Binder for solid electrolyte battery, slurry, electrode, and solid electrolyte battery

Abstract

This binder for a solid electrolyte battery contains a polymer including a segment A having a glass transition temperature of 25°C or lower and a segment B having a melting point of 50°C or higher.

Description

Binder for solid electrolyte battery, slurry, electrode and solid electrolyte battery

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

[0002] Patent Document 1 describes a binder used in a slurry for a solid battery containing sulfide-based solid electrolyte particles, in which the binder has a resin terminal functional group of 0.01≦([-CH ２ OH]+[-COOH]) / ([-CH ３ ]+[-CF ２ H] + [-CH ２ OH] + [-CH ２ I] + [-OC(O)RH] + [-COOH] ≦ 0.25 (wherein R represents an alkyl group having 1 to 20 carbon atoms).

[0003] Patent Document 2 describes a binder used in a slurry for a solid battery containing sulfide-based solid electrolyte particles, which binder is characterized by containing a polymer having a vinylidene fluoride unit and at least one copolymerization unit (A) selected from the group consisting of a monomer unit having a structure represented by the following general formula (1) and a monomer unit having a structure represented by the following general formula (2): General formula (b1): -(CH ２ -CFRf １ )-General formula (b2):-(CHF-CHRf ２ )--wherein, Rf １ , 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 carbon atoms.

[0004] International Publication No. 2021 / 015230 International Publication No. 2021 / 015229

[0005] An object of the present disclosure is to provide a binder for a solid electrolyte battery that can form a solid electrolyte layer or an electrode material layer that has excellent adhesion and toughness.

[0006] According to the present disclosure, there is provided a binder for solid electrolyte batteries, 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.

[0007] According to the present disclosure, it is possible to provide a binder for a solid electrolyte battery that can form a solid electrolyte layer or an electrode material layer that is excellent in adhesion and toughness.

[0008] Specific embodiments of the present disclosure will be described in detail below, but the present disclosure is not limited to the following embodiments.

[0009] Solid electrolyte batteries are known that include a positive electrode material layer, a negative electrode material layer, and a solid electrolyte layer formed between the positive electrode material layer and the negative electrode material layer. Because bending stress is applied to the solid electrolyte layer and the electrode material layer of the electrode, the binder used to form the solid electrolyte layer and the electrode material layer is required to have excellent flexibility and properties that allow it to provide a solid electrolyte layer and an electrode material layer that can withstand bending stress. Patent Document 1 proposes a binder that contains a fluorine-containing elastomer as a binder with excellent flexibility.

[0010] The solid electrolyte layer and electrode material layer formed using the binder described in Patent Document 1 have sufficient flexibility to prevent cracking. However, in some battery manufacturing methods, not only bending stress but also tension is applied to the solid electrolyte layer and electrode material layer. The present inventors have found that if the solid electrolyte layer and electrode material layer used in such manufacturing methods can be imparted with not only flexibility but also toughness, a battery exhibiting high performance can be manufactured.

[0011] The binder for a solid electrolyte battery according to the present disclosure has been developed in view of such current circumstances, and by using the binder for a solid electrolyte battery according to the present disclosure, a solid electrolyte layer or an electrode material layer having excellent toughness can be formed without impairing excellent flexibility.

[0012] In the present disclosure, the flexibility and toughness of the solid electrolyte layer and the electrode material layer can be confirmed, for example, by performing a three-point bending test on a test laminate including a solid electrolyte layer and a transfer sheet, or an electrode including an electrode material layer. A solid electrolyte layer of a test laminate or 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, a solid electrolyte layer of a test laminate or 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 using the results of the three-point bending test to draw a curve with the stroke of an autograph on the horizontal axis and stress on the vertical axis, and then determining the peak width at half the stress of the peak stress.

[0013] Furthermore, the solid electrolyte layer and the electrode material layer obtained by using the binder for a solid electrolyte battery of the present disclosure have excellent adhesion to metal foil, and therefore, even when bent, the solid electrolyte layer and the electrode material layer obtained by using the binder for a solid electrolyte battery of the present disclosure are sufficiently adhered to other layers and are not easily peeled off.

[0014] That is, according to the present disclosure, there is provided a binder for solid electrolyte batteries (hereinafter, sometimes referred to as a first binder for solid 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] Furthermore, according to the present disclosure, there is provided a binder for solid 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, this binder may be referred to as a second binder for solid electrolyte batteries).

