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

Abstract

The present invention provides a binder for a solid electrolyte battery, which contains a polymer containing a segment A having a glass transition temperature of 25 DEG C or less and a segment B having a melting point of 50 DEG C or more.

Description

Technical Field

[0001] This disclosure relates to binders, slurries, electrodes, and solid electrolyte batteries for use in solid electrolyte batteries. Background Technology

[0002] Patent Document 1 discloses a binder used in a slurry for solid-state batteries containing sulfide-based solid electrolyte particles, characterized in that the binder contains a fluorinated elastomer with resin terminal functional groups satisfying the following formula.

[0003] 0.01≤([-CH2OH]+[-COOH]) / ([-CH3]+[-CF2H]+[-CH2OH]+[-CH2I]+[-OC(O)RH]+[-COOH]≤0.25

[0004] (In the formula, R represents an alkyl group having 1 to 20 carbon atoms.)

[0005] Patent document 2 describes an adhesive for use in a slurry for a solid-state battery containing sulfide-based solid electrolyte particles, characterized in that the adhesive comprises a polymer having: a vinylidene fluoride unit; and at least one copolymer unit (A) selected from the group consisting of monomer units having the structure represented by the following general formula (1) and monomer units having the structure represented by the following general formula (2).

[0006] General formula (b1): -(CH2-CFRf1)-

[0007] General formula (b2): -(CHF-CHRf2)-

[0008] In the formula, Rf1 and Rf2 are straight-chain or branched fluoroalkyl or fluoroalkoxy groups with 1 to 12 carbon atoms. When the number of carbon atoms is 2 or more, oxygen atoms may be present between carbon atoms.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: International Publication No. 2021 / 015230

[0012] Patent Document 2: International Publication No. 2021 / 015229 Summary of the Invention

[0013] The problem that the invention aims to solve

[0014] The purpose of this disclosure is to provide a binder for solid electrolyte batteries that can form a solid electrolyte layer or electrode material layer with excellent adhesion and toughness.

[0015] Methods for solving problems

[0016] According to this disclosure, a binder for solid electrolyte batteries is provided, which contains a polymer comprising a segment A having a glass transition temperature below 25°C and a segment B having a melting point above 50°C.

[0017] The effects of the invention

[0018] According to this disclosure, a binder for solid electrolyte batteries that can form a solid electrolyte layer or electrode material layer with excellent adhesion and toughness can be provided. Detailed Implementation

[0019] The following describes in detail the specific embodiments of this disclosure, but this disclosure is not limited to the following embodiments.

[0020] Solid electrolyte batteries are known to have a positive electrode material layer, a negative electrode material layer, and a solid electrolyte layer formed between the positive and negative electrode material layers. Since bending stress is applied to the solid electrolyte layer and the electrode material layer, the binder used to form the solid electrolyte layer and the electrode material layer is required to have properties that provide excellent flexibility and can withstand bending stress. Patent Document 1 discloses a binder with excellent flexibility, characterized by containing a fluorinated elastomer.

[0021] The solid electrolyte layer and electrode material layer formed using the binder described in Patent Document 1 possess sufficient flexibility to prevent cracking. On the other hand, in some battery manufacturing methods, not only bending stress but also tension is applied to the solid electrolyte layer and electrode material layer. The inventors have discovered that if both flexibility and toughness can be imparted to the solid electrolyte layer and electrode material layer used in such manufacturing methods, it is possible to manufacture batteries exhibiting high performance.

[0022] The solid electrolyte battery binder disclosed herein was developed in view of the current situation, and by using the solid electrolyte battery binder disclosed herein, it is possible to form a solid electrolyte layer or electrode material layer with excellent toughness without compromising excellent flexibility.

[0023] In this disclosure, the flexibility and toughness of the solid electrolyte layer and electrode material layer can be confirmed, for example, by performing a three-point bending test on a test laminate having a solid electrolyte layer and a transfer sheet, or on an electrode having an electrode material layer. A solid electrolyte layer of a test laminate or an electrode material layer of an electrode with a small maximum test force as determined by the three-point bending test can be said to exhibit excellent flexibility. Furthermore, a solid electrolyte layer of a test laminate or an electrode material layer of an electrode with a large half-peak width as determined by the three-point bending test can be said to exhibit excellent toughness. The half-peak width can be determined by plotting a curve with the stroke of the universal testing machine (Autograph) as the horizontal axis and stress as the vertical axis, using the results of the three-point bending test as the peak width at half the stress peak value.

[0024] Furthermore, the solid electrolyte layer and electrode material layer obtained by using the adhesive for solid electrolyte batteries of this disclosure exhibit excellent adhesion to the metal foil. Therefore, the solid electrolyte layer and electrode material layer obtained by using the adhesive for solid electrolyte batteries of this disclosure maintain sufficient adhesion to other layers even when bent, making them difficult to peel off.

[0025] That is, according to this disclosure, a binder for solid electrolyte batteries (hereinafter sometimes referred to as a first solid electrolyte battery binder) is provided, which contains a polymer, said polymer comprising a segment A having a glass transition temperature of less than 25°C and a segment B having a melting point of more than 50°C.

[0026] Additionally, according to this disclosure, a binder for solid electrolyte batteries (hereinafter sometimes referred to as a second solid electrolyte battery binder) is provided, which is 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-tetrafluoropropylene units, and has a tetrahydrofuran extraction amount of 5% by mass or less at 25°C.

[0027] In this disclosure, the solid electrolyte is a solid electrolyte, as opposed to a liquid electrolyte (non-aqueous electrolyte). Solid electrolytes include polymeric electrolytes and inorganic solid electrolytes. The solid electrolyte battery binder of this disclosure is particularly suitable for use as a binder for inorganic solid electrolyte batteries or all-solid-state batteries.

[0028] First, the composition of the binder for the first solid electrolyte battery will be described in detail.

[0029] 1. Binder for the first solid electrolyte battery

[0030] The binder for the first solid electrolyte battery contains a polymer comprising segment A and segment B. The polymer may contain other segments that constitute different structures from segments A and B, provided that it contains segments A and B.

[0031] (Polymer segment A)

[0032] 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 solid electrolyte battery binder contains a polymer comprising segment A having a glass transition temperature, thus enabling the formation of a solid electrolyte layer or electrode material layer with flexibility that does not significantly deteriorate, compared to the use of conventional binders.

[0033] The glass transition temperature can be determined as follows: Using a differential scanning calorimeter (DSC822e manufactured by Mettler Toredo or X-DSC7000 manufactured by Hitachi High-Tech Science), cool 10 mg of sample to -75°C, and then heat it at 20°C / min to obtain a DSC curve. Calculate the temperature at the intersection of the extension of the baseline representing the second-order phase transition of the DSC curve and the tangent at the inflection point of the DSC curve, and take this temperature as the glass transition temperature.

[0034] Since it can further improve the flexibility of the solid electrolyte layer or electrode material layer, 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.

[0035] The heat of fusion can be determined using a differential scanning calorimeter (DSC) by heating the sample from 30°C to 220°C at a rate of 10°C / min, and calculating it based on the magnitude of the melting peak (ΔH) in the resulting endothermic curve. If the polymer does not exhibit a clear melting peak, it has no heat of fusion; that is, the heat of fusion of the polymer is 0 J / g.

[0036] Segment A can be a segment that does not show a definite melting point.

[0037] Since it can improve the flame retardancy and heat resistance of the solid electrolyte layer and electrode material layer, segment A preferably contains a fluorinated monomer unit. As a fluorinated monomer that can constitute segment A, there is no particular limitation as long as it contains fluorine atoms, and examples include vinylidene fluoride [VdF], trifluoroethylene, tetrafluoroethylene [TFE], hexafluoropropylene, perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether), trifluorochloroethylene, hexafluoroisobutylene, fluorinated vinyl, monomers that provide repeating units as shown in general formula (b1) described later, monomers that provide repeating units as shown in general formula (b2) described later, etc.

[0038] The content of the fluorinated monomer unit in segment A is preferably 50 mol% or more, more preferably 90 mol% or more, even more preferably 99 mol% or more, preferably 100 mol% or less, or 100 mol% relative to all monomer units constituting segment A.

[0039] Segment A may further contain fluorine-free monomer units. Examples of fluorine-free monomers include ethylene, propylene, and alkyl vinyl ethers. The content of fluorine-free monomer units relative to all monomer units constituting segment A is preferably 0 to 50 mol%, more preferably 0 to 10 mol%, even more preferably 0 to 1 mol%, and may also be 0 mol%.

[0040] Segment A may further contain units based on monomers having reactive groups such as cyano, carboxyl, alkoxycarbonyl, I, Br, -CH2OH, or intercarbon double bonds. The content of units based on monomers having reactive groups relative to all monomer units constituting segment A is preferably 0 to 50 mol%, more preferably 0 to 10 mol%, even more preferably 0 to 1 mol%, and may also be 0 mol%.

[0041] In this disclosure, the content of each monomer unit can be determined by NMR.

[0042] Segment A preferably contains at least a VdF unit or a TFE unit as a fluorinated monomer unit, more preferably at least a VdF unit. By including a VdF unit in segment A, the glass transition temperature of segment A can be easily adjusted to the desired range, further improving the flexibility of the solid electrolyte layer or electrode material layer. Furthermore, by including a VdF unit in segment A, the solvent solubility of the binder in solvents such as butyl butyrate can be improved.

[0043] The content of VdF units in segment A is preferably 99 to 15 mol% relative to all monomer units constituting segment A, more preferably 94 mol% or less, even more preferably 88 mol% or less, even 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, even more preferably 60 mol% or more, and particularly preferably 70 mol% or more.

[0044] Since it can further improve the flexibility of the solid electrolyte layer or electrode material layer, and further improve the solvent solubility of the binder in solvents such as butyl butyrate, segment A is more preferably composed of at least one of the group consisting of VdF units and repeating units selected from any of the following formulas.

[0045] Formula: -CF2-CF[-CF3]-

[0046] General formula (b1): -CH2-CFRf1 -

[0047] (where Rf) 1 It is a straight-chain or branched fluoroalkyl or fluoroalkoxy group with 1 to 12 carbon atoms. If the number of carbon atoms is 2 or more, it may or may not contain oxygen atoms between carbon atoms.

[0048] General formula (b2): -CHF-CHRf 2 -

[0049] (where Rf) 2 It is a straight-chain or branched fluoroalkyl or fluoroalkoxy group with 1 to 12 carbon atoms. If the number of carbon atoms is 2 or more, it may or may not contain oxygen atoms between carbon atoms.

[0050] The content of at least one unit selected from the group of repeating units shown in any of the above formulas in segment A is preferably 1 mol% to 85 mol% relative to all the monomer units constituting segment A, more preferably 6 mol% or more, even more preferably 12 mol% or more, even 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, even more preferably 40 mol% or less, and particularly preferably 30 mol% or less.

[0051] The repeating unit shown in the formula -CF2-CF[-CF3]- is a repeating unit based on hexafluoropropylene. Therefore, in one embodiment, segment A contains VdF units and hexafluoropropylene units.

[0052] General formula (b1): -CH2-CFRf 1 -in, Rf 1 It is a straight-chain or branched fluoroalkyl group with 1 to 12 carbon atoms, or a straight-chain or branched fluoroalkoxy group with 1 to 12 carbon atoms. When the number of carbon atoms is 2 or more, both fluoroalkyl and fluoroalkoxy groups may contain oxygen atoms (-O-) between carbon atoms.

[0053] Rf 1 The fluoroalkyl group can be a partially fluoroalkyl group in which some of the hydrogen atoms bonded to the carbon atom are replaced by fluorine atoms, or a perfluoroalkyl group in which all of the hydrogen atoms bonded to the carbon atom are replaced by fluorine atoms. Additionally, Rf... 1 The hydrogen atoms of the fluoroalkyl group may be replaced by substituents other than fluorine atoms, but preferably do not contain substituents other than fluorine atoms.

