Resin composition, adhesive resin, polymer film, and battery

Abstract

A resin composition comprising a copolymer containing a structural unit represented by the following general formula (1) and 0.3 mol% or more and 20.0 mol% or less of a structural unit represented by the following general formula (2). (In the above general formula (1) and the above general formula (2), R 1 is a hydrogen atom or an alkyl group having 1 or more and 3 or less carbon atoms, L 1 and L 2 are each independently a single bond or an alkylene group having 1 or more and 3 or less carbon atoms, X 1 is any of the reactive groups represented by the following structural formula (2-1) and the following structural formula (2-2).

Description

Technical Field

[0001] This invention relates to resin compositions, adhesive resins, polymer films, and batteries. Background Technology

[0002] Polycarbonate has been used for various applications, including in battery materials. Polycarbonate-containing adhesive resins are used, for example, as binders for electrode formation. Additionally, polycarbonate-containing polymer films are used, for example, in battery separators.

[0003] For example, Patent Document 1 discloses a polymeric adhesive comprising three-dimensional cross-linked aliphatic polycarbonate.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2020 / 203882 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] The polymeric adhesive described in Patent Document 1 is an adhesive for solid electrolytes and is not intended for use in batteries using electrolyte. Therefore, if an electrode made using this polymeric adhesive is used in a battery using electrolyte, there is a potential risk that the polymeric adhesive may dissolve into the electrolyte.

[0009] The purpose of this invention is to provide crosslinkable resin compositions, as well as adhesive resins, polymer films, and batteries.

[0010] Problem Solving Methods

[0011] [1] A resin composition comprising a copolymer containing structural units represented by the following general formula (1) and structural units represented by the following general formula (2) in amounts of 0.3 mol% and 20.0 mol% or more.

[0012] [Chemical Formula 1]

[0013]

[0014] In the above general formulas (1) and (2), R 1 It is an alkyl group having 1 or more hydrogen atoms and less than 3 carbon atoms, L 1 and L 2 Each is independently a single bond or an alkylene group having 1 or more but less than 3 carbon atoms, X 1 It can be any reactive group among the groups represented by the following structural formulas (2-1) and (2-2).

[0015] [Chemical Formula 2]

[0016] .

[0017] [2] According to the resin composition described in [1], wherein,

[0018] The copolymer further comprises 0.1 mol% and 30.0 mol% or less of at least one structural unit selected from the structural units represented by general formula (3) and general formula (4) below.

[0019] [Chemical Formula 3]

[0020]

[0021] In the above general formulas (3) and (4), R 2 It is an alkyl group having 1 or more hydrogen atoms and less than 3 carbon atoms, L 3 and L 4 Each is independently a single bond or an alkylene group having 1 or more but less than 3 carbon atoms, X 2 It can be any reactive group among the groups represented by the following structural formulas (4-1) and (4-2).

[0022] [Chemical Formula 4]

[0023] .

[0024] [3] The resin composition according to [1] or [2], wherein,

[0025] In the crosslinked product of the above resin composition,

[0026] The above copolymer dissolves less than 10% in ethyl acetate.

[0027] The swelling rate of the above copolymer in a mixed solvent of ethylene carbonate and dimethyl carbonate in a volume ratio of 1:1 is more than 100%.

[0028] [4] An adhesive resin comprising any one of the resin compositions described in [1] to [3].

[0029] [5] A battery comprising the adhesive resin described in [4].

[0030] [6] A polymer film comprising any one of the resin compositions described in [1] to [3].

[0031] [7] A battery comprising the polymer film described in [6].

[0032] According to one aspect of the present invention, a crosslinkable resin composition, as well as an adhesive resin, a polymer film, and a battery can be provided. Attached Figure Description

[0033] Figure 1 This is a cross-sectional view schematically showing an example of the main parts of the battery in this embodiment.

[0034] Figure 2 This diagram illustrates the effect of using the polymer film of this embodiment as a battery separator.

[0035] Figure 3 This illustrates the copolymer manufactured in Example 1. 1 A graph showing the H-NMR measurement results.

[0036] Figure 4 This illustrates the copolymer manufactured in Example 3. 1 A graph showing the H-NMR measurement results.