[0016] In the present disclosure, a solid electrolyte is a solid electrolyte and is distinguished from a liquid electrolyte (nonaqueous electrolyte). Solid electrolytes include polymer electrolytes and inorganic solid electrolytes. The binder for a solid electrolyte battery of the present disclosure can be particularly suitably used as a binder for an inorganic solid electrolyte battery or an all-solid-state battery.

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

[0018] 1. First Binder for Solid Electrolyte Battery The first binder for solid electrolyte batteries 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. The first binder for solid electrolyte batteries contains a polymer including segment A having a glass transition temperature, and therefore can form a solid electrolyte layer or electrode material layer having flexibility that is not significantly inferior to that when conventional binders are used.

[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 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, because this can further improve the flexibility of the solid electrolyte layer or 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 flame retardancy and heat resistance of the solid electrolyte layer and 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 ２The 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 within a desired range, and the flexibility of the solid electrolyte layer or electrode material layer can be further improved. Furthermore, by containing a VdF unit in segment A, the solubility of the binder in solvents such as butyl butyrate 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 solid electrolyte layer or the electrode material layer and can further improve the solubility of the binder in solvents such as butyl butyrate. ２ -CF [-CF ３ ]- General formula (b1): -CH ２ -CFRf １ - (wherein, Rf１ 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 １The 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 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.

[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, segment A preferably 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 solid electrolyte layer or the electrode material layer can be further improved. In addition, the solubility of the binder in solvents such as butyl butyrate 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 solid 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 a solid electrolyte layer or electrode material layer excellent in adhesion and toughness without impairing excellent flexibility.

[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 adhesion, flexibility, and toughness of the solid electrolyte layer or 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 of the solid electrolyte layer and 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, and the adhesion and toughness of the solid electrolyte layer or electrode material layer can be further improved. Furthermore, by containing a VdF unit in segment B, the solubility of the binder in a solvent such as butyl butyrate 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 adhesion and toughness of the solid electrolyte layer or the electrode material layer and further improve the solvent solubility of the binder in a solvent such as butyl butyrate. Therefore, the content of VdF units in segment B is preferably 97 mol % or more, more preferably more than 99 mol %, and even more preferably 99.5 mol % or more and may be 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 adhesion and toughness of the solid electrolyte layer or the electrode material layer and further improve the solvent solubility of the binder in a solvent such as butyl butyrate. 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, and may be 0 mol % or more, relative to all monomer units constituting segment B.

[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 solid electrolyte batteries 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 solid electrolyte batteries includes 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 (In the formulas, A represents segment A, B represents segment B, and C represents segment C.)

[0090] The polymer contained in the first binder for solid electrolyte batteries preferably contains a chain structure represented by general formula (1) or general formula (2), because it can form a solid electrolyte layer or an electrode material layer that is more excellent in adhesion, 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 solid 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 adhesion and toughness.

[0092] The number average molecular weight (polystyrene equivalent) of the polymer contained in the first binder for solid 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 solid 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 solid 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 then 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 then 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 solid 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 Solid Electrolyte Battery The second binder for a solid electrolyte battery 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 solid 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 solid electrolyte batteries contains a polymer having a glass transition temperature, it is possible to form a solid electrolyte layer or an electrode material layer having flexibility that is not significantly inferior to that when a conventional binder is used.

[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 solid 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 solid electrolyte batteries contains a polymer having a melting point in addition to having a glass transition temperature, and therefore can form a solid electrolyte layer or an electrode material layer that is excellent in adhesion and toughness without impairing excellent flexibility.

[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 solid 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 solid electrolyte batteries contains a polymer whose tetrahydrofuran extractable amount is within the above numerical range, it has flexibility that is not significantly inferior to that when conventional binders are used, and can form a solid electrolyte layer or electrode material layer that is also excellent in adhesion and toughness. 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 solid electrolyte batteries contains 2,3,3,3-tetrafluoropropene units. Because the second binder for solid electrolyte batteries contains 2,3,3,3-tetrafluoropropene units, the binder can be imparted with solvent solubility in solvents such as butyl butyrate, and a solid electrolyte layer or electrode material layer having excellent adhesion, flexibility, and toughness can be formed.

[0120] The polymer contained in the second binder for solid 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, and a solid electrolyte layer or electrode material layer having even more excellent adhesion, flexibility, and toughness can be formed.

[0121] The fluorine-containing monomer that can constitute the polymer contained in the second binder for solid 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 solid 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 solid electrolyte batteries contains a VdF unit as a fluorine-containing monomer unit, the solvent solubility of the binder in a solvent such as butyl butyrate is further improved, and by using the second binder for solid electrolyte batteries, a solid electrolyte layer or an electrode material layer having even more excellent adhesion, flexibility, and toughness can be formed.