[0054] Rf 1The fluoroalkoxy group can be a partially fluoroalkoxy group where some of the hydrogen atoms bonded to the carbon atom are replaced by fluorine atoms, or a perfluoroalkoxy group where all the hydrogen atoms bonded to the carbon atom are replaced by fluorine atoms. Additionally, Rf... 1 The hydrogen atom of the fluoroalkoxy group can be replaced by a substituent other than a fluorine atom, but preferably does not contain a substituent other than a fluorine atom.

[0055] As Rf 1 The number of carbon atoms is preferably 1 to 10, more preferably 1 to 6, even more preferably 1 to 4, and particularly preferably 1.

[0056] As Rf 1 The preferred formula is: -(Rf 11 ) m -(O) p -(Rf 12 -O) n -Rf 13 (where Rf) 11 and Rf 12 Independently, it is a straight-chain or branched fluoroalkylene group having 1 to 4 carbon atoms, Rf 13 It is a group consisting of a straight-chain or branched fluoroalkyl group with 1 to 4 carbon atoms, where p is 0 or 1, m is an integer from 0 to 4, and n is an integer from 0 to 4.

[0057] Rf 11 and Rf 12 The fluoroalkylene group can be a partially fluoroalkylene group in which some of the hydrogen atoms bonded to the carbon atom are replaced by fluorine atoms, or a perfluoroalkylene group in which all of the hydrogen atoms bonded to the carbon atom are replaced by fluorine atoms. Additionally, Rf... 11 and Rf 12 The hydrogen atoms of the fluoroalkylene group can be replaced by substituents other than fluorine atoms, but preferably do not contain substituents other than fluorine atoms. Rf 11 and Rf 12 The occurrences can be the same or different each time they appear.

[0058] As Rf 11Examples of fluorinated alkylene groups include -CHF-, -CF2-, -CH2-CF2-, -CHF-CF2-, -CF2-CF2-, -CF(CF3)-, -CH2-CF2-CF2-, -CHF-CF2-CF2-, -CF2-CF2-CF2-, -CF(CF3)-CF2-, -CF2-CF(CF3)-, -C(CF3)2-, -CH2-CF2-CF2-CF2-, -CHF-CF2-CF2-CF2-, -CF2-CF2-CF2-CF2-, -CH(CF3)-CF2-CF2-, -CF(CF3)-CF2-CF2-, -C(CF3)2-CF2-, etc., among which, perfluorinated alkylene groups with 1 or 2 carbon atoms are preferred, and -CF2- is more preferred.

[0059] As Rf 12 Examples of fluoroalkyl groups include -CHF-, -CF2-, -CH2-CF2-, -CHF-CF2-, -CF2-CF2-, -CF(CF3)-, -CH2-CF2-CF2-, -CHF-CF2-CF2-, -CF2-CF2-CF2-, -CF(CF3)-CF2-, -CF2-CF(CF3)-, -C(CF3)2-, -CH2-CF2-CF2-CF2-, and -CH F-CF2-CF2-CF2-, -CF2-CF2-CF2-CF2-, -CH(CF3)-CF2-CF2-, -CF(CF3)-CF2-CF2-, -C(CF3)2-CF2-, etc., wherein, preferably, it is a perfluorinated alkylene group having 1 to 3 carbon atoms, and more preferably, -CF2-, -CF2CF2-, -CF2-CF2-CF2-, -CF(CF3)-CF2- or -CF2-CF(CF3)-.

[0060] As Rf 13 The fluoroalkyl group can be a partially fluoroalkyl group in which some of the hydrogen atoms bonded to the carbon atom are replaced by fluorine atoms, or a perfluoroalkyl group in which all of the hydrogen atoms bonded to the carbon atom are replaced by fluorine atoms. Additionally, Rf... 13 The hydrogen atom of the fluoroalkyl group may be replaced by a substituent other than the fluorine atom, but preferably does not contain a substituent other than the fluorine atom (e.g., reactive functional groups such as -CN, -I, -Br).

[0061] As Rf 13Examples of fluoroalkyl groups include -CH2F, -CHF2, -CF3, -CH2-CH2F, -CH2-CHF2, -CH2-CF3, -CHF-CH2F, -CHF-CHF2, -CHF-CF3, -CF2-CH2F, -CF2-CHF2, -CF2-CF3, -CH2-CF2-CH2F, -CHF-CF2-CH2F, -CF2-CF2-CH2F, -CF(CF3)-CH2F, -CH2-CF2-CHF2, -CHF-CF2-CHF2, -CF2-CF2-CHF2, -CF(CF3)-CHF2, -CH2-CF2-CF3, and -CHF-CF 2-CF3, -CF2-CF2-CF3, -CF(CF3)-CF3, -CH2-CF2-CF2-CF3, -CHF-CF2-CF2-CF3, -CF2-CF2-CF2-CF3, -CH(CF3)-CF2-CF3, -CF(CF3)-CF2-CF3, -C(CF3 )2-CF3, etc., among which -CF3, -CHF-CF3, -CF2-CHF2, -CF2-CF3, -CF2-CF2-CF3, -CF(CF3)-CF3, -CF2-CF2-CF2-CF3, -CH(CF3)-CF2-CF3 or -CF(CF3)-CF2-CF3 are preferred.

[0062] As for p, 0 is preferred.

[0063] The value of m is preferably an integer from 0 to 2, more preferably 0 or 1, and even more preferably 0. Furthermore, when p is 0, m is also preferably 0.

[0064] The value of n is preferably an integer from 0 to 2, more preferably 0 or 1, and even more preferably 0.

[0065] As the repeating unit shown in general formula (b1), preferably

[0066] -CH2-CF[-CF3]-、 -CH2-CF[-CF2CF3]-、 -CH2-CF[-CF2CF2CF3]-、 -CH2-CF[-CF2CF2CF2CF3]-、 -CH2-CF[-CF2-O-CF(CF3)-CF2-O-CHF-CF3]-, -CH2-CF[-CF2-O-CF(CF3)-CF2-O-CF2-CF3]-, -CH2-CF[-CF2-O-CF(CF3)-CF2-O-CF(CF3)-CF3]-, -CH2-CF[-CF2-O-CF(CF3)-CF2-O-CH(CF3)-CF2-CF3]-, -CH2-CF[-CF2-O-CF(CF3)-CF2-O-CF(CF3)-CF2-CF3]-, -CH2-CF[-OCF2OCF3]-、 -CH2-CF[-OCF2CF2CF2OCF3]-、 -CH2-CF[-CF2OCF2OCF3]-、 -CH2-CF[-CF2OCF2CF2CF2OCF3]-or -CH2-CF[-O-CF2-CF3]-, More preferably -CH2-CF[-CF3]- or -CH2-CF[-CF2-O-CF(CF3)-CF2-O-CHF-CF3]-.

[0067] General formula (b2): -CHF-CHRf 2 -in, Rf 2 It is a straight-chain or branched fluoroalkyl group with 1 to 12 carbon atoms, or a straight-chain or branched fluoroalkoxy group with 1 to 12 carbon atoms. Both fluoroalkyl and fluoroalkoxy groups can contain oxygen atoms (-O-) between carbon atoms when they have 2 or more carbon atoms.

[0068] Rf 2 The fluoroalkyl group can be a partially fluoroalkyl group in which some of the hydrogen atoms bonded to the carbon atom are replaced by fluorine atoms, or a perfluoroalkyl group in which all of the hydrogen atoms bonded to the carbon atom are replaced by fluorine atoms. Additionally, Rf... 2 The hydrogen atoms of the fluoroalkyl group may be replaced by substituents other than fluorine atoms, but preferably do not contain substituents other than fluorine atoms.

[0069] Rf 2 The fluoroalkoxy group can be a partially fluoroalkoxy group where some of the hydrogen atoms bonded to the carbon atom are replaced by fluorine atoms, or a perfluoroalkoxy group where all the hydrogen atoms bonded to the carbon atom are replaced by fluorine atoms. Additionally, Rf... 2 The hydrogen atom of the fluoroalkoxy group can be replaced by a substituent other than a fluorine atom, but preferably does not contain a substituent other than a fluorine atom.

[0070] As Rf 2 The number of carbon atoms is preferably 1 to 10, more preferably 1 to 6, even more preferably 1 to 4, and particularly preferably 1.

[0071] As Rf2 The preferred formula is: -(Rf 21 ) m -(O) p -(Rf 22 -O) n -Rf 23 (where Rf) 21 and Rf 22 Independently, it is a straight-chain or branched fluoroalkylene group having 1 to 4 carbon atoms, Rf 23 It is a straight-chain or branched fluoroalkyl group with 1 to 4 carbon atoms, where p is 0 or 1, m is an integer from 0 to 4, and n is an integer from 0 to 4.

[0072] Rf 21 and Rf 22 The fluoroalkylene group can be a partially fluoroalkylene group in which some of the hydrogen atoms bonded to the carbon atom are replaced by fluorine atoms, or a perfluoroalkylene group in which all of the hydrogen atoms bonded to the carbon atom are replaced by fluorine atoms. Additionally, Rf... 21 and Rf 22 The hydrogen atoms of the fluoroalkylene group can be replaced by substituents other than fluorine atoms, but preferably do not contain substituents other than fluorine atoms. Rf 21 and Rf 22 The occurrences can be the same or different each time they appear.

[0073] As Rf 21 Examples of fluorinated alkylene groups include -CHF-, -CF2-, -CH2-CF2-, -CHF-CF2-, -CF2-CF2-, -CF(CF3)-, -CH2-CF2-CF2-, -CHF-CF2-CF2-, -CF2-CF2-CF2-, -CF(CF3)-CF2-, -CF2-CF(CF3)-, -C(CF3)2-, -CH2-CF2-CF2-CF2-, -CHF-CF2-CF2-CF2-, -CF2-CF2-CF2-CF2-, -CH(CF3)-CF2-CF2-, -CF(CF3)-CF2-CF2-, -C(CF3)2-CF2-, etc., among which, perfluorinated alkylene groups with 1 or 2 carbon atoms are preferred, and -CF2- is more preferred.

[0074] As Rf 22Examples of fluoroalkyl groups include -CHF-, -CF2-, -CH2-CF2-, -CHF-CF2-, -CF2-CF2-, -CF(CF3)-, -CH2-CF2-CF2-, -CHF-CF2-CF2-, -CF2-CF2-CF2-, -CF(CF3)-CF2-, -CF2-CF(CF3)-, -C(CF3)2-, -CH2-CF2-CF2-CF2-, and -CH F-CF2-CF2-CF2-, -CF2-CF2-CF2-CF2-, -CH(CF3)-CF2-CF2-, -CF(CF3)-CF2-CF2-, -C(CF3)2-CF2-, etc., wherein, preferably, it is a perfluorinated alkylene group having 1 to 3 carbon atoms, and more preferably, -CF2-, -CF2CF2-, -CF2-CF2-CF2-, -CF(CF3)-CF2- or -CF2-CF(CF3)-.

[0075] As Rf 23 The fluoroalkyl group can be a partially fluoroalkyl group in which some of the hydrogen atoms bonded to the carbon atom are replaced by fluorine atoms, or a perfluoroalkyl group in which all of the hydrogen atoms bonded to the carbon atom are replaced by fluorine atoms. Additionally, Rf... 23 The hydrogen atom of the fluoroalkyl group may be replaced by a substituent other than the fluorine atom, but preferably does not contain a substituent other than the fluorine atom (e.g., reactive functional groups such as -CN, -I, -Br).