[0037] Symbol Explanation

[0038] 10··· Positive electrode, 11··· Positive electrode flux layer, 13··· Positive electrode current collector, 20··· Negative electrode, 21··· Negative electrode flux layer, 23··· Negative electrode current collector, 30··· Electrolyte layer, 31··· Separator, 33··· Electrolyte, 100··· Battery. Detailed Implementation

[0039] The present invention will be described below with examples of embodiments. The present invention is not limited to the embodiments described herein.

[0040] [Resin Composition]

[0041] A preferred example of the resin composition of this embodiment will be described.

[0042] The resin composition of this embodiment comprises a copolymer containing a structural unit represented by general formula (1) and a structural unit represented by general formula (2) in an amount of 0.3 mol% or more and 20.0 mol% or less.

[0043] The resin composition according to this embodiment exhibits crosslinking properties due to the above-described structure. Furthermore, by using the resin composition of this embodiment, an adhesive resin with excellent adhesion to metal foils and inorganic materials can be obtained. Additionally, by using the resin composition of this embodiment, a polymer film with high swelling capacity to electrolytes and the like can be obtained.

[0044] Furthermore, for example, when the resin composition of this embodiment is used in battery materials, the compatibility with the electrolyte is improved for the copolymer used in the resin composition of this embodiment by setting the main polymer backbone as a carbonate backbone. Therefore, when assembling the battery, the polymer film serving as the separator can be swollen after the electrolyte is injected. Moreover, the crosslinking reaction is carried out moderately by containing 0.3 mol% or more and 20.0 mol% or less of structural units represented by general formula (2) with reactive groups, thus achieving both high swelling degree and low dissolution.

[0045] The resin composition of this embodiment may contain any specific copolymer having the above-described structure, and may also contain other components as long as it does not impair the purpose of the present invention.

[0046] (copolymer)

[0047] The copolymer contained in the resin composition of this embodiment is a copolymer containing structural units represented by the following general formula (1) and structural units represented by the following general formula (2) in amounts of 0.3 mol% or more and 20.0 mol% or less.

[0048] [Chemical Formula 5]

[0049]

[0050] In general formulas (1) and (2),

[0051] R 1 It is an alkyl group having 1 or more but less than 3 hydrogen atoms, preferably a hydrogen atom or a methyl group, and particularly preferably a methyl group.

[0052] L 1 and L 2 Each is independently a single bond or an alkylene group having 1 or more but less than 3 carbon atoms, preferably methylene or ethylene, and particularly preferably methylene.

[0053] X 1 This refers to any reactive group represented by the structural formulas (2-1) and (2-2) below. It should be noted that the wavy lines in the structural formulas indicate bonding positions.

[0054] [Chemical Formula 6]

[0055]

[0056] Such copolymers can be random copolymers or block copolymers. From the viewpoint of ease of synthesis, the above copolymers are preferably random copolymers.

[0057] The copolymer contained in the resin composition of this embodiment, for example, in the case of a copolymer formed by structural units represented by general formula (1) and structural units represented by general formula (2), has the following composition ratio.

[0058] The ratio of structural units represented by general formula (2) relative to all structural units must be between 0.3 mol% and 20 mol%. If the ratio is less than 0.3 mol%, the dissolution rate will be high. On the other hand, if the ratio exceeds 20.0 mol%, there will be problems with increased crosslinking density and decreased swelling properties of the copolymer.

[0059] From the same point of view, the ratio of structural units represented by general formula (2) is preferably 1.0 mol% or more, more preferably 1.5 mol% or more, and even more preferably 1.8 mol% or more. On the other hand, the ratio of structural units represented by general formula (2) is preferably 19.0 mol% or less, more preferably 18.0 mol% or less, even more preferably 12.0 mol% or less, and particularly preferably 6.0 mol% or less.