[0124] The content of 2,3,3,3-tetrafluoropropene units in the polymer contained in the second binder for solid 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 solid 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 the monomer units constituting the polymer.

[0126] The content of VdF units in the polymer contained in the second binder for solid 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 solid 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 solid electrolyte battery is a polymer having 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 solid 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 solid 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 solid 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 solid 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 solid 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 solid 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 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 solid electrolyte battery contains 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 also to easily adjust the glass transition temperature and melting point of the polymer, thereby further improving the adhesion, flexibility, and toughness of the solid electrolyte layer or electrode material layer.

[0138] When the polymer contained in the second binder for a solid 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 solid electrolyte battery. That is, the polymer contained in the second binder for a solid electrolyte battery can contain Segment A and Segment B, like the polymer contained in the first binder for a solid electrolyte battery, and can have the same configuration as the polymer contained in the first binder for a solid electrolyte battery.

[0139] The polymer contained in the second binder for a solid 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 solid electrolyte battery.

[0140] The first binder for solid electrolyte batteries and the second binder for solid electrolyte batteries (hereinafter sometimes simply referred to as "binders for solid electrolyte batteries") may contain a polymer other than the above-mentioned polymers. Examples of the other polymer include fluoropolymer, polymethacrylate, polymethyl methacrylate, polyacrylonitrile, polyimide, polyamide, polyamideimide, polycarbonate, styrene rubber, butadiene rubber, styrene-butadiene rubber, and polyacrylic acid.

[0141] The binder for solid electrolyte batteries according to 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 solid electrolyte battery. The binder can be particularly suitably used for forming a solid electrolyte layer or an electrode material layer of a solid electrolyte battery.

[0143] The present disclosure also relates to use of a binder for forming a solid 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 a solid electrolyte layer or an electrode material layer of a solid electrolyte battery.

[0144] The solid electrolyte battery may be a primary battery, a storage battery (secondary battery), or an energy storage element. The solid electrolyte battery is preferably an all-solid-state lithium-ion secondary battery using an inorganic solid electrolyte. Examples of the solid electrolyte battery include oxide-based solid batteries and sulfide-based solid batteries. The binder for solid electrolyte batteries of the present disclosure can be particularly suitably used as a binder for solid batteries using an inorganic solid electrolyte, such as sulfide-based solid batteries. The sulfide-based solid battery is preferably an all-solid-state lithium-ion secondary battery using a sulfide-based solid electrolyte as the electrolyte.

[0145] 3. Slurry The slurry for a solid electrolyte battery according to the present disclosure contains the above-described binder for a solid electrolyte battery, a solid electrolyte, and a solvent. Because the slurry according to the present disclosure contains the above-described binder for a solid electrolyte battery, it has flexibility that is not significantly inferior to that when a conventional binder is used, and can form a solid electrolyte layer or an electrode material layer that is excellent in adhesion and toughness.

[0146] The slurry for a solid electrolyte battery of the present disclosure is used to form a layer containing a solid electrolyte. The slurry for a solid electrolyte battery of the present disclosure can be used to form a positive electrode material layer containing a solid electrolyte, a solid electrolyte layer containing a solid electrolyte, or a negative electrode material layer containing a solid electrolyte.

[0147] The slurry for a solid electrolyte battery of the present disclosure contains a solid electrolyte, preferably an inorganic solid electrolyte. A solid electrolyte capable of absorbing and releasing metal ions such as lithium ions can be used as the solid electrolyte. Examples of the solid electrolyte include sulfide-based solid electrolytes, oxide-based solid electrolytes, and crystalline oxides and oxynitrides. It is particularly preferable that the slurry for a solid electrolyte battery contain a sulfide-based solid electrolyte.

[0148] The sulfide-based solid electrolyte is not particularly limited as long as it contains sulfur atoms. ２ S-P ２ S ５ , Li ２ S-P ２ S ３ , Li ２ S-P２ S ３ -P ２ S ５ , Li ２ S-SiS ２ , LiI-Li ２ S-SiS ２ , LiI-Li ２ S-P ２ S ５ , LiI-Li ２ S-P ２ O ５ , LiI-Li ３ P.O. ４ -P ２ S ５ , LiI-Li ２ S-SiS ２ -P ２ S ５ , Li ２ S-SiS ２ -Li ４ SiO ４ , Li ２ S-SiS ２ -Li ３ P.O. ４ , Li ３ P.S. ４ -Li ４ GeS ４ , Li ３．４ P ０．６ Si ０．４ S ４ , Li ３．２５ P ０．２５ Ge ０．７６ S ４ , Li ４－ｘ Ge １－ｘ P ｘ S ４ Examples include:

