Composition, binder composition for secondary batteries, molded article, electrode, and battery

Abstract

The present invention relates to: a composition comprising a polymer (A) that includes a structural unit (a) derived from 1,1-dicyanoethylene and an electrode active material; a molded article formed from said composition; an electrode comprising said molded article; a battery comprising said molded article; a binder composition for secondary batteries comprising a polymer (A) that includes a structural unit (a) derived from 1,1-dicyanoethylene and an electrode active material; a molded article formed from said binder composition for secondary batteries; an electrode comprising a molded article formed from said binder for secondary batteries; and a battery comprising a molded article formed from said binder for secondary batteries.

Description

Composition, binder composition for secondary battery, molded body, electrode and battery

[0001] The present invention relates to a composition, a binder composition for a secondary battery, a molded article, an electrode, and a battery.

[0002] Patent Document 1 discloses a nonaqueous electrolyte battery. The nonaqueous electrolyte battery includes a positive electrode, a negative electrode, and a nonaqueous electrolyte. The negative electrode typically includes a negative electrode active material and a negative electrode binder. Patent Document 1 proposes using polyvinylidene fluoride (hereinafter also referred to as "PVDF") having a molecular weight of 400,000 or more and 1,000,000 or less as the negative electrode binder.

[0003] Patent Document 2 discloses a binder composition for electrodes of secondary batteries. The binder composition disclosed in Patent Document 2 includes a copolymer containing three types of structural units, one of which is derived from a nitrile group-containing monomer, an ether group-containing monomer, an epoxy group-containing monomer, a carbonyl group-containing monomer, a fluorine-containing monomer, or a combination thereof (claim 1). Patent Document 2 also lists vinylidene cyanide (another name for "1,1-dicyanoethylene") as an example of a nitrile group-containing monomer (claim 6).

[0004] International Publication No. WO 2017 / 154908 International Publication No. WO 2021 / 254300

[0005] Recently, from the viewpoint of reducing environmental impact, it has become necessary to avoid the use of halogen-containing materials. In this regard, the polyvinylidene fluoride disclosed in Patent Document 1 is a halogen-containing material because it contains fluorine. Therefore, in technical fields that use electrode active materials, such as nonaqueous electrolyte batteries, there is a need for alternative materials to polyvinylidene fluoride.

[0006] Here, Patent Document 2 lists vinylidene cyanide as an example of a monomer capable of forming one structural unit. However, Patent Document 2 also lists a fluorine-containing monomer as an example of a monomer capable of forming such a structural unit. Therefore, the technology described in Patent Document 2 is not a technology that aims to avoid the use of halogen-containing materials. Specifically, Patent Document 2 does not teach that vinylidene cyanide should be used instead of a fluorine-containing monomer to form one structural unit, and in fact, the examples do not disclose a structural unit formed using vinylidene cyanide.

[0007] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a composition containing an electrode active material, which reduces the environmental load and has excellent oxidation resistance, a binder composition for secondary batteries, a molded body, an electrode, and a battery.

[0008] The present invention provides the following: [1] A composition comprising a polymer (A) containing a structural unit (a) derived from 1,1-dicyanoethylene, and an electrode active material. [2] The composition according to [1], wherein the polymer (A) is a copolymer containing at least one structural unit (b) derived from a compound represented by the following general formula (1): CH ２ =CR １ R ２ (1) [In the general formula (1), R １ is one selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an alkoxy group, and a nitrile group, and R ２ represents a hydrogen atom, an alkyl group, an alkoxy group, a carboxy group, -COOR ３ (R ３ is an alkyl group having 1 to 12 carbon atoms. ４ (R ４ is an alkyl group having 1 to 12 carbon atoms; ５ (R ５is an alkyl group having 1 to 12 carbon atoms. It is one selected from the group consisting of an acyloxy group and a cyanoalkyl group represented by the following formula (3): [3] The composition according to the above [2], wherein the compound represented by the general formula (1) is one or more selected from the group consisting of ethylene, propylene, vinyl acetate, methyl methacrylate, styrene, and isobutylene. [4] The composition according to the above [2] or [3], wherein the value of e of the compound represented by the general formula (1) is 0.50 or less. [5] The composition according to any one of the above [2] to [4], wherein the polymer (A) comprises an alternating copolymer structure [(b)-(a)-(b)] formed by bonding two of the structural units (b) to both sides of the structural unit (a), with the structural unit (a) at the center, and the content of the structural unit (a) forming the alternating copolymer structure [(b)-(a)-(b)] in the polymer (A) is 80 mol % or more out of a total of 100 mol % of the structural units (a) contained in the polymer (A). [6] The composition according to any one of [1] to [5], wherein the content of the structural unit (a) in the polymer (A) is 25 to 75 mol % relative to 100 mol % of the total amount of structural units in the polymer (A). [7] The composition according to any one of [1] to [6], wherein the mass swelling degree of the polymer (A) in an electrolyte solution is 101 to 800 mass %. [8] The cumulative current value calculated by cyclic voltammetry measurement of the polymer (A) is 0.05 μA / cm ２ The composition according to any one of [1] to [7], wherein the voltage value reached when the voltage reaches the predetermined value is 4.0 V or higher. [9] A binder composition for secondary batteries, comprising a polymer (A) containing a structural unit (a) derived from 1,1-dicyanoethylene, and an electrode active material.

[10] The binder composition for secondary batteries according to [9], wherein the electrode active material is a positive electrode active material.

[11] A molded article formed from the composition according to any one of [1] to [8] or the binder composition for secondary batteries according to [9] or

[10] .

[12] An electrode comprising the molded article according to

[11] .

[13] A battery comprising the molded article according to

[11] .

[0009] According to the present invention, it is possible to provide a composition containing an electrode active material, which reduces the environmental load and has excellent oxidation resistance, a binder composition for secondary batteries, a molded article, an electrode, and a battery.

[0010] The following describes an example of a mode for carrying out the present invention (hereinafter, sometimes referred to as the "present embodiment"). However, the embodiment described below is merely an example for embodying the technical concept of the present invention, and the present invention is not limited to the following description. Furthermore, although preferred embodiments are shown in this specification, combinations of two or more of the individual preferred embodiments are also preferred. For matters indicated by numerical ranges, when there are several numerical ranges, the lower and upper limits can be selectively combined to form preferred embodiments. In this specification, when a numerical range is described as "XX to YY," it means "XX or more and YY or less." In this specification, "100% by mass of the total amount of the composition" does not include the content of the "solvent" described below. In other words, when a composition according to one embodiment of the present invention contains a solvent, the term "100% by mass of the total amount of the composition" is synonymous with "100% by mass of the total content of components in the composition excluding the solvent." Furthermore, in this specification, "100 mol% of the total amount of the structural units of polymer (A)" refers to the total amount of structural units derived from the raw material monomers and does not include structural units derived from the initiator used in polymerization. Furthermore, in this specification, unless otherwise specified, the term "oxidation resistance" refers to a property of the polymer (A) contained in the composition of one embodiment of the present invention, and specifically, is a property evaluated by the method described in the examples.

[0011] [Composition] A composition according to one embodiment of the present invention comprises a polymer (hereinafter also referred to as "polymer (A)") containing a structural unit (a) derived from 1,1-dicyanoethylene, and an electrode active material. According to this embodiment, it is possible to provide a composition that contains an electrode active material, reduces environmental impact, and has excellent oxidation resistance. The composition may contain one type of polymer (A) alone, or may contain two or more types in combination. When the composition is used in a battery, the polymer (A) can function as a binder. Therefore, in one aspect of the composition, the composition is a binder composition for a secondary battery.

[0012] <Polymer (A)> The polymer (A) contained in the composition contains a structural unit (a) derived from 1,1-dicyanoethylene. The polymer (A) contained in the composition may be a copolymer containing the structural unit (a) and a structural unit other than the structural unit (a). The polymer (A) is preferably a copolymer.

[0013] (Structural Unit (a)) The structural unit (a) is derived from 1,1-dicyanoethylene. 1,1-Dicyanoethylene may be produced, for example, according to the production method described in J. Am. Chem. Soc. (USA), 1989, Vol. 111, No. 25, pp. 9078-9081 or the production method described in U.S. Pat. No. 2,476,270. 1,1-Dicyanoethylene is preferably produced by the production method described in Production Example 1 below.

[0014] The content of the structural unit (a) in the polymer (A) is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 10 mol% or more, and even more preferably 20 mol% or more, based on 100 mol% of the total amount of structural units in the polymer (A), from the viewpoint of more easily achieving the effects of the present invention. The upper limit of the content of the structural unit (a) in the polymer (A) is 100 mol%, but may be, for example, 95 mol% or less or 90 mol% or less. Furthermore, in one embodiment of the present invention, from the viewpoint of obtaining a polymer (A) having excellent oxidation resistance, the content of the structural unit (a) in the polymer (A) is more preferably 20 mol% or more, even more preferably 25 mol% or more, even more preferably 30 mol% or more, even more preferably 35 mol% or more, and even more preferably 40 mol% or more, based on 100 mol% of the total amount of structural units in the polymer (A). Furthermore, as described above, these stepwise lower and upper limits can be independently combined. For example, in one embodiment of the present invention, the content of the structural unit (a) in the polymer (A) is preferably 1 to 100 mol%, more preferably 5 to 100 mol%, even more preferably 10 to 100 mol%, still more preferably 20 to 100 mol%, even more preferably 25 to 100 mol%, still more preferably 30 to 100 mol%, and still more preferably 35 to 100 mol%, based on 100 mol% of the total amount of the structural units of the polymer (A). mol%, and even more preferably 40 to 100 mol%, and may be, for example, 1 to 95 mol%, 5 to 95 mol%, 10 to 95 mol%, 20 to 95 mol%, 25 to 95 mol%, 30 to 95 mol%, 35 to 95 mol%, 40 to 95 mol%, 1 to 90 mol%, 5 to 90 mol%, 10 to 90 mol%, 20 to 90 mol%, 25 to 90 mol%, 30 to 90 mol%, 35 to 90 mol%, or 40 to 90 mol%. The reason why polymer (A) has excellent oxidation resistance is thought to be because the structural unit (a) contains two cyano groups with strong electron-withdrawing properties that 1,1-dicyanoethylene has.