[0076] As Rf 23Examples of fluoroalkyl groups include -CH2F, -CHF2, -CF3, -CH2-CH2F, -CH2-CHF2, -CH2-CF3, -CHF-CH2F, -CHF-CHF2, -CHF-CF3, -CF2-CH2F, -CF2-CHF2, -CF2-CF3, -CH2-CF2-CH2F, -CHF-CF2-CH2F, -CF2-CF2-CH2F, -CF(CF3)-CH2F, -CH2-CF2-CHF2, -CHF-CF2-CHF2, -CF2-CF2-CHF2, -CF(CF3)-CHF2, -CH2-CF2-CF3, and -CHF-CF 2-CF3, -CF2-CF2-CF3, -CF(CF3)-CF3, -CH2-CF2-CF2-CF3, -CHF-CF2-CF2-CF3, -CF2-CF2-CF2-CF3, -CH(CF3)-CF2-CF3, -CF(CF3)-CF2-CF3, -C(CF3 )2-CF3, etc., among which -CF3, -CHF-CF3, -CF2-CHF2, -CF2-CF3, -CF2-CF2-CF3, -CF(CF3)-CF3, -CF2-CF2-CF2-CF3, -CH(CF3)-CF2-CF3 or -CF(CF3)-CF2-CF3 are preferred.

[0077] As for p, 0 is preferred.

[0078] The value of m is preferably an integer from 0 to 2, more preferably 0 or 1, and even more preferably 0. Furthermore, when p is 0, m is also preferably 0.

[0079] The value of n is preferably an integer from 0 to 2, more preferably 0 or 1, and even more preferably 0.

[0080] As the repeating unit shown in general formula (b2), preferably

[0081] -CHF-CH[-CF3]-、 -CHF-CH[-CF2CF3]-、 -CHF-CH[-CF2CF2CF3]- or -CHF-CH[-CF2CF2CF2CF3]-, More preferably -CHF-CH[-CF3]-.

[0082] Segment A preferably contains VdF units and 2,3,3,3-tetrafluoropropylene units. By including VdF units and 2,3,3,3-tetrafluoropropylene units in segment A, the flexibility of the solid electrolyte layer or electrode material layer can be further improved. Additionally, it can improve the solvent solubility of the binder in solvents such as butyl butyrate.

[0083] The content of 2,3,3,3-tetrafluoropropylene units in segment A is preferably 1 mol% to 85 mol% relative to all monomer units constituting segment A, more preferably 6 mol% or more, even more preferably 12 mol% or more, even 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, even more preferably 40 mol% or less, and particularly preferably 30 mol% or less.

[0084] In one embodiment, segment A can be formed from a 2,3,3,3-tetrafluoropropylene / VdF copolymer or a 2,3,3,3-tetrafluoropropylene / VdF / TFE copolymer.

[0085] In the 2,3,3,3-tetrafluoropropylene / VdF copolymer, the composition (molar percentage) of the 2,3,3,3-tetrafluoropropylene unit / VdF unit is preferably (18-40) / (82-60), more preferably (20-30) / (80-70).

[0086] In the 2,3,3,3-tetrafluoropropylene / VdF / TFE copolymer, the composition (molar percentage) of the 2,3,3,3-tetrafluoropropylene unit / VdF unit / TFE unit is preferably (18-40) / (81-25) / (1-35), more preferably (20-40) / (75-30) / (5-30).

[0087] In one embodiment, segment A contains 2,3,3,3-tetrafluoropropylene units and VdF units. The content of monomer units other than 2,3,3,3-tetrafluoropropylene units and VdF units relative to all monomer units constituting segment A is preferably 0 to 10 mol%, more preferably 0 to 2 mol%, further preferably 0 to 1 mol%, even more preferably 0 to 0.1 mol%, and particularly preferably 0 mol%. The content of 2,3,3,3-tetrafluoropropylene units and VdF units can be within the above ranges.

[0088] (Polymer segment B)

[0089] 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, more preferably 240°C or lower, more preferably 220°C or lower, and even more preferably 200°C or lower. The binder for the first solid electrolyte battery, containing a polymer that includes segment B with a melting point in addition to segment A having a glass transition temperature, can form a solid electrolyte layer or electrode material layer with excellent adhesion and toughness without compromising excellent flexibility.

[0090] The melting point can be determined using a differential scanning calorimetry (DSC) device by heating the sample from 30°C to 220°C at a rate of 10°C / min, and using the temperature at the peak of the resulting endothermic curve.

[0091] Typically, the melting point of segment B is the same as that of the first polymer. Therefore, by determining the melting point of the first polymer, the melting point of segment B in the first polymer can be determined.

[0092] Since it can further improve the adhesion, flexibility and toughness of the solid electrolyte layer or electrode material layer, 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, even more preferably 35 J / g or more, preferably 90 J / g or less, more preferably 60 J / g or less, and even more preferably 55 J / g or less.

[0093] The heat of fusion can be determined using a differential scanning calorimeter (DSC) device. The sample is heated from 30°C to 220°C at a rate of 10°C / min, and the heat is calculated based on the magnitude of the melting peak (ΔH) of the resulting endothermic curve.

[0094] Segment B preferably contains fluorinated monomer units to improve the oxidation resistance of the solid electrolyte layer and electrode material layer. As for the fluorinated monomers that can constitute segment B, there are no particular limitations on any monomer containing fluorine atoms; examples include vinylidene fluoride [VdF], trifluoroethylene, tetrafluoroethylene [TFE], hexafluoropropylene, perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether), trifluorochloroethylene, hexafluoroisobutylene, and vinyl fluoride.

[0095] The content of fluorinated monomer units in segment B is preferably 50 mol% or more, more preferably 90 mol% or more, even more preferably 99 mol% or more, and more preferably 100 mol% or less, relative to all monomer units constituting segment B.

[0096] Segment B may further contain fluorine-free monomer units. Examples of fluorine-free monomers include ethylene, propylene, and alkyl vinyl ethers. The content of fluorine-free monomer units relative to all monomer units constituting segment B is preferably 0 to 50 mol%, more preferably 0 to 10 mol%, even more preferably 0 to 1 mol%, and may also be 0 mol%.

[0097] Segment B may further contain units based on monomers having polar groups such as carbonyl groups, epoxy groups, hydroxyl groups, sulfonic acid groups, sulfate groups, phosphate groups, amino groups, amide groups, and alkoxy groups.

[0098] Examples of monomers with polar groups include hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and other (meth)acrylate hydroxyalkyl esters; unsaturated monocarboxylic 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 dicarboxylic acids such as maleic acid, maleic anhydride, citralic acid, and citralic anhydride; alkylidene malonate esters such as dimethyl methylene malonate; and vinyl carboxymethyl ether, vinyl carboxyethyl ether, etc. Alkenyl carboxyl alkyl ethers; carboxyl alkyl esters of (meth)acrylic acid such as 2-carboxyethyl acrylate and 2-carboxyethyl methacrylate; (meth)acryloyloxyalkyl dicarboxylic acid esters such as acryloyloxyethyl succinate, methacryloyloxyethyl succinate, acryloyloxyethyl phthalate, methacryloyloxyethyl phthalate; monoesters of unsaturated dicarboxylic acids such as monomethyl maleate, monoethyl maleate, monomethyl citrate, and monoethyl citrate; etc.

[0099] Segment B preferably contains at least a VdF unit as a fluorinated monomer unit. By including a VdF unit in segment B, the melting point of segment B can be easily adjusted to the desired range, further improving the adhesion and toughness of the solid electrolyte layer or electrode material layer. Furthermore, including a VdF unit in segment B improves the solvent solubility of the binder in solvents such as butyl butyrate.

[0100] In addition to the VdF unit, segment B may also contain other monomer units besides the VdF unit. The other monomers may be either fluorinated monomers or non-fluorinated monomers, preferably fluorinated monomers (excluding trifluoroethylene) or non-fluorinated monomers.

[0101] Examples of fluorinated monomers that can form segment B together with VdF include TFE, hexafluoropropylene, perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether), trifluorochloroethylene, hexafluoroisobutylene, and vinyl fluoride.

[0102] Examples of fluorine-free monomers that can form segment B together with VdF include ethylene and propylene.

[0103] In addition to the VdF unit, segment B may further contain units based on monomers having polar groups such as carbonyl groups, epoxy groups, hydroxyl groups, sulfonic acid groups, sulfate groups, phosphate groups, amino groups, amide groups, and alkoxy groups. Monomers having polar groups are as already exemplified.

[0104] As other monomers that can form segment B together with VdF, preferably at least one is selected from the group consisting of TFE, hexafluoropropylene, 2,3,3,3-tetrafluoropropylene and (meth)acrylic acid.

[0105] Because it can further improve the adhesion and toughness of the solid electrolyte layer or electrode material layer, the adhesive's solvent solubility in solvents such as butyl butyrate is further improved. The content of VdF units in segment B is preferably 97 mol% or more, more preferably 99 mol% or more, and even more preferably 99.5 mol% or more, or it can be 100 mol% or less.

[0106] Because it can further improve the adhesion and toughness of the solid electrolyte layer or electrode material layer, the binder's solvent solubility in solvents such as butyl butyrate is further improved. The content of other monomer units in segment B, other than the VdF unit, is preferably less than 3 mol% relative to all monomer units constituting segment B, more preferably less than 1 mol%, even more preferably less than 0.5 mol%, and may also be more than 0 mol%.

[0107] 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-tetrafluoropropylene units and (meth)acrylic acid units.

[0108] In copolymers containing VdF units and other monomer units, the VdF unit / other monomer unit composition (molar percentage) is preferably (97.0 to 99.9) / (3.0 to 0.1).

[0109] The polymer contained in the binder for the first solid electrolyte battery may contain segments A and B, and may also contain other segments C that are different from segments A and B.

[0110] As a polymer contained in the binder for a first solid electrolyte battery, examples include block copolymers containing chain structures shown in any of the following general formulas.

[0111] General formula: AB

[0112] General formula: ABA

[0113] General formula: BAB

[0114] General formula: ABC

[0115] General formula: BAC

[0116] (In the formula, A represents chain segment A, B represents chain segment B, and C represents chain segment C.)

[0117] The polymer contained in the binder for the first solid electrolyte battery is preferably a chain structure containing the chain structure shown in general formula (1) or general formula (2) because it can form a solid electrolyte layer or electrode material layer with better adhesion, flexibility and toughness.

[0118] General formula (1): ABA

[0119] General formula (2): BAB

[0120] (In the formula, A represents chain segment A, and B represents chain segment B.)

[0121] From the viewpoint of balancing excellent flexibility with excellent adhesion and toughness, the mass ratio (A / B) of segment A to segment B in the polymer contained in the first solid electrolyte battery 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.

[0122] The number-average molecular weight (converted to polystyrene) of the polymer contained in the binder for the first solid electrolyte battery 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 above-mentioned number-average molecular weight can be determined by gel permeation chromatography (GPC) using dimethylformamide as a solvent.

[0123] The weight-average molecular weight (converted to polystyrene) of the polymer contained in the binder for the first solid electrolyte battery is preferably 50,000 to 3,000,000, more preferably 80,000 or more, further preferably 100,000 or more, even more preferably 200,000 or more, particularly preferably 500,000 or more, more preferably 2,400,000 or less, further preferably 2,200,000 or less, and particularly preferably 2,000,000 or less. The above-mentioned weight-average molecular weight can be determined by gel permeation chromatography (GPC) using dimethylformamide as a solvent.

[0124] The polymer contained in the binder for the first solid electrolyte battery can be manufactured, for example, by the following method: (1) A method for preparing a polymer that forms a chain segment B by polymerizing monomers that can form a chain segment B in the presence of a bromine compound or an iodine compound as a chain transfer agent, and by polymerizing monomers that can form a chain segment A in the presence of a polymer that forms a chain segment B. (2) A method for preparing a polymer forming a chain segment A by polymerizing monomers capable of forming a chain segment A in the presence of a bromine compound or an iodine compound as a chain transfer agent, and for preparing a polymer forming a chain segment B by polymerizing monomers capable of forming a chain segment B in the presence of the polymer forming a chain segment A; etc.