[0149] The oxide-based solid electrolytes include LiPON (lithium phosphate oxynitride), Li ２ Alumni ２ O ３ -P ２ O ５ , Li ２ O—SiO ２ , Li １．３ Al ０．３ Ti ０．７ (P.O. ４ ) ３ , La ０．５１Li ０．３４ TiO ０．７４ , Li ３ P.O. ４ , Li ２ SiO ２ , Li ２ SiO ４ , Li ０．５ La ０．５ TiO ３ , Li １．５ Al ０．５ Ge １．５ (P.O. ４ ) ３ Examples include:

[0150] Crystalline oxides and oxynitrides include LiI, Li ３ N., Li. ５ La ３ Ta ２ O １２ , Li ７ La ３ Zr ２ O １２ , Li ６ BaLa ２ Ta ２ O １２ , Li ３ P.O. （４－３／２ｗ） N ｗ (w<1), Li ３．６ Si ０．６ P ０．４ O ４ Examples include:

[0151] The slurry for a solid electrolyte battery according to the present disclosure contains a solvent. A low-polarity solvent is preferred as the solvent. Use of a low-polarity solvent is preferred because it makes it less likely for the solvent to react with the sulfide-based solid electrolyte. In the present disclosure, a low-polarity solvent is defined as one having a relative dielectric constant of less than 20 at a frequency of 100 kHz. A low-polarity solvent is more preferably one having a relative dielectric constant of less than 10 at a frequency of 100 kHz.

[0152] The solvent preferably contains at least one compound selected from the group consisting of aromatic compounds, ester compounds, aliphatic hydrocarbon compounds, ether compounds, and carbonate compounds, preferably aromatic compounds and ester compounds, and most preferably ester compounds.

[0153] The low-polarity solvent is not particularly limited, and examples thereof include n-octane, n-nonane, n-decane, n-butyl ether, diisopentyl ether, ethylbenzene, ethyl acetate, ethyl butyrate, butyl butyrate, propyl propionate, butyl methacrylate, dimethyl carbonate, diethyl carbonate, methyl phenyl ether, cyclopentyl methyl ether, ethylene carbonate, diphenyl ether, fluorobenzene, trifluoromethylbenzene, bistrifluoromethylbenzene, benzene, and thiol.

[0154] Among these, at least one solvent selected from the group consisting of propyl propionate, butyl methacrylate, ethyl acetate, ethyl butyrate, and butyl butyrate is more preferably used as the solvent. A mixed solvent containing two or more of these solvents may also be used.

[0155] The slurry for a solid electrolyte battery according to the present disclosure preferably further contains a conductive additive, such as carbon black (e.g., acetylene black, ketjen black, etc.), carbon fibers (e.g., multi-walled carbon nanotubes, single-walled carbon nanotubes, carbon nanofibers, and vapor-grown carbon fibers (VGCF)), and metal powders (e.g., SUS powder, aluminum powder, etc.).

[0156] The slurry for a solid electrolyte battery according to the present disclosure may further contain an electrode active material. The electrode active material may be either a positive electrode active material or a negative electrode active material.

[0157] The positive electrode active material is, for example, LiCoO ２ , Li(Ni,Co,Al)O ２ , Li １＋ｘ Ni １／３ Mn １／３ Co １／３ O ２ (x is a real number greater than or equal to 0), LiNiO ２ , LiMn ２ O ４ , LiCoMnO ４ , Li ２ NiMn ３ O ８ , Li ３ Fe２ (P.O. ４ ) ３ , Li ３ V ２ (P.O. ４ ) ３ , Li １＋ｘ Mn ２－ｘ－ｙ M ｙ O ４ (M is at least one metal selected from the group consisting of Al, Mg, Co, Fe, Ni, and Zn, and y is a real number of 0 or more), and lithium titanate (Li ｘ TiO ｙ ), LiMPO ４ Examples of the lithium phosphate include lithium metal phosphate having a composition represented by the formula (wherein M is Fe, Mn, Co, or Ni).

[0158] As the positive electrode active material, LiCoO ２ , Li(Ni,Co,Al)O ２ , LiNi １／３ Mn １／３ Co １／３ O ２ In the present disclosure, a positive electrode active material in which the surface of each of these materials is coated may also be used. The coating material that can be used in the present disclosure may contain a material that has lithium ion conductivity and can maintain the shape of a coating layer on the surface of the active material. Examples of the coating material include LiNbO ３ , Li ４ Ti ５ O １２ , Li ３ P.O. ４ The form of the positive electrode active material is not particularly limited, but powder form is preferred.

