 23.80% by mass.

[0224] Aluminum sulfate was added to this dispersion to cause coagulation, followed by drying, yielding 1,248 g of polymer. The resulting block polymer had a molar ratio of VdF / R1234yf = 82.7 / 17.3, and the content of segment B calculated from the composition was 24.1 mass%. The weight-average molecular weight Mw was 1,426,000, the glass transition temperature was -10.4°C, the melting point was 160.8°C, and the heat of fusion was 10.8 mJ / mg. The THF extractable amount was 3 mass%.

[0225] Examples 1 to 11 and Comparative Examples 1 to 5 (Preparation of Binder Solution) A fluorine-containing copolymer and PVdF were dissolved in N-methyl-2-pyrrolidone (NMP) in the compositions (mass ratios) shown in Table 1 so that the concentration of the binder (fluorine-containing copolymer and PVdF) in the NMP solution became 7% by mass, to prepare a composition (binder solution).

[0226] (Preparation of Positive Electrode Mixture) The composition obtained above was mixed with a positive electrode active material (NMC(LiNi ０．９ Mn ０．０５ Co ０．０５ O ２ )) and a conductive agent (Ketjen Black (Super P Li, manufactured by TIMCAL)) were added and thoroughly mixed with a stirrer to prepare a positive electrode mixture. The mass ratio of the positive electrode active material, conductive agent, and binder in the positive electrode mixture was 97 / 1.5 / 1.5. The solid content concentration in the positive electrode mixture was 74 mass%.

[0227] (Preparation of a positive electrode having a positive electrode material layer on one side) The obtained positive electrode mixture was applied to one side of a positive electrode current collector (aluminum foil having a thickness of 20 μm) in an amount of 24.5 mg / cm ２ After the NMP was completely evaporated, the mixture was pressed twice using a roll press machine at a pressure of 10 tons to prepare a positive electrode including a positive electrode material layer and a positive electrode current collector.

[0228] (Preparation of a positive electrode having a positive electrode material layer on both sides) The obtained positive electrode mixture was applied to both sides of a positive electrode current collector (aluminum foil having a thickness of 20 μm) in an amount of 32.0 mg / cm per side. ２ After the NMP was completely evaporated, the mixture was pressed using a roll press under a pressure of 7 tons to prepare a positive electrode including a positive electrode material layer and a positive electrode current collector.

[0229] The evaluation results of the positive electrode mixture and the electrode are shown in Table 1.

[0230]

[0231] Example 12: 19.2% by mass of graphite-coated silicon oxide powder (powder in which the surface of silicon oxide is coated with graphite) as the negative electrode active material, 76.8% by mass of graphite powder, and 4.0% by mass of fluorine-containing copolymer c (7% NMP solution) as the binder were mixed, and an appropriate amount of NMP was added to prepare a negative electrode mixture slurry. Next, this negative electrode mixture slurry was applied to both sides of a negative electrode current collector made of copper foil and dried. This was cut to a predetermined electrode size and rolled using a roll press at a pressure of 10 tons to produce a negative electrode with a negative electrode material layer formed on both sides of the negative electrode current collector. The evaluation results are shown in Table 2.

[0232] Example 13 A negative electrode was prepared in the same manner as in Example 12, except that the negative electrode active materials used were 48.0 mass% of graphite-coated silicon oxide powder and 48.0 mass% of graphite powder, and the binders used were 0.8 mass% of PVdF A and 3.2 mass% of fluorine-containing copolymer c. The evaluation results are shown in Table 2.

[0233] Comparative Example 6 A negative electrode was produced in the same manner as in Example 12, except that polyacrylic acid (manufactured by Aldrich, weight average molecular weight 450,000) was used as the binder. The evaluation results are shown in Table 2.

[0234] Comparative Example 7 A negative electrode was produced in the same manner as in Example 13, except that styrene-butadiene rubber (TRD2001, manufactured by JSR Corporation) was used as the binder. The evaluation results are shown in Table 2.

[0235]

[0236] Example 14 A negative electrode was produced in the same manner as in Example 12, except that 19.2 mass % of silicon powder and 76.8 mass % of graphite powder were used as the negative electrode active material.

[0237] Example 15 A negative electrode was produced in the same manner as in Example 13, except that 47.5% by mass of silicon powder and 47.5% by mass of graphite powder were used as the negative electrode active material.

[0238] Comparative Example 8 A negative electrode was produced in the same manner as in Example 14, except that styrene-butadiene rubber (TRD2001, manufactured by JSR Corporation) was used as the binder.

[0239] Comparative Example 9 A negative electrode was produced in the same manner as in Example 15, except that polyacrylic acid (manufactured by Aldrich, weight average molecular weight: 450,000) was used as the binder. The evaluation results are shown in Table 3.

[0240]

Claims

1. A binder for non-aqueous electrolyte batteries, comprising a polymer including a segment A having a glass transition temperature of 25°C or less and a segment B having a melting point of 50°C or more.

2. The binder for a non-aqueous electrolyte battery according to claim 1, wherein segment A has a heat of fusion of less than 5 J / g, and segment B has a heat of fusion of 5 J / g or more.

3. The binder for non-aqueous electrolyte batteries according to claim 1 or 2, wherein the polymer contains a chain structure represented by general formula (1) or general formula (2): General formula (1): A-B-A General formula (2): B-A-B (wherein A represents segment A, and B represents segment B).