[0015] Furthermore, in one embodiment of the present invention, from the viewpoint of facilitating the production of a molded article, electrode, or battery having excellent electrochemical stability, the content of the structural unit (a) in the polymer (A) is more preferably 25 to 75 mol%, even more preferably 30 to 70 mol%, even more preferably 35 to 65 mol%, even more preferably 40 to 60 mol%, and even more preferably 45 to 55 mol%, based on 100 mol% of the total amount of the structural units of the polymer (A). In this case, such polymer (A) is a copolymer.

[0016] (Other Structural Units) The polymer (A) may contain other structural units other than the structural unit (a). A first example of such other structural units is a structural unit derived from an olefin having two or more carbon atoms in its main chain or a derivative thereof. A second example of such other structural units is a structural unit other than the first example.

[0017] [First example of other structural units] The polymer (A) preferably contains a structural unit derived from an olefin having two or more carbon atoms in its main chain or a derivative thereof. By containing such a structural unit, the polymer (A) can enjoy the physical properties based on such a structural unit. A structural unit derived from an olefin having two or more carbon atoms in its main chain or a derivative thereof has excellent hydrophobicity, and therefore is preferable from the viewpoint of, for example, reducing the solubility of the polymer (A) in polar solvents such as an electrolyte solution, thereby increasing the swelling property in the electrolyte solution.

[0018] {Structural Unit (b)} The structural unit derived from an olefin or a derivative thereof having two or more carbon atoms in its main chain is preferably a structural unit (b) derived from a compound represented by the following general formula (1): In other words, the polymer (A) is preferably a copolymer that includes the above-mentioned structural unit (a) and at least one structural unit (b) derived from a compound represented by the following general formula (1):

[0019] CH ２ =CR １ R ２ (1) [In the general formula (1), R １ is one selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an alkoxy group, and a nitrile group, and R２ represents a hydrogen atom, an alkyl group, an alkoxy group, a carboxy group, -COOR ３ (R ３ is an alkyl group having 1 to 12 carbon atoms. ４ (R ４ is an alkyl group having 1 to 12 carbon atoms; ５ (R ５ is an alkyl group having 1 to 12 carbon atoms. It is one selected from the group consisting of an acyloxy group and a cyanoalkyl group represented by the following formula:

[0020] In general formula (1), R １ The alkyl group that may be represented by is preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms, even more preferably an alkyl group having 1 to 6 carbon atoms, and still more preferably an alkyl group having 1 to 4 carbon atoms, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, and an n-hexyl group.

[0021] R １ The cycloalkyl group that may be represented by is preferably a cycloalkyl group having 3 to 12 carbon atoms, more preferably a cycloalkyl group having 3 to 8 carbon atoms, and even more preferably a cycloalkyl group having 3 to 6 carbon atoms, and examples thereof include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group.

[0022] R １ The aryl group that may be represented by is preferably an aryl group having 6 to 20 carbon atoms, more preferably an aryl group having 6 to 14 carbon atoms, and even more preferably an aryl group having 6 to 10 carbon atoms, and examples thereof include a phenyl group, a tolyl group, a xylyl group, and a naphthyl group.

[0023] R １The alkoxy group that may be represented by is preferably an alkoxy group having 1 to 12 carbon atoms, more preferably an alkoxy group having 1 to 6 carbon atoms, and even more preferably an alkoxy group having 1 to 4 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a sec-butoxy group, and a tert-butoxy group.

[0024] From the viewpoint of improving oxidation resistance, R １ is preferably a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and even more preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, or an n-butyl group. １ is more preferably a hydrogen atom or a methyl group. １ may be an aryl group having 6 to 10 carbon atoms, preferably a phenyl group.

[0025] In general formula (1), R ２ The alkyl group that may be represented by is preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms, even more preferably an alkyl group having 1 to 6 carbon atoms, and still more preferably an alkyl group having 1 to 4 carbon atoms, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, and an n-hexyl group.

[0026] R ２ The alkoxy group that may be represented by is preferably an alkoxy group having 1 to 10 carbon atoms, more preferably an alkoxy group having 1 to 6 carbon atoms, and even more preferably an alkoxy group having 1 to 4 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a sec-butoxy group, and a tert-butoxy group.

[0027] R ２ Ha-COOR ３ and R３ represents an alkyl group having 1 to 12 carbon atoms, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, an n-hexyl group, a heptyl group, an octyl group, a decyl group, and a dodecyl group. ３ The alkyl group represented by may be substituted with, for example, one or more cyano groups or one or more alkoxy groups. ３ In one embodiment, R ３ is preferably a monocyanoalkyl group, more preferably a 2-cyanoethyl group. ３ In another embodiment of the present invention, R ３ is preferably an alkoxyalkyl group.

[0028] R ２ Examples of the acid anhydride group that can be represented by include acid anhydride groups derived from phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylnadic anhydride, nadic anhydride, glutaric anhydride, dimethylglutaric anhydride, diethylglutaric anhydride, succinic anhydride, methylhexahydrophthalic anhydride, and methyltetrahydrophthalic anhydride.

[0029] R ２ Ha-COR ４ and R ４ represents an alkyl group having 1 to 12 carbon atoms, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, and an n-hexyl group.

[0030] R ２ Ha-OCOR ５ and R ５is an alkyl group having 1 to 12 carbon atoms, preferably an alkyl group having 1 to 8 carbon atoms, and more preferably an alkyl group having 1 to 6 carbon atoms, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, and an n-hexyl group. ５ In one embodiment, R ５ is even more preferably an alkyl group having 1 to 4 carbon atoms, even more preferably a methyl group or an ethyl group, even more preferably a methyl group.

[0031] R ２ The cyanoalkyl group that can be represented by R is preferably an alkyl group having a cyano group and having 2 to 12 carbon atoms. ２ The cyanoalkyl group may contain one or more cyano groups. ２ In one embodiment, R ２ The cyanoalkyl group is more preferably an alkyl group having one cyano group and 2 to 6 carbon atoms, and even more preferably an alkyl group having one cyano group and 2 to 4 carbon atoms.

[0032] From the viewpoint of improving oxidation resistance, R ２ is preferably a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an acyloxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms, more preferably a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an acyloxy group having 1 to 4 carbon atoms, and even more preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an n-butyl group, or an acetyloxy group. ２ However, it may be an aryl group having 6 to 10 carbon atoms, and a phenyl group is preferred.

[0033] From the viewpoint of improving oxidation resistance, R １ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and R ２ is preferably a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an acyloxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and R １is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ２ is more preferably a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an acyloxy group having 1 to 4 carbon atoms, and in one embodiment, R １ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ２ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an acyloxy group having 1 to 6 carbon atoms. １ is an aryl group having 6 to 10 carbon atoms, and R ２ is preferably a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an acyloxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and in one embodiment, R １ is a phenyl group, and R ２ is a hydrogen atom.

[0034] Specific examples of the compound represented by the general formula (1) include ethylene, propylene, isobutylene, 1-hexene, styrene, vinyl acetate, methyl methacrylate, 1-butylene, 1-pentene, and 4-methyl-1-pentene.

[0035] The e value of the compound represented by the general formula (1) is preferably 0.50 or less. The e value can be a literature value. Examples of such literature include J. Brandrup, E. H. Immergut, and E. A. Grulke, "Polymer Handbook Fourth Edition," Vol. III (USA), John Wiley & Sons Inc., 1999, p. II / 309.

[0036] The e value of the compound represented by the general formula (1) is more preferably 0.40 or less, even more preferably 0.10 or less, even more preferably -0.80 or less, and even more preferably -1.00 or less. The lower limit of the e value is not particularly limited, but can be, for example, -9.00 or more, -6.00 or more, -3.00 or more, or -2.00 or more. Furthermore, as described above, these stepwise lower limit values ​​and upper limit values ​​can be independently combined. For example, in one embodiment of the present invention, the e value of the compound represented by the general formula (1) may be, for example, -9.00 to 0.50, -9.00 to 0.40, -9.00 to 0.10, -9.00 to -0.80, -9.00 to -1.00, -6.00 to 0.50, -6.00 to 0.40, -6.00 to 0.10, -6.00 to -0.80, -6.00 to -1.00, -3.00 to 0.50, -3.00 to 0.40, -3.00 to 0.10, -3.00 to -0.80, -3.00 to -1.00, -2.00 to 0.50, -2.00 to 0.40, -2.00 to 0.10, or -2.00 to -0.80. It is preferable for the value of e to be within the above range, from the viewpoint of being able to satisfactorily form an alternating copolymer structure in which the compound represented by general formula (1) capable of forming the structural unit (b) and 1,1-dicyanoethylene capable of forming the structural unit (a) are alternately bonded.