[0159] The average particle size of the positive electrode active material is, for example, 1 to 50 μm, preferably 1 to 20 μm, and particularly preferably 3 to 7 μm. If the average particle size of the positive electrode active material is too small, it may be difficult to handle, while if the average particle size of the positive electrode active material is too large, it may be difficult to obtain a flat positive electrode material layer. The average particle size of the positive electrode active material can be determined, for example, by measuring the particle size of the active material support observed with a scanning electron microscope (SEM) and averaging the measured values.

[0160] Examples of the negative electrode active material include carbonaceous materials such as artificial graphite, graphite carbon fiber, resin-baked carbon, pyrolytic vapor-grown carbon, coke, mesocarbon microbeads (MCMB), furfuryl alcohol resin-baked carbon, polyacene, pitch-based carbon fiber, vapor-grown carbon fiber, natural graphite, and non-graphitizable carbon; silicon-containing compounds such as silicon and silicon alloys; Li ４ Ti ５ O １２ Among these, those containing at least a carbonaceous material and silicon-containing compounds are particularly suitable.

[0161] The content of the binder in the slurry for a solid electrolyte battery of the present disclosure is preferably 0.5 to 4.5 parts by mass per 100 parts by mass of the solid content of the slurry for a solid electrolyte battery.

[0162] The solid content concentration of the slurry for a solid electrolyte battery of the present disclosure is preferably 20 to 75 mass %, and more preferably 30 to 70 mass %.

[0163] A method for preparing a slurry for a solid electrolyte battery includes dispersing and mixing a solid electrolyte and, optionally, an electrode active material in a solution or dispersion in which a binder is dissolved or dispersed in a solvent. Alternatively, the binder and solid electrolyte may be mixed first, and then a solvent may be added to prepare a slurry for a solid electrolyte battery.

[0164] (Solid Electrolyte Layer) The slurry for a solid electrolyte battery according to the present disclosure can be used to form a solid electrolyte layer of a solid electrolyte battery. The solid electrolyte layer can be produced, for example, by applying the slurry for a solid electrolyte battery to a transfer sheet, drying the resulting coating, placing the transfer sheet on an electrode material layer so that the coating surface is in contact with the electrode material layer, pressing the electrode material layer, and peeling off the transfer sheet.

[0165] Examples of methods for applying the solid electrolyte battery slurry to a transfer sheet include spraying, screen printing, doctor blade printing, bar coating, roll coating, gravure printing, and die coating. Examples of drying methods include vacuum drying, heat drying, and vacuum heat drying. There are no specific restrictions on the conditions for vacuum drying and heat drying, and they may be set appropriately.

[0166] 4. Electrodes The solid electrolyte battery slurry of the present disclosure can be used to form electrode material layers such as a positive electrode material layer and a negative electrode material layer. The solid electrolyte battery electrode of the present disclosure includes an electrode material layer formed from the above-described solid electrolyte battery slurry. The solid electrolyte battery electrode of the present disclosure can be used as a positive electrode or a negative electrode.

[0167] The electrode of the present disclosure may include only an electrode material layer formed using the above-mentioned slurry for a solid electrolyte battery, or may include a current collector and an electrode material layer formed using the above-mentioned slurry for a solid electrolyte battery. The electrode material layer is formed using the slurry for a solid electrolyte battery of the present disclosure and may be provided on one side or both sides of the current collector.

[0168] The thickness of the electrode material layer varies depending on the intended use of the solid electrolyte battery, but is preferably 10 to 250 μm, more preferably 20 to 200 μm, and even more preferably 30 to 150 μm.

[0169] Examples of the material of the current collector include aluminum, stainless steel (SUS), nickel, iron, titanium, chromium, gold, platinum, and zinc, with aluminum and stainless steel (SUS) being preferred. Examples of the shape of the current collector include foil, plate, and mesh, with foil being preferred.

[0170] The electrode can be produced, for example, by applying the above-mentioned solid electrolyte battery slurry to a current collector and drying the resulting coating. Coating methods include spraying, screen printing, doctor blade printing, bar coating, roll coating, gravure printing, and die coating. Drying methods include, for example, vacuum drying, heat drying, and vacuum heat drying. There are no specific restrictions on the conditions for vacuum drying and heat drying, and they may be set appropriately.