[0125] When using method (1), a polymer forming segment A is obtained by bonding the two ends of the polymer chain forming segment B, i.e., a polymer containing the chain structure shown in general formula (1): ABA.

[0126] In addition, when using method (2), a polymer forming segment B is obtained by bonding the two ends of the polymer chain forming segment A, that is, a polymer containing the chain structure shown in general formula (2): BAB.

[0127] In 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, iodine atoms or bromine atoms are introduced into the end of a polymer chain forming one segment, functioning as a bonding site for other segments.

[0128] Examples of polymerization methods using bromine or iodine compounds include emulsion polymerization (iodine transfer polymerization) carried out under pressure in an aqueous medium in a substantially oxygen-free environment, in the presence of bromine or iodine compounds. Representative examples of the bromine or iodine compounds used include...

[0129] General formula: R 8 I x Br y

[0130] (In the formula, x and y are integers from 0 to 2 and satisfy 1≤x+y≤2, R) 8 The R group is a saturated or unsaturated fluorocarbon or chlorofluorocarbon group with 1 to 16 carbon atoms, or a hydrocarbon group with 1 to 3 carbon atoms. 8 Compounds (with or without oxygen atoms).

[0131] Examples of iodine compounds include, for instance, 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-diiodopropane, CF₂Br₂, BrCF₂CF₂Br, CF₃CFBrCF₂Br, CFClBr₂, and BrC. F2CFClBr, CFBrClCFClBr, BrCF2CF2CF2Br, BrCF2CFBrOCF3, 1-bromo-2-iodoperfluoroethane, 1-bromo-3-iodoperfluoropropane, 1-bromo-4-iodoperfluorobutane, 2-bromo-3-iodoperfluorobutane, 3-bromo-4-iodoperfluoro-1-butene, 2-bromo-4-iodoperfluoro-1-butene, monoiodomonobromine substituted derivatives of benzene, diiodomonobromine substituted derivatives, and (2-iodoethyl) and (2-bromoethyl) substituted derivatives, etc., these compounds can be used alone or in combination with each other.

[0132] Among these, 1,4-diiodoperfluorobutane, 1,6-diiodoperfluorohexane, and 2-iodoperfluoropropane are preferred in terms of polymerization reactivity, crosslinking reactivity, and ease of acquisition.

[0133] In the above manufacturing method, the polymerization of monomers is preferably carried out using emulsion polymerization. In one embodiment, the polymerization of monomers is carried out in the presence of a polymerization initiator, a surfactant, and a solvent.

[0134] Examples of polymerization initiators include oil-soluble free radical polymerization initiators and water-soluble free radical initiators.

[0135] As an oil-soluble free radical polymerization initiator, it can be a known oil-soluble peroxide, such as the following substances as representative examples: dialkyl percarbonate peroxides such as diisopropyl peroxide and disec-butyl peroxide; peroxide esters such as tert-butyl peroxide and tert-butyl peroxypentanoate; dialkyl peroxides such as di-tert-butyl peroxide; and bis(ω-hydro-dodecylfluoroheptanoyl) peroxide, bis(ω-hydro-tetradecylfluorooctanoyl) peroxide, bis(ω-hydro-hexadecylfluorononanoyl) peroxide, bis(perfluorobutyryl) peroxide, bis(perfluoropentanoyl) peroxide, bis(perfluorohexanoyl) peroxide, bis(perfluoroheptanoyl) peroxide, and bis(perfluorooctanoyl) peroxide. Peroxides, including di(perfluorononanoyl)peroxides, di(ω-chloro-hexafluorobutyryl)peroxides, di(ω-chloro-decafluorohexanoyl)peroxides, di(ω-chloro-tetrafluorooctanoyl)peroxides, ω-hydro-dodecanoyl-ω-hydrohexafluorononanoyl-peroxides, ω-chloro-hexafluorobutyryl-ω-chloro-decafluorohexanoyl-peroxides, ω-hydro-dodecanoyl-perfluorobutyryl-peroxides, di(dichloropentafluorobutyryl)peroxides, di(trichlorooctafluorohexanoyl)peroxides, di(tetrachloroundecanoyl)peroxides, di(pentachlorotetrafluorodecanoyl)peroxides, di(undecachlorotetrafluorotidecanoyl)peroxides, and other di[perfluoro(or fluorochloro)acyl]peroxides.

[0136] As a water-soluble free radical polymerization initiator, it can be a known water-soluble peroxide, such as ammonium salts, potassium salts, sodium salts of persulfate, perboric acid, perchloric acid, superphosphoric acid, and percarbonate, as well as tert-butyl maleate peroxide and tert-butyl hydroperoxide. It can also contain reducing agents such as sulfites, which can be used in amounts ranging from 0.1 to 20 times relative to the peroxide.

[0137] There is no particular limitation on the amount of polymerization initiator to be added. It can be added in a single, gradual, or continuous manner at the beginning of polymerization, in an amount that will not significantly reduce the polymerization rate (e.g., a few ppm relative to the concentration of water). The upper limit is the range that can remove the heat of polymerization reaction from the surface of the equipment.

[0138] As a surfactant, nonionic surfactants, anionic surfactants, cationic surfactants, etc., can be used. The amount added (relative to the solvent) is preferably 10 ppm to 20% by mass, more preferably 10 ppm to 10% by mass, even more preferably 10 ppm to 5000 ppm by mass, and particularly preferably 50 ppm to 5000 ppm by mass.

[0139] Alternatively, polymerizable emulsifiers can be used as surfactants. There are no particular limitations on polymerizable emulsifiers, as long as they are compounds having one or more unsaturated bonds and hydrophilic groups respectively; examples include CH2=CFCF2OCF(CF3)CF2OCF(CF3)COONH4, CH2=CFCF2CF(CF3)OCF2CF2COONH4, and CF2=CFOCF2CF(CF3)OCF(CF3)COONH4. The amount added (relative to the solvent) is preferably 10 ppm to 5000 ppm by mass, more preferably 50 ppm to 5000 ppm by mass.

[0140] As a solvent, a solvent that does not have chain transfer properties is preferred. Examples of solvents include water, mixtures of water and water-soluble organic solvents, or mixtures of water and non-water-soluble organic solvents.

[0141] In monomer polymerization, the polymerization temperature, polymerization pressure, and polymerization time vary depending on the type of solvent or polymerization initiator, and can range from -15°C to 150°C, atmospheric pressure to 6.5 MPa, and 1 hour to 24 hours. When using an oil-soluble free radical polymerization initiator, the polymerization temperature is preferably 30°C to 95°C. When using a water-soluble free radical polymerization initiator, the polymerization temperature is preferably 0°C to 100°C, and more preferably 10°C to 95°C.

[0142] When monomers are polymerized via emulsion polymerization, an aqueous dispersion containing the polymer is obtained. In the above manufacturing method, polymer powder can be obtained by precipitating the polymer from the aqueous dispersion and then washing, dehydrating, and drying it. Precipitation can be achieved by adding inorganic salts such as aluminum sulfate or inorganic acids to the dispersion, applying mechanical shear force to the dispersion, or freezing the dispersion.

[0143] Alternatively, the polymer contained in the binder for the first solid electrolyte battery can also be manufactured by using at least 2,3,3,3-tetrafluoropropylene as a monomer, according to the methods described in Japanese Patent Application Publication No. 53-3495 and Japanese Patent Application Publication No. 61-49327.

[0144] 2. Binder for the second solid electrolyte battery

[0145] The second solid electrolyte battery binder disclosed herein contains a polymer having a glass transition temperature and a melting point, containing 2,3,3,3-tetrafluoropropylene units, and having a tetrahydrofuran extract content of less than 5% by mass at 25°C.

[0146] The polymer contained in the binder for the second solid electrolyte battery preferably has a glass transition temperature of 25°C or less, more preferably 0°C or less, further preferably -5°C or less, and even more preferably -10°C or less. The lower limit is not limited and can be -40°C or more. Since the binder for the second solid electrolyte battery contains a polymer with a glass transition temperature, it is possible to form a solid electrolyte layer or electrode material layer with flexibility that does not significantly deteriorate compared to the use of conventional binders.

[0147] The glass transition temperature can be determined as follows: Using a differential scanning calorimeter (DSC822e manufactured by Mettler Toredo or X-DSC7000 manufactured by Hitachi High-Tech Science), cool 10 mg of sample to -75°C, and then heat it at 20°C / min to obtain a DSC curve. Calculate the temperature at the intersection of the extension of the baseline representing the second-order phase transition of the DSC curve and the tangent at the inflection point of the DSC curve, and take this temperature as the glass transition temperature.

[0148] The polymer contained in the binder for the second solid electrolyte battery preferably has a melting point of 50°C or higher, more preferably 90°C or higher, even more preferably 140°C or higher, preferably 240°C or lower, more preferably 220°C or lower, and even more preferably 200°C or lower. Since the binder for the second solid electrolyte battery contains a polymer that has a melting point in addition to a glass transition temperature, it is possible to form a solid electrolyte layer or electrode material layer that exhibits excellent adhesion and toughness without compromising excellent flexibility.

[0149] The melting point can be determined using a differential scanning calorimetry (DSC) device by heating the sample from 30°C to 220°C at a rate of 10°C / min, and using the temperature at the peak of the resulting endothermic curve.

[0150] The binder for the second solid electrolyte battery contains a polymer with a tetrahydrofuran extraction content of 5% by mass or less, preferably 4% by mass or less, and more preferably 3% by mass or less. Since the binder for the second solid electrolyte battery contains a polymer with a tetrahydrofuran extraction content within the above-mentioned range, it is possible to form a solid electrolyte layer or electrode material layer with excellent flexibility, adhesion, and toughness without significant degradation, compared to the use of conventional binders. The lower limit of the tetrahydrofuran extraction content is not particularly limited and can be 1% by mass or more, or 2% by mass or more.

[0151] The amount of tetrahydrofuran extracted can be determined by immersing the polymer in tetrahydrofuran at 25°C for 24 hours, allowing the filtered solution to partially dry.

[0152] The polymer contained in the binder for the second solid electrolyte battery contains 2,3,3,3-tetrafluoropropylene units. Because the binder contains 2,3,3,3-tetrafluoropropylene units, it can impart solvent solubility to solvents such as butyl butyrate, enabling the formation of a solid electrolyte layer or electrode material layer with excellent adhesion, flexibility, and toughness.

[0153] The polymer contained in the binder for the second solid electrolyte battery preferably contains fluorinated monomer units (excluding 2,3,3,3-tetrafluoropropylene units). By introducing fluorinated monomer units into the polymer, the glass transition temperature and melting point of the polymer can be easily adjusted, enabling the formation of a solid electrolyte layer or electrode material layer with superior adhesion, flexibility, and toughness.

[0154] As for the fluorinated monomers that can form the polymer contained in the binder for the second solid electrolyte battery, there are no particular limitations as long as they are monomers other than 2,3,3,3-tetrafluoropropylene and contain fluorine atoms. Examples include vinylidene fluoride [VdF], trifluoroethylene, tetrafluoroethylene [TFE], hexafluoropropylene, perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether), trifluorochloroethylene, hexafluoroisobutylene, and vinyl fluoride.

[0155] As a fluorinated monomer capable of constituting the polymer contained in the binder for a second solid electrolyte battery, it is preferably selected from at least one of the group consisting of VdF, TFE, hexafluoropropylene, perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether), and trifluorochloroethylene, more preferably from at least one of the group consisting of VdF and TFE, and even more preferably VdF.

[0156] The polymer contained in the second solid electrolyte battery binder, when containing VdF units as fluorinated monomer units, further improves the solvent solubility of the binder in solvents such as butyl butyrate. Furthermore, by using the second solid electrolyte battery binder, a solid electrolyte layer or electrode material layer with superior adhesion, flexibility, and toughness can be formed.