[0037] In one embodiment of the present invention, the polymer (A) preferably contains an alternating copolymer structure formed by alternating bonding of the structural unit (a) and the structural unit (b). In this specification, the term "alternating copolymer structure" refers to an alternating copolymer structure [(b)-(a)-(b)] formed by bonding two structural units (b) to both sides of the structural unit (a) at the center. In an embodiment in which the polymer (A) contains the alternating copolymer structure, the content of the structural unit (a) forming the alternating copolymer structure [(b)-(a)-(b)] in the polymer (A) (also referred to herein as the "proportion of alternating copolymer structures in the polymer (A)") is preferably 80 mol% or more, more preferably 85 mol% or more, and even more preferably 90 mol% or more, based on a total of 100 mol% of the structural units (a) contained in the polymer (A). Including the alternating copolymer structure in the polymer (A) is preferable because it can enhance oxidation resistance. The presence of the structural unit (a) having two electron-withdrawing cyano groups alternately adjacent to the structural unit (b) reduces the number of interlocking structures susceptible to electron oxidation in the polymer (A), which is believed to result in improved oxidation resistance compared to a polymer that does not contain the alternating copolymer structure. The proportion of the alternating copolymer structure in the polymer (A) can be determined by the method described in the Examples section below. In the above-described embodiment, the content of the structural unit (a) forming the alternating copolymer structure [(b)-(a)-(b)] in the polymer (A) may be, for example, 100 mol% or less, 99.5 mol% or less, or 99 mol% or less, based on a total of 100 mol% of the structural units (a) contained in the polymer (A). As described above, these stepwise lower and upper limits can be independently combined. For example, in one embodiment of the present invention, the content of the structural units (a) forming the alternating copolymer structure [(b)-(a)-(b)] in the polymer (A) is preferably 80 to 100 mol%, more preferably 85 to 100 mol%, and even more preferably 90 to 100 mol%, based on a total of 100 mol% of the structural units (a) contained in the polymer (A), and may be, for example, 80 to 99.5 mol%, 85 to 99.5 mol%, 90 to 99.5 mol%, 80 to 99 mol%, 85 to 99 mol%, or 90 to 99 mol%.

[0038] Examples of compounds having an e value of 0.50 or less include propylene (e value: -1.69), isobutylene (e value: -1.20), vinyl acetate (e value: -0.88), styrene (e value: -0.80), ethylene (e value: 0.05), and methyl methacrylate (e value: 0.40). Therefore, the compound represented by formula (1) preferably contains at least one selected from the group consisting of ethylene, propylene, vinyl acetate, methyl methacrylate, styrene, and isobutylene, more preferably contains at least one selected from the group consisting of ethylene, propylene, vinyl acetate, styrene, and isobutylene, even more preferably contains at least one selected from the group consisting of propylene, vinyl acetate, styrene, and isobutylene, and even more preferably contains at least one selected from the group consisting of propylene and isobutylene.

[0039] From the viewpoint of obtaining a molded article, electrode, or battery having excellent electrochemical stability, the content of the structural unit according to the first example described above in polymer (A) is preferably 75 to 25 mol%, more preferably 65 to 35 mol%, and even more preferably 55 to 45 mol%. From the same viewpoint, the content of structural unit (b) in polymer (A) is preferably 75 to 25 mol%, more preferably 65 to 35 mol%, and even more preferably 55 to 45 mol%, based on the total amount (100 mol%) of the structural units of polymer (A). In this case, such polymer (A) is a copolymer of 1,1-dicyanoethylene forming structural unit (a) and the structural unit according to the first example described above, and polymer (A) is preferably a copolymer of 1,1-dicyanoethylene forming structural unit (a) and the compound represented by general formula (1) forming structural unit (b).

[0040] Here, the content of the structural unit (a) in the polymer (A) and the content of the structural unit (b) in the polymer (A) can each independently take the respective contents described above, but when the selected contents are combined, the total content of the structural unit (a) and the structural unit (b) in the polymer (A) does not exceed 100 mol% of the total amount of the structural units of the polymer (A), which is 100 mol%. In other words, the total content of the structural unit (a) and the structural unit (b) in the polymer (A) is 100 mol% or less of the total amount of the structural units of the polymer (A), which is 100 mol%. The same applies to the total content of the structural unit (a) in the polymer (A) and the content of the first example of the other structural unit in the polymer (A). Furthermore, in one embodiment of the polymer (A), when the polymer (A) contains the structural unit (b), the total content of the structural units (a) and (b) in the polymer (A) is, relative to the total amount (100 mol%) of the structural units of the polymer (A), preferably 50 to 100 mol%, more preferably 75 to 100 mol%, even more preferably 80 to 100 mol%, still more preferably 90 to 100 mol%, still more preferably 95 to 100 mol%, and may even be 100 mol%.

[0041] [Second Example of Other Structural Units] The polymer (A) contained in the composition may or may not contain structural units other than structural units derived from olefins or derivatives thereof having two or more carbon atoms in their main chains. By including such structural units, the polymer (A) can enjoy the physical properties inherent to such structural units. The structural unit according to the second example may be, for example, a structural unit derived from one or more polymerizable monomers selected from 2-cyanopentadienoic acid alkyl esters, methylidenemalonic acid dialkyl esters, maleic anhydride, and other carboxylic acid-containing polymerizable monomers, acrylates, maleic anhydride, and methacrylates, butadiene, and isoprene. From the viewpoint of more easily achieving the effects of the present invention, the content of the structural unit according to the second example in the polymer (A) is preferably less than the content of the structural unit (a), and is preferably less than the combined content of the structural unit (a) and the structural unit according to the first example described above. The content of the structural unit according to the second example in polymer (A) is preferably 10 mol% or less, more preferably 5 mol% or less, and more preferably 1 mol% or less, based on 100 mol% of the total amount of structural units in polymer (A). The lower limit of the content of the structural unit according to the second example in polymer (A) may be 0 mol% (i.e., not present), or, when polymer (A) contains the structural unit according to the second example, it may be 0.1 mol% or more or 0.5 mol% or more. Furthermore, as described above, these stepwise lower and upper limits can be independently combined. For example, in one embodiment of the present invention, the content of the structural unit according to the second example in polymer (A) is preferably 0 to 10 mol%, more preferably 0 to 5 mol%, and even more preferably 0 to 1 mol%, based on 100 mol% of the total amount of structural units in polymer (A). Furthermore, when the polymer (A) contains the structural unit according to the second example, the structural unit may account for, for example, 0.1 to 10 mol %, 0.1 to 5 mol %, 0.1 to 1 mol %, 0.5 to 10 mol %, 0.5 to 5 mol %, or 0.5 to 1 mol % relative to the total amount (100 mol %) of the structural units of the polymer (A).

[0042] (Content of Polymer (A)) In the composition, the content (parts by mass) of the polymer (A) is preferably the same as or less than the content (parts by mass) of the electrode active material, from the viewpoint of ensuring conductivity in the battery. In one embodiment of the composition, the content of the polymer (A) in the composition is, based on 100% by mass of the total amount of the composition, preferably 50% by mass or less, more preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably 20% by mass or less, even more preferably 10% by mass or less, even more preferably 8% by mass or less, and even more preferably 5% by mass or less. From the viewpoint of ensuring the binding ability as a binder, the content of the polymer (A) in the composition is, based on 100% by mass of the total amount of the composition, preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, and even more preferably 0.5% by mass or more. As described above, these stepwise lower and upper limits can be independently combined. For example, in one embodiment of the present invention, the content of polymer (A) in the composition is, relative to 100% by mass of the total amount of the composition, preferably 0.01 to 50% by mass, more preferably 0.05 to 30% by mass, even more preferably 0.1 to 10% by mass, and still more preferably 0.5 to 5% by mass. Also, for example, in one embodiment of the present invention, the content of polymer (A) in the composition is, relative to 100% by mass of the total amount of the composition, preferably 0.01 to 30% by mass, 0.01 to 25% by mass, 0.01 to 20% by mass, 0.01 to 10% by mass, 0.01 to 8% by mass, 0.01 to 5% by mass, 0.05 to 50% by mass, 0.05 to 25% by mass, 0.05 to 20% by mass, 0.0 5 to 10 mass%, 0.05 to 8 mass%, 0.05 to 5 mass%, 0.1 to 50 mass%, 0.1 to 30 mass%, 0.1 to 25 mass%, 0.1 to 20 mass%, 0.1 to 8 mass%, It may be 0.1-5% by weight, 0.5-50% by weight, 0.5-30% by weight, 0.5-25% by weight, 0.5-20% by weight, 0.5-10% by weight, or 0.5-8% by weight.

[0043] <Electrode active material> The electrode active material contained in the composition according to the present embodiment may be a positive electrode active material or a negative electrode active material. As the electrode active material, a commercially available material may be used. When the electrode active material is a positive electrode active material, there is no particular limitation as long as it is a material that can reversibly absorb and release alkali metal ions such as lithium ions, and it can be appropriately selected depending on the purpose. Examples of the electrode active material include LiNi ｘ Co ｙ Mn ｚ O ２ Lithium nickel cobalt manganese oxide (abbreviated as "NCM"), where (x + y + z = 1, x > 0, 0 < y < 1, 0 < z < 1), LiNi ｘ Co ｙ Al ｚ O ２ Lithium nickel cobalt aluminum oxide (abbreviated as "NCA"), where (x + y + z = 1, x > 0, z > 0), LiMn ２ O ４ Lithium manganese phosphate, LiCoO ２ Lithium cobalt oxide (abbreviated as "LCO"), LiNi ０．５ Mn １．５ O ４ Lithium nickel manganese oxide (abbreviated as "LNMO"), Li ｘ Me ｙ (P.O. ４ ) ｚ (0.5≦x≦4, Me=transition metal, 0.5≦y≦2.5, 0.5≦z≦3.5) and the like.