[0171] The amount of the slurry for solid electrolyte batteries to be applied varies depending on the composition of the slurry for solid electrolyte batteries and the intended use of the electrode, but is generally 5 to 30 mg / cm in a dry state. ２ The thickness of the electrode is not particularly limited, but is about 10 to 250 μm.

[0172] 5. Solid Electrolyte Battery One embodiment of the solid electrolyte battery of the present disclosure includes a positive electrode material layer, a negative electrode material layer, and a solid electrolyte layer formed between the positive electrode material layer and the negative electrode material layer. Also, one embodiment of the solid electrolyte battery of the present disclosure includes a positive electrode including a positive electrode material layer and a current collector, a negative electrode including a negative electrode material layer and a current collector, and a solid electrolyte layer formed between the positive electrode and the negative electrode. In the solid electrolyte battery of the present disclosure, at least one of the positive electrode material layer, the negative electrode material layer, and the solid electrolyte layer is formed from the slurry for a solid electrolyte battery of the present disclosure.

[0173] The solid electrolyte battery may be a primary battery, a storage battery (secondary battery), or a storage element. The solid electrolyte battery is preferably an all-solid-state lithium ion secondary battery using an inorganic solid electrolyte. Examples of the solid electrolyte battery include oxide-based solid batteries and sulfide-based solid batteries. The sulfide-based solid battery is preferably an all-solid-state lithium ion secondary battery using a sulfide-based solid electrolyte as the electrolyte.

[0174] The solid electrolyte battery of the present disclosure may include a separator between the positive electrode and the negative electrode, such as a porous membrane made of polyethylene, polypropylene, or the like; a nonwoven fabric made of a resin such as polypropylene; or a nonwoven fabric made of glass fiber, or the like.

[0175] The solid electrolyte battery of the present disclosure may further include a battery case. The shape of the battery case is not particularly limited as long as it can accommodate the above-mentioned positive electrode, negative electrode, solid electrolyte layer, etc., but examples of the battery case include a cylindrical shape, a prismatic shape, a coin shape, and a laminate shape.

[0176] The solid electrolyte layer of the present disclosure has excellent adhesion, flexibility, and toughness, and therefore can be suitably used as a solid electrolyte layer for a solid electrolyte battery. Also, the electrode for a solid electrolyte battery of the present disclosure has an electrode material layer with excellent adhesion, flexibility, and toughness, and therefore can be suitably used as an electrode for a solid electrolyte battery.

[0177] 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.

[0178] <1> According to a first aspect of the present disclosure, there is provided a binder for solid 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 more. <2> According to a second aspect of the present disclosure, there is provided a binder for solid 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 solid electrolyte batteries according to the first or second aspect, in which 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> According to a fourth aspect of the present disclosure, there is provided a binder for solid 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 solid 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 solid 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 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.) 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 solid 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 solid 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 solid 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 solid 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 solid 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 solid 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 solid electrolyte battery according to any one of the first to twelfth aspects, wherein a mass ratio (A / B) 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 solid 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 solid 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 solid 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 solid electrolyte batteries according to any of the fifteenth to seventeenth aspects, wherein: the polymer has a glass transition temperature of −10° C. or lower; the polymer has a melting point of 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 being 9 to 24 mol % based on all monomer units constituting the polymer, and the content of the vinylidene fluoride units being 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 polymer has a weight average molecular weight of 200,000 to 2,000,000. <19> According to a nineteenth aspect of the present disclosure, there is provided a slurry for a solid electrolyte battery, comprising the binder for a solid electrolyte battery according to any one of the first to eighteenth aspects, a solid electrolyte, and a solvent. <20> According to a twentieth aspect of the present disclosure, there is provided a slurry for a solid electrolyte battery according to the nineteenth aspect, further comprising an electrode active material. <21> According to a twenty-first aspect of the present disclosure, there is provided an electrode for a solid electrolyte battery, comprising an electrode material layer formed from the slurry for a solid electrolyte battery according to the nineteenth or twentieth aspect. <22> According to a twenty-second aspect of the present disclosure, there is provided a solid electrolyte battery comprising the electrode according to the twenty-first aspect. <23> According to a twenty-third aspect of the present disclosure, there is provided a solid electrolyte battery comprising a solid electrolyte layer formed from the slurry for a solid electrolyte battery according to the nineteenth or twentieth aspect.

[0179] Next, embodiments of the present disclosure will be described with reference to examples, but the present disclosure is not limited to these examples.

[0180] The values ​​in the examples were measured by the following methods.

