Binder composition for nonaqueous secondary battery electrodes, slurry composition for nonaqueous secondary battery electrodes, electrode for nonaqueous secondary batteries, and nonaqueous secondary battery

Abstract

The purpose of the present invention is to provide a binder composition for nonaqueous secondary battery electrodes, which can be suitably used in the production of an electrode having excellent flexibility and can improve the battery characteristics of a secondary battery having the obtained electrode. The present invention is a binder composition for nonaqueous secondary battery electrodes, which contains a polymer (A), and which is characterized in that when the binder composition for nonaqueous secondary battery electrodes is made into a film (X), the breaking stress [MPa] and breaking strain [-] of the film (X) as measured by a tensile test satisfy the following relational expression. And 0.010 < = fracture stress [MPa] / fracture strain [-] < = 1.000.

Description

Technical Field

[0001] The present invention relates to a binder composition for non-aqueous secondary battery electrodes, a slurry composition for non-aqueous secondary battery electrodes, a non-aqueous secondary battery electrode, and a non-aqueous secondary battery. Background Art

[0002] Non-aqueous secondary batteries such as lithium-ion secondary batteries (hereinafter sometimes abbreviated as "secondary batteries") have the characteristics of being small, light, having a high energy density, and being capable of repeated charge and discharge, and are used in a wide range of applications. Therefore, in recent years, in order to further improve the performance of non-aqueous secondary batteries, improvements in battery components such as electrodes have been studied.

[0003] Here, an electrode for a secondary battery such as a lithium-ion secondary battery generally has a current collector and an electrode composite layer (a positive electrode composite layer or a negative electrode composite layer) formed on the current collector. Moreover, this electrode composite layer is formed, for example, by coating a slurry composition containing an electrode active material and a binder composition containing a binder material on the current collector and drying the coated slurry composition.

[0004] In recent years, in order to further improve the performance of secondary batteries, attempts have been made to improve the electrode composite layer.

[0005] For example, Patent Document 1 discloses that in a positive electrode active material layer (electrode composite layer) containing a positive electrode active material, a conductive material, and a binder (binder material), as the above binder, a binder containing a first polymer and a second polymer is used, the first polymer being a fluorine-containing polymer defined, and the second polymer containing a polymerization unit having a nitrile group, a polymerization unit having a hydrophilic group, a (meth)acrylate polymerization unit, and a linear alkylene polymerization unit having 4 or more carbon atoms in a prescribed ratio, respectively.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-143075. Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] In recent years, in order to increase the energy density of secondary batteries, thickening of electrodes has been studied. However, when the electrode is thickened, the flexibility of the electrode decreases, and particularly in a wound-type secondary battery, the electrode sometimes breaks when the innermost electrode is wound. In addition, when the blending amount of the binder is increased in order to improve the flexibility of the electrode, sometimes battery characteristics such as the IV characteristics, cycle characteristics, and rate characteristics of the secondary battery deteriorate.

[0011] Therefore, an object of the present invention is to provide a binder composition for non-aqueous secondary battery electrodes, which can be suitably used for manufacturing electrodes with excellent flexibility and can improve the battery characteristics of secondary batteries having the obtained electrodes.

[0012] In addition, an object of the present invention is to provide a slurry composition for non-aqueous secondary battery electrodes, which can form electrodes with excellent flexibility and can improve the battery characteristics of secondary batteries having the obtained electrodes.

[0013] Furthermore, an object of the present invention is to provide a non-aqueous secondary battery electrode capable of improving the battery characteristics of non-aqueous secondary batteries, and a non-aqueous secondary battery having excellent battery characteristics.

[0014] Means for Solving the Problems

[0015] The present inventors conducted in-depth research for the purpose of solving the above problems. Then, the present inventors newly found that by using a binder composition for non-aqueous secondary battery electrodes containing a specified polymer, in which when the film is formed, the breaking stress [MPa] and breaking strain [-] in the tensile test of the film satisfy a specified relationship, electrodes with excellent flexibility can be manufactured, and the battery characteristics of secondary batteries can be improved, thus completing the present invention.

[0016] That is, an object of the present invention is to advantageously solve the above problems, and the present invention is [1] a binder composition for non-aqueous secondary battery electrodes, which contains polymer A, and when the binder composition for non-aqueous secondary battery electrodes is formed into film X, the breaking stress [MPa] and breaking strain [-] in the tensile test of the film X satisfy the relational expression: 0.010 ≤ breaking stress [MPa] / breaking strain [-] ≤ 1.000. Thus, if the values of the breaking stress and breaking strain when the binder composition for non-aqueous secondary battery electrodes is formed into a film and subjected to a tensile test satisfy the above-specified relational expression, the flexibility of the electrodes formed using the binder composition for non-aqueous secondary battery electrodes can be improved, and the battery characteristics of secondary batteries using the electrodes can be improved.

[0017] In addition, in the present invention, the breaking stress and breaking strain in the tensile test of film X of the binder composition for non-aqueous secondary battery electrodes can be measured by the method described in the examples.

[0018] [2] In the binder composition for non-aqueous secondary battery electrodes of the above [1], preferably, the breaking strain in the tensile test of the film X is 6.0 or more. Thus, if the breaking strain of the film X of the binder composition for non-aqueous secondary battery electrodes in the tensile test is above the above lower limit, the flexibility of the obtained electrodes can be further improved.

[0019] [3] In the binder composition for non-aqueous secondary battery electrodes described in [1] or [2] above, it is preferred that the polymer A contains two or more polymers. Thus, if the polymer A contains two or more polymers, the flexibility of the resulting electrode can be further improved, and the battery characteristics of the secondary battery using this electrode can be further improved.

[0020] [4] In the binder composition for non-aqueous secondary battery electrodes described in any one of [1] to [3] above, it is preferred that the polymer A contains polymer A1. When forming film Y from the polymer A1, the breaking stress of the film Y in the tensile test is 0.3 MPa or more, and the breaking strain is 6.0 or more and less than 25.0. Thus, if the polymer A contains polymer A1 with the breaking stress and breaking strain in the above-specified ranges when forming a film, the electrode composite layer can be maintained, and the cycle characteristics of the secondary battery using this electrode can be further improved.

[0021] In addition, in the present invention, the breaking stress and breaking strain of the polymer film Y during the tensile test can be measured by the method described in the examples.

[0022] [5] In the binder composition for non-aqueous secondary battery electrodes described in [4] above, it is preferred that the polymer A further contains polymer A2. When forming film Y from the polymer A2, the breaking stress of the film Y in the tensile test is 0.3 MPa or more, and the breaking strain is 25.0 or more. Thus, if the polymer A further contains polymer A2 with the breaking stress and breaking strain in the above-specified ranges when forming a film, the flexibility of the resulting electrode can be further improved, and the winding secondary battery using this electrode can also maintain the IV characteristics.

[0023] [6] In the binder composition for non-aqueous secondary battery electrodes described in [5] above, it is preferred that the mass ratio of the polymer A1 to the polymer A2 (polymer A1∶polymer A2) is 9∶1 or more and 1∶9 or less. Thus, if the mass ratio of the polymer A1 to the polymer A2 is within the above-specified range, the flexibility of the resulting electrode can be further improved, and the battery characteristics of the secondary battery using this electrode can be further improved.

[0024] [7] In the binder composition for non-aqueous secondary battery electrodes described in any one of [4] to [6] above, it is preferred that the polymer A1 contains a nitrile group monomer unit and an alkylene structural unit. Thus, if the polymer A1 contains a nitrile group monomer unit and an alkylene structural unit, the flexibility of the resulting electrode can be further improved, and the IV characteristics of the winding secondary battery using this electrode can be further improved.

[0025] In addition, in the present invention, the "monomer unit" of a polymer refers to "the repeating unit derived from the monomer contained in the polymer obtained using the monomer". Further, regarding whether a polymer contains a specified structural unit or monomer unit, it can be determined using 1 nuclear magnetic resonance (NMR) methods such as 1H-NMR.

[0026] [8] In the binder composition for a non-aqueous secondary battery electrode according to any one of [5] to [7] above, it is preferable that the above polymer A2 contains (meth)acrylate monomer units. Thus, if the above polymer A2 contains (meth)acrylate monomer units, the flexibility of the electrode can be further improved, and the battery characteristics of the secondary battery using the electrode can be further improved.

[0027] In addition, in the present invention, "(meth)acrylic acid" means acrylic acid and / or methacrylic acid.

[0028] Furthermore, an object of the present invention is to advantageously solve the above problems, and the present invention is [9] a slurry composition for a non-aqueous secondary battery electrode, which contains an electrode active material and the binder composition for a non-aqueous secondary battery electrode according to any one of [1] to [8] above. Thus, if the above binder composition for a non-aqueous secondary battery electrode and an electrode active material are blended, a slurry composition for a non-aqueous secondary battery electrode that can easily produce an electrode with excellent flexibility and can improve the battery characteristics of the secondary battery having the obtained electrode can be obtained.

[0029] Furthermore, an object of the present invention is to advantageously solve the above problems, and the present invention is

[10] a non-aqueous secondary battery electrode having an electrode composite layer formed using the slurry composition for a non-aqueous secondary battery electrode of [9] above. Thus, if the above slurry composition for a non-aqueous secondary battery electrode is used, a non-aqueous secondary battery electrode with excellent flexibility can be well produced, and the battery characteristics of the secondary battery using the non-aqueous secondary battery electrode can be improved.

[0030] Furthermore, an object of the present invention is to advantageously solve the above problems, and the present invention is

[11] a non-aqueous secondary battery having the non-aqueous secondary battery electrode of

[10] above. Thus, if the above non-aqueous secondary battery electrode is used, the battery characteristics of the secondary battery can be improved.

[0031] Advantages of the Invention

[0032] According to the present invention, a binder composition for a non-aqueous secondary battery electrode can be provided, which can be suitably used for manufacturing an electrode with excellent flexibility and can improve the battery characteristics of the secondary battery having the obtained electrode.

[0033] In addition, according to the present invention, it is possible to provide a non-aqueous secondary battery electrode paste composition that can form an electrode with excellent flexibility and can improve the battery characteristics of a secondary battery having the obtained electrode.

[0034] Furthermore, according to the present invention, it is possible to provide a non-aqueous secondary battery electrode that can improve the battery characteristics of a non-aqueous secondary battery, and a non-aqueous secondary battery having excellent battery characteristics. Detailed Embodiments

[0035] Hereinafter, the embodiments of the present invention will be described in detail.

[0036] Here, the binder composition for non-aqueous secondary battery electrodes of the present invention (hereinafter, also simply referred to as "binder composition") can be preferably used, for example, when preparing the paste composition for non-aqueous secondary battery electrodes of the present invention (hereinafter, also simply referred to as "paste composition"). In addition, the paste composition for non-aqueous secondary battery electrodes of the present invention can be preferably used, for example, when manufacturing the non-aqueous secondary battery electrodes of the present invention. Furthermore, the non-aqueous secondary battery of the present invention is characterized by using a non-aqueous secondary battery electrode formed by using the paste composition for non-aqueous secondary battery electrodes of the present invention.