[0044] The LiNi ｘ Co ｙ Mn ｚ O ２ The lithium nickel cobalt manganese oxide (x+y+z=1, x>0, 0<y<1, 0<z<1) is not particularly limited and can be appropriately selected depending on the purpose. For example, LiNi １／３ Co １／３ Mn １／３ O ２ (abbreviated as "NCM111"), LiNi ０．３ Co ０．２ Mn ０．５ O ２ , LiNi０．８ Co ０．１ Mn ０．１ O ２ , LiNi ０．５ Co ０．２ Mn ０．３ O ２ , LiNi ０．５ Co ０．３ Mn ０．２ O ２ , LiNi ０．６ Co ０．１ Mn ０．３ O ２ , LiNi ０．６ Co ０．２ Mn ０．２ O ２ Examples include:

[0045] The Li ｘ Me ｙ (P.O. ４ ) ｚ The lithium phosphate material having a basic skeleton of (0.5≦x≦4, Me=transition metal, 0.5≦y≦2.5, 0.5≦z≦3.5) is not particularly limited and can be appropriately selected depending on the purpose. For example, lithium vanadium phosphate (Li ３ V ２ (P.O. ４ ) ３ ), iron olivine (LiFePO ４ ), olivine manganese (LiMnPO ４ ), olivine cobalt (LiCoPO ４ ), olivine nickel (LiNiPO ４ ), olivine vanadium (LiVOPO ４ ), and similar compounds that have these basic skeletons and are doped with different elements.

[0046] Examples of the NCA include LiNi ０．８ Co ０．１５ Al ０．０５ O ２ Examples include:

[0047] In one embodiment of the present invention, the electrode active material is preferably NCM111.

[0048] (Electrode Active Material Content) From the viewpoint of increasing the capacity of the battery, the content of the electrode active material in the composition is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 75% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 92% by mass or more, and even more preferably 95% by mass or more, based on the total amount (100% by mass) of the composition. The upper limit of the content of the electrode active material in the composition is determined automatically depending on the content of other components. In one embodiment of the present invention, the content of the electrode active material in the composition may be, for example, 99.99% by mass, 99.95% by mass, 99.9% by mass, or 99.5% by mass, based on the total amount (100% by mass) of the composition. As described above, these stepwise lower and upper limits can be independently combined. For example, in one embodiment of the present invention, the content of the electrode active material in the composition is, for example, 50 to 99.99 mass%, 70 to 99.99 mass%, 75 to 99.99 mass%, 80 to 99.99 mass%, 90 to 99.99 mass%, 92 to 99.99 mass%, 95 to 99.99 mass%, 50 to 99.95 mass%, 70 to 99.95 mass%, 75 to 99.95 mass%, 80 to 99.95 ...92 to 99.99 mass%, 95 to 5% by mass, 92-99.95% by mass, 95-99.95% by mass, 50-99.9% by mass, 70-99.9% by mass, 75-99.9% by mass, 80-99.9% by mass, 90-99.9% by mass, 92-99.9% by mass, 9 It may be 5-99.9% by mass, 50-99.5% by mass, 70-99.5% by mass, 75-99.5% by mass, 80-99.5% by mass, 90-99.5% by mass, 92-99.5% by mass, or 95-99.5% by mass.

[0049] Furthermore, in one embodiment of the present invention, the respective contents of the polymer (A) and the electrode active material can each independently be the respective contents described above, but when the selected contents are combined, the total content of the polymer (A) and the electrode active material does not exceed 100% by mass, based on 100% by mass of the total amount of the composition. That is, the total content of the polymer (A) and the electrode active material is 100% by mass or less, based on 100% by mass of the total amount of the composition. As mentioned above, the "total amount of the composition 100% by mass" does not include the content of the solvent described below.

[0050] <Conductive Aid> The composition may further contain a conductive aid. Examples of the conductive aid include acetylene black and carbon black. When the composition contains a conductive aid, in one embodiment, the conductive aid is preferably carbon black.

[0051] In the composition, the content of the conductive additive is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, and even more preferably 0.5 parts by mass or more, relative to 100 parts by mass of the electrode active material, from the viewpoint of increasing the conductivity of the battery. The upper limit of the content of the conductive additive is not particularly limited, but may be, for example, 10 parts by mass or less, 8 parts by mass or less, or 6 parts by mass or less, relative to 100 parts by mass of the electrode active material. Furthermore, as described above, these stepwise lower limit values ​​and upper limit values ​​can be independently combined. For example, in one embodiment of the present invention, the content of the conductive auxiliary in the composition may be, for example, 0.01 to 10 parts by mass, 0.05 to 10 parts by mass, 0.1 to 10 parts by mass, 0.5 to 10 parts by mass, 0.01 to 8 parts by mass, 0.05 to 8 parts by mass, 0.1 to 8 parts by mass, 0.5 to 8 parts by mass, 0.01 to 6 parts by mass, 0.05 to 6 parts by mass, 0.1 to 6 parts by mass, or 0.5 to 6 parts by mass, relative to 100 parts by mass of the electrode active material.

[0052] Furthermore, in one embodiment of the present invention, when the composition contains a conductive aid, the contents of the polymer (A), electrode active material, and conductive aid described above can each independently be as described above, but when the selected contents are combined, the total content of the polymer (A), electrode active material, and conductive aid does not exceed 100% by mass of the total amount of the composition (100% by mass). That is, the total content of the polymer (A), electrode active material, and conductive aid is 100% by mass or less of the total amount of the composition (100% by mass). Furthermore, in one embodiment of the present invention, when the composition contains a conductive aid, the total content of the polymer (A), electrode active material, and conductive aid is preferably 51 to 100% by mass, more preferably 70 to 100% by mass, even more preferably 80 to 100% by mass, even more preferably 90 to 100% by mass, even more preferably 95 to 100% by mass, even more preferably 98 to 100% by mass, and may even be 100% by mass. As mentioned above, the "total amount of the composition (100% by mass)" does not include the content of the solvent described below.

[0053] <Solvent> The composition may contain a solvent (dispersion medium). By containing a solvent in the composition, the dispersibility of the polymer (A) and the electrode active material can be improved. Any solvent can be used, and a non-aqueous solvent is preferable. The solvent is preferably a solvent in which the polymer (A) has a high solubility. Furthermore, when the composition is used for an electrode or a battery, the solvent is not particularly limited, but examples thereof include amides such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide; ureas such as N,N-dimethylethyleneurea, N,N-dimethylpropyleneurea, and tetramethylurea; lactones such as γ-butyrolactone and γ-caprolactone; carbonates such as propylene carbonate; and ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples of suitable solvents include esters such as methyl acetate, ethyl acetate, n-butyl acetate, butyl cellosolve acetate, butyl carbitol acetate, ethyl cellosolve acetate, and ethyl carbitol acetate; glymes such as diglyme, triglyme, and tetraglyme; hydrocarbons such as toluene, xylene, and cyclohexane; sulfoxides such as dimethyl sulfoxide; sulfones such as sulfolane; alcohols such as methanol, isopropanol, and n-butanol; nitriles such as acetonitrile; and water. Among these solvents, amides, ureas, lactones, or mixed solvents containing at least one selected from these are preferred in terms of solubility of the polymer (A) contained in the composition, and among these, N-methyl-2-pyrrolidone or mixed solvents containing N-methyl-2-pyrrolidone are more preferred. These solvents may be used alone or in combination of two or more. When the composition contains a solvent, the content of the solvent in the composition is arbitrary; however, from the viewpoint of making it easier to achieve desired coatability, the content of the solvent in the composition is preferably 1 to 400 parts by mass, more preferably 5 to 100 parts by mass, even more preferably 10 to 70 parts by mass, still more preferably 20 to 60 parts by mass, and even more preferably 30 to 50 parts by mass, relative to 100 parts by mass of the total of the components other than the solvent in the composition.

[0054] <Other Components> Examples of other components include other binders, electrolytes, thickeners, pigments, organic fillers, inorganic fillers, antioxidants, plasticizers, flame retardants, stabilizers, antioxidants, rubbers, antifoaming agents, anti-settling agents, and leveling agents. The other components can be used in an amount that does not excessively impair the effects of the present invention.

[0055] Examples of the other binder include polyacrylonitrile (PAN) and its copolymer, styrene-butadiene rubber (SBR), polypropylene (PP), polyethylene (PE), and carboxymethyl cellulose (CMC). When the composition according to the present embodiment contains another binder, the content (parts by mass) of the other binder is preferably less than the content (parts by mass) of the polymer (A), from the viewpoint of easily enhancing the effects of the present invention.

[0056] Furthermore, in one embodiment of the present invention, the composition is preferably substantially free of fluorine-containing polymers such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and fluorine-based rubber. Here, "substantially free" specifically means that, based on 100% by mass of the total amount of the composition, the content of the fluorine-containing polymer is 0 to 1% by mass, preferably 0 to 0.5% by mass, more preferably 0 to 0.1% by mass, even more preferably 0 to 0.05% by mass, still more preferably 0 to 0.01% by mass, and even more preferably 0% by mass (absence of fluorine). Similarly, in one embodiment of the present invention, the composition is preferably substantially free of halogen-containing polymers. Here, "substantially free" specifically means that, based on 100% by mass of the total amount of the composition, the content of the halogen-containing polymer is 0 to 1% by mass, preferably 0 to 0.5% by mass, more preferably 0 to 0.1% by mass, even more preferably 0 to 0.05% by mass, still more preferably 0 to 0.01% by mass, and even more preferably 0% by mass (absence of fluorine).

[0057] <Method for producing composition> The method for producing the composition is not particularly limited, and the composition can be produced, for example, by a production method including a mixing step of mixing the polymer (A), the electrode active material, and the conductive assistant, the solvent, and other components that are used as needed. The method for mixing the components is not particularly limited, and they can be mixed by a known method.

[0058] <Characteristics of Polymer (A) and Composition> (Swellability of Polymer (A)) The polymer (A) contained in the composition tends to have excellent swelling properties in an electrolytic solution. Furthermore, when the composition contains an electrolytic solution, the polymer (A) tends to have excellent swelling properties in the electrolytic solution. In one embodiment of the polymer (A), the polymer (A) contained in the composition has swelling properties comparable to those of PVDF. The swelling properties can be evaluated, for example, by the method described in the Examples section below. Because the polymer (A) has excellent swelling properties, the composition according to this embodiment is useful as a binder composition for batteries, and is even more useful as a binder composition for secondary batteries. The swelling properties in an electrolytic solution can be evaluated by the mass swelling degree (mass%) measured by the method described in the Examples section, and is preferably 800 mass% or less, more preferably 500 mass% or less, even more preferably 300 mass% or less, even more preferably 250 mass% or less, and even more preferably 200 mass% or less. The lower limit is preferably 101 mass% or more. A mass swelling degree within this range is preferable because it is possible to alleviate the expansion and contraction of the battery that accompanies charge and discharge, thereby improving the quality of the battery.