[0060] The ratio of structural units represented by general formula (1) relative to all structural units must be 80.0 mol% or more and 99.7 mol% or less. Furthermore, the ratio of structural units represented by general formula (1) is preferably 81.0 mol% or more, more preferably 82.0 mol% or more, even more preferably 88.0 mol% or more, and particularly preferably 94.0 mol% or more. On the other hand, the ratio of structural units represented by general formula (1) is preferably 99.0 mol% or less, more preferably 98.5 mol% or less, and even more preferably 98.2 mol% or less.

[0061] Preferably, the copolymer contained in the resin composition of this embodiment further comprises 0.1 mol% or more and 30.0 mol% or less of at least one structural unit selected from the structural units represented by the following general formula (3) and the structural units represented by the following general formula (4).

[0062] By preparing copolymers containing ether skeletons with structural units represented by general formula (3) or general formula (4), the glass transition temperature of the copolymer is reduced, the film is softened, and thus high ionic conductivity can be expected.

[0063] [Chemical Formula 7]

[0064]

[0065] In general formulas (3) and (4),

[0066] R 2 It is an alkyl group having 1 or more but less than 3 hydrogen atoms, preferably a hydrogen atom or a methyl group, and particularly preferably a methyl group.

[0067] L 3 and L 4 Each is independently a single bond or an alkylene group having 1 or more but less than 3 carbon atoms, preferably methylene or ethylene, and particularly preferably methylene.

[0068] X 2 This refers to any reactive group among the groups represented by the structural formulas (4-1) and (4-2) below. It should be noted that the wavy lines in the structural formulas indicate bonding positions.

[0069] [Chemical Formula 8]

[0070]

[0071] In the case where the copolymer contained in the resin composition of this embodiment is, for example, a copolymer formed by structural units represented by general formula (1), general formula (2), general formula (3), and general formula (4), the composition ratio is as described below.

[0072] The ratio of structural units represented by general formula (2) is as described above.

[0073] The ratio of the structural units represented by general formula (3) to the structural units represented by general formula (4) is preferably 0.1 mol% or more and 30.0 mol% or less, relative to all structural units. If their total ratio is less than 0.1 mol%, there is a tendency that the effect brought about by the ether skeleton cannot be fully exerted. On the other hand, if their total ratio exceeds 30.0 mol%, the compatibility with the electrolyte deteriorates, the swelling degree decreases, and there is a tendency that the ionic conductivity decreases.

[0074] From the same point of view, their combined ratio is preferably 1.0 mol% or more, more preferably 2.0 mol% or more. On the other hand, their combined ratio is preferably 25.0 mol% or less, more preferably 20.0 mol% or less, and particularly preferably 10.0 mol% or less.

[0075] The ratio of structural units represented by general formula (1) relative to all structural units is preferably 50.0 mol% or more and 99.6 mol% or less. Furthermore, the ratio of structural units represented by general formula (1) is preferably 55.0 mol% or more, more preferably 60.0 mol% or more. On the other hand, the ratio of structural units represented by general formula (1) is preferably 98.0 mol% or less, more preferably 94.0 mol% or less.

[0076] For the molecular weight measured by the method shown in the copolymer measurement example of this embodiment, when expressed as weight-average molecular weight (Mw), it is preferably 5,000 or more and 5,000,000 or less, more preferably 10,000 or more and 1,000,000 or less.

[0077] Furthermore, for the molecular weight measured by the method shown in the copolymer measurement example of this embodiment, when expressed as number average molecular weight (Mn), it is preferably 3,000 or more and 3,000,000 or less, more preferably 5,000 or more and 500,000 or less.

[0078] Furthermore, the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) (Mw / Mn) is preferably 1 or more and 10 or less, more preferably 1.1 or more and 5 or less. By ensuring that the molecular weight and molecular weight distribution of the copolymer are within the above range, sufficient processability can be achieved when molding it into a film. In addition, when the copolymer is used as a binder, by ensuring that the molecular weight and molecular weight distribution of the copolymer are within the above range, the viscosity of the electrode paste can be made appropriate during preparation, the sedimentation of the active material and conductive additives can be suppressed, and sufficient dispersibility of the active material and conductive additives can be obtained.

[0079] (Method for manufacturing copolymers)

[0080] The method for manufacturing the copolymer contained in the resin composition of this embodiment is not particularly limited, and it can be obtained by known methods, such as by the method described below.