[0037] In addition, the binder composition for non-aqueous secondary battery electrodes and the paste composition for non-aqueous secondary battery electrodes of the present invention can be particularly preferably used when forming the positive electrode of a non-aqueous secondary battery.

[0038] (Binder Composition for Non-Aqueous Secondary Battery Electrodes)

[0039] The binder composition of the present invention contains polymer A and optionally at least one selected from solvents and other components.

[0040] Moreover, the binder composition of the present invention is characterized in that when forming film X, the breaking stress [MPa] and breaking strain [-] in the tensile test of the film X satisfy the relational expression of 0.010 ≤ breaking stress [MPa] / breaking strain [-] ≤ 1.000. Therefore, when manufacturing an electrode by forming an electrode composite layer on a current collector using a paste composition prepared with the binder composition, a certain strength for functioning as an electrode can be imparted to the electrode, and sufficient flexibility can be imparted. As a result, breakage during winding the electrode or the like can be suppressed, and the battery characteristics of a secondary battery having the electrode can be improved.

[0041] <Polymer A>

[0042] In an electrode manufactured by forming an electrode composite layer on a current collector using a slurry composition prepared with a binder composition, polymer A is a component that functions to impart flexibility to the electrode and retain components such as electrode active materials contained in the electrode composite layer from detaching from the electrode composite layer.

[0043] <<Composition>>

[0044] The polymer constituting polymer A is not particularly limited as long as it can exhibit the above functions, and polymers with any composition can be used. In addition, the polymer constituting polymer A can be one type or two or more types. Furthermore, hereinafter, when polymer A is composed of two or more polymers, the content ratio of the structural units and / or monomer units in polymer A is the total content ratio of the structural units and / or monomer units in all the polymers constituting polymer A.

[0045] Examples of polymers suitable for use as polymer A include polymers containing at least one structural unit and / or monomer unit selected from a nitrile group-containing monomer unit, an alkylene structural unit, a (meth)acrylate monomer unit, a hydrophilic group-containing monomer unit, and an aromatic vinyl monomer. Among them, from the viewpoint of further improving the flexibility of the obtained electrode and further improving the battery characteristics of the secondary battery, as polymer A, a polymer containing at least a nitrile group-containing monomer unit and an alkylene structural unit is preferred, and a polymer containing a nitrile group-containing monomer unit, an alkylene structural unit, and at least one monomer unit selected from a (meth)acrylate monomer unit, a hydrophilic group-containing monomer unit, and an aromatic vinyl monomer unit is more preferred, and a polymer containing all of a nitrile group-containing monomer unit, an alkylene structural unit, and a (meth)acrylate monomer unit is further preferred. In addition, polymer A preferably does not contain a fluorine-containing monomer unit.

[0046] [Nitrile group-containing monomer unit]

[0047] The nitrile group-containing monomer unit is a repeating unit derived from a nitrile group-containing monomer unit. Moreover, as the nitrile group-containing monomer capable of forming a nitrile group-containing monomer unit, α,β-ethylenically unsaturated nitrile monomers can be cited. Moreover, as the α,β-ethylenically unsaturated nitrile monomer, there is no particular limitation as long as it is an α,β-ethylenically unsaturated compound having a nitrile group, and examples thereof include acrylonitrile; α-halopropionitriles such as α-chloropropionitrile and α-bromopropionitrile; α-alkylacrylonitriles such as methacrylonitrile and α-ethylacrylonitrile. Among these, as the nitrile group-containing monomer, acrylonitrile and methacrylonitrile are preferred, and acrylonitrile is more preferred.

[0048] These can be used alone or in combination of two or more.

[0049] Moreover, when all the repeating units (total of structural units and monomer units) in Polymer A are set to 100% by mass, the content ratio of the nitrile group-containing monomer units in Polymer A is preferably 5% by mass or more, more preferably 10% by mass or more, preferably 40% by mass or less, and more preferably 30% by mass or less. When the content ratio of the nitrile group-containing monomer units in Polymer A exceeds the above upper limit, the flexibility may decrease, and in addition, when the coating film is formed on the conductive material, the IV characteristics also deteriorate. When the content ratio of the nitrile group-containing monomer units in Polymer A is less than the above lower limit, the solubility of Polymer A may deteriorate when preparing the slurry composition, and the electrode formability may deteriorate. If the content ratio of the nitrile group-containing monomer units is within the above-specified range, the flexibility of the obtained electrode can be further improved, and the adaptability of the manufacturing process of the secondary battery and the battery characteristics can be further improved.

[0050] [Alkylene structural unit]

[0051] The alkylene structural unit is a repeating unit composed only of an alkylene structure represented by the general formula: -C n H 2n -[wherein, n is an integer of 2 or more]. By Polymer A containing an alkylene structural unit, the flexibility of the obtained electrode can be further improved, and the battery characteristics of the secondary battery can be further improved.

[0052] The alkylene structural unit may be linear or branched. From the viewpoint of further improving the flexibility of the obtained electrode, the alkylene structural unit is preferably linear, that is, a linear alkylene structural unit. In addition, the number of carbon atoms of the alkylene structural unit is preferably 4 or more (that is, n in the above general formula -C n H 2n - is an integer of 4 or more).

[0053] Moreover, the method for introducing an alkylene structural unit into Polymer A is not particularly limited, and for example, the following methods (1) or (2) can be cited:

[0054] (1) A method of preparing a polymer from a monomer composition containing a conjugated diene monomer and hydrogenating (hydrogenating) the polymer to convert the conjugated diene monomer units into alkylene structural units;

[0055] (2) A method of preparing a polymer from a monomer composition containing a 1-alkene monomer.

[0056] Among these, the method (1) is easy to manufacture the polymer, so it is preferred.

[0057] That is, the alkylene structural unit is preferably a structural unit obtained by hydrogenating (hydrogenating) a conjugated diene monomer unit (conjugated diene hydride unit), more preferably a structural unit obtained by hydrogenating an isoprene unit (isoprene hydride unit) or a structural unit obtained by hydrogenating a 1,3-butadiene unit (1,3-butadiene hydride unit), and still more preferably a structural unit obtained by hydrogenating a 1,3-butadiene unit (1,3-butadiene hydride unit). Here, hydrogenation can be carried out by a known method as described later.

[0058] In addition, examples of the 1-alkene monomer include 1-butene and 1-hexene.

[0059] These conjugated diene monomers and 1-alkene monomers can be used alone or in combination of two or more.

[0060] In addition, examples of the conjugated diene monomer that can be used in the method (1) above include conjugated diene compounds such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene. Among them, isoprene and 1,3-butadiene are preferred, and 1,3-butadiene is more preferred.

[0061] In addition, when the alkylene structural unit is introduced into polymer A by the method (1) above, when the conjugated diene monomer unit is not completely hydrogenated, the conjugated diene monomer unit may remain in polymer A. In other words, polymer A may optionally contain a conjugated diene monomer unit as a repeating unit.

[0062] When the total of all repeating units (the sum of the structural unit and the monomer unit) in polymer A is set to 100% by mass, the total content ratio of the alkylene structural unit and the conjugated diene monomer unit in polymer A is preferably 20% by mass or more, more preferably 25% by mass or more, still more preferably 30% by mass or more, preferably 70% by mass or less, more preferably 65% by mass or less, and still more preferably 60% by mass or less. When the total content ratio of the alkylene structural unit and the conjugated diene monomer unit in polymer A exceeds the above upper limit, the solubility of polymer A may deteriorate when preparing the slurry composition, and the electrode formability may deteriorate. When the total content ratio of the alkylene structural unit and the conjugated diene monomer unit in polymer A is less than the above lower limit, it may be difficult to form a carbon conductive path, and the IV characteristics may deteriorate. In addition, the flexibility of the electrode may deteriorate. If the total content ratio of the alkylene structural unit and the conjugated diene monomer unit is within the above-specified range, the flexibility of the obtained electrode can be further improved, and the battery characteristics of the secondary battery can be further improved.

[0063] In addition, in the case where polymer A does not contain a conjugated diene monomer unit, for example, in the case where the conjugated diene monomer unit is completely hydrogenated in the above-mentioned method (1), or in the case where polymer A is produced by the method (2) above, when the total of all repeating units (the sum of structural units and monomer units) in polymer A is set to 100% by mass, the content ratio of the alkylene structural unit in polymer A is preferably 20% by mass or more, more preferably 25% by mass or more, still more preferably 30% by mass or more, preferably 70% by mass or less, more preferably 65% by mass or less, and still more preferably 60% by mass or less. When the content ratio of the alkylene structural unit in polymer A exceeds the above upper limit, the solubility of polymer A may deteriorate when preparing the slurry composition, and the electrode formability may deteriorate. In addition, when the content ratio of the alkylene structural unit in polymer A is less than the above lower limit, it may be difficult to form a carbon conductive path, and the IV characteristics may deteriorate. In addition, the flexibility of the electrode may deteriorate. If the content ratio of the alkylene structural unit is within the above-specified range, the flexibility of the obtained electrode can be further improved, and the battery characteristics of the secondary battery can be further improved.

[0064] -(meth)acrylate monomer unit-

[0065] (Meth)acrylate monomer unit refers to the repeating unit derived from a (meth)acrylate monomer.

[0066] Examples of the (meth)acrylate monomer include: alkyl acrylates such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, tert-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, isopentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, lauryl acrylate, n-tetradecyl acrylate, stearyl acrylate, cyclohexyl acrylate; and alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, isobutyl methacrylate, n-pentyl methacrylate, isopentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, decyl methacrylate, lauryl methacrylate, n-tetradecyl methacrylate, stearyl methacrylate, cyclohexyl methacrylate. Among them, n-butyl acrylate or ethyl acrylate is preferred, and ethyl acrylate is more preferred.

[0067] When all the repeating units (total of structural units and monomer units) in Polymer A are set to 100% by mass, the content ratio of (meth)acrylate monomer units in Polymer A is preferably 20% by mass or more, more preferably 30% by mass or more, preferably 60% by mass or less, more preferably 50% by mass or less, and further preferably 40% by mass or less. When the content ratio of (meth)acrylate monomer units in Polymer A exceeds the above upper limit, the electrolyte swelling degree may become high and the IV characteristics may deteriorate. When the content ratio of (meth)acrylate monomer units in Polymer A is less than the above lower limit, the flexibility of the electrode may deteriorate. If the content ratio of (meth)acrylate monomer units is within the above-specified range, the flexibility of the obtained electrode can be further improved, and the battery characteristics of the secondary battery can be further improved.

[0068] [Monomer unit containing a hydrophilic group]

[0069] The monomer unit containing a hydrophilic group is a repeating unit derived from a monomer containing a hydrophilic group.

[0070] Examples of the monomer containing a hydrophilic group that can form a monomer unit containing a hydrophilic group include monomers having a carboxyl group, monomers having a sulfonic acid group, monomers having a phosphoric acid group, and monomers having a hydroxyl group.