[0059] (Oxidation Resistance of Polymer (A)) The polymer (A) contained in the composition tends to have excellent oxidation resistance. The oxidation resistance of the polymer (A) can be evaluated, for example, by the voltage value measured by the method described in the Examples section below. When the polymer (A) is used in the positive electrode of a battery, the cumulative current value calculated by cyclic voltammetry measurement of the polymer (A) is 0.05 μA / cm ２The voltage value reached is preferably 4.0 V or higher, more preferably 4.2 V or higher, even more preferably 4.4 V or higher, and even more preferably 4.7 V or higher. The upper limit of the voltage is not particularly limited as long as the effects of the present invention are achieved, but may be, for example, 5.5 V. In one embodiment of the present invention, the voltage value for the polymer (A) is preferably 4.0 to 5.5 V, more preferably 4.2 to 5.5 V, even more preferably 4.4 to 5.5 V, and even more preferably 4.7 to 5.5 V. Because the polymer (A) has excellent oxidation resistance, the composition is useful in applications exposed to harsh environments such as electrolytic solutions, for example, as a binder composition for batteries, and is more useful as a binder composition for secondary batteries. Because the polymer (A) has excellent oxidation resistance, the composition containing the polymer (A) tends to have excellent electrochemical stability when formed into a molded article. Electrochemical stability can be evaluated, for example, by the method described in the Examples section below. Since a molded article having excellent electrochemical stability can be obtained, the composition is useful in applications requiring electrical conduction, such as electrodes or batteries.

[0060] (Cycle characteristics of composition) When the composition is formed into a molded article, it tends to have excellent cycle characteristics. The cycle characteristics can be evaluated, for example, by the method described in the Examples section below. Since a molded article having excellent cycle characteristics can be obtained, the composition is useful for applications requiring electrical conduction, such as electrodes or batteries.

[0061] <Uses of the Composition> The composition has the above-described properties and is therefore useful, for example, as a binder composition for secondary batteries, and is also useful for electrodes or batteries. Examples of electrodes include positive electrodes and negative electrodes. In one embodiment of the present invention, the composition can be used, for example, as a binder composition for positive electrodes and electrolyte retention agents for positive electrodes, and is preferably used as a binder composition for positive electrodes. Examples of the battery include secondary batteries. In one embodiment of the present invention, the composition is more preferably a binder composition for secondary batteries.

[0062] [Binder Composition for Secondary Batteries] A binder composition for secondary batteries according to one embodiment of the present invention includes a polymer (A) containing a structural unit (a) derived from 1,1-dicyanoethylene and an electrode active material. The polymer (A) containing a structural unit (a) derived from 1,1-dicyanoethylene contained in the binder composition for secondary batteries is the same as the polymer (A) described above in the section "Composition Containing Electrode Active Material," and preferred embodiments thereof are also the same. The electrode active material contained in the binder composition for secondary batteries is the same as the electrode active material described above in the section "Composition Containing Electrode Active Material," and preferred embodiments thereof are also the same. The binder composition for secondary batteries may be the composition according to one embodiment of the present invention described above in the section "Composition." Furthermore, the binder composition for secondary batteries may further include optional components, or may not include any optional components.

[0063] [Molded Article] A molded article according to one embodiment of the present invention is a molded article formed from the composition according to one embodiment of the present invention described above in the "Composition" section or the binder composition for a secondary battery according to one embodiment of the present invention described above. Therefore, the molded article contains at least a polymer (A) containing a structural unit (a) derived from 1,1-dicyanoethylene and the electrode active material. Furthermore, the molded article may further contain optional components, or may not contain any optional components.

[0064] [Electrode] An electrode according to one embodiment of the present invention is an electrode including the molded article according to one embodiment of the present invention described above. The electrode may be a positive electrode or a negative electrode. From the viewpoint of ensuring swelling properties in an electrolytic solution, the electrode is preferably a positive electrode.

[0065] When the electrode is a positive electrode, the electrode typically includes a positive electrode current collector and a positive electrode active material layer in contact with the current collector. The current collector is made of a material with high electrical conductivity. In one embodiment of the current collector, the material of the current collector is aluminum or an aluminum alloy. The shape of the current collector is not particularly limited, but is preferably a sheet, and more preferably a foil with a thickness of 50 μm or less. In one embodiment of the current collector, the thickness of the current collector is not particularly limited, but is preferably 5 to 50 μm, more preferably 10 to 40 μm. In one embodiment of the positive electrode active material layer, the thickness of the positive electrode active material layer is not particularly limited, but is preferably 20 to 500 μm, more preferably 50 to 400 μm.

[0066] In one embodiment of the electrode, the positive electrode active material layer is a layer containing the molded article according to the embodiment of the present invention described above, or a layer consisting solely of the molded article according to the embodiment of the present invention described above. The polymer (A) contained in the composition capable of forming the molded article or the binder composition for a secondary battery functions as a binder as described above, and is fixed to the surface of the current collector together with the electrode active material to form a positive electrode active material layer. The positive electrode active material layer may be, for example, a positive electrode mixture layer.

[0067] <Method for manufacturing electrode> The electrode can be manufactured, for example, according to a known method. For example, the electrode can be manufactured by the following procedure. First, the composition described in the above embodiment or the binder composition for a secondary battery, which is made into a slurry state by using a solvent, is applied or coated on the surface of a current collector to form a coating film. Then, it is preferable that the formed coating film is dried. Then, if necessary, the coating film is pressed to form an electrode active material layer having a desired thickness or desired density. In this way, an electrode including a current collector and an electrode active material layer formed on the surface of the current collector is manufactured.

[0068] [Battery] An electrode according to one embodiment of the present invention is a battery including the molded article according to one embodiment of the present invention described above. Since the polymer (A) included in the molded article according to one embodiment of the present invention described above has swelling properties in an electrolytic solution, the battery according to this embodiment is preferably a secondary battery.

[0069] The battery typically includes a positive electrode, a separator, and a negative electrode. The battery typically includes a housing and an electrolyte (solid electrolyte if the battery is an all-solid-state battery) filled in the housing. The configuration of the positive electrode is as described above, and preferably the positive electrode active material layer is a layer containing the molded article according to one embodiment of the present invention or a layer consisting solely of the molded article according to one embodiment of the present invention. The configuration of the negative electrode is similar to that of the positive electrode, and typically includes a negative electrode current collector and a negative electrode active material layer in contact with the current collector. The negative electrode active material layer may be a layer containing the molded article according to one embodiment of the present invention or a layer consisting solely of the molded article according to one embodiment of the present invention. In one embodiment of the battery, the negative electrode active material layer does not necessarily have to be a layer containing the molded article according to one embodiment of the present invention or a layer consisting solely of the molded article according to one embodiment of the present invention. The separator is disposed between the positive electrode and the negative electrode. Commercially available separators can be used as the separator.

[0070] <Electrolyte> The electrolyte usually contains an electrolyte and a solvent to dissolve the electrolyte. Any electrolyte used in a battery can be used as the electrolyte.

[0071] Any electrolyte can be used. Examples of the electrolyte include an alkali salt, and preferably a lithium salt. In one embodiment of the electrolytic solution, the electrolyte is, for example, lithium hexafluorophosphate (LiPF ６ ) are listed.

[0072] Any solvent can be used for the electrolyte solution. In one embodiment of the electrolyte solution, the solvent is, for example, a non-aqueous solvent. Examples of the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), γ-butyrolactone, acetonitrile, methyl propionate, ethyl propionate, tetrahydrofuran (THF), 2-methyltetrahydrofuran, dimethoxyethane, and diethoxyethane. Two or more of these solvents may be used in combination as a mixed solvent.

[0073] In one aspect of the electrolyte solution, as a solvent for the electrolyte solution, propylene carbonate (PC); ethyl methyl carbonate (EMC); dimethyl carbonate (DMC); ethylene carbonate (EC); dimethyl carbonate (DMC); a mixed solvent of ethylene carbonate (EC) and dimethyl carbonate (DMC); a mixed solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC); propylene carbonate (PC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), a mixed solvent of ethylene carbonate (EC) and dimethyl carbonate (DMC); and a mixed solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC). One solvent selected from the group consisting of a mixed solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) is used. From the viewpoint of easily adjusting the swelling property of the polymer contained in the composition of the present embodiment, the solvent is preferably a carbonate-based solvent, and more preferably at least one solvent selected from the group consisting of propylene carbonate (PC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), ethylene carbonate (EC), and dimethyl carbonate (DMC).

[0074] The electrolyte solution may further contain additives as other components, or may not contain additives. Examples of the additives include vinylene carbonate (VC), propane sultone (PS), fluoroethylene carbonate (FEC), monofluorophosphate, difluorophosphate, and lithium hexafluorophosphate (LiPF ６ ), fluorosulfonate, lithium bisborate, nitrate, acetate, and propionate. The additive may be contained alone or in combination of two or more. The additive may be used in any amount as long as it does not excessively impair the effects of the present invention.

[0075] <Method for manufacturing battery> The battery can be manufactured, for example, according to a known method. For example, the battery can be manufactured by the following procedure. First, a positive electrode, a negative electrode, and a separator are placed in a case. Next, an electrolyte is filled into the case. If necessary, the case is sealed. In this manner, the battery is manufactured.

[0076] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0077] [Components] The materials and components used in preparing the compositions of the Examples and Reference Examples are as follows.