[0157] The content of 2,3,3,3-tetrafluoropropylene units in the polymer contained in the binder for the second solid electrolyte battery is preferably 1 mol% to 65 mol% relative to all monomer units constituting the polymer, more preferably 5 mol% or more, even more preferably 9 mol% or more, even 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, even more preferably 32 mol% or less, and particularly preferably 24 mol% or less.

[0158] The content of fluorinated monomer units in the polymer contained in the binder for the second solid electrolyte battery is preferably 99 mol% to 35 mol% relative to all monomer units constituting the polymer, more preferably 95 mol% or less, even more preferably 91 mol% or less, even 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, even more preferably 68 mol% or more, and particularly preferably 76 mol% or more.

[0159] The content of VdF units in the polymer contained in the binder for the second solid electrolyte battery is preferably 99 mol% to 35 mol% relative to all monomer units constituting the polymer, more preferably 95 mol% or less, even more preferably 91 mol% or less, even 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, even more preferably 68 mol% or more, and particularly preferably 76 mol% or more.

[0160] The polymer contained in the binder for the second solid electrolyte battery may further contain fluorine-free monomer units. Examples of fluorine-free monomers include ethylene, propylene, and alkyl vinyl ethers. The content of fluorine-free monomer units relative to all monomer units constituting the polymer is preferably 0 to 40 mol%, more preferably 0 to 8 mol%, even more preferably 0 to 1 mol%, and may also be 0 mol%.

[0161] The polymer contained in the binder for the second solid electrolyte battery may further contain units based on monomers having reactive groups such as cyano, carboxyl, alkoxycarbonyl, I, Br, -CH2OH, and intercarbon double bonds. The content of units based on monomers having reactive groups is preferably 0 to 10 mol% relative to all monomer units constituting the polymer, more preferably 0 to 2 mol%, even more preferably 0 to 1 mol%, and may also be 0 mol%.

[0162] The polymer contained in the binder for the second solid electrolyte battery may further contain units based on monomers having polar groups such as carbonyl groups, epoxy groups, hydroxyl groups, sulfonic acid groups, sulfuric acid groups, phosphate groups, amino groups, amide groups, and alkoxy groups.

[0163] Examples of monomers with polar groups include hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and other (meth)acrylate hydroxyalkyl esters; unsaturated monocarboxylic 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 dicarboxylic acids such as maleic acid, maleic anhydride, citralic acid, and citralic anhydride; alkylidene malonate esters such as dimethyl methylene malonate; and vinyl carboxymethyl ether, vinyl carboxyethyl ether, etc. Alkenyl carboxyl alkyl ethers; carboxyl alkyl esters of (meth)acrylic acid such as 2-carboxyethyl acrylate and 2-carboxyethyl methacrylate; (meth)acryloyloxyalkyl dicarboxylic acid esters such as acryloyloxyethyl succinate, methacryloyloxyethyl succinate, acryloyloxyethyl phthalate, methacryloyloxyethyl phthalate; monoesters of unsaturated dicarboxylic acids such as monomethyl maleate, monoethyl maleate, monomethyl citrate, and monoethyl citrate; etc.

[0164] The content of monomer units with polar groups relative to all monomer units constituting the polymer is preferably 0 to 10 mol%, more preferably 0 to 2 mol%, even more preferably 0 to 1 mol%, and may also be 0 mol.

[0165] In one embodiment, the polymer contained in the binder for the second solid electrolyte battery comprises 2,3,3,3-tetrafluoropropylene units and fluorinated monomer units (excluding 2,3,3,3-tetrafluoropropylene units). The content of monomer units other than 2,3,3,3-tetrafluoropropylene units and fluorinated monomer units relative to all monomer units constituting the polymer is preferably 0 to 10 mol%, more preferably 0 to 2 mol%, further preferably 0 to 1 mol%, even more preferably 0 to 0.1 mol%, and particularly preferably 0 mol%. The content of 2,3,3,3-tetrafluoropropylene units and the content of fluorinated monomer units can be within the above ranges.

[0166] In one embodiment, the polymer contained in the binder for the second solid electrolyte battery comprises 2,3,3,3-tetrafluoropropylene units and VdF units. The content of monomer units other than 2,3,3,3-tetrafluoropropylene units and VdF units is preferably 0 to 10 mol% relative to all monomer units constituting the polymer, more preferably 0 to 2 mol%, further preferably 0 to 1 mol%, even more preferably 0 to 0.1 mol%, and particularly preferably 0 mol%. The content of 2,3,3,3-tetrafluoropropylene units and the content of VdF units can be within the above ranges.

[0167] The number-average molecular weight (converted to polystyrene) of the polymer contained in the binder for the second solid electrolyte battery is preferably 20,000 to 1,500,000, more preferably 40,000 or more, further preferably 70,000 or more, particularly preferably 140,000 or more, more preferably 1,400,000 or less, further preferably 1,200,000 or less, and particularly preferably 1,100,000 or less. The above-mentioned number-average molecular weight can be determined by gel permeation chromatography (GPC) using dimethylformamide as a solvent.

[0168] The weight-average molecular weight (converted to polystyrene) of the polymer contained in the binder for the second solid electrolyte battery is preferably 50,000 to 3,000,000, more preferably 80,000 or more, further preferably 100,000 or more, even more preferably 200,000 or more, particularly preferably 500,000 or more, more preferably 2,400,000 or less, further preferably 2,200,000 or less, and particularly preferably 2,000,000 or less. The above-mentioned weight-average molecular weight can be determined by gel permeation chromatography (GPC) using dimethylformamide as a solvent.

[0169] The heat of fusion of the polymer contained in the binder for the second solid electrolyte battery is preferably 1 J / g or more, more preferably 3 J / g or more, even more preferably 5 J / g or more, even more preferably 8 J / g or more, preferably 40 J / g or less, more preferably 30 J / g or less, and even more preferably 20 J / g or less.

[0170] In one embodiment of the polymer contained in the binder for the second solid electrolyte battery, it comprises two or more chain segments. By constituting the polymer with two or more chain segments, it is possible to easily impart a glass transition temperature and melting point to the polymer, and it is possible 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.

[0171] When the polymer contained in the second solid electrolyte battery binder comprises two or more chain segments, the composition of each chain segment can be the same as that of each chain segment in the polymer contained in the first solid electrolyte battery binder. That is, the polymer contained in the second solid electrolyte battery binder can contain chain segment A and chain segment B in the same way as the polymer contained in the first solid electrolyte battery binder, and can adopt the same composition as the polymer contained in the first solid electrolyte battery binder.

[0172] The polymer contained in the binder for the second solid electrolyte battery can be manufactured, for example, by the method described above as the method for manufacturing the polymer contained in the binder for the first solid electrolyte battery.

[0173] The binder for the first and second solid electrolyte batteries (hereinafter sometimes simply referred to as "binder for solid electrolyte batteries") may also contain polymers other than those described above. Examples of other polymers include fluoropolymers, polymethyl methacrylate, polyacrylonitrile, polyimide, polyamide, polyamide-imide, polycarbonate, styrene rubber, butadiene rubber, styrene-butadiene rubber, and polyacrylic acid.

[0174] The solid electrolyte battery binder disclosed herein is suitable for use as a material for forming batteries such as secondary batteries and capacitors.

[0175] This disclosure also relates to the use of a binder for forming a solid electrolyte battery, the binder comprising a polymer having a glass transition temperature below 25°C and a segment B having a melting point above 50°C. The binder is particularly suitable for forming a solid electrolyte layer or electrode material layer in a solid electrolyte battery.

[0176] Additionally, this disclosure relates to the use of a binder for forming a solid electrolyte battery, the binder containing a polymer having a glass transition temperature and melting point, containing 2,3,3,3-tetrafluoropropylene units, and having a tetrahydrofuran extract content of less than 5% by mass at 25°C. The binder is particularly suitable for forming the solid electrolyte layer or electrode material layer of a solid electrolyte battery.

[0177] Solid electrolyte batteries can be primary batteries, rechargeable batteries (secondary batteries), or energy storage elements. As solid electrolyte batteries, all-solid-state lithium-ion secondary batteries using inorganic solid electrolytes are preferred. Examples of solid electrolyte batteries include oxide-based solid-state batteries and sulfide-based solid-state batteries. The binder for solid electrolyte batteries disclosed herein is particularly suitable as a binder for solid-state batteries using inorganic solid electrolytes, such as sulfide-based solid-state batteries. As sulfide-based solid-state batteries, all-solid-state lithium-ion secondary batteries using sulfide-based solid electrolytes as the electrolyte are preferred.

[0178] 3. Slurry

[0179] The solid electrolyte battery slurry disclosed herein contains the aforementioned solid electrolyte battery binder, solid electrolyte, and solvent. Because the slurry of this disclosure contains the aforementioned solid electrolyte battery binder, compared to the use of conventional binders, it is possible to form a solid electrolyte layer or electrode material layer with excellent flexibility, adhesion, and toughness without significant degradation.

[0180] The solid electrolyte battery slurry disclosed herein is used to form a layer containing a solid electrolyte. The solid electrolyte battery slurry disclosed herein 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.

[0181] The solid electrolyte battery slurry disclosed herein contains a solid electrolyte, and is suitable for containing an inorganic solid electrolyte. As the solid electrolyte, a solid electrolyte capable of encapsulating and releasing metal ions such as lithium ions can be used. Examples of solid electrolytes include sulfide-based solid electrolytes, oxide-based solid electrolytes, and crystalline oxides / nitrogen oxides. Among these, the solid electrolyte battery slurry preferably contains a sulfide-based solid electrolyte.

[0182] As a sulfide-based solid electrolyte, there are no particular limitations as long as it contains sulfur atoms. Examples include Li₂S-P₂S₅, Li₂S-P₂S₃, Li₂S-P₂S₃-P₂S₅, Li₂S-SiS₂, LiI-Li₂S-SiS₂, LiI-Li₂S-P₂S₅, LiI-Li₂S-P₂O₅, LiI-Li₃PO₄-P₂S₅, LiI-Li₂S-SiS₂-P₂S₅, Li₂S-SiS₂-Li₄SiO₄, Li₂S-SiS₂-Li₃PO₄, Li₃PS₄-Li₄GeS₄, and Li₂S-P₂S₅. 3.4 P 0.6 Si 0.4 S4, Li 3.25 P 0.25 Ge 0.76 S4, Li 4-x Ge 1-x P x S4, etc.

[0183] Examples of oxide-based solid electrolytes include LiPON (lithium oxynitride phosphate), Li₂O-B₂O₃-P₂O₅, Li₂O-SiO₂, and Li₂O-SiO₂. 1.3 Al 0.3 Ti 0.7 (PO4)3, La 0.51 Li 0.34 TiO 0.74 , Li3PO4, Li2SiO2, Li2SiO4, Li 0.5 La 0.5 TiO3, Li 1.5 Al 0.5 Ge 1.5 (PO4)3, etc.

[0184] Examples of crystalline oxides and nitrogen oxides include LiI, Li3N, and Li5La3Ta2O.12 Li7La3Zr2O 12 Li6BaLa2Ta2O 12 Li3PO (4-3 / 2w) N w (w<1), Li 3.6 Si 0.6 P 0.4 O4, etc.

[0185] The solid electrolyte battery slurry disclosed herein contains a solvent. A low-polarity solvent is preferred. This is advantageous because the use of a low-polarity solvent reduces the likelihood of reaction between the solvent and the sulfide-based solid electrolyte. In this disclosure, a low-polarity solvent is defined as a solvent with a relative permittivity of less than 20 at a frequency of 100 kHz. More preferably, it is less than 10.

[0186] The solvent preferably comprises at least one compound selected from aromatic compounds, ester compounds, aliphatic hydrocarbon compounds, ether compounds, and carbonate compounds. It is preferably an aromatic compound or an ester compound, and most preferably an ester compound.