[0071] Examples of the monomer having a carboxyl group include monocarboxylic acids and their derivatives, dicarboxylic acids and their acid anhydrides, and their derivatives.

[0072] Examples of the monocarboxylic acid include acrylic acid, methacrylic acid, crotonic acid, etc.

[0073] Examples of the monocarboxylic acid derivative include 2-ethylacrylic acid, isocrotonic acid, α-acetoxyacrylic acid, β-trans-aryloxyacrylic acid, α-chloro-β-E-methoxyacrylic acid, β-diaminoacrylic acid, etc.

[0074] Examples of the dicarboxylic acid include maleic acid, fumaric acid, itaconic acid, etc.

[0075] Examples of the dicarboxylic acid derivative include maleic acid esters such as methylmaleic acid, dimethylmaleic acid, phenylmaleic acid, chloromaleic acid, dichloromaleic acid, fluoromaleic acid, maleic acid methyl allyl ester, maleic acid diphenyl ester, maleic acid nonyl ester, maleic acid decyl ester, maleic acid dodecyl ester, maleic acid octadecyl ester, maleic acid fluoroalkyl ester, etc.

[0076] Examples of the acid anhydride of the dicarboxylic acid include maleic anhydride, acrylic anhydride, methylmaleic anhydride, dimethylmaleic anhydride, etc.

[0077] In addition, as the monomer having a carboxyl group, an acid anhydride that generates a carboxyl group by hydrolysis can also be used.

[0078] In addition, the following can be cited: monoethyl maleate, diethyl maleate, monobutyl maleate, dibutyl maleate, monoethyl fumarate, diethyl fumarate, monobutyl fumarate, dibutyl fumarate, monocyclohexyl fumarate, dicyclohexyl fumarate, monoethyl itaconate, diethyl itaconate, monobutyl itaconate, dibutyl itaconate, etc., which are monoesters and diesters of α,β-ethylenically unsaturated polycarboxylic acids.

[0079] Examples of the monomer having a sulfonic acid group include vinyl sulfonic acid, methyl vinyl sulfonic acid, (meth)allyl sulfonic acid, styrene sulfonic acid, 2-sulfoethyl (meth)acrylate, 2-acrylamido-2-methylpropane sulfonic acid, 3-allyloxy-2-hydroxypropane sulfonic acid, and the like.

[0080] In addition, in the present invention, “(meth)allyl” means allyl and / or methallyl.

[0081] Examples of the monomer having a phosphoric acid group include 2-(meth)acryloyloxyethyl phosphate, methyl-2-(meth)acryloyloxyethyl phosphate, ethyl-(meth)acryloyloxyethyl phosphate, vinylphosphonic acid, dimethyl vinylphosphonate, and the like.

[0082] In addition, in the present invention, “(meth)acryloyl” means acryloyl and / or methacryloyl.

[0083] Examples of the monomer having a hydroxyl group include: ethylenically unsaturated alcohols such as (meth)allyl alcohol, 3-buten-1-ol, 5-hexen-1-ol; alkanoate esters of ethylenically unsaturated carboxylic acids such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, di-2-hydroxyethyl maleate, di-4-hydroxybutyl maleate, di-2-hydroxypropyl itaconate; the general formula CH2=CR1-COO-(C n H 2n O) mesters of polyalkylene glycols represented by -H (wherein m represents an integer of 2 to 9, n represents an integer of 2 to 4, and R1 represents hydrogen or methyl) and (meth)acrylic acid; mono(meth)acrylates of dihydroxy esters of dicarboxylic acids such as 2-hydroxyethyl-2'-(meth)acryloyloxy phthalate and 2-hydroxyethyl-2'-(meth)acryloyloxy succinate; vinyl ethers such as 2-hydroxyethyl vinyl ether and 2-hydroxypropyl vinyl ether; mono(meth)allyl ethers of alkylene glycols such as (meth)allyl-2-hydroxyethyl ether, (meth)allyl-2-hydroxypropyl ether, (meth)allyl-3-hydroxypropyl ether, (meth)allyl-2-hydroxybutyl ether, (meth)allyl-3-hydroxybutyl ether, (meth)allyl-4-hydroxybutyl ether, and (meth)allyl-6-hydroxyhexyl ether; mono(meth)allyl ethers of polyoxyalkylene glycols such as diethylene glycol mono(meth)allyl ether and dipropylene glycol mono(meth)allyl ether; mono(meth)allyl ethers of (poly)alkylene glycols substituted with halogen and hydroxyl groups such as glycerol mono(meth)allyl ether, (meth)allyl-2-chloro-3-hydroxypropyl ether, and (meth)allyl-2-hydroxy-3-chloropropyl ether; mono(meth)allyl ethers of polyphenols such as eugenol and isoeugenol and their halogen-substituted products; (meth)allyl sulfides of alkylene glycols such as (meth)allyl-2-hydroxyethyl sulfide and (meth)allyl-2-hydroxypropyl sulfide, etc.

[0084] When all the repeating units (the total of structural units and monomer units) in polymer A are set to 100% by mass, the content ratio of the monomer units containing hydrophilic groups in polymer A is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, preferably 5% by mass or less, and more preferably 3% by mass or less. If the content ratio of the monomer units containing hydrophilic groups in polymer A is within the above range, the manufacturability of polymer A can be improved. In addition, by suppressing the coating of the active material, the rate characteristics of the secondary battery can be improved.

[0085] - aromatic vinyl monomer unit -

[0086] The aromatic vinyl monomer unit is a repeating unit derived from an aromatic vinyl monomer. Here, examples of the aromatic vinyl monomer that can form the aromatic vinyl monomer unit include styrene, α-methylstyrene, vinyltoluene, divinylbenzene, etc. These can be used alone or in combination of two or more.

[0087] When all the repeating units (total of structural units and monomer units) in Polymer A are set to 100% by mass, the content ratio of aromatic vinyl monomer units in Polymer A is preferably 1% by mass or more, more preferably 3% by mass or more, preferably 30% by mass or less, and more preferably 20% by mass or less. If within the above range, the electrochemical stability of Polymer A can be improved, and by suppressing the coating of the conductive material, the rate characteristics of the secondary battery can be improved.

[0088] <<Properties>>

[0089] [Breaking stress]

[0090] When Polymer A is made into Film Y, the breaking stress of Film Y in the tensile test (hereinafter sometimes simply referred to as "breaking stress") is preferably 0.3 MPa or more, preferably 0.5 MPa or more, more preferably 1.0 MPa or more. In addition, it is preferably 20 MPa or less, more preferably 15 MPa or less, and further preferably 10 MPa or less. When the breaking stress exceeds the above upper limit, there is a possibility of high rigidity and a decrease in the flexibility of the electrode. In addition, when the breaking stress is less than the above lower limit, it may be difficult to maintain the electrode composite layer, and the cycle characteristics of the secondary battery may deteriorate. If the above breaking stress is within the above range, the strength and flexibility of the obtained electrode can be well balanced, and the battery characteristics of the secondary battery can be further improved.

[0091] The breaking stress of Polymer A can be controlled by, for example, changing the composition, molecular weight, branches of the polymer chain, and arrangement of monomers of Polymer A.

[0092] [Breaking strain]

[0093] When Polymer A is made into Film Y, the breaking strain of Film Y in the tensile test (hereinafter sometimes simply referred to as "breaking strain") is preferably 6.0 or more, preferably 8.0 or more, more preferably 10.0 or more. In addition, it is preferably 80 or less, more preferably 70 or less, and further preferably 60 or less. When the breaking strain exceeds the above upper limit, it may be difficult to maintain the electrode composite layer, and the cycle characteristics of the secondary battery may deteriorate. When the breaking strain is less than the above lower limit, the flexibility of the electrode may deteriorate. If the above breaking strain is within the above range, the strength and flexibility of the obtained electrode can be well balanced, and the battery characteristics of the secondary battery can be further improved.

[0094] The breaking strain of Polymer A can be controlled by, for example, changing the composition, molecular weight distribution, and entanglement density of Polymer A.

[0095] [Iodine value]

[0096] The iodine value of Polymer A is preferably 5 mg / 100 mg or more, more preferably 10 mg / 100 mg or more, preferably 30 mg / 100 mg or less, more preferably 25 mg / 100 mg or less, and further preferably 20 mg / 100 mg or less. Within the above range, the electrochemical stability of Polymer A is improved, and the cycle characteristics of the secondary battery can be enhanced.

[0097] In addition, the iodine value of Polymer A can be measured by the method described in the examples. The iodine value of Polymer A can be controlled based on, for example, the amount of the hydrogenation catalyst used and / or the hydrogenation conditions (pressure, time) during the hydrogenation of the polymer in the preparation of Polymer A.

[0098] <<Combination of Types of Polymer A>>

[0099] From the viewpoint of further improving the flexibility of the obtained electrode and further enhancing the battery characteristics of the secondary battery, Polymer A preferably contains two or more polymers. Specifically, Polymer A preferably contains two or more polymers that are different in at least one selected from the group consisting of composition, breaking stress, breaking strain, iodine value, molecular weight, and glass transition temperature. Among them, Polymer A preferably contains two polymers A1 and A2 that are different in at least one selected from the group consisting of composition, breaking stress, breaking strain, iodine value, molecular weight, and glass transition temperature, more preferably contains two polymers A1 and A2 that are different in composition and / or breaking strain, and further preferably is composed of two polymers A1 and A2 that are different in at least one selected from the group consisting of composition, breaking stress, breaking strain, iodine value, molecular weight, and glass transition temperature, and particularly preferably is composed of two polymers A1 and A2 that are different in composition and / or breaking strain.

[0100] As a combination of polymers A1 and A2 with different compositions, for example, a polymer containing a nitrile group monomer unit and an alkylene structural unit as Polymer A1 is preferably combined with a polymer containing at least one structural unit and / or monomer unit selected from the group consisting of a nitrile group monomer unit, an alkylene structural unit, a (meth)acrylate monomer unit, a monomer unit containing a hydrophilic group, and an aromatic vinyl monomer unit as Polymer A2; among them, a polymer containing a nitrile group monomer unit and an alkylene structural unit as Polymer A1 is more preferably combined with a polymer containing a (meth)acrylate monomer unit as Polymer A2.

[0101] Specifically, as Polymer A1, a polymer containing a nitrile group monomer unit and an alkylene structural unit is preferred, and a polymer composed of a nitrile group monomer unit and an alkylene structural unit is more preferred.

[0102] Here, when the total of all repeating units (the sum of structural units and monomer units) in Polymer A1 is set to 100% by mass, the content ratio of the nitrile group-containing monomer units in Polymer A1 is preferably 20% by mass or more, more preferably 25% by mass or more, preferably 50% by mass or less, and more preferably 40% by mass or less.

[0103] When the total of all repeating units (the sum of structural units and monomer units) in Polymer A1 is set to 100% by mass, the content ratio of the alkylene structural units in Polymer A1 is preferably 50% by mass or more, more preferably 60% by mass or more, preferably 80% by mass or less, and more preferably 75% by mass or less.