[0078] <Polymer (A) Containing Structural Unit (a) Derived from 1,1-Dicyanoethylene> The following materials were used in producing the polymer (A) to be incorporated into the compositions of the Examples and Reference Examples.

[0079] 1,1-dicyanoethylene: 1,1-dicyanoethylene (purity 99%) produced according to Production Example 1 below

[0080] (Production Example 1: Production of 1,1-dicyanoethylene) 1,1-dicyanoethylene was produced as follows. 1,1,3,3-tetracyanopropane was synthesized from malononitrile in a yield of 73% by the production method described in J. Am. Chem. Soc. (USA), 1989, Vol. 111, No. 25, pp. 9078-9081. The resulting crystalline 1,1,3,3-tetracyanopropane was mixed with diphosphorus pentoxide and subjected to thermal decomposition at 180°C, yielding a crude product of 1,1-dicyanoethylene (yield: 60%). The crude product was purified by distillation under reduced pressure (480 Pa) to obtain 1,1-dicyanoethylene with a purity of 99%.

[0081] Isobutylene: manufactured by Tokyo Chemical Industry Co., Ltd., e value: -1.20 Styrene: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., e value: -0.80 Vinyl acetate: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., e value: -0.88 Propylene: manufactured by Tokyo Chemical Industry Co., Ltd., e value: -1.69

[0082] <Solvent> Ethyl acetate: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Toluene: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[0083] <Polymerization initiator> 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile): manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Bis(1-oxododecyl) peroxide (dilauroyl peroxide): trade name "Luperox (registered trademark) LP" (manufactured by Arkema)

[0084] The following materials were used for the evaluation.

[0085] <Electrode active material> ・LiNi １／３ Co １／３ Mn １／３ O ２ (hereinafter also referred to as "NCM111"): manufactured by MERCK

[0086] <Conductive additive> Carbon black: trade name "Super P (registered trademark)" (manufactured by Imerys Graphite & Carbon Co.)

[0087] <Solvent> N-methyl-2-pyrrolidone (abbreviated as "NMP"): manufactured by Tokyo Chemical Industry Co., Ltd.

[0088] <Electrolyte> Electrolyte A: Ethyl methyl carbonate (abbreviated as "EMC", manufactured by Tokyo Chemical Industry Co., Ltd.) containing LiPF ６ Electrolyte B: A mixture of EC / EMC / DMC = 1 / 1 / 1 (volume ratio) and LiPF ６ (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to a concentration of 1.0 M. Here, "EC" is an abbreviation for ethylene carbonate, and EC manufactured by Tokyo Chemical Industry Co., Ltd. was used. Also, "DMC" is an abbreviation for dimethyl carbonate, and DMC manufactured by Tokyo Chemical Industry Co., Ltd. was used. The same applies below. Electrolyte C: DMC with LiPF ６ Electrolyte solution D: A mixture of EC / DMC = 1 / 1 (volume ratio) and LiPF ６ (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to an electrolyte solution with a concentration of 1.0M.

[0089] <Polymers used in Reference Example 2> Polyvinylidene fluoride (abbreviated as "PVDF"): trade name "Kureha KF Polymer (registered trademark) W#1700" (manufactured by Kureha Corporation)

[0090] [Evaluation Method] The compositions obtained in the Examples and Reference Examples were used as samples and evaluated as follows.

[0091] <1. Content of Structural Unit (a)> Using a nuclear magnetic resonance spectrometer (NMR), the powders of the polymers obtained in the examples and Reference Example 1 were used as samples. １ By measuring H-NMR, １ H-NMR spectrum was obtained. １ The content (mol %) of the structural unit (a) was determined by measuring the ratio of the signal derived from the methylene group between the structural unit (a) and the structural unit (b) appearing in the vicinity of 1.5 ppm to 3.0 ppm in the H-NMR spectrum to the signal derived from the functional group of the structural unit (b). The content (mol %) of the structural unit (a) is shown in Table 1. １H-NMR measurement conditions) Apparatus: "JNM-ECX400" manufactured by JEOL Ltd. Measurement solvent: dimethyl sulfoxide-d6 Sample concentration: 25 mg / mL Measurement temperature: 65°C Chemical shift value reference: tetramethylsilane Number of accumulations: 32

[0092] <2. Calculation of the ratio of alternating copolymer structure> Using a nuclear magnetic resonance spectrometer (NMR), the powders of the polymers obtained in Examples and Reference Example 1 were used as samples under the following conditions. １３ By measuring C-NMR, １３ A C-NMR spectrum was obtained. １３ C-NMR measurement conditions) Apparatus: "JNM-ECX400" manufactured by JEOL Ltd. Measurement solvent: dimethyl sulfoxide-d6 Sample concentration: 25 mg / mL Measurement temperature: 65°C Measurement method: proton decoupling method Pulse width: 45 degrees Pulse repetition time: 10 seconds Chemical shift value reference: tetramethylsilane Number of accumulations: 14,000

[0093] The ratio (mol %) of the alternating copolymer structure in the polymer (A) obtained in each of the Examples and Reference Example 1 was calculated as follows. Specifically, for the polymer of 1,1-dicyanoethylene and vinyl acetate used in Examples 3-1 and 3-2, and the polymer of 1,1-dicyanoethylene and styrene used in Example 2, first, as described above, １３A C-NMR spectrum was obtained. Next, when considering a structure in which three structural units (a) derived from 1,1-dicyanoethylene and three structural units (b) derived from the compound represented by the general formula (1) are linked together, with the structural unit (a) at the center, the ratio of the peak area of ​​the alternating copolymer structure "(b)-(a)-(b)" in which two structural units (b) are bonded to both sides of the structural unit (a) at the center to the peak area of ​​all possible structures centered on the structural unit (a), i.e., the first non-alternating copolymer structure "(a)-(a)-(a)," the alternating copolymer structure "(b)-(a)-(b)," the second non-alternating copolymer structure "(b)-(a)-(a)," and the third non-alternating copolymer structure "(a)-(a)-(b)" was calculated to determine the proportion (mol %) of the alternating copolymer structure in polymer (A). The "proportion (mol %) of the alternating copolymer structure" refers to the content (mol %) of the structural unit (a) forming the alternating copolymer structure "(b)-(a)-(b)" out of a total of 100 mol % of the structural units (a) contained in the polymer (A). Here, in order to identify the structural unit (a) and the structural unit (b) and to identify the alternating copolymer structure or the non-alternating copolymer structure, reference is made to J. Brandrup, E. H. Immergut, E. A. Grulke, "Polymer Handbook Fourth Edition", Vol. III, (USA), John Wiley & Sons Inc., 1999, p. II / 309, and Macromolecules, (USA), 1985, Vol. 18, No. 10, pp. 1850-1855 １３ Specific chemical shift values ​​from the C-NMR spectrum were used.

[0094] For the copolymers of 1,1-dicyanoethylene and isobutylene used in Reference Example 1, Example 1-1, and Example 1-2, the areas of the peak near 115 ppm corresponding to the third non-alternating copolymer structure "(a)-(a)-(b)" and the peak near 117 ppm corresponding to the alternating copolymer structure "(b)-(a)-(b)" were calculated, and the ratio of the alternating copolymer structure was determined in the same manner as above. Note that the peak near 113 ppm corresponding to "(a)-(a)-(a)" was below the lower limit of detection. For the copolymers of 1,1-dicyanoethylene and propylene used in Examples 5-1 and 5-2, the areas of the peak near 114 ppm corresponding to the third non-alternating copolymer structure "(a)-(a)-(b)" and the peak near 116 ppm corresponding to the alternating copolymer structure "(b)-(a)-(b)" were calculated, and the proportion of the alternating copolymer structure was determined in the same manner as above. The peak near 113 ppm corresponding to "(a)-(a)-(a)" was below the lower limit of detection. The proportion (mol %) of the alternating copolymer structure is shown in Table 1. It was confirmed that the higher the value of the proportion (mol %) of the alternating copolymer structure, the more likely the polymer would have good oxidation resistance, as evaluated in the section <5. Evaluation of electrochemical stability> described below.

[0095] <3. Measurement of Weight Average Molecular Weight (Mw)> The weight average molecular weight (Mw) of the polymer (A) used in the Examples and Reference Examples was calculated in terms of standard polystyrene by gel permeation chromatography (GPC). The measurement apparatus and conditions were as follows: Apparatus: "HLC (registered trademark)-8320GPC EcoSEC (registered trademark)" manufactured by Tosoh Corporation Separation column: "TSKgel (registered trademark) GMH" manufactured by Tosoh Corporation ＸＬ (average particle size = 9 μm, column inner diameter = 7.8 mm, column length = 30 cm) Eluent: dimethylformamide (DMF) / 0.01 M LiBr Eluent flow rate: 0.7 mL / min Sample concentration: 0.5 mg / 1 mL Column temperature: 40°C

[0096] <4. Swelling Property Evaluation> The polymer or polymer mixture used in the Examples and Reference Examples (hereinafter simply referred to as "polymer" in this evaluation item) was further dried in a hot air dryer at 100°C for 24 hours. 0.025 g of this polymer (referred to as the mass S0 (g) before immersion) was immersed in the electrolyte solution shown in Table 1 or Table 2 so that the entire surface of the polymer was in contact with the electrolyte solution, and allowed to swell for 10 hours in an environment at 25°C. The swollen polymer was then removed, and excess electrolyte was removed by pressing a paper towel against the polymer surface, after which the mass S1 (g) was measured. The mass swelling degree S (mass %) was calculated using the following formula: S = {(S1) / (S0)} × 100. The mass swelling degree S (mass %) is shown in Table 1 or Table 2. A polymer with a mass swelling degree S of 101% by mass or greater and 800% by mass or less was evaluated as having practical swelling properties for batteries or battery electrodes.