[0187] As a low-polarity solvent, there are no particular limitations, but examples 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, bis(trifluoromethylbenzene), benzene, thiols, etc.

[0188] As a solvent, it is preferable to use at least one solvent selected from the group consisting of propyl propionate, butyl methacrylate, ethyl acetate, ethyl butyrate, and butyl butyrate. Alternatively, a mixture of two or more of these solvents may be used.

[0189] The solid electrolyte battery slurry disclosed herein preferably also includes conductive additives. Examples of conductive additives include carbon black such as acetylene black and Ketjen black; carbon fibers such as multi-walled carbon nanotubes, single-walled carbon nanotubes, carbon nanofibers, and vapor-grown carbon fibers (VGCF); and metal powders such as SUS powder and aluminum powder.

[0190] The solid electrolyte battery slurry disclosed herein may also contain electrode active materials. These electrode active materials can be either positive or negative electrode active materials.

[0191] Examples of positive electrode active materials include LiCoO2, Li(Ni,Co,Al)O2, and Li 1+x Ni 1 / 3 Mn 1 / 3 Co 1 / 3O2 (x is a real number greater than or equal to 0), LiNiO2, LiMn2O4, LiCoMnO4, Li2NiMn3O8, Li3Fe2(PO4)3, Li3V2(PO4)3, Li 1+ x Mn 2-x-y M y The composition represented by O4 (where 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 greater than 0) is a heteroelement substitution of Li-Mn spinel and lithium titanate (Li x TiO y Lithium metal phosphate, etc., with a composition represented by LiMPO4 (M being Fe, Mn, Co, or Ni).

[0192] Among the positive electrode active materials, LiCoO2, Li(Ni,Co,Al)O2, and LiNi are preferred. 1 / 3 Mn 1 / 3 Co 1 / 3 O2. Additionally, in this disclosure, a positive electrode active material coated on the surface of each of these materials can also be used. Regarding the coating material that can be used in this disclosure, any material containing lithium-ion conductivity and capable of maintaining a coating morphology on the surface of the active material is acceptable. Examples of coating materials include, for instance, LiNbO3 and Li4Ti5O. 12 Examples include Li3PO4. The shape of the positive electrode active material is not particularly limited, but it is preferably in powder form.

[0193] The average particle size of the positive electrode active material is preferably, for example, 1 μm to 50 μm, more preferably 1 μm to 20 μm, and particularly preferably 3 μm to 7 μm. This is because if the average particle size of the positive electrode active material is too small, the processability may deteriorate; if the average particle size of the positive electrode active material is too large, it may be difficult to obtain a flat positive electrode active material layer. It should be noted that the average particle size of the positive electrode active material can be obtained by measuring the particle size of the observed active material carrier using, for example, a scanning electron microscope (SEM) and averaging the results.

[0194] Examples of anode active materials include substances selected from carbonaceous materials containing artificial graphite, graphite carbon fibers, resin-calcined carbon, pyrolytic vapor-grown carbon, coke, mesophase carbon microspheres (MCMB), furfuryl alcohol resin-calcined carbon, polyphenylene oxide, pitch-based carbon fibers, vapor-grown carbon fibers, natural graphite, and difficult-to-graphitize carbon, as well as silicon-containing compounds such as silicon and silicon alloys, and Li4Ti5O. 12 Any one or a mixture of two or more of the above. Among them, it is particularly suitable to use at least a portion of a substance containing carbonaceous material or a silicon-containing compound.

[0195] The binder content in the solid electrolyte battery slurry disclosed herein is preferably 0.5 to 4.5 parts by mass relative to 100 parts by mass of the solid component of the solid electrolyte battery slurry.

[0196] The solid component concentration of the solid electrolyte battery slurry disclosed herein is preferably 20% to 75% by mass, and more preferably 30% to 70% by mass.

[0197] One method for preparing a slurry for solid electrolyte batteries is to disperse and mix a solid electrolyte and any electrode active material in a solution or dispersion in which a binder is dissolved or dispersed in a solvent. Alternatively, a slurry for solid electrolyte batteries can be prepared by first mixing the binder and the solid electrolyte and then adding a solvent.

[0198] (Solid electrolyte layer)

[0199] The solid electrolyte battery slurry disclosed herein can be used to form a solid electrolyte layer in a solid electrolyte battery. The solid electrolyte layer can be fabricated, for example, by coating a transfer sheet with the solid electrolyte battery slurry, drying the resulting coating, setting the transfer sheet in contact with the electrode material layer, pressing it, and then peeling off the transfer sheet.

[0200] Methods for coating transfer sheets with slurry for solid electrolyte batteries include spraying, screen printing, doctor blade coating, bar coating, roller coating, gravure printing, and die coating. Drying methods include, for example, vacuum drying, heat drying, and vacuum-heat drying. There are no restrictions on the specific conditions for vacuum drying and heat drying; they can be set appropriately.

[0201] 4. Electrodes

[0202] The solid electrolyte battery slurry disclosed herein 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 disclosed herein includes an electrode material layer formed from the aforementioned solid electrolyte battery slurry. The solid electrolyte battery electrode disclosed herein can be used as a positive electrode or a negative electrode.

[0203] The electrode of this disclosure may consist only of an electrode material layer formed from the aforementioned solid electrolyte battery slurry, or it may consist of a current collector and an electrode material layer formed from the aforementioned solid electrolyte battery slurry. The electrode material layer is formed using the solid electrolyte battery slurry of this disclosure and may be disposed on one side or both sides of the current collector.

[0204] The thickness of the electrode material layer varies depending on the intended use of the target solid electrolyte battery, and is preferably 10 μm to 250 μm, more preferably 20 μm to 200 μm, and even more preferably 30 μm to 150 μm.

[0205] Examples of materials that can be used as current collectors include aluminum, stainless steel (SUS), nickel, iron, titanium, chromium, gold, platinum, and zinc, with aluminum and stainless steel (SUS) being preferred. Additionally, examples of shapes that can be used as current collectors include foil, plate, and mesh, with foil being preferred.

[0206] Electrodes can be manufactured, for example, by coating the current collector with the aforementioned solid electrolyte battery slurry and then drying the resulting coating. Examples of coating methods include spraying, screen printing, doctor blade coating, bar coating, roller coating, gravure printing, and die coating. Examples of drying methods include vacuum drying, heat drying, and vacuum-heat drying. There are no restrictions on the specific conditions used in vacuum drying and heat drying; they can be set appropriately.

[0207] The coating amount of the slurry for solid electrolyte batteries varies depending on the composition of the slurry and the application of the target electrode, but is typically 5 mg / cm³ in the dry state. 2 ~30mg / cm 2 Approximately. Additionally, the electrode thickness is not specifically limited, ranging from approximately 10 μm to 250 μm.

[0208] 5. Solid electrolyte battery

[0209] In one embodiment of the solid electrolyte battery disclosed herein, 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 are included. In another embodiment of the solid electrolyte battery disclosed herein, a positive electrode having a positive electrode material layer and a current collector, a negative electrode having a negative electrode material layer and a current collector, and a solid electrolyte layer formed between the positive electrode and the negative electrode are included. In the solid electrolyte battery of this disclosure, at least one of the positive electrode material layer, the negative electrode material layer, and the solid electrolyte layer is formed from the solid electrolyte battery slurry of this disclosure.

[0210] Solid electrolyte batteries can be primary batteries, rechargeable batteries (secondary batteries), or energy storage devices. As solid electrolyte batteries, all-solid-state lithium-ion secondary batteries using inorganic solid electrolytes are preferred. Examples of solid electrolyte batteries include oxide-based solid-state batteries and sulfide-based solid-state batteries. As sulfide-based solid-state batteries, all-solid-state lithium-ion secondary batteries using sulfide-based solid electrolytes as the electrolyte are preferred.

[0211] The solid electrolyte battery disclosed herein can have a separator between the positive and negative electrodes. Examples of such separators include porous membranes such as polyethylene and polypropylene; and nonwoven fabrics such as nonwoven fabrics made of resins such as polypropylene and glass fiber nonwoven fabrics.

[0212] The solid electrolyte battery disclosed herein may also include a battery casing. The shape of the battery casing is not particularly limited as long as it can accommodate the aforementioned positive electrode, negative electrode, and solid electrolyte layer; examples include cylindrical, square, button-shaped, and laminated shapes.

[0213] The solid electrolyte layer disclosed herein is suitable for use as a solid electrolyte layer in solid electrolyte batteries due to its excellent adhesion, flexibility, and toughness. Furthermore, the electrode for solid electrolyte batteries disclosed herein is suitable for use as an electrode in solid electrolyte batteries due to its electrode material layer possessing excellent adhesion, flexibility, and toughness.

[0214] The embodiments have been described above, but it is understood that various changes can be made to the methods and details without departing from the spirit and scope of the claims.

[0215] <1> According to a first aspect of this disclosure, a binder for solid electrolyte batteries is provided, which contains a polymer comprising a segment A having a glass transition temperature below 25°C and a segment B having a melting point above 50°C.

[0216] <2> According to the second aspect of this disclosure, a binder for solid electrolyte batteries based on the first aspect is provided, wherein segment A has a heat of fusion of less than 5 J / g and segment B has a heat of fusion of more than 5 J / g.

[0217] <3> According to a third aspect of this disclosure, a binder for solid electrolyte batteries based on a first or second aspect is provided, wherein the polymer contains a chain structure represented by general formula (1) or general formula (2).

[0218] General formula (1): ABA

[0219] General formula (2): BAB

[0220] (In the formula, A represents chain segment A, and B represents chain segment B.)

[0221] <4> According to the fourth aspect of this disclosure, a binder for solid electrolyte batteries based on any one of the first to third aspects is provided, wherein segment A of the polymer contains fluorinated monomer units.

[0222] <5> According to the fifth aspect of this disclosure, a binder for solid electrolyte batteries based on any one of the first to fourth aspects is provided, wherein segment A of the polymer contains vinylidene fluoride units.

[0223] <6> According to the sixth aspect of this disclosure, a binder for solid electrolyte batteries based on any one of the first to fifth aspects is provided, wherein the polymer segment A contains vinylidene fluoride units and at least one of the group consisting of repeating units selected from any of the following formulas.

[0224] Formula: -CF2-CF[-CF3]-

[0225] Formula: -CH2-CFRf 1 -

[0226] (where Rf) 1 It is a straight-chain or branched fluoroalkyl or fluoroalkoxy group with 1 to 12 carbon atoms. If the number of carbon atoms is 2 or more, it may or may not contain oxygen atoms between carbon atoms.

[0227] Formula: -CHF-CHRf 2 -

[0228] (where Rf) 2 It is a straight-chain or branched fluoroalkyl or fluoroalkoxy group with 1 to 12 carbon atoms. If the number of carbon atoms is 2 or more, it may or may not contain oxygen atoms between carbon atoms.

[0229] <7> According to the seventh aspect of this disclosure, a binder for solid electrolyte batteries based on any one of the first to sixth aspects is provided, wherein segment A of the polymer contains vinylidene fluoride units and 2,3,3,3-tetrafluoropropylene units.

[0230] <8> According to the eighth aspect of this disclosure, a binder for solid electrolyte batteries based on any one of the fifth to seventh aspects is provided, wherein the content of vinylidene fluoride units in segment A of the polymer is 99 mol% to 15 mol% relative to all monomer units constituting segment A.

[0231] <9> According to the ninth aspect of this disclosure, a binder for solid electrolyte batteries based on any one of the first to eighth aspects is provided, wherein segment B of the polymer contains fluorinated monomer units.

[0232] <10> According to the 10th aspect of this disclosure, a binder for solid electrolyte batteries based on any one of the 1st to 9th aspects is provided, wherein segment B of the polymer contains vinylidene fluoride units.