[0104] In addition, when the total of all repeating units (the sum of structural units and monomer units) in Polymer A1 is set to 100% by mass, the total content ratio of the alkylene structural units and the conjugated diene monomer units in Polymer A1 is preferably 50% by mass or more, more preferably 60% by mass or more, preferably 80% by mass or less, and more preferably 75% by mass or less.

[0105] The breaking strain when forming Polymer A1 into Film Y is preferably 6.0 or more, more preferably 10.0 or more, preferably less than 25.0, and more preferably 20.0 or less.

[0106] In addition, the breaking stress when forming Polymer A1 into Film Y is preferably 0.3 MPa or more, more preferably 0.5 MPa or more, preferably 3.0 MPa or less, and more preferably 2.0 MPa or less.

[0107] As Polymer A2, a polymer preferably containing at least one structural unit and / or monomer unit selected from nitrile group-containing monomer units, alkylene structural units, (meth)acrylate monomer units, monomer units containing hydrophilic groups, and aromatic vinyl monomer units is more preferably a polymer containing (meth)acrylate monomer units.

[0108] Here, when the total of all repeating units (the sum of structural units and monomer units) in Polymer A2 is set to 100% by mass, the content ratio of the nitrile group-containing monomer units in Polymer A2 is preferably 10% by mass or more, more preferably 15% by mass or more, preferably 30% by mass or less, and more preferably 25% by mass or less.

[0109] When the total of all repeating units (the sum of structural units and monomer units) in Polymer A2 is set to 100% by mass, the content ratio of the alkylene structural units in Polymer A2 is preferably 20% by mass or more, further preferably 30% by mass or more, preferably 60% by mass or less, and more preferably 50% by mass or less.

[0110] In addition, when the total of all repeating units (the sum of structural units and monomer units) in Polymer A2 is 100% by mass, the total content ratio of the alkylene structural units and conjugated diene monomer units in Polymer A2 is preferably 20% by mass or more, more preferably 30% by mass or more, preferably 60% by mass or less, and more preferably 50% by mass or less.

[0111] When the total of all repeating units (the sum of structural units and monomer units) in Polymer A2 is 100% by mass, the content ratio of the (meth)acrylate monomer units in Polymer A2 is preferably 20% by mass or more, more preferably 30% by mass or more, preferably 60% by mass or less, and more preferably 50% by mass or less.

[0112] The breaking strain when forming Polymer A2 into Film Y is preferably 20.0 or more, more preferably 25 or more, preferably 80 or less, and more preferably 75 or less.

[0113] In addition, the breaking stress when forming Polymer A2 into Film Y is preferably 0.3 MPa or more, more preferably 0.5 MPa or more, preferably 3.0 MPa or less, and more preferably 2.0 MPa or less.

[0114] From the viewpoint of further improving the flexibility of the obtained electrode and further improving the battery characteristics of the secondary battery, the mass ratio of Polymer A1 to Polymer A2 (Polymer A1:Polymer A2) is preferably 9:1 or more and 1:9 or less, and more preferably 2:8 or more and 8:2 or less.

[0115] For example, the mass ratio of Polymer A1 having a breaking strain of 6.0 or more and less than 25.0 to Polymer A2 having a breaking strain of 25.0 or more (Polymer A1:Polymer A2) is preferably 9:1 or more and 1:9 or less, and more preferably 2:8 or more and 8:2 or less.

[0116] In addition, when Polymer A contains polymers other than Polymer A1 and A2, the content of the polymers other than Polymer A1 and A2 in Polymer A is usually preferably 15% by mass or less. The polymers other than Polymer A1 and A2 are not particularly limited as long as they do not hinder the manifestation of the desired effects of the present invention.

[0117] <<Method for Preparing Polymer A>>

[0118] The method for manufacturing the above-described Polymer A is not particularly limited, and any method such as solution polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, etc. can also be used.

[0119] In addition, as the polymerization method, addition polymerization such as ionic polymerization, radical polymerization, and living radical polymerization can be used. Further, as the polymerization initiator, known polymerization initiators can be used.

[0120] Moreover, during polymerization, a molecular weight regulator having a sulfur-containing group such as a mercapto group is preferably used. Examples of the compound having a mercapto group used as the molecular weight regulator include mercaptans having 8 to 12 carbon atoms such as octyl mercaptan, 2,2,4,6,6-pentamethyl-4-heptanethiol, 2,4,4,6,6-pentamethyl-2-heptanethiol, 2,3,4,6,6-pentamethyl-2-heptanethiol, 2,3,4,6,6-pentamethyl-3-heptanethiol, tert-dodecyl mercaptan, and n-dodecyl mercaptan; mercaptans having a mercapto group such as 2,2,4,6,6-pentamethyl-4-octanethiol, 2,2,4,6,6,8,8-heptamethyl-4-nonanethiol, bis(2-mercaptoethyl) sulfide, methyl 3-mercaptopropionate, and 1-butane thiol. Among them, mercaptans having 8 to 12 carbon atoms are preferred, and tert-dodecyl mercaptan is more preferred.

[0121] The compounding amount of the mercapto group-containing compound as the molecular weight regulator can be appropriately adjusted.

[0122] In addition, in the case of producing the above polymer by the method of (1) above, as the polymerization method of the hydrogenated polymer, radical polymerization using a redox polymerization initiator containing an iron-based compound is preferably used. There is no particular limitation on the redox polymerization initiator, and for example, a combination of cumene hydroperoxide, sodium iron ethylenediaminetetraacetate, sodium hydroxymethanesulfinate, and ethylenediaminetetraacetic acid tetrasodium salt (EDTA·4Na) can be used.

[0123] In the case of producing the above polymer A by the method of (1) above, after emulsion polymerization, a coagulant can be added to the aqueous dispersion of the pre-hydrogenated polymer (i.e., the precursor of polymer A) obtained to coagulate it, the pre-hydrogenated polymer can be recovered, and the recovered polymer (optionally, after performing the "metathesis reaction" described later) can be hydrogenated.

[0124] In addition, hydrogenation can be carried out using known hydrogenation methods such as an oil-phase hydrogenation method or an aqueous-phase hydrogenation method. Further, as the catalyst for hydrogenation, any known selective hydrogenation catalyst can be used without limitation, and palladium-based catalysts and rhodium-based catalysts can be used. Two or more of these can be used in combination.

[0125] In addition, the hydrogenation of the polymer can be carried out using, for example, the method described in Japanese Patent No. 4509792. Specifically, the hydrogenation of the polymer can be carried out after performing a metathesis reaction of the polymer in the presence of a catalyst and a co-olefin.

[0126] Here, as the catalyst for the metathesis reaction, known ruthenium-based catalysts can be used. Among them, as the catalyst for the metathesis reaction, Grubbs catalysts such as bis(tricyclohexylphosphine)benzylidene ruthenium dichloride and 1,3-bis(2,4,6-trimethylphenyl)-2-(imidazolidinylidene)(dichlorobenzylidene)(tricyclohexylphosphine)ruthenium are preferably used. In addition, as the co-olefin, olefins having 2 to 16 carbon atoms such as ethylene, isobutane, and 1-hexane can be used. In addition, as the hydrogenation catalyst during hydrogenation after the metathesis reaction, known homogeneous hydrogenation catalysts such as Wilkinson's catalyst ((PPh3)3RhCl) can be used.

[0127] <Solvent>

[0128] The solvent contained in the binder composition is not particularly limited, and either water or an organic solvent can be used. Examples of the organic solvent include N-methylpyrrolidone (hereinafter simply referred to as "NMP"), N,N-dimethylformamide, and acetone. From the viewpoints of improving the stability of the binder composition and the manufacturability of the electrode, N-methylpyrrolidone is preferably used as the organic solvent. In addition, as the solvent, one kind can be used alone, or two or more kinds can be mixed at any ratio.

[0129] <Other Components>

[0130] Examples of other components that can be optionally included in the binder composition of the present invention include dispersants, reinforcing materials, leveling agents, viscosity regulators, and electrolyte additives. As long as these do not affect the battery reaction, there are no particular limitations, and these known components can be used, such as those described in International Publication No. 2012 / 115096. In addition, these components can be used alone or two or more of them can be combined at any ratio.

[0131] <Physical Properties of the Binder Composition>

[0132] [Tensile Stress [MPa] / Tensile Strain [-]]

[0133] As described above, when the binder composition of the present invention is made into the film X, the tensile stress [MPa] and the tensile strain [-] of the film X in the tensile test need to satisfy the relational expression of 0.010 ≤ tensile stress [MPa] / tensile strain [-] ≤ 1.000. When the value of tensile stress [MPa] / tensile strain [-] is less than 0.001, the battery characteristics (especially the cycle characteristics) of the secondary battery deteriorate. In addition, when the value of tensile stress [MPa] / tensile strain [-] exceeds 1.000, sufficient flexibility cannot be imparted to the obtained electrode, so the rupture of the electrode cannot be sufficiently suppressed, and in addition, the battery characteristics of the secondary battery deteriorate.

[0134] From the viewpoint of further improving the flexibility of the obtained electrode and further improving the battery characteristics of the obtained secondary battery, the value of the above-mentioned breaking stress [MPa] / breaking strain [-] of the binder composition of the present invention when formed into film X is preferably 0.050 or more, more preferably 0.267 or more, and further preferably 0.800 or less, more preferably 0.769 or less.

[0135] [Breaking stress]

[0136] From the viewpoint of further improving the flexibility of the obtained electrode and further improving the battery characteristics of the obtained secondary battery, in the case where the binder composition of the present invention is formed into film X, the breaking stress of the film X in the tensile test is preferably 0.3 MPa or more, more preferably 0.5 MPa or more, and further preferably 10 MPa or less.

[0137] The above-mentioned breaking stress of the binder composition can be controlled by, for example, changing the composition of polymer A, the mass ratio of polymer A1 to polymer A2, and the solvent.

[0138] [Breaking strain]

[0139] From the viewpoint of further improving the flexibility of the obtained electrode and further improving the battery characteristics of the obtained secondary battery, in the case where the binder composition of the present invention is formed into film X, the breaking strain of the film X in the tensile test is preferably 6.0 or more, more preferably 8.0 or more, further preferably 13.5 or more, and further preferably 80 or less, more preferably 70 or less, further preferably 35 or less.

[0140] The above-mentioned breaking strain of the binder composition can be controlled by, for example, changing the composition of polymer A, the mass ratio of polymer A1 to polymer A2, and the solvent.

[0141] <Preparation of binder composition>

[0142] When the binder composition of the present invention contains a solvent, it can be prepared by dissolving or dispersing the above-mentioned polymer A and any other components in the solvent. Specifically, the binder composition can be prepared by mixing the above-mentioned components with the solvent using a mixer such as a ball mill, sand mill, bead mill, pigment disperser, grinder, ultrasonic disperser, homogenizer, planetary mixer, Filmix, etc.