[0097] 5. Evaluation of Electrochemical Stability CV measurements were carried out as follows, and the electrochemical stability was evaluated from the results.

[0098] (5-1. Preparation for First Three-Electrode Cell) (5-1-1. Preparation of Electrode) First, a positive electrode was prepared as an electrode using the composition obtained in the Examples and Reference Examples and a current collector as follows. First, the composition obtained in the Examples and Reference Examples was applied to an aluminum foil (size: width 9 cm, length 15 cm, thickness 20 μm) used as a current collector using an applicator to a thickness of 180 μm. The solvent was removed by drying at 80°C for 0.5 hours under reduced pressure of 1 kPa, and a positive electrode active material layer was formed on the current collector as an electrode active material layer. In this way, a laminate of the current collector and the positive electrode active material layer was obtained. This laminate was pressed using a roll press with a load of 2.3 tons to prepare a positive electrode. In the obtained positive electrode, the thickness of the positive electrode active material layer was 50 μm. When the composition obtained in the Examples was used, the amount of electrode active material supported in the positive electrode active material layer was 15 mg / cm. ２ When the composition obtained in Reference Example 1 was used, the amount of the electrode active material carried in the positive electrode active material layer was 0 mg / cm ２ It was.

[0099] (5-1-2. Fabrication of First Triode Cell) The positive electrode fabricated in 5-1-1 above was dried at 140°C for 3 hours under reduced pressure of 1 kPa and then transferred to a glove box (manufactured by Miwa Manufacturing Co., Ltd.) under an argon gas atmosphere. Subsequently, a triode cell was constructed in the glove box as follows. The positive electrode fabricated in 4-1-1 above was used as the working electrode. A Li wire (φ2 mm, length 6 mm) was used as the reference electrode. A metallic lithium foil (thickness 0.2 mm, φ16 mm) was used as the counter electrode. A polypropylene separator (Celgard (registered trademark) #2400 manufactured by Polypore Corporation) was used as the separator. The separator was placed between the counter electrode and working electrode in the cell. The electrolyte solution shown in Table 1 or Table 2 was injected into the cell. In this manner, a triode cell was fabricated. This triode cell is also referred to as the "first triode cell" in this specification.

[0100] (5-2. Preparation of second three-electrode cell) (5-2-1. Preparation of foil-attached molded body) The polymer or polymer mixture used in the examples and reference examples was dissolved in NMP to a solids concentration (concentration of the polymer or polymer mixture) of 10 mass %. The obtained polymer-containing composition was applied to an aluminum foil (size: width 9 cm, length 15 cm, thickness 20 μm) serving as a current collector using an applicator. This was dried at 80°C for 0.5 hours under reduced pressure of 1 kPa to remove the NMP. This produced a film-like foil-attached molded body in which the layer consisting only of the polymer was 10 μm thick.

[0101] (5-2-2. Fabrication of second three-electrode cell) A three-electrode cell was fabricated in the same manner as in 5-1-2 above, except that the foil-coated molded body fabricated in 5-2-1 above was used as the working electrode instead of the positive electrode fabricated in 5-1-1 above. This three-electrode cell is also referred to as the "second three-electrode cell" in this specification.

[0102] (5-3. Cyclic Voltammetry (CV) Measurement) Using the second three-electrode cell prepared in 5-2 above, redox current measurement was performed with a potentiostat / galvanostat (VMP3 manufactured by Bio-Logic Science Instruments). Furthermore, redox potential measurement was performed using the second three-electrode cell. The measurement conditions were a sweep rate of 0.1 mV / s and a sweep range of 1 to 5 V. As a result of the measurement, a cyclic voltammogram of the current value during scanning in each cycle was obtained.

[0103] (5-4. Evaluation) The positive oxidation current value was read from the cyclic voltammogram of the current value at 1 to 5 V during the third cycle scan for the second three-electrode cell. When judging the oxidation resistance of the polymer or polymer mixture, the results of the CV measurement of the second three-electrode cell (i.e., the foil-covered molded article on the film) were read, and the amount of current was accumulated and calculated based on the area of ​​the working electrode (1.54 cm ２ ) divided by (μA / cm ２ ) was calculated, and the values ​​were less than or equal to 0.05 μA / cm ２ The voltage at which the cumulative current value reached 0.05 μA / cm ２ When the voltage reached was 4.0 V or higher, the polymer or polymer mixture used in the working electrode of the battery or battery electrode was evaluated to have excellent electrochemical stability.

[0104] Furthermore, CV was measured under the same conditions as above using the first three-electrode cell (i.e., an electrode containing a polymer or a mixture of polymers with excellent electrochemical stability) prepared in 5-1. When the second three-electrode cell was used, the cumulative current value was 0.05 μA / cm ２ When neither a ground fault nor an abnormal increase in current value was observed in the first three-electrode cell at the voltage when the voltage reached 0 V, the electrode was judged to be "passed." When either or both of a ground fault and an abnormal increase in current value were observed, the electrode was judged to be "failed." However, in this example, no electrode was judged to be "failed." Furthermore, since Reference Example 1 does not contain an electrode active material and therefore cannot be used to form an electrode, evaluation as an electrode was not possible, and therefore the judgment result for the oxidation resistance of the electrode in Table 1 is marked as "impossible to measure."

[0105] <6. Evaluation of Cycle Characteristics> Charge / discharge cycle measurements were carried out as follows, and the cycle characteristics were evaluated from the results.

[0106] (6-1. Preparation of Electrode) A positive electrode was prepared in the same manner as in 5-1-1 above.

[0107] (6-2. Fabrication of Coin Battery) The positive electrode fabricated in 6-1 above was transferred into a glove box (manufactured by Miwa Manufacturing Co., Ltd.) under an argon gas atmosphere. Subsequently, a coin battery was fabricated in the glove box as follows. A CR2032 case (cell) was used as the coin battery case (cell). The positive electrode fabricated in 6-1 above was used as the working electrode. A metal lithium foil (thickness 0.2 mm, diameter 16 mm) was used as the reference electrode and counter electrode. A separator made of polypropylene (Celgard (registered trademark) #2400 manufactured by Polypore) was used as the separator. The separator was placed in the space between the working electrode and counter electrode inside the case. The electrolyte solution shown in Table 1 or Table 2 was injected into the case. The case was then sealed. In this manner, a coin battery was fabricated. Ten coin batteries were fabricated.

[0108] (6-3. Charge-Discharge Cycle Measurement) A charge-discharge test was performed on the coin battery prepared in 6-2 above using a commercially available charge-discharge tester (TOSCAT (registered trademark) 3100 manufactured by Toyo Systems Co., Ltd.) as follows. The coin battery was placed in a thermostatic chamber at 25°C. Charge-discharge cycles were repeated, with the battery being charged to 4.0 V relative to the lithium potential and subsequently discharged to 3.0 V, at a constant current of 0.2 C relative to the capacity per unit weight of the active material (mAh / g) (constant-current charge-discharge test). In the constant-current charge-discharge test, the capacitance values ​​(mAh) were measured at the end of 5 charge-discharge cycles and at the end of 50 cycles. The average capacitance values ​​obtained from the measurements for 10 cells was calculated. The charge-discharge capacity retention rate C, expressed as a percentage (%) of the ratio of the capacitance C50 at the end of 50 cycles to the capacitance C5 at the end of 5 cycles (i.e., C50 / C5), was calculated.

[0109] (6-4. Evaluation) The charge / discharge capacity retention rate C was evaluated according to the following criteria. The evaluation result "G" is the poorest, and going from "F" to "A" means that the cycle characteristics (battery life) are better. The evaluation results are shown in Table 1 or Table 2. A: 95% or more B: 92% or more and less than 95% C: 90% or more and less than 92% D: 80% or more and less than 90% E: 60% or more and less than 80% F: 30% or more and less than 60% G: Less than 30%

[0110] Example 1-1 (Production of Polymer) 2.0 g (0.026 mol) of 1,1-dicyanoethylene, 4.0 g (0.071 mol) of isobutylene, 19 mL of ethyl acetate, and 80 mg of dilauroyl peroxide were placed in a 300 mL autoclave equipped with a stirrer and a thermometer, and the mixture was heated and stirred at 60° C. for 4 hours under a nitrogen gas stream to carry out radical polymerization.

[0111] After the polymerization was completed, the precipitated polymer was recovered by filtration. The recovered polymer was then washed with ethyl acetate and then dried under reduced pressure at 50°C for 24 hours to obtain a polymer powder. Considering the materials used, the obtained polymer was a copolymer of 1,1-dicyanoethylene and isobutylene (weight average molecular weight (Mw) by GPC: 608,000) and was halogen-free. １ H-NMR and １３ The copolymer was also confirmed to have been obtained by C-NMR. The mass swelling index S described above was measured and evaluated using the obtained polymer. The results are shown in Table 1.

[0112] (Preparation of Composition) NCM111 was used as the positive electrode active material. Carbon black was used as the conductive additive. NMP was used as the solvent. A composition was prepared by mixing 95 parts by mass of the positive electrode active material (NCM111), 2 parts by mass of the conductive additive (carbon black), 3 parts by mass of a polymer, and 47 parts by mass of a solvent (NMP). The composition was in the form of a slurry. This composition was subjected to the above-described evaluation as a binder composition for a secondary battery. In the evaluation, electrolytic solution A was used as the electrolytic solution.

[0113] [Example 1-2] When the composition obtained in Example 1-1 was subjected to evaluation, in Example 1-2, the electrolyte solution used was changed from electrolyte solution A to electrolyte solution B. Otherwise, evaluation was performed in the same manner as in Example 1-1. The results are shown in Table 1.

[0114] Example 2 Production of Polymer 2.0 g (0.026 mol) of 1,1-dicyanoethylene, 2.7 g (0.026 mol) of styrene, and 18 mL of toluene were placed in a 300 mL autoclave equipped with a stirrer and a thermometer, and polymerization was carried out by heating and stirring under a nitrogen gas stream at 40° C. for 3 hours without using an initiator.