4. The binder for non-aqueous electrolyte batteries according to any one of claims 1 to 3, wherein segment A of the polymer contains a fluorine-containing monomer unit.

5. The binder for non-aqueous electrolyte batteries according to any one of claims 1 to 4, wherein segment A of the polymer contains a vinylidene fluoride unit.

6. The binder for non-aqueous electrolyte batteries according to any one of claims 1 to 5, wherein segment A of the polymer contains a vinylidene fluoride unit and at least one repeating unit selected from the group consisting of repeating units represented by any one of the following formulas: Formula: -CF ２ -CF[-CF ３ ]- Formula:-CH ２ -CFRf １ - (wherein, Rf １ is a linear or branched fluorinated alkyl or alkoxy group having 1 to 12 carbon atoms, and when the number of carbon atoms is 2 or more, it may contain an oxygen atom between the carbon atoms. ２ - (wherein, Rf ２ is a linear or branched fluorinated alkyl or fluorinated alkoxy group having 1 to 12 carbon atoms, and when it has 2 or more carbon atoms, it may contain an oxygen atom between the carbon atoms.

7. The binder for non-aqueous electrolyte batteries according to any one of claims 1 to 6, wherein segment A of the polymer contains vinylidene fluoride units and 2,3,3,3-tetrafluoropropene units.

8. The binder for non-aqueous electrolyte batteries according to any one of claims 5 to 7, wherein the content of vinylidene fluoride units in segment A of the polymer is 99 to 15 mol % based on the total monomer units constituting segment A.

9. The binder for non-aqueous electrolyte batteries according to any one of claims 1 to 8, wherein segment B of the polymer contains a fluorine-containing monomer unit.

10. The binder for non-aqueous electrolyte batteries according to any one of claims 1 to 9, wherein segment B of the polymer contains a vinylidene fluoride unit.

11. The binder for non-aqueous electrolyte batteries according to claim 10, wherein the content of vinylidene fluoride units in segment B of the polymer is 97 mol % or more based on the total monomer units constituting segment B.

12. The binder for non-aqueous electrolyte batteries according to any one of claims 1 to 11, wherein segment B of the polymer contains only vinylidene fluoride units, or contains vinylidene fluoride units and at least one monomer unit selected from the group consisting of tetrafluoroethylene units, hexafluoropropylene units, 2,3,3,3-tetrafluoropropene units and (meth)acrylic acid units.

13. The binder for non-aqueous electrolyte batteries according to any one of claims 1 to 12, wherein the mass ratio of segment A to segment B in the polymer is 40 / 60 to 95 / 5.

14. The polymer contains a chain structure represented by general formula (1) or general formula (2), General formula (1): A-B-A General formula (2): B-A-B (wherein A represents segment A and B represents segment B). Segment A of the polymer has a glass transition temperature of -10°C or lower, contains vinylidene fluoride units and 2,3,3,3-tetrafluoropropene units, the content of 2,3,3,3-tetrafluoropropene units in segment A is 18 to 30 mol% based on all monomer units constituting segment A, and the content of vinylidene fluoride units in segment A is 70 to 82 mol% based on all monomer units constituting segment A, and segment B of the polymer has a melting point of 140 to 200°C, The binder for nonaqueous electrolyte batteries according to any one of claims 1 to 13, comprising a vinylidene fluoride unit, a content of the vinylidene fluoride unit in segment B being 97 mol % or more relative to all monomer units constituting segment B, a mass ratio of segment A to segment B in the polymer being 50 / 50 to 90 / 10, and a weight average molecular weight of the polymer being 200,000 to 2,000,000.

15. A binder for non-aqueous electrolyte batteries containing a polymer, the polymer having a glass transition temperature and a melting point, containing 2,3,3,3-tetrafluoropropene units, and having a tetrahydrofuran extractable amount at 25°C of 5 mass% or less.

16. The binder for non-aqueous electrolyte batteries according to claim 15, wherein the polymer further contains vinylidene fluoride units.

17. The binder for a non-aqueous electrolyte battery according to claim 15 or 16, wherein the polymer contains two or more segments.

18. The binder for nonaqueous electrolyte batteries according to any one of claims 15 to 17, wherein the glass transition temperature of the polymer is -10°C or lower, the melting point of the polymer is 140 to 200°C, the polymer contains vinylidene fluoride units and 2,3,3,3-tetrafluoropropene units, the content of the 2,3,3,3-tetrafluoropropene units is 9 to 24 mol% with respect to all monomer units constituting the polymer, and the content of the vinylidene fluoride units is 76 to 91 mol% with respect to all monomer units constituting the polymer, the amount of tetrahydrofuran extraction of the polymer at 25°C is 2 to 4 mass%, and the weight average molecular weight of the polymer is 200,000 to 2,000,000.

19. An electrode mixture for a non-aqueous electrolyte battery, comprising the binder for a non-aqueous electrolyte battery according to any one of claims 1 to 18.

20. The electrode mixture for a non-aqueous electrolyte battery according to claim 19, further comprising a powdered electrode material, and water or a non-aqueous solvent.

21. An electrode for a non-aqueous electrolyte battery, comprising an electrode material layer formed from the electrode mixture according to claim 19 or 20.

22. A non-aqueous electrolyte battery comprising the electrode according to claim 21.

Images