[0143] In addition, when polymer A is prepared in the state of an aqueous dispersion, the aqueous dispersion can be directly used as the binder composition, or the aqueous dispersion of polymer A can be mixed with an organic solvent and then the water can be removed to be used as the binder composition.

[0144] (Slurry composition for non-aqueous secondary battery electrode)

[0145] The paste composition of the present invention comprises the above-mentioned binder composition of the present invention and an electrode active material, and optionally further comprises at least one selected from a conductive material, a solvent, and other components. Moreover, since the paste composition of the present invention comprises the above-mentioned binder composition of the present invention, an electrode excellent in flexibility can be manufactured. In addition, according to the paste composition of the present invention, a secondary battery can exhibit excellent battery characteristics.

[0146] In addition, hereinafter, as an example, a case where the paste composition for a non-aqueous secondary battery electrode is a paste composition for a positive electrode of a lithium ion secondary battery will be described, but the present invention is not limited to the following example.

[0147] <Binder Composition>

[0148] As the binder composition, the above-mentioned binder composition for a non-aqueous secondary battery electrode of the present invention is used. In addition, based on the total solid content in the paste composition being 100% by mass, the content ratio (in terms of solid content) of the binder composition in the paste composition of the present invention can be, for example, 0.1% by mass or more and 5% by mass or less.

[0149] <Electrode Active Material>

[0150] The electrode active material is a material that conducts electrons in the electrode of a secondary battery. Moreover, as the positive electrode active material for a lithium ion secondary battery, a material that can absorb and release lithium is usually used.

[0151] Specifically, as the positive electrode active material for a lithium ion secondary battery, there is no particular limitation, and examples include lithium cobalt oxide (LiCoO2), lithium manganate (LiMn2O4), lithium nickel oxide (LiNiO2), lithium-containing composite oxide of Co-Ni-Mn (Li(Co,Mn,Ni)O2), lithium-containing composite oxide of Ni-Mn-Al, lithium-containing composite oxide of Ni-Co-Al, olivine-type lithium iron phosphate (LiFePO4), olivine-type lithium manganese phosphate (LiMnPO4), Li2MnO3-LiNiO2-based solid solution, lithium 1+x Mn 2-x O4 (0 < X < 2) of a lithium-excess spinel compound represented by, Li[Ni 0.17 Li 0.2 Co 0.07 Mn 0.56 O2, LiNi 0.5 Mn 1.5 O4, LiNi 0.5 Mn 0.3 Co 0.2 O2 and other known positive electrode active materials.

[0152] In addition, the particle size of the positive electrode active material is not particularly limited and can be the same as that of the positive electrode active material used in the past. Further, based on the total solid content in the slurry composition being 100% by mass, the content ratio of the positive electrode active material in the slurry composition can be, for example, 90% by mass or more and 99% by mass or less.

[0153] <Conductive Material>

[0154] The conductive material that can be included in the slurry composition of the present invention is used to ensure electrical contact between the electrode active materials. Moreover, as the conductive material, carbon black (e.g., acetylene black, Ketjenblack (registered trademark), furnace black, etc.), single-walled or multi-walled carbon nanotubes (the multi-walled carbon nanotubes include stacked cup type), carbon nanohorns, vapor-grown carbon fibers, ground carbon fibers obtained by sintering and pulverizing polymer fibers, single-layer or multi-layer graphene, carbon non-woven fabric sheets obtained by sintering non-woven fabrics formed of polymer fibers, etc., conductive carbon materials; fibers or foils of various metals can be used. Among them, acetylene black is preferably used.

[0155] These can be used alone or in combination of two or more. In addition, the particle size of the conductive material is not particularly limited and can be the same as that of the conductive material used in the past. Further, based on the total solid content in the slurry composition being 100% by mass, the content ratio of the conductive material in the slurry composition can be, for example, 0.1% by mass or more and 3% by mass or less.

[0156] <Other Components>

[0157] As other components that can be incorporated into the slurry composition, there is no particular limitation, and examples include the same components as those that can be incorporated into the binder composition of the present invention. In addition, one kind of other component can be used alone, or two or more kinds can be used in combination at any ratio. Among them, in the case where the slurry composition is a slurry composition for a positive electrode of a lithium ion secondary battery, in addition to the above polymer A, it is preferable to use a binder material other than polymer A (e.g., fluorine-containing polymers such as polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE)). In the case where the slurry composition contains one or more binder materials in addition to the above polymer A, when the total content of the one or more binder materials is set to 100 parts by mass, the ratio of the above polymer A can be 10 parts by mass or more and 90 parts by mass or less. If the content ratio of the above polymer A in the slurry composition is at least the above lower limit value, the flexibility of the electrode can be made good, and the battery characteristics of the resulting secondary battery can be improved. In addition, if the content ratio of the above polymer A is at most the above upper limit value, the adhesiveness of the electrode composite layer (positive electrode composite layer) can be improved.

[0158] <Preparation of Slurry Composition>

[0159] The method for preparing the slurry composition is not particularly limited. The slurry composition of the present invention can be prepared, for example, by mixing the above-mentioned binder composition of the present invention, the electrode active material, and the conductive material and / or other components used as needed in the presence of a solvent. As the above-mentioned solvent, the same solvent as that described in the item of the binder composition can be used. In addition, as the above-mentioned solvent, the solvent contained in the binder composition can be directly used, or a newly added solvent can be used. Further, the mixing method used in preparing the slurry composition is not particularly limited, and mixers such as ball mills, sand mills, bead mills, pigment dispersers, grinders, ultrasonic dispersers, homogenizers, planetary mixers, and Filmix can be used.

[0160] (Electrode for non-aqueous secondary battery)

[0161] The electrode for non-aqueous secondary battery of the present invention has a current collector and an electrode composite layer formed on the current collector. The electrode composite layer is formed using the above-mentioned slurry composition of the present invention. That is, the electrode composite layer is a dried product of the above-mentioned slurry composition of the present invention, and contains at least polymer A and an electrode active material, and optionally further contains at least one selected from a conductive material and other components. In addition, each component contained in the electrode composite layer is the same as each component contained in the above-mentioned slurry composition, and the preferred ratio of existence of these components is the same as the preferred ratio of existence of the components in the slurry composition. Further, the above-mentioned polymer A can be in a particulate shape or other shapes in the electrode composite layer.

[0162] Moreover, since the electrode for non-aqueous secondary battery of the present invention is formed using a slurry composition containing the binder composition of the present invention, it has excellent flexibility. In addition, if this electrode is used, a secondary battery with excellent battery characteristics can be obtained.

[0163] <Method for manufacturing electrode>

[0164] The electrode for non-aqueous secondary battery of the present invention is manufactured via, for example, a step of coating the above-mentioned slurry composition on a current collector (coating step), and a step of drying the slurry composition coated on the current collector to form an electrode composite layer on the current collector (drying step).

[0165] [Coating step]

[0166] As a method for applying the above slurry composition onto a current collector, there is no particular limitation, and known methods can be used. Specifically, as the coating method, a doctor blade method, dipping method, reverse roll method, direct roll method, gravure printing method, extrusion method, brush coating method, etc. can be used. At this time, the slurry composition can be applied only on one side of the current collector, or on both sides of the current collector. The thickness of the slurry film on the current collector before drying after application can be appropriately set according to the thickness of the electrode composite material layer obtained by drying.

[0167] Here, as the current collector for applying the slurry composition, a material having conductivity and electrochemical durability can be used. Specifically, as the current collector, for example, a current collector formed of iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, platinum, etc. can be used. In addition, the above materials can be used alone or two or more of them can be used in any ratio in combination.

[0168] [Drying process]

[0169] As a method for drying the slurry composition on the current collector, there is no particular limitation, and known methods can be used. Examples include: drying methods using warm air, hot air, and low-humidity air; vacuum drying method; drying methods using irradiation of infrared rays, electron beams, etc. By drying the slurry composition on the current collector in this way, an electrode composite material layer can be formed on the current collector, and a secondary battery electrode having a current collector and an electrode composite material layer can be obtained.

[0170] In addition, after the drying process, a pressing treatment can be performed on the electrode composite material layer using a metal mold press or a roll press, etc. By the pressing treatment, the adhesion between the electrode composite material layer and the current collector can be improved. In addition, when the electrode composite material layer contains a curable polymer, it is preferable to cure the above polymer after forming the electrode composite material layer.

[0171] (Non-aqueous secondary battery)

[0172] The non-aqueous secondary battery of the present invention has the non-aqueous secondary battery electrode of the present invention. More specifically, the non-aqueous secondary battery of the present invention has a positive electrode, a negative electrode, an electrolyte, and a spacer, and uses the non-aqueous secondary battery electrode of the present invention as at least one of the positive electrode and the negative electrode. Moreover, since the non-aqueous secondary battery of the present invention has the non-aqueous secondary battery electrode of the present invention, the battery characteristics are excellent.

[0173] In addition, it is preferable to use the non-aqueous secondary battery electrode of the present invention as the positive electrode in the non-aqueous secondary battery of the present invention. In addition, hereinafter, as an example, the case where the secondary battery is a lithium ion secondary battery will be described, but the present invention is not limited to the following example.

[0174] <Electrode>

[0175] As an electrode other than the above-described non-aqueous secondary battery electrode that can be used in the non-aqueous secondary battery of the present invention, there is no particular limitation, and known electrodes used in the manufacture of non-aqueous secondary batteries can be used. Specifically, as an electrode other than the above-described non-aqueous secondary battery electrode, an electrode formed by forming an electrode composite layer on a current collector using a known manufacturing method can be used.

[0176] <Electrolyte>

[0177] As the electrolyte, an organic electrolyte in which a supporting electrolyte is dissolved in an organic solvent is usually used. As the supporting electrolyte for a lithium-ion secondary battery, for example, a lithium salt can be used. Examples of the lithium salt include LiPF6, LiAsF6, LiBF4, LiSbF6, LiAlCl4, LiClO4, CF3SO3Li, C4F9SO3Li, CF3COOLi, (CF3CO)2NLi, (CF3SO2)2NLi, (C2F5SO2)NLi, etc. Among them, since it is easily soluble in the solvent and shows a high dissociation degree, LiPF6, LiClO4, and CF3SO3Li are preferred, and LiPF6 is particularly preferred. In addition, the electrolyte can be used alone or in combination of two or more in any ratio. Generally, there is a tendency that the higher the dissociation degree of the supporting electrolyte, the higher the lithium-ion conductivity. Therefore, the lithium-ion conductivity can be adjusted by the type of the supporting electrolyte.

[0178] The organic solvent used in the electrolyte is not particularly limited as long as it can dissolve the supporting electrolyte. For example, carbonate esters such as dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), butylene carbonate (BC), and ethyl methyl carbonate (EMC) can be preferably used; esters such as γ-butyrolactone and methyl formate; ethers such as 1,2-dimethoxyethane and tetrahydrofuran; sulfur-containing compound classes such as sulfolane and dimethyl sulfoxide, etc. In addition, a mixture of these solvents can also be used. Among them, carbonate esters are preferably used because of their high dielectric constant and wide stable potential region, and a mixture of ethylene carbonate and diethyl carbonate is further preferably used.