[0233] <11> According to the 11th aspect of this disclosure, a binder for solid electrolyte batteries based on the 10th aspect is provided, wherein the content of vinylidene fluoride units in segment B of the polymer is 97 mol% or more relative to all monomer units constituting segment B.

[0234] <12> According to the 12th aspect of this disclosure, a binder for solid electrolyte batteries based on any one of the 1st to 11th aspects is provided, wherein the polymer segment B 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-tetrafluoropropylene units and (meth)acrylic acid units.

[0235] <13> According to the 13th aspect of this disclosure, a binder for solid electrolyte batteries based on any one of the 1st to 12th aspects is provided, wherein the mass ratio (A / B) of segment A to segment B in the polymer is 40 / 60 to 95 / 5.

[0236] <14> According to the 14th aspect of this disclosure, a binder for solid electrolyte batteries based on any one of the 1st to 13th aspects is provided, wherein the polymer contains a chain structure represented by general formula (1) or general formula (2). General formula (1): ABA General formula (2): BAB (In the formula, A represents chain segment A, and B represents chain segment B.) Segment A of the aforementioned polymer has a glass transition temperature below -10°C and contains vinylidene fluoride units and 2,3,3,3-tetrafluoropropylene units. The content of 2,3,3,3-tetrafluoropropylene units in segment A is 18 mol% to 30 mol% relative to all monomer units constituting segment A, and the content of vinylidene fluoride units in segment A is 70 mol% to 82 mol% relative to all monomer units constituting segment A. Segment B of the polymer has a melting point of 140°C to 200°C and contains vinylidene fluoride units. The content of vinylidene fluoride units in segment B is more than 97 mol% relative to all monomer units constituting segment B. The mass ratio of chain segment A to chain segment B in the polymer is 50 / 50 to 90 / 10. The weight-average molecular weight of the polymer is 200,000 to 2,000,000.

[0237] <15> According to the 15th aspect of this disclosure, a binder for solid electrolyte batteries is provided, which is 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-tetrafluoropropylene units, and has a tetrahydrofuran extraction amount of less than 5% by mass at 25°C.

[0238] <16> According to the 16th aspect of this disclosure, a binder for solid electrolyte batteries based on the 15th aspect is provided, wherein the polymer further contains vinylidene fluoride units.

[0239] <17> According to the 17th aspect of this disclosure, a binder for solid electrolyte batteries based on the 15th or 16th aspect is provided, wherein the polymer comprises two or more chain segments.

[0240] <18> According to aspect 18 of this disclosure, a binder for solid electrolyte batteries based on any one of aspects 15 to 17 is provided, wherein... The glass transition temperature of the polymer is below -10°C. The polymer has a melting point of 140℃~200℃. The polymer contains vinylidene fluoride units and 2,3,3,3-tetrafluoropropylene units, wherein the content of 2,3,3,3-tetrafluoropropylene units is 9 mol% to 24 mol% relative to all monomer units constituting the polymer, and the content of vinylidene fluoride units is 76 mol% to 91 mol% relative to all monomer units constituting the polymer. The tetrahydrofuran extract yield of the polymer at 25°C is 2%–4% by mass. The weight-average molecular weight of the polymer is 200,000 to 2,000,000.

[0241] <19> According to the 19th aspect of this disclosure, a slurry for a solid electrolyte battery is provided, comprising a binder, a solid electrolyte, and a solvent based on any one of the 1st to 18th aspects of the present disclosure.

[0242] <20> According to the 20th aspect of this disclosure, a slurry for a solid electrolyte battery based on the 19th aspect is provided, which further contains electrode active materials.

[0243] <21> According to the 21st aspect of this disclosure, an electrode for a solid electrolyte battery is provided, which has an electrode material layer formed from a slurry for a solid electrolyte battery based on the 19th or 20th aspect.

[0244] <22> According to the 22nd aspect of this disclosure, a solid electrolyte battery is provided, which has electrodes based on the 21st aspect.

[0245] <23> According to the 23rd aspect of this disclosure, a solid electrolyte battery is provided, which has a solid electrolyte layer formed from a solid electrolyte battery slurry based on the 19th or 20th aspect.

[0246] Example

[0247] Next, embodiments will be given to illustrate the implementation of this disclosure, but this disclosure is not limited to the embodiments described.

[0248] The values ​​in the examples were measured using the following methods.

[0249] <Polymer Composition>

[0250] The composition of the fluorinated copolymer was determined by solution NMR.

[0251] Measuring apparatus: VNMRS400 manufactured by Varian

[0252] Resonant frequency: 376.04 (Sfrq)

[0253] Pulse width: 30° (pw=6.8)

[0254] Glass transition temperature (Tg)

[0255] Using a differential scanning calorimeter (DSC822e manufactured by Mettler Toredo or X-DSC7000 manufactured by Hitachi High-Tech Science), a 10 mg sample was heated at 20 °C / min to obtain a DSC curve. The temperature at which the extended line representing the second-order phase transition of the DSC curve intersects the tangent at the inflection point of the DSC curve is taken as the glass transition temperature.

[0256] Heat of fusion

[0257] Using a differential scanning calorimeter (DSC822e manufactured by Mettler Toredo or X-DSC7000 manufactured by Hitachi High-Tech Science), the sample was heated 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.

[0258] <Weight-average molecular weight>

[0259] Based on the results determined by the GPC method, the molecular weight was calculated using standard polystyrene as a reference.

[0260] GPC Unit: TOSOH HLC-8320GPC

[0261] Columns: 1 SuperAW-H, 3 SuperAWM-H

[0262] Development solvent: Dimethylformamide [DMF]

[0263] Sample concentration: 0.05% by mass

[0264] Measured temperature: 40°C

[0265] <Melting point>

[0266] Using a differential scanning calorimetry (DSC) apparatus, the temperature corresponding to the peak of the endothermic curve when the sample is heated from 30°C to 220°C at a rate of 10°C / min is determined as the melting point.

[0267] <THF extraction amount>

[0268] To 1 g of the polymer obtained in each example, 9 g of tetrahydrofuran (THF) is added, and stirring is carried out at 25°C using a stirrer. After 24 hours, the solid components are filtered, the solution is dried, the weight of the dried solid is measured, and the extraction amount (the ratio (mass%) of the weight of the dried solid to the weight of the polymer (1 g)) is calculated therefrom.

[0269] <Maximum test force>

[0270] The flexural strength (flexural strength, three-point bending test) is measured using the method according to ASTM D790. A positive electrode having a positive electrode material layer on one side or a negative electrode having a negative electrode material layer on a single sheet or a laminate containing a solid electrolyte layer is cut into a size of 15 mm × 20 mm to prepare a test piece. Using the three-point bending method, the test piece is placed between the first location and the second location at an interval of 10 mm, and the middle of the test piece (the third location) is pressed at a constant speed in the thickness direction of the test piece using a probe to perform a bending test. While moving at a moving speed of 5 mm / min in the thickness direction of the third location, the applied force is measured. The maximum flexural strength (maximum bending force or maximum bending strength) is the maximum value of the force applied to the test piece according to the moving distance of the probe. The comparative example is set to 100 for relative evaluation.

[0271] <Half-peak width>

[0272] Bending strength (bending strength, three-point bending test) is determined according to ASTM D790. A positive electrode with a single-sided positive electrode layer, a negative electrode with a single-sided negative electrode layer, or a laminate containing a solid electrolyte layer is cut into 15mm × 20mm pieces to prepare test specimens. Using a three-point bending method, the specimen is positioned between points 1 and 2, spaced 10mm apart. A probe is used to press the specimen at its center (point 3) along the thickness direction at a constant speed to perform the bending property test. The applied force is measured while moving the probe at point 3 at a thickness direction speed of 5mm / min. The maximum bending force (or maximum bending strength) is the maximum force applied to the specimen based on the probe's movement distance. Next, the test force equal to half the maximum bending strength is calculated. The distance from the first stroke when the test force increases to the stroke when the test force decreases to equal the half-peak strength is the half-peak width. That is, by plotting a curve with the stroke of the Autograph as the horizontal axis and stress as the vertical axis, the peak width at half the stress peak can be used to determine the value. A comparative example of 100 is set for relative evaluation.

[0273] <Seamlessness>

[0274] Adhesion was evaluated by performing a 90-degree peel test at the electrode material layer / current collector interface. In the 90-degree peel test, a 1.2 × 8.0 cm section of the positive or negative electrode material layer was fixed to a movable fixture, and adhesive tape was applied to the current collector side. The stress (N / mm) when the tape was stretched 90 degrees at a speed of 100 mm / min was measured using an Autograph force sensor of 1 N. A comparative example of 100 was used for relative evaluation.

[0275] The following polymers were used in the examples and comparative examples.

[0276] Manufacturing Example 1: Fluorinated copolymer a

[0277] (Manufacturing of BAB block polymers (where A represents segment A and B represents segment B.))

[0278] (Process 1)

[0279] Add 4000ml of pure water, 0.8001g of a 50% aqueous solution of CH2=CFCF2OCF(CF3)CF2OCF(CF3)COONH4, and C5F to a 6L stainless steel autoclave. 1124.021 g of a 50% aqueous solution of COONH4 was purged with nitrogen and micro-pressurized with VdF. The temperature was adjusted to 80°C while stirring at 400 rpm. VdF was added to a pressure of 1.64 MPa. A mixture of VdF and 2,3,3,3-tetrafluoropropylene (R1234yf) in a molar ratio of 77.2 / 22.8 was then added to a pressure of 2.001 MPa. A solution of 0.16 g of ammonium persulfate dissolved in 4 ml of pure water was added under nitrogen pressure to initiate polymerization. When the mixed monomer solution reached 24 g, 1.009 g of 1,4-diiodoperfluorobutane was added. The pressure was increased to 2.01 MPa by adding the mixed monomer solution when the pressure decreased to 1.98 MPa. This process was repeated until 1020 g was added. The gas in the autoclave was then released to 0.05 MPa, followed by a 3-hour heat treatment. A 10g sample of the dispersion in the autoclave was taken and allowed to dry. The resulting polymer composition, expressed as a molar ratio, was VdF / R1234yf = 77.6 / 22.4, with a glass transition temperature of -12.5℃ and no heat of fusion.

[0280] (Process 2)

[0281] After the heat treatment in step 1, the autoclave was maintained at 80°C. Under this condition, the pressure was increased to 2.003 MPa using VdF. A solution of 0.08 g of ammonium persulfate dissolved in 4 ml of pure water was introduced under nitrogen pressure to begin polymerization. When the pressure dropped to 1.98 MPa, it was increased to 2.01 MPa using VdF, and this process was repeated. When 180 g was added, the gas in the autoclave was released and the autoclave was cooled, recovering 5270 g of dispersion. The solid content of the dispersion was 23.83% by mass.

[0282] Aluminum sulfate was added to the dispersion for precipitation, followed by drying to obtain 1250 g of polymer. The composition of the obtained block polymer, in molar ratio, was VdF / R1234yf = 82.0 / 18.0, and the content of segment B, calculated from the composition, was 17.2% by mass. The weight-average molecular weight (Mw) was 1.266 million, the glass transition temperature was -12.9℃, the melting point was 160.3℃, and the heat of fusion was 8.2 mJ / mg. Additionally, the THF extraction yield was 3% by mass.

[0283] Manufacturing Example 2 Fluorinated Copolymer b

[0284] (Manufacturing of BAB block polymers (where A represents segment A and B represents segment B.))

[0285] The amount of monomer added to the mixture in step 1 was changed from 1020g to 900g, and the amount of VdF added in step 2 was changed from 180g to 300g. Otherwise, 5236g of dispersion was recovered following the same steps as in manufacturing example 1. The solid content of the dispersion was 24.10% by mass.