[0181] <Polymer Composition> The composition of the fluorine-containing copolymer was measured by solution NMR. Measuring device: Varian VNMRS400 Resonance frequency: 376.04 (Sfrq) Pulse width: 30° (pw=6.8)

[0182] <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.

[0183] <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.

[0184] <Weight-average molecular weight> Based on the results of measurement by GPC, the molecular weight was calculated using standard polystyrene as the standard. GPC apparatus: TOSOH HLC-8320GPC Columns: 1 SuperAW-H, 3 SuperAWM-H Developing solvent: dimethylformamide (DMF) Sample concentration: 0.05% by mass Measurement temperature: 40°C

[0185] <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.

[0186] <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).

[0187] <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 one side, a negative electrode having a negative electrode material layer on one side, or a solid electrolyte layer-containing laminate was cut to 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 force applied to the specimen depending on the moving distance of the probe. The comparative example was set as 100 and the maximum bending strength was evaluated relative to the comparative example.

[0188] <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 one side, a negative electrode having a negative electrode material layer on one side, or a solid electrolyte layer-containing laminate was cut to 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 value of the force applied to the test piece depending on the movement distance of the probe. Next, the test force at half the maximum bending strength is calculated, and 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 is the half-width. That is, a curve is drawn with the stroke of the autograph on the horizontal axis and the stress on the vertical axis, and it can be specified as the peak width at half the stress of the peak stress. Comparative Example was evaluated relative to 100.

[0189] <Adhesion> Adhesion was evaluated by performing a 90-degree peel test at the electrode material layer / current collector interface. In the 90-degree peel test, the electrode material layer side of a positive or negative electrode cut to 1.2 × 8.0 cm was fixed to a movable jig, tape was attached to the current collector side, and the stress (N / mm) when the tape was pulled 90 degrees at a rate of 100 mm / min was measured using an autograph. A 1 N load cell was used for the autograph. Evaluation was made relative to the comparative example, which was set to 100.

[0190] The following polymers were used in the examples and comparative examples.

[0191] 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, CH２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COONH ４ 0.8001 g of 50% aqueous solution, C ５ F １１ COONH ４ 24.021 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.

[0192] (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.

[0193] 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%.

[0194] 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%.

[0195] 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%.

[0196] 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 mass%.

[0197] 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%.

[0198] Production Example 4 Fluorine-containing copolymer d (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 0.8003 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.

[0199] (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.

[0200] 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 wt%. 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% by mass.

[0201] Production Example 5: Fluorine-containing copolymer e: A fluoroelastomer having a VdF / R1234yf molar ratio of 78.6 / 21.4 was obtained according to the production method described in Example 12 of JP-A 2013-216915. There was no heat of fusion. The amount of THF extracted was 100% by mass.

[0202] Examples 1 to 12 and Comparative Examples 1 to 3 (Preparation of Binder Solution) As a binder, a polymer shown in Table 1 was added to butyl butyrate, and the mixture was stirred overnight at 50°C, followed by three cycles of ultrasonic treatment (90 seconds) using an ultrasonic homogenizer to prepare a binder solution. Here, the binder was contained in an amount of 5% by mass, with the entire binder solution being 100% by mass.

[0203] In the present disclosure, the positive electrode, negative electrode slurry, and solid electrolyte layer were prepared by the following procedure.

[0204] (1) The binder solution obtained by the above-described method and a separately prepared active material (positive electrode active material or negative electrode active material) or a sulfide-based solid electrolyte are added to butyl butyrate, and a dispersion treatment (e.g., ultrasonic treatment) is performed to obtain a "positive electrode active material / binder slurry," a "negative electrode active material / binder slurry," or a "solid electrolyte / binder slurry" in which the active material or sulfide-based solid electrolyte and binder are highly dispersed in a low-polarity solvent.

[0205] (2) A sulfide-based solid electrolyte or an active material (a positive electrode active material or a negative electrode active material) is added to the "positive electrode active material / binder slurry," "negative electrode active material / binder slurry," or "solid electrolyte / binder slurry" obtained in (1), and a dispersion treatment (e.g., ultrasonic treatment) is performed to obtain a "positive electrode slurry" or "negative electrode slurry" in which the active material, sulfide-based solid electrolyte, and binder are highly dispersed in the solvent. A more specific preparation method is shown below.

[0206] (Preparation of Slurry for Negative Electrode) Using the prepared binder solution, slurries for negative electrodes according to the examples and comparative examples were prepared as follows.