[0179] In addition, the concentration of the electrolyte in the electrolyte can be appropriately adjusted. In addition, known additives such as vinylene carbonate can be added to the electrolyte.

[0180] <Separator>

[0181] As the spacer, there is no particular limitation, and for example, the spacer described in Japanese Patent Application Laid-Open No. 2012-204303 can be used. Among these, from the aspect of being able to reduce the film thickness of the entire spacer, thereby increasing the ratio of the electrode active material in the secondary battery and increasing the capacity per unit volume, a microporous membrane formed of a polyolefin-based (polyethylene, polypropylene, polybutene, polyvinyl chloride) resin is preferred.

[0182] <Manufacturing method of non-aqueous secondary battery>

[0183] The non-aqueous secondary battery of the present invention can be manufactured, for example, by overlapping a positive electrode and a negative electrode with a spacer therebetween, winding, folding, etc. according to the battery shape as needed, placing it in a battery container, injecting an electrolyte into the battery container, and sealing it. In order to prevent the occurrence of pressure rise, overcharge and over-discharge, etc. inside the secondary battery, overcurrent protection elements such as fuses and PTC elements, porous metal meshes, guide plates, etc. can be provided as needed. The shape of the secondary battery can be any one of, for example, coin type, button type, sheet type, cylindrical type, square type, flat type, etc.

[0184] Examples

[0185] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. In addition, in the following description, unless otherwise specified, "%" and "parts" representing amounts are based on mass.

[0186] In addition, unless otherwise stated, in a polymer manufactured by copolymerizing a plurality of monomers, the proportion of the monomer unit formed by polymerizing a certain monomer in the above polymer is usually the same as the ratio (feed ratio) of the certain monomer in all the monomers used in the polymerization of the polymer. In addition, in the case where the polymer is a hydrogenated polymer obtained by hydrogenating (hydrogenating) a polymer containing a conjugated diene monomer unit, for the total content ratio of the unhydrogenated conjugated diene monomer unit and the alkylene structural unit as the hydrogenated conjugated diene monomer unit in the hydrogenated polymer, it is the same as the ratio (addition ratio) of the conjugated diene monomer in all the monomers used in the polymerization of the polymer.

[0187] In the examples and comparative examples, various measurements and evaluations were carried out by the following methods.

[0188] <Tensile strength [MPa] / Tensile strain value>

[0189] An 8 mass% NMP solution of the binder composition prepared in the examples and comparative examples or the polymer prepared in the synthesis examples was cast into a Teflon (registered trademark) petri dish and dried in an oven at 150 °C for 10 hours to produce a film with a thickness of 500 μm. It was punched into a dumbbell shape according to JIS K-6251 and stretched with a tensile testing machine at a speed of 100 mm / min, and the breaking strain [-] and breaking stress [MPa] at this time were recorded. Then, the value of breaking stress [MPa] / breaking strain [-] was calculated.

[0190] <Iodine value>

[0191] The iodine value of the polymer prepared in the synthesis examples was measured according to JIS K6235; 2006.

[0192] <Flexibility of electrode>

[0193] An aluminum foil with a thickness of 15 μm was prepared as a current collector, and the positive electrode slurry compositions prepared in the examples and comparative examples were coated on the aluminum foil with a bevel wheel coater at a dry unit area mass of 30 mg / cm 2 and dried at 120 °C to obtain positive electrode raw materials. The positive electrode raw materials were rolled by a roll press to produce a positive electrode composed of a positive electrode active material layer with a density of 3.7 g / cm 3 and the aluminum foil. For the fabricated positive electrode, a bending test was conducted according to JIS K5600-5-1. Specifically, a positive electrode with a cut width of 10 mm was installed on a mandrel testing machine, and the positive electrode was bent in such a way that the positive electrode active material layer was on the outside. The positive electrode active material layer was observed under a microscope in the bent state to check for any cracks in the positive electrode. Then, the diameter of the mandrel was slowly increased until the positive electrode no longer cracked, and the diameter value of the mandrel at which the positive electrode did not crack was recorded. The smaller the diameter of the mandrel, the better the flexibility (winding property) of the positive electrode.

[0194] A: No crack at a diameter of 5 mm

[0195] B: No crack at a diameter of 8 mm

[0196] C: No crack at a diameter of 10 mm

[0197] <IV characteristics>

[0198] After injecting the electrolyte into the lithium-ion secondary batteries fabricated in the examples and comparative examples, they were left standing at a temperature of 25 degrees for 5 hours. Subsequently, at a temperature of 25 °C, a constant current method of 0.2C was used to charge the battery to a cell voltage of 3.65V, and then an aging treatment was carried out at a temperature of 60 °C for 12 hours. The charge-discharge operation of charging the battery to a battery voltage of 4.2V by a constant current method of 0.2C and discharging it to a battery voltage of 3.0V was repeated three times to measure the initial capacity. Then, after charging to a state of charge (SOC) of 50%, centered around 50% of the SOC, charging and discharging were carried out at 0.5C, 1.0C, 1.5C, and 2.0C for 20 seconds respectively. The battery voltage after 20 seconds in each case (charging side and discharging side) was plotted against the current value, and the slope was obtained as the IV resistance (Ω) (charging IV resistance and discharging IV resistance). For the obtained IV resistance values (Ω), the evaluation was carried out according to the following criteria. The smaller the value of the IV resistance, the lower the internal resistance and the more excellent the IV characteristics.

[0199] A: The IV resistance value is less than 2.3 Ω

[0200] B: The IV resistance value is 2.3 Ω or more and less than 2.5 Ω

[0201] C: The IV resistance value is 2.5 Ω or more

[0202] <Rate performance>

[0203] After injecting the electrolyte into the lithium-ion secondary batteries fabricated in the examples and comparative examples, they were left standing at a temperature of 25 °C for 5 hours. Subsequently, at a temperature of 25 °C, a constant current method of 0.2C was used to charge the battery to a cell voltage of 3.65V, and then an aging treatment was carried out at a temperature of 60 °C for 12 hours. Then, at a temperature of 25 °C, it was discharged to a cell voltage of 3.0V by a constant current method of 0.2C. Thereafter, CC-CV charging was carried out at a constant current of 0.2C (upper limit cell voltage 4.20V), and CC discharging was carried out at a constant current of 0.2C until the cell voltage reached 3.00V. This 0.2C charge-discharge was repeated three times.

[0204] Next, at an ambient temperature of 25°C, a constant current charge and discharge of 0.2C is performed between a battery cell voltage of 3.00 to 4.20V, and the discharge capacity at this time is defined as C0. After that, CC-CV charging is similarly performed at a constant current of 0.2C, and at an ambient temperature of 25°C, CC discharge is performed at a constant current of 3.0C until 3.00V, and the discharge capacity at this time is defined as C1. Then, the ratio (percentage, capacity retention rate) of the discharge capacity (C1) at 3.0C to the discharge capacity (C0) at 0.2C, represented by (C1 / C0)×100(%), is obtained as the rate performance and evaluated according to the following criteria. The larger the value of this capacity retention rate, the less the discharge capacity decreases at high currents and the lower the internal resistance (i.e., the better the rate performance).

[0205] A: The capacity retention rate is 65% or more

[0206] B: The capacity retention rate is 55% or more and less than 65%

[0207] C: The capacity retention rate is less than 55%

[0208] <Cycle characteristics>

[0209] The lithium-ion secondary batteries manufactured in the examples and comparative examples are charged at a constant current of 1.0C to 4.2V and discharged to 3.0V in a 45°C environment, and the charge and discharge are repeated 200 cycles. Then, the cycle capacitance retention rate, represented by the ratio of the capacitance at the end of 200 cycles to the initial capacitance (= [capacitance at the end of the cycle] / [initial capacitance]×100(%)), is obtained and evaluated according to the following criteria. The larger this cycle capacity retention rate, the better the cycle characteristics.

[0210] A: The cycle capacity retention rate is 90% or more

[0211] B: The cycle capacity retention rate is 80% or more and less than 90%

[0212] C: The cycle capacity retention rate is less than 80%

[0213] (Synthesis Example 1)

[0214] [Manufacture of Polymer 1]

[0215] Add 200 parts of ion-exchanged water and 0.2 part of sodium carbonate to a reactor. After dissolving the sodium carbonate, add 2.25 parts of potassium fatty acid soap (potassium salt of fatty acid) to prepare a soap aqueous solution. Then, sequentially add 30 parts of acrylonitrile and 0.4 part of tert-dodecyl mercaptan to the obtained soap aqueous solution. After displacing the internal gas with nitrogen three times, add 70 parts of 1,3-butadiene. Next, maintain the temperature in the reactor at 10 °C, and add a redox polymerization initiator composed of 0.1 part of cumene hydroperoxide, 0.01 part of sodium iron(III) ethylenediaminetetraacetate monohydrate, 0.03 part of sodium hydroxymethanesulfinate dihydrate, and 0.02 part of EDTA·4Na·4H2O to initiate the polymerization reaction. At the moment when the polymerization conversion rate reaches 85%, add 0.1 part of an aqueous solution of hydroquinone (polymerization terminator) with a concentration of 10% to terminate the polymerization reaction. Use a rotary evaporator with a water temperature of 60 °C to remove the residual monomers to obtain a latex of nitrile rubber. Then, add a part of the obtained latex to an aqueous solution of magnesium sulfate as a coagulant in an amount of 1.0% by mass relative to the amount of the nitrile rubber component, and stir to coagulate the latex. Then, filter while washing the coagulated latex with water, and vacuum-dry the obtained coagulum at 60 °C for 12 hours to obtain nitrile rubber as a polymer precursor.

[0216] Dissolve the obtained nitrile rubber in acetone at a concentration of 12%, put it into an autoclave, add 500 mass ppm of palladium-silica catalyst relative to the nitrile rubber, and carry out a hydrogenation reaction under a hydrogen pressure of 3.0 MPa. After the hydrogenation reaction is completed, inject it into a large amount of water to coagulate it, and carry out filtration and drying to obtain hydrogenated nitrile rubber as Polymer 1. Then, measure the iodine value of Polymer 1, and the breaking stress and breaking strain when Polymer 1 is made into a film. The results are shown in Table 1.