[0286] Aluminum sulfate was added to the dispersion for precipitation, followed by drying to obtain 1257 g of polymer. The composition of the obtained block polymer, in molar ratio, was VdF / R1234yf = 84.2 / 15.8, and the content of segment B, calculated from the composition, was 28.1% by mass. The weight-average molecular weight (Mw) was 1.206 million, the glass transition temperature was -11.0℃, the melting point was 161.1℃, and the heat of fusion was 11.0 mJ / mg. Additionally, the THF extraction yield was 3% by mass.

[0287] Manufacturing Example 3 Fluorinated Copolymer c

[0288] (Manufacturing of BAB block polymers (where A represents segment A and B represents segment B.))

[0289] The amount of monomer added to the mixture in step 1 was changed from 1020g to 780g, and the amount of VdF added in step 2 was changed from 180g to 420g. Otherwise, 5252g of dispersion was recovered following the same steps as in manufacturing example 1. The solid content of the dispersion was 23.74wt%.

[0290] Aluminum sulfate was added to the dispersion for precipitation, followed by drying to obtain 1250 g of polymer. The composition of the obtained block polymer, in molar ratio, was VdF / R1234yf = 85.9 / 14.1, and the content of segment B, calculated from the composition, was 36.0% by mass. The weight-average molecular weight (Mw) was 1.29 million, the glass transition temperature was -11.2℃, the melting point was 161.4℃, and the heat of fusion was 17.1 mJ / mg. Additionally, the THF extraction yield was 3% by mass.

[0291] Manufacturing Example 4: Fluorinated copolymer d

[0292] (Manufacturing of BAB block polymers (where A represents segment A and B represents segment B.))

[0293] (Process 1)

[0294] Add 4000ml of pure water, 0.8003g of a 50% aqueous solution of CH2=CFCF2OCF(CF3)CF2OCF(CF3)COONH4, and C5F to a 6L stainless steel autoclave. 1124.014 g of a 50% aqueous solution of COONH4 was purged with nitrogen and micro-pressurized with VdF while stirring at 400 rpm and adjusting the temperature to 80°C. The pressure was increased to 2.00 MPa with VdF. A solution of 0.16 g of ammonium persulfate dissolved in 4 ml of pure water was introduced under nitrogen pressure to initiate polymerization. When VdF reached 24 g, 1.009 g of 1,4-diiodoperfluorobutane was added. When the pressure decreased to 1.98 MPa, it 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-treated for 3 hours. A 10 g sample of the dispersion in the autoclave was taken and allowed to dry. The resulting polymer did not show a glass transition temperature, had a melting point of 161.1°C, and a heat of fusion of 44.8 mJ / mg.

[0295] (Process 2)

[0296] After the heat treatment in step 1, the autoclave was maintained at 80°C. Under this condition, VdF was injected to a pressure of 1.64 MPa, and a monomer mixture of VdF and R1234yf in a molar ratio of 77.5 / 22.5 was injected to a pressure of 2.001 MPa. A solution of 0.08 g of ammonium persulfate dissolved in 4 ml of pure water was injected under nitrogen pressure to initiate polymerization. When the pressure dropped to 1.98 MPa, the pressure was increased to 2.01 MPa using the monomer mixture. This process was repeated until 900 g was added. The gas in the autoclave was then released and the autoclave was cooled, recovering 5271 g of the dispersion. The solid content of the dispersion was 23.80% by mass.

[0297] Aluminum sulfate was added to the dispersion for precipitation, followed by drying to obtain 1248 g of polymer. The composition of the obtained block polymer, in molar ratio, was VdF / R1234yf = 82.7 / 17.3, and the content of segment B, calculated from the composition, was 24.1% by mass. The weight-average molecular weight (Mw) was 1.426 million, the glass transition temperature was -10.4℃, the melting point was 160.8℃, and the heat of fusion was 10.8 mJ / mg. Additionally, the THF extraction yield was 3% by mass.

[0298] Manufacturing Example 5 Fluorinated Copolymer e

[0299] A fluorinated elastomer with a VdF / R1234yf molar ratio of 78.6 / 21.4 was obtained according to the manufacturing method described in Example 12 of Japanese Patent Application Publication No. 2013-216915. No heat of fusion was observed. The THF extraction yield was 100% by mass.

[0300] Examples 1-12 and Comparative Examples 1-3

[0301] (Preparation of adhesive solution)

[0302] As a binder, the polymers listed in Table 1 were added to butyl butyrate, stirred at 50°C overnight, and then subjected to repeated ultrasonic treatment three times (90 seconds each) using an ultrasonic homogenizer to prepare a binder solution. Here, the binder solution was made to be 100% by mass, containing 5% by mass of binder.

[0303] In this disclosure, the slurry for the positive electrode and the negative electrode and the solid electrolyte layer are fabricated according to the following steps.

[0304] (1) Add the binder solution obtained by the above method and the separately prepared active material (positive active material or negative active material) or sulfide-based solid electrolyte to butyl butyrate, and perform dispersion treatment (e.g., ultrasonic treatment) to obtain "positive active material-binder slurry", "negative active material-binder slurry" or "solid electrolyte-binder slurry" in which the active material or sulfide-based solid electrolyte and binder are highly dispersed in a low polarity solvent.

[0305] (2) Add a sulfide-based solid electrolyte or active material (positive or negative active material) to the "positive active material and binder slurry", "negative active material and binder slurry" or "solid electrolyte and binder slurry" obtained in (1), and perform dispersion treatment (e.g., ultrasonic treatment) 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 a solvent. A more specific manufacturing method is shown below.

[0306] (Preparation of negative electrode paste)

[0307] The prepared binder solution was used to prepare the negative electrode slurry for the examples and comparative examples. Specifically, it is described below.

[0308] The binder solution, graphite as the negative electrode active material, and butyl butyrate were added to a PFA container, and the mixture was ultrasonically treated once (50 seconds) using an ultrasonic homogenizer to prepare a "negative electrode active material and binder slurry". The binder solution, butyl butyrate, and a sulfide-based solid electrolyte (30LiI·70(0.75Li2S·0.25P2S5)) were further added to the obtained negative electrode active material and binder slurry, and the mixture was ultrasonically treated three times (30 seconds) using an ultrasonic homogenizer to obtain a "negative electrode slurry" with highly dispersed negative electrode active material, sulfide-based solid electrolyte, and binder. Regarding the solid component concentration in the final slurry, the solid component concentration of the active material and binder was 3.0% by mass.

[0309] (Making the negative electrode)

[0310] Using a scraper, each negative electrode is coated with slurry onto a copper foil serving as the negative electrode current collector, and then dried to obtain a negative electrode with a negative electrode material layer of 110 μm thickness formed on the surface of the negative electrode current collector.

[0311] (Preparation of the positive electrode paste)

[0312] The prepared binder solution was used to prepare the positive electrode slurry for the examples and comparative examples. Specifically, it is described below.

[0313] The above-mentioned binder solution and the ternary active material Li(NiMnCo) as the positive electrode active material are added to the PFA container. 1 / 3 O2 and butyl butyrate were subjected to one ultrasonic treatment (50 seconds) using an ultrasonic homogenizer to prepare a "positive electrode active material and binder slurry". A binder solution, butyl butyrate, and a sulfide-based solid electrolyte (30LiI·70(0.75Li2S·0.25P2S5)) were further added to the obtained positive electrode active material and binder slurry, and the mixture was subjected to three ultrasonic treatments (30 seconds each) using an ultrasonic homogenizer to obtain a "positive electrode slurry" with highly dispersed positive electrode active material, sulfide-based solid electrolyte, and binder. The final slurry had a binder solid component concentration of 3.0% by mass.

[0314] (The production of the positive electrode)

[0315] Using a scraper, each positive electrode slurry is applied to the aluminum foil serving as the current collector, and then dried to obtain a positive electrode with a positive electrode material layer of 85 μm thickness formed on the surface of the positive electrode current collector.

[0316] (Fabrication of the solid electrolyte layer)

[0317] An electrolyte slurry was prepared using butyl butyrate, the aforementioned sulfide-based solid electrolyte as a solid electrolyte, and a binder solution. The prepared electrolyte slurry was then applied to a peelable substrate (aluminum foil) using a doctor blade and allowed to dry, forming a 45 μm thick solid electrolyte layer on the substrate. The mass ratio of solid electrolyte to binder in the solid electrolyte layer was 100 parts by mass to 1 part by mass for solid electrolyte to binder. A laminate containing the solid electrolyte layer and the substrate (aluminum foil) was used in the determination of the maximum test force and half-maximum width (WHM). (Sometimes referred to in this disclosure as a "laminate containing a solid electrolyte layer").

[0318] The electrolyte slurry is prepared as follows: A solid electrolyte and binder solution are added to butyl butyrate as a solvent, and the mixture is subjected to one ultrasonic treatment (30 seconds) using an ultrasonic homogenizer to obtain an electrolyte slurry in which the solid electrolyte and binder are highly dissolved or dispersed. It should be noted that the solid content at this stage is 39%.

[0319] The results are shown in Table 1.

[0320] [Table 1] .

Claims

1. A binder for solid electrolyte batteries, comprising a polymer, said polymer including a segment A having a glass transition temperature below 25°C and a segment B having a melting point above 50°C.

2. The binder for solid electrolyte batteries according to claim 1, wherein, Segment A has a heat of fusion of less than 5 J / g, while segment B has a heat of fusion of more than 5 J / g.

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): ABA General formula (2): BAB In the formula, A represents chain segment A, and B represents chain 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 fluorinated monomer units.

5. The binder for solid electrolyte batteries according to any one of claims 1 to 4, wherein, Segment A of the polymer contains vinylidene fluoride units.

6. The binder for solid electrolyte batteries according to any one of claims 1 to 5, wherein, Segment A of the polymer contains vinylidene fluoride units and at least one type of repeating unit selected from the group consisting of any of the following formulas. Formula: -CF2-CF[-CF3]- Formula: -CH2-CFRf 1 - In the formula, Rf 1 It is a straight-chain or branched fluoroalkyl or fluoroalkoxy group with 1 to 12 carbon atoms; if it has 2 or more carbon atoms, it may or may not contain oxygen atoms between carbon atoms. Formula: -CHF-CHRf 2 - In the formula, Rf 2 It is a straight-chain or branched fluoroalkyl or fluoroalkoxy group with 1 to 12 carbon atoms. When the number of carbon atoms is 2 or more, it may or may not contain oxygen atoms between 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-tetrafluoropropylene 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 mol% to 15 mol% relative to all 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 fluorinated monomer units.

10. The binder for solid electrolyte batteries according to any one of claims 1 to 9, wherein, Segment B of the polymer contains vinylidene fluoride units.

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 relative to all 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-tetrafluoropropylene 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 of chain segment A to chain segment B in the polymer, i.e., A / B, is 40 / 60 to 95 / 5.

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

15. A binder for solid electrolyte batteries, wherein the binder contains a polymer, and... The polymer has a glass transition temperature and melting point, contains 2,3,3,3-tetrafluoropropylene units, and has a tetrahydrofuran extract content of less than 5% by mass at 25°C.

16. The binder for solid electrolyte batteries according to claim 15, wherein, The polymer also contains vinylidene fluoride units.

17. The binder for solid electrolyte batteries according to claim 15 or 16, wherein, The polymer contains two or more chain 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 below -10°C. The polymer has a melting point of 140℃~200℃. The polymer contains vinylidene fluoride units and 2,3,3,3-tetrafluoropropylene units, wherein the content of 2,3,3,3-tetrafluoropropylene units is 9 mol% to 24 mol% relative to all monomer units constituting the polymer, and the content of vinylidene fluoride units is 76 mol% to 91 mol% relative to all monomer units constituting the polymer. The tetrahydrofuran extract yield of the polymer at 25°C is 2%–4% by mass. 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, solid electrolyte, and solvent as described in any one of claims 1 to 18.

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

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

22. A solid electrolyte battery comprising the electrode of claim 21.

23. A solid electrolyte battery having a solid electrolyte layer formed from the solid electrolyte battery slurry of claim 19 or 20.