[0207] The binder solution, graphite as the negative electrode active material, and butyl butyrate were added to a PFA container, and ultrasonic treatment (50 seconds) was performed once using an ultrasonic homogenizer to prepare a "negative electrode active material / binder slurry." The obtained negative electrode active material / binder slurry was further mixed with the binder solution, butyl butyrate, and a sulfide-based solid electrolyte (30LiI.70 (0.75Li ２ S 0.25P ２ S ５ )) was added to the slurry, and ultrasonic treatment (30 seconds each) was performed three times using an ultrasonic homogenizer to obtain a "slurry for negative electrode" in which the negative electrode active material, sulfide-based solid electrolyte, and binder were highly dispersed. The final solid concentration of the active material and binder in the slurry was 3.0 mass%.

[0208] (Preparation of Negative Electrode) Each negative electrode slurry was applied to a copper foil negative electrode current collector using a doctor blade and dried to obtain a negative electrode having a 110 μm thick negative electrode material layer formed on the surface of the negative electrode current collector.

[0209] (Preparation of Slurry for Positive Electrode) Using the prepared binder solution, slurries for positive electrodes according to the examples and comparative examples were prepared as follows.

[0210] The above binder solution and the ternary active material Li(NiMnCo) as the positive electrode active material were placed in a PFA container. １／３ O ２ The resulting positive electrode active material / binder slurry was further mixed with a binder solution, butyl butyrate, and a sulfide-based solid electrolyte (30LiI.70 (0.75LiI ２ S 0.25P ２ S ５ )) was added to the slurry, and ultrasonic treatment (30 seconds each) was performed three times using an ultrasonic homogenizer to obtain a "positive electrode slurry" in which the positive electrode active material, sulfide-based solid electrolyte, and binder were highly dispersed. The final binder solid content in the slurry was 3.0 mass%.

[0211] (Preparation of Positive Electrode) Each positive electrode slurry was applied onto an aluminum foil current collector using a doctor blade and dried to obtain a positive electrode having a positive electrode material layer with a thickness of 85 μm formed on the surface of the positive electrode current collector.

[0212] (Preparation of Solid Electrolyte Layer) An electrolyte slurry was prepared using butyl butyrate, the above-mentioned sulfide-based solid electrolyte as the solid electrolyte, and a binder solution. The prepared electrolyte slurry was applied to a peelable substrate (aluminum foil) using a doctor blade, dried, and then a 45 μm-thick solid electrolyte layer was formed on the substrate. The mass ratio of the solid electrolyte to the binder in the solid electrolyte layer was solid electrolyte: binder = 100 parts by mass: 1 part by mass. For measuring the maximum test force and half-width, a laminate (sometimes referred to as a "solid electrolyte layer-containing laminate" in this disclosure) including a solid electrolyte layer and a substrate (aluminum foil) was used.

[0213] The electrolyte slurry was prepared as follows: A solid electrolyte and binder solution were added to a butyl butyrate solvent, and ultrasonic treatment (30 seconds) was performed once using an ultrasonic homogenizer to obtain an electrolyte slurry in which the solid electrolyte and binder were highly dissolved or dispersed. The solid content at this time was 39%.

[0214] The results are shown in Table 1.

[0215]

Claims

1. A binder for solid 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 solid 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 solid 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 solid 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 solid 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 solid 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 solid 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 solid 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 solid 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 solid 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 solid 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 solid 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 solid electrolyte batteries according to any one of claims 1 to 12, wherein the mass ratio (A / B) 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 solid 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 solid 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 a solid electrolyte battery according to claim 15, wherein the polymer further contains a vinylidene fluoride unit.

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

18. The binder for solid 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 being 9 to 24 mol% with respect to all monomer units constituting the polymer, and the content of the vinylidene fluoride units being 76 to 91 mol% with respect to all monomer units constituting the polymer, the amount of tetrahydrofuran extraction of the polymer at 25°C being 2 to 4 mass%, and the weight average molecular weight of the polymer is 200,000 to 2,000,000.

19. A slurry for a solid electrolyte battery comprising the binder for a solid electrolyte battery according to any one of claims 1 to 18, a solid electrolyte, and a solvent.

20. The slurry for a solid electrolyte battery according to claim 19, further comprising an electrode active material.

21. An electrode for a solid electrolyte battery comprising an electrode material layer formed from the slurry for a solid electrolyte battery according to claim 19 or 20.

22. A solid electrolyte battery comprising the electrode according to claim 21.

23. A solid electrolyte battery comprising a solid electrolyte layer formed from the slurry for a solid electrolyte battery according to claim 19 or 20.

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