[0217] (Synthesis Example 2)

[0218] [Manufacture of Polymer 2]

[0219] Add 200 parts of ion-exchanged water and 0.2 part of sodium carbonate to the reactor. After dissolving the sodium carbonate, add 2.25 parts of potassium fatty acid soap (potassium salt of fatty acid) to prepare a soap aqueous solution. Then, sequentially add 20 parts of acrylonitrile, 40 parts of ethyl acrylate, and 0.4 part of tert-dodecyl mercaptan to the obtained soap aqueous solution. After replacing the internal gas with nitrogen three times, add 40 parts of 1,3-butadiene. Next, maintain the temperature in the reactor at 10 °C, and add a redox polymerization initiator composed of 0.1 part of cumene hydroperoxide, 0.01 part of sodium iron(III) ethylenediaminetetraacetate monohydrate, 0.03 part of sodium hydroxymethanesulfinate dihydrate, and 0.02 part of EDTA·4Na·4H2O to initiate the polymerization reaction. At the moment when the polymerization conversion rate reaches 85%, add 0.1 part of an aqueous solution of hydroquinone (polymerization terminator) with a concentration of 10% to terminate the polymerization reaction. Use a rotary evaporator with a water temperature of 60 °C to remove the residual monomers to obtain a latex of nitrile rubber. Then, add a part of the obtained latex to an aqueous solution of magnesium sulfate as a coagulant in an amount of 1.0% by mass based on the amount of the nitrile rubber component, and stir to coagulate the latex. Then, filter and separate while washing with water, and vacuum-dry the obtained coagulum at 60 °C for 12 hours to obtain nitrile rubber as a polymer precursor.

[0220] Dissolve the obtained nitrile rubber in acetone at a concentration of 12%, put it into an autoclave, add 500 mass ppm of palladium-silica catalyst relative to the nitrile rubber, and carry out a hydrogenation reaction under a hydrogen pressure of 3.0 MPa. After the hydrogenation reaction is completed, inject it into a large amount of water to coagulate it, and carry out filtration and drying to obtain hydrogenated nitrile rubber as Polymer 2. Then, measure the iodine value of Polymer 2, and the breaking stress and breaking strain when Polymer 2 is made into a film. The results are shown in Table 1.

[0221] (Synthesis Example 3)

[0222] [Manufacture of Polymer 3]

[0223] Add 200 parts of ion-exchanged water and 0.2 part of sodium carbonate to a reactor. After dissolving the sodium carbonate, add 2.25 parts of potassium fatty acid soap (potassium salt of fatty acid) to prepare a soap aqueous solution. Then, successively add 18 parts of acrylonitrile and 0.3 part of tert-dodecyl mercaptan to the obtained soap aqueous solution. After displacing the internal gas with nitrogen three times, add 42 parts of 1,3-butadiene. Next, maintain the temperature in the reactor at 10 °C, and add a redox polymerization initiator composed of 0.1 part of cumene hydroperoxide, 0.01 part of sodium iron(III) ethylenediaminetetraacetate monohydrate, 0.03 part of sodium hydroxymethanesulfinate dihydrate, and 0.02 part of EDTA·4Na·4H2O to initiate the polymerization reaction. At the moment when the polymerization conversion rate reaches 60%, add 12 parts of acrylonitrile and 28 parts of 1,3-butadiene, and further carry out the polymerization reaction. At the moment when the polymerization conversion rate reaches 90%, add 0.1 part of an aqueous solution of hydroquinone (polymerization terminator) with a concentration of 10% to terminate the polymerization reaction. Use a rotary evaporator with a water temperature of 60 °C to remove the residual monomers to obtain a latex of nitrile rubber. Then, add a part of the obtained latex to an aqueous solution of magnesium sulfate as a coagulant in an amount of 1.0% by mass relative to the amount of the nitrile rubber component, and stir to coagulate the latex. Then, filter and separate while washing with water, and vacuum-dry the obtained coagulum at 60 °C for 12 hours to obtain nitrile rubber as a polymer precursor.

[0224] Dissolve the obtained nitrile rubber in acetone at a concentration of 12%, put it into an autoclave, add a palladium-silica catalyst at 500 mass ppm relative to the nitrile rubber, and carry out a hydrogenation reaction under a hydrogen pressure of 3.0 MPa. After the hydrogenation reaction is completed, inject it into a large amount of water to coagulate it, and carry out filtration and drying to obtain hydrogenated nitrile rubber as Polymer 3. Then, measure the iodine value of Polymer 3, as well as the breaking stress and breaking strain when Polymer 3 is made into a film. The results are shown in Table 1.

[0225] (Synthesis Example 4)

[0226] [Manufacture of Polymer 4]

[0227] Add 200 parts of ion-exchanged water and 0.2 part of sodium carbonate to the reactor. After dissolving the sodium carbonate, add 2.25 parts of potassium fatty acid soap (potassium salt of fatty acid) to prepare a soap aqueous solution. Then, sequentially add 30 parts of acrylonitrile and 1.0 part of tert-dodecyl mercaptan to the obtained soap aqueous solution. After displacing the internal gas with nitrogen three times, add 70 parts of 1,3-butadiene. Next, maintain the temperature in the reactor at 10 °C, and add a redox polymerization initiator composed of 0.1 part of cumene hydroperoxide, 0.01 part of sodium iron(III) ethylenediaminetetraacetate monohydrate, 0.03 part of sodium hydroxymethanesulfinate dihydrate, and 0.02 part of EDTA·4Na·4H2O to initiate the polymerization reaction. At the moment when the polymerization conversion rate reaches 80%, add 0.1 part of an aqueous solution of hydroquinone (polymerization terminator) with a concentration of 10% to terminate the polymerization reaction. Use a rotary evaporator with a water temperature of 60 °C to remove the residual monomers to obtain a latex of nitrile rubber. Then, add a part of the obtained latex to an aqueous solution of magnesium sulfate as a coagulant in an amount of 1.0% by mass relative to the amount of the nitrile rubber component, and stir to coagulate the latex. Then, filter and separate while washing with water, and vacuum-dry the obtained coagulum at 60 °C for 12 hours to obtain nitrile rubber as a polymer precursor.

[0228] Dissolve the obtained nitrile rubber in acetone at a concentration of 12%, put it into an autoclave, add 500 mass ppm of palladium-silica catalyst relative to the nitrile rubber, and carry out a hydrogenation reaction under a hydrogen pressure of 3.0 MPa. After the hydrogenation reaction is completed, inject it into a large amount of water to coagulate it, and carry out filtration and drying to obtain hydrogenated nitrile rubber as Polymer 4. Then, measure the iodine value of Polymer 4, as well as the breaking stress and breaking strain when Polymer 4 is made into a film. The results are shown in Table 1.

[0229] (Synthesis Example 5)

[0230] [Manufacture of Polymer 5]

[0231] Add 200 parts of ion-exchanged water and 0.2 part of sodium carbonate to a reactor. After dissolving the sodium carbonate, add 2.25 parts of potassium fatty acid soap (potassium salt of fatty acid) to prepare a soap aqueous solution. Then, add 50 parts of acrylonitrile and 1.0 part of tert-dodecyl mercaptan to the obtained soap aqueous solution in sequence. After replacing the internal gas with nitrogen three times, add 20 parts of 1,3-butadiene. Next, maintain the temperature in the reactor at 10 °C, and add a redox polymerization initiator composed of 0.1 part of cumene hydroperoxide, 0.01 part of sodium iron(III) ethylenediaminetetraacetate monohydrate, 0.03 part of sodium hydroxymethanesulfinate dihydrate, and 0.02 part of EDTA·4Na·4H2O to initiate the polymerization reaction. When the polymerization conversion rate reaches 50%, add 30 parts of acrylonitrile and further carry out the polymerization reaction. At the moment when the polymerization conversion rate reaches 70%, add 0.1 part of an aqueous solution of hydroquinone (polymerization terminator) with a concentration of 10% to terminate the polymerization reaction. Use a rotary evaporator with a water temperature of 60 °C to remove the residual monomers to obtain a latex of nitrile rubber. Then, add a part of the obtained latex to an aqueous solution of magnesium sulfate as a coagulant in an amount of 1.0 mass% based on the amount of the nitrile rubber component, and stir to coagulate the latex. Then, filter and separate while washing with water, and dry the obtained coagulum in a vacuum at 60 °C for 12 hours to obtain nitrile rubber as a polymer precursor.

[0232] Dissolve the obtained nitrile rubber in acetone at a concentration of 12%, put it into an autoclave, add a palladium-silica catalyst at 1000 mass ppm relative to the nitrile rubber, and carry out a hydrogenation reaction under a hydrogen pressure of 3.0 MPa. After the hydrogenation reaction is completed, inject it into a large amount of water to coagulate it, and carry out filtration and drying to obtain hydrogenated nitrile rubber as Polymer 5. Then, measure the iodine value of Polymer 5, and the breaking stress and breaking strain when Polymer 5 is made into a film. The results are shown in Table 1.

[0233] (Synthesis Example 6)

[0234] [Manufacture of Polymer 6]

[0235] Add 200 parts of ion-exchanged water and 0.2 part of sodium carbonate to the reactor. After dissolving the sodium carbonate, add 2.25 parts of potassium fatty acid soap (potassium salt of fatty acid) to prepare a soap aqueous solution. Then, sequentially add 17 parts of acrylonitrile, 50 parts of ethyl acrylate, and 0.4 part of tert-dodecyl mercaptan to the obtained soap aqueous solution. After replacing the internal gas with nitrogen three times, add 33 parts of 1,3-butadiene. Next, maintain the temperature in the reactor at 10 °C, and add a redox polymerization initiator composed of 0.1 part of cumene hydroperoxide, 0.01 part of sodium iron ethylenediaminetetraacetate monohydrate, 0.03 part of sodium hydroxymethanesulfinate dihydrate, and 0.02 part of EDTA·4Na·4H2O to initiate the polymerization reaction. At the moment when the polymerization conversion rate reaches 85%, add 0.1 part of an aqueous solution of hydroquinone (polymerization terminator) with a concentration of 10% to terminate the polymerization reaction. Use a rotary evaporator with a water temperature of 60 °C to remove the residual monomers to obtain a latex of nitrile rubber. Then, add a part of the obtained latex to an aqueous solution of magnesium sulfate as a coagulant in an amount of 1.0% by mass relative to the amount of the nitrile rubber component, and stir to coagulate the latex. Then, filter and separate while washing with water, and vacuum-dry the obtained coagulum at 60 °C for 12 hours to obtain nitrile rubber as a polymer precursor.

[0236] Dissolve the obtained nitrile rubber in acetone at a concentration of 12%, put it into an autoclave, add a palladium-silica catalyst at 1500 mass ppm relative to the nitrile rubber, and carry out a hydrogenation reaction under a hydrogen pressure of 3.0 MPa. After the hydrogenation reaction is completed, inject it into a large amount of water to coagulate it, and carry out filtration and drying to obtain hydrogenated nitrile rubber as Polymer 6. Then, measure the iodine value of Polymer 6, as well as the breaking stress and breaking strain when Polymer 6 is made into a film. The results are shown in Table 1.

[0237] (Example 1)

[0238] [Preparation of Binder Composition]

[0239] As Polymer A, prepare a binder composition (solid component concentration: 8% by mass) by stirring 0.25 part of Polymer 1 prepared in Synthesis Example 1 and 0.25 part of Polymer 2 prepared in Synthesis Example 2 in the presence of NMP using a disperser. Make the binder composition into a film, conduct a tensile test, and measure the breaking strain and breaking stress. Then, calculate the value of breaking stress [MPa] / breaking strain. The results are shown in Table 2.