[0115] After the polymerization was completed, the precipitated polymer was recovered by filtration. The recovered polymer was then washed with ethyl acetate and then dried under reduced pressure at 50°C for 24 hours to obtain a polymer powder. Considering the materials used, the obtained polymer was a copolymer of 1,1-dicyanoethylene and styrene (weight average molecular weight (Mw) by GPC: 298,000) and was halogen-free. １ H-NMR and １３ The copolymer was also confirmed to have been obtained by C-NMR. The mass swelling index S described above was measured and evaluated using the obtained polymer. The results are shown in Table 1.

[0116] (Preparation of Composition) A composition was prepared using the obtained polymer, the same positive electrode active material, conductive additive, and solvent as in Example 1-1, in the same mass ratio as in Example 1-1. The obtained composition was used for evaluation in the same manner as in Example 1-1. In the evaluation, electrolytic solution A was used as the electrolytic solution, as in Example 1-1.

[0117] Example 3-1 (Production of Polymer) 2.0 g (0.026 mol) of 1,1-dicyanoethylene, 5.5 g (0.064 mol) of vinyl acetate, 25 mL of ethyl acetate, and 17 mg of 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile) were placed in a 300 mL autoclave equipped with a stirrer and a thermometer, and the mixture was heated and stirred at 40° C. for 6 hours under a nitrogen gas stream to carry out radical polymerization.

[0118] After the polymerization was completed, the precipitated polymer was recovered by filtration. The recovered polymer was then washed with ethyl acetate and then dried under reduced pressure at 50°C for 24 hours to obtain a polymer powder. Considering the materials used, the obtained polymer was a copolymer of 1,1-dicyanoethylene and vinyl acetate (weight average molecular weight (Mw) by GPC: 560,000) and was halogen-free. １ H-NMR and １３ The copolymer was also confirmed to have been obtained by C-NMR. The mass swelling index S described above was measured and evaluated using the obtained polymer. The results are shown in Table 1.

[0119] (Preparation of Composition) A composition was prepared using the obtained polymer, the same positive electrode active material, conductive additive, and solvent as in Example 1-1, in the same mass ratio as in Example 1-1. The obtained composition was used for evaluation in the same manner as in Example 1-1. However, in the evaluation, electrolytic solution C was used instead of electrolytic solution A. The results are shown in Table 1.

[0120] [Example 3-2] When the composition obtained in Example 3-1 was subjected to evaluation, in Example 3-2, the electrolyte solution used was changed from electrolyte solution C to electrolyte solution D. Otherwise, evaluation was performed in the same manner as in Example 3-1. The results are shown in Table 1.

[0121] Example 4 Production of Polymer 2.0 g (0.026 mol) of 1,1-dicyanoethylene, 2.1 g (0.024 mol) of vinyl acetate, 12 mL of ethyl acetate, and 16 mg of 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile) were placed in a 300 mL autoclave equipped with a stirrer and a thermometer, and the mixture was heated and stirred at 40° C. for 6 hours under a nitrogen gas stream to carry out radical polymerization.

[0122] After the polymerization was completed, the precipitated polymer was recovered by filtration. The recovered polymer was then washed with ethyl acetate and then dried under reduced pressure at 50°C for 24 hours to obtain a polymer powder. Considering the materials used, the obtained polymer was a copolymer of 1,1-dicyanoethylene and vinyl acetate (weight average molecular weight (Mw) by GPC: 182,000) and was halogen-free. １ H-NMR and １３ It was also confirmed by C-NMR that the copolymer was obtained. The mass swelling index S described above was measured and evaluated using the obtained polymer.

[0123] (Preparation of Composition) A composition was prepared using the obtained polymer, the same positive electrode active material, conductive additive, and solvent as in Example 1-1, in the same mass ratio as in Example 1-1. The obtained composition was evaluated in the same manner as in Example 3-1, using electrolytic solution C as the electrolytic solution. The results are shown in Table 1.

[0124] Example 5-1 (Production of Polymer) 2.0 g (0.026 mol) of 1,1-dicyanoethylene, 2.7 g (0.064 mol) of propylene, 19 mL of ethyl acetate, and 16 mg of 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile) were placed in a 100 mL autoclave equipped with a stirrer and a thermometer, and the mixture was heated and stirred at 40° C. for 6 hours under a nitrogen gas stream to carry out radical polymerization.

[0125] After the polymerization was completed, the precipitated polymer was recovered by filtration. The recovered polymer was then washed with ethyl acetate and then dried under reduced pressure at 50°C for 24 hours to obtain a polymer powder. Considering the materials used, the obtained polymer was a copolymer of 1,1-dicyanoethylene and propylene (weight average molecular weight (Mw) by GPC: 150,000) and was halogen-free. １ H-NMR and １３ The copolymer was also confirmed to have been obtained by C-NMR. The mass swelling index S described above was measured and evaluated using the obtained polymer. The results are shown in Table 1.

[0126] (Preparation of Composition) A composition was prepared using the obtained polymer, the same positive electrode active material, conductive additive, and solvent as in Example 1-1, in the same mass ratio as in Example 1-1. The obtained composition was evaluated in the same manner as in Example 1-1, using electrolyte solution A as the electrolyte solution. The results are shown in Table 1.

[0127] [Example 5-2] When the composition obtained in Example 5-1 was subjected to evaluation, in Example 5-2, the electrolyte solution used was changed from electrolyte solution A to electrolyte solution B. Otherwise, evaluation was performed in the same manner as in Example 5-1. The results are shown in Table 1.

[0128] [Reference Example 1] A composition having a polymer:conductive aid mass ratio of 2:98 (i.e., a composition containing no electrode active material) was prepared using the polymer obtained in Example 1-1, a conductive aid (carbon black), and 47 parts by mass of a solvent (NMP). The obtained composition was in the form of a slurry. This composition was subjected to evaluation in the same manner as in Example 1-2, using electrolyte solution B as the electrolyte solution. The results are shown in Table 1. However, charge / discharge cycle measurement was not possible because it was not possible to carry out the measurement.

[0129] The results are shown in Table 1.

[0130]

[0131] From Table 1, it was found that the compositions according to the examples can reduce the halogen content at least to the extent that the polymer (A) contains structural units (a) derived from 1,1-dicyanoethylene, thereby reducing the environmental impact. Furthermore, it was found that the polymer (A) contained in the compositions according to the examples has excellent swelling properties in an electrolyte solution and oxidation resistance, and therefore the compositions according to the examples are useful as binder compositions for batteries. Furthermore, it was found that the compositions according to the examples have excellent electrochemical stability when used to form electrodes or batteries.

[0132] Examples 6 to 9 Evaluations were carried out in the same manner as in Example 1-1, except that two types of polymers were used in the proportions shown in Table 2, and electrolytic solution A was used as the electrolytic solution. The results are shown in Table 2.

[0133]

[0134] From Table 2, it was found that the polymer (A) according to one embodiment of the present invention, even when used in combination with a plurality of types, exhibits excellent swelling properties in an electrolyte and oxidation resistance, similar to when used alone. Furthermore, it was found that the compositions according to Examples 6 to 9 also have excellent electrochemical stability when used to form electrodes or batteries.

Claims

1. A composition comprising a polymer (A) containing a structural unit (a) derived from 1,1-dicyanoethylene and an electrode active material.

2. The composition according to claim 1, wherein the polymer (A) is a copolymer containing at least one kind of a structural unit (b) derived from a compound represented by the following general formula (1). CH ２ =CR １ R ２ (1) [In the general formula (1), R １ is one selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an alkoxy group, and a nitrile group, and R ２ is a hydrogen atom, an alkyl group, an alkoxy group, a carboxy group, -COOR ３ (R ３ is an alkyl group having 1 to 12 carbon atoms.), an ester group represented by an acid anhydride group, -COR ４ (R ４ is an alkyl group having 1 to 12 carbon atoms.), an acyl group represented by -OCOR ５ (R ５ is an alkyl group having 1 to 12 carbon atoms.), and one selected from the group consisting of an acyloxy group and a cyanoalkyl group represented by the formula:]] 3. The composition according to claim 2, wherein the compound represented by the general formula (1) is at least one selected from the group consisting of ethylene, propylene, vinyl acetate, methyl methacrylate, styrene, and isobutylene.

4. The composition according to claim 2, wherein the e value of the compound represented by the general formula (1) is 0.50 or less.

5. The polymer (A) contains an alternating copolymer structure [(b)-(a)-(b)] formed by bonding two of the structural units (b) on both sides of the structural unit (a) as a center, and the content of the structural unit (a) forming the alternating copolymer structure [(b)-(a)-(b)] in the polymer (A) is 80 mol% or more in 100 mol% of the total structural units (a) contained in the polymer (A). The composition according to claim 2.

6. The composition according to claim 1, wherein the content of the structural unit (a) in the polymer (A) is 25 to 75 mol% in 100 mol% of the total amount of the structural units of the polymer (A).

7. The composition according to claim 1, wherein the mass swelling degree of the polymer (A) with respect to the electrolyte is 101 to 800 mass%.

8. The voltage value at which the cumulative value of the current amount calculated by cyclic voltammetry measurement of the polymer (A) reaches 0.05 μA / cm ２ is 4.0 V or more. The composition according to claim 1.

9. A binder composition for a secondary battery, comprising a polymer (A) containing a structural unit (a) derived from 1,1-dicyanoethylene and an electrode active material.

10. The binder composition for a secondary battery according to claim 9, wherein the electrode active material is a positive electrode active material.

11. A molded body formed of the composition according to any one of claims 1 to 8 or the binder composition for a secondary battery according to claim 9.

12. An electrode comprising the molded body according to claim 11.

13. A battery comprising the molded body according to claim 11.

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