[0240] [Preparation of Slurry Composition]

[0241] To 96.8 parts of NMC532 with a layered structure as a positive electrode active material (LiNi 0.5 Mn 0.3 Co0.2 Add 0.5 parts of PVdF and 0.5 parts (equivalent amount of solid components) of the above binder composition to O2). Add 2.0 parts of acetylene black (Li435: manufactured by Denka Co., Ltd.) as a conductive material and 0.2 parts of a carbon paste mixed with (hydrogenated nitrile rubber (H-NBR)) as a dispersant. Add an appropriate amount of NMP, and stir the resulting mixture with a planetary mixer to prepare a slurry composition (slurry composition for the positive electrode).

[0242] [Manufacture of Positive Electrode]

[0243] Prepare an aluminum foil with a thickness of 15 μm as a current collector. Coat the above slurry composition on both sides of the aluminum foil with a beveled wheel coater at a dried coating amount of 23 mg / cm 2 respectively, and dry at 120 °C. Calender the positive electrode with a roller press to produce a positive electrode composed of a positive electrode active material layer with a density of 3.7 g / cm 3 and the aluminum foil.

[0244] [Manufacture of Negative Electrode]

[0245] Add 100 parts of artificial graphite with a specific surface area of 4 m 2 / g as a negative electrode active material and a 1% aqueous solution of carboxymethyl cellulose (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., "BSH-12") with 1 part (equivalent amount of solid components) as a dispersant to a planetary mixer with a disperser. After adjusting the solid component concentration to 55% with ion-exchanged water, mix at 25 °C for 60 minutes. Then, adjust the solid component concentration to 52% with ion-exchanged water. Then, mix for another 15 minutes to obtain a mixed solution. Add a 40% aqueous solution containing styrene-butadiene copolymer and ion-exchanged water with 1.0 part (equivalent amount of solid components) to the above mixed solution, and adjust to a final solid component concentration of 50%, and mix for another 10 minutes. Perform a defoaming treatment on it to obtain a slurry composition for the negative electrode with good fluidity. Coat the above slurry composition for the negative electrode on both sides of a copper foil current collector with a thickness of 20 μm with a beveled wheel coater at a unit area mass after drying of 13 mg / cm 2 respectively, and dry at 60 °C. Then, perform a heat treatment at 120 °C for 2 minutes to obtain a negative electrode raw material. Calender the negative electrode raw material with a roller press to obtain a negative electrode with a negative electrode active material layer with a thickness of 80 μm.

[0246] [Separator]

[0247] Use a single-layer polypropylene separator (thickness 25 μm, porosity 55%).

[0248] [Manufacture of Lithium-Ion Secondary Battery]

[0249] As the outer package of the battery, an aluminum packaging material was prepared. The positive electrode obtained above was cut into a width of 25.0 mm and a length of 60 cm, and the negative electrode obtained above was cut into a width of 35.0 mm and a length of 70 cm to form sheets. The electrode composite material layers of the positive electrode for the lithium-ion secondary battery and the negative electrode for the lithium-ion secondary battery produced were opposed to each other, with the above spacer interposed therebetween, and wound around a core having a diameter of 20 mm to obtain a wound body. Then, the obtained wound body was pressed at a speed of 10 mm / second to form a flat body, and then packaged with the aluminum packaging material as the outer package of the battery, and a 1.0 M LiPF6 solution (solvent: a mixed solvent of ethylene carbonate (EC) / diethyl carbonate (DEC) = 3 / 7 (volume ratio), containing an additive: 2% by volume (solvent ratio) of vinylene carbonate) was injected in a manner that no air remained as the electrolyte. Then, the opening of the aluminum packaging material was heat-sealed at a temperature of 150 °C to seal it, and a wound-type lithium-ion secondary battery with a capacity of 620 mAh was produced. Then, the IV characteristics, rate characteristics, and cycle characteristics were evaluated. The results are shown in Table 2.

[0250] (Example 2)

[0251] In the preparation of the binder composition of Example 1, polymer 2 (0.1 part) and polymer 3 prepared in Synthesis Example 3 (0.4 part) were used instead of polymer 1 (0.25 part) and polymer 2 (0.25 part). Otherwise, the binder composition, slurry composition, positive electrode, negative electrode, and lithium-ion secondary battery were prepared or manufactured in the same manner as in Example 1. Then, various operations and measurements were carried out in the same manner as in Example 1. The results are shown in Table 1 and Table 2.

[0252] (Example 3)

[0253] In the preparation of the binder composition of Example 1, the compounding amount of polymer 1 was changed from 0.25 part to 0.05 part, and the compounding amount of polymer 2 was changed from 0.25 part to 0.45 part. Otherwise, the binder composition, slurry composition, positive electrode, negative electrode, and lithium-ion secondary battery were prepared or manufactured in the same manner as in Example 1. Then, various operations and measurements were carried out in the same manner as in Example 1. The results are shown in Table 1 and Table 2.

[0254] (Example 4)

[0255] In the preparation of the binder composition of Example 1, only polymer 3 prepared in Synthesis Example 3 (0.5 part) was used instead of polymer 1 (0.25 part) and polymer 2 (0.25 part). Otherwise, the binder composition, slurry composition, positive electrode, negative electrode, and lithium-ion secondary battery were prepared or manufactured in the same manner as in Example 1. Then, various operations and measurements were carried out in the same manner as in Example 1. The results are shown in Table 1 and Table 2.

[0256] (Example 5)

[0257] In the preparation of the binder composition of Example 1, only the polymer 4 (0.5 parts) prepared in Synthesis Example 4 was used instead of polymer 1 (0.25 parts) and polymer 2 (0.25 parts). Except for this, the binder composition, slurry composition, positive electrode, negative electrode, and lithium ion secondary battery were prepared or manufactured in the same manner as in Example 1. Then, various operations and measurements were carried out in the same manner as in Example 1. The results are shown in Table 1 and Table 2.

[0258] (Example 6)

[0259] In the preparation of the slurry composition of Example 1, the compounding amounts of polymer 1 and polymer 2 were changed from 0.25 parts to 0.50 parts, and PVdF as a binder material was not compounded. Except for this, the binder composition, slurry composition, positive electrode, negative electrode, and lithium ion secondary battery were prepared or manufactured in the same manner as in Example 1. Then, various operations and measurements were carried out in the same manner as in Example 1. The results are shown in Table 1 and Table 2.

[0260] (Comparative Example 1)

[0261] In the preparation of the binder composition of Example 1, only the polymer 5 (0.5 parts) prepared in Synthesis Example 5 was used instead of polymer 1 (0.25 parts) and polymer 2 (0.25 parts). Except for this, the binder composition, slurry composition, positive electrode, negative electrode, and lithium ion secondary battery were prepared or manufactured in the same manner as in Example 1. Then, various operations and measurements were carried out in the same manner as in Example 1. The results are shown in Table 1 and Table 2.

[0262] (Comparative Example 2)

[0263] In the preparation of the binder composition of Example 1, only the polymer 6 (0.5 parts) prepared in Synthesis Example 6 was used instead of polymer 1 (0.25 parts) and polymer 2 (0.25 parts). Except for this, the binder composition, slurry composition, positive electrode, negative electrode, and lithium ion secondary battery were prepared or manufactured in the same manner as in Example 1. Then, various operations and measurements were carried out in the same manner as in Example 1. The results are shown in Table 1 and Table 2.

[0264] [Table 1]

[0265]

[0266] In Table 1,

[0267] AN represents acrylonitrile,

[0268] BD represents 1,3 - butadiene,

[0269] EA represents ethyl acrylate.

[0270] [Table 2]

[0271]

[0272] In Table 2,

[0273] PVdF represents polyvinylidene fluoride.

[0274] From the results in Table 2, it can be seen that when forming the film, in Examples 1 to 6 of the binder composition for non-aqueous secondary battery electrodes where the breaking stress [MPa] and breaking strain [-] in the tensile test of the film satisfy the relational expression of 0.010 ≤ breaking stress [MPa] / breaking strain [-] ≤ 1.000, the obtained electrodes have excellent flexibility and the battery characteristics of the secondary battery are excellent.

[0275] Industrial applicability

[0276] According to the present invention, it is possible to provide a binder composition for non-aqueous secondary battery electrodes, which can be suitably used for manufacturing electrodes with excellent flexibility and can improve the battery characteristics of a secondary battery having the obtained electrodes.

[0277] Furthermore, according to the present invention, it is possible to provide a slurry composition for non-aqueous secondary battery electrodes, which can form electrodes with excellent flexibility and can improve the battery characteristics of a secondary battery having the obtained electrodes.

[0278] Furthermore, according to the present invention, it is possible to provide a non-aqueous secondary battery electrode capable of improving the battery characteristics of a non-aqueous secondary battery, and a non-aqueous secondary battery having excellent battery characteristics.

Claims

1. A binder composition for a non-aqueous secondary battery electrode, which contains polymer A, When the binder composition for a non-aqueous secondary battery electrode is made into film X, the breaking stress [MPa] and breaking strain [-] in the tensile test of the film X satisfy the following relational expression: 0.010 ≤ breaking stress [MPa] / breaking strain [-] ≤ 1.

000.

2. The binder composition for non-aqueous secondary battery electrodes according to claim 1, wherein, The breaking strain in the tensile test of the film X is 6.0 or more.

3. The binder composition for non-aqueous secondary battery electrodes according to claim 1 or 2, wherein, The polymer A contains two or more polymers.

4. The binder composition for non-aqueous secondary battery electrodes according to any one of claims 1 to 3, wherein, The polymer A contains polymer A1. When the polymer A1 is made into film Y, the breaking stress in the tensile test of the film Y is 0.3 MPa or more, and the breaking strain is 6.0 or more and less than 25.

0.

5. The binder composition for non-aqueous secondary battery electrodes according to claim 4, wherein, The polymer A further contains polymer A2. When the polymer A2 is made into film Y, the breaking stress in the tensile test of the film Y is 0.3 MPa or more, and the breaking strain is 25.0 or more.

6. The binder composition for non-aqueous secondary battery electrodes according to claim 5, wherein, The mass ratio of the polymer A1 to the polymer A2 (polymer A1∶polymer A2) is 9∶1 or more and 1∶9 or less.

7. The binder composition for non-aqueous secondary battery electrodes according to any one of claims 4 to 6, wherein, The polymer A1 contains a nitrile group-containing monomer unit and an alkylene structural unit.

8. The binder composition for non-aqueous secondary battery electrodes according to any one of claims 5 to 7, wherein, The polymer A2 contains a (meth)acrylate monomer unit.

9. A slurry composition for a non-aqueous secondary battery electrode, which contains an electrode active material and the binder composition for a non-aqueous secondary battery electrode according to any one of claims 1 to 8.

10. A non-aqueous secondary battery electrode, which has an electrode composite layer formed by using the slurry composition for a non-aqueous secondary battery electrode according to claim 9.

11. A non-aqueous secondary battery, which has the non-aqueous secondary battery electrode according to claim 10.

Images