[0081] As described in the examples below, it can be manufactured by copolymerizing epoxide monomers such as propylene oxide with carbon dioxide in the presence of a polymerization catalyst. Specifically, propylene oxide becomes a structural unit represented by general formula (3) by ring-opening, and becomes a structural unit represented by general formula (1) by polymerizing a portion of propylene oxide with carbon dioxide while ring-opening.

[0082] There are no particular limitations on the polymerization catalysts used in the manufacture of copolymers, and examples include metal Salen complex catalysts such as cobalt Salen catalysts and organozinc catalysts.

[0083] Regarding the amount of polymerization catalyst used in the copolymerization reaction of epoxide monomer and carbon dioxide, for example in the case of a metal Salen complex catalyst, it is preferably 0.05 moles or less, more preferably 0.01 moles or less, and particularly preferably 0.001 moles or less relative to 1 mole of epoxide monomer.

[0084] Furthermore, when using a metal Salen complex catalyst, a co-catalyst can be used. As a co-catalyst, a preferred example is... Salt compounds. As described above... Specific examples of salt compounds are not particularly limited, but from the viewpoint of having high reactivity, preferred examples include bis(triphenylphosphoranylidene)ammonium chloride, piperidine, bis(triphenylphosphorany)ammonium fluoride, ammonium pentafluorobenzoate, and tetrabutylammonium chloride.

[0085] It should be noted that the optimal conditions for polymerization vary depending on the type of catalyst. For example, the pressure of carbon dioxide in the reaction vessel is 0.1 MPa or higher and 10 MPa or lower, preferably 0.5 MPa or higher and 5 MPa or lower.

[0086] Furthermore, regarding the polymerization temperature, for example in the case of a cobalt Salen complex catalyst, from the viewpoint of effectively utilizing the catalyst and promoting the reaction rate, a temperature of around room temperature (25°C) is preferred.

[0087] In methods for copolymerizing epoxide monomers with carbon dioxide, examples of epoxide monomers that can be used as starting materials include ethylene oxide, propylene oxide, 1,2-epoxide butane, allyl glycidyl ether, and 4-hydroxybutyl acrylate glycidyl ether. It should be noted that the molar ratio of the structural unit represented by general formula (1) to the structural unit represented by general formula (2) in the copolymer may sometimes differ from the molar ratio of the epoxide monomers that are the starting materials for the structural units represented by general formula (1) and the epoxide monomers that are the starting materials for the structural units represented by general formula (2), depending on their reactivity.

[0088] (Characteristics of the crosslinking of the resin composition)

[0089] In the crosslinked resin composition of this embodiment, the amount of copolymer dissolved in ethyl acetate is preferably 40% or less, more preferably 30% or less, further preferably 20% or less, particularly preferably 10% or less, and very preferably 7% or less. Since the low molecular weight components of the dissolved copolymer constitute irreversible capacity, it is preferable that the amount of dissolution is as low as possible. The lower limit of the amount of copolymer dissolved is not particularly limited, for example, it can be 1% or more, 0.1% or more, or even 0%.

[0090] In the crosslinked resin composition of this embodiment, the copolymer is preferably dissolved in ethyl acetate within the range described above, and the copolymer has a swelling degree of 100% or more in a mixed solvent of ethylene carbonate and dimethyl carbonate in a volume ratio of 1:1.

[0091] The crosslinked resin composition of this embodiment preferably exhibits high swelling capacity for electrolytes and carbonate solvents used as solvents for electrolytes. From this viewpoint, the copolymer's swelling degree in a mixed solvent of ethylene carbonate and dimethyl carbonate in a volume ratio of 1:1 is preferably 100% or more, more preferably 200% or more, further preferably 300% or more, particularly preferably 500% or more, very preferably 700% or more, and most preferably 900% or more. The upper limit of this swelling degree is not particularly limited, and for example, it can be 2000% or less.

[0092] (Crosslinking method of resin composition)

[0093] From the viewpoint of easily obtaining a polymer film formed by crosslinking the copolymer, the resin composition of this embodiment preferably uses a photopolymerization initiator. In the resin composition of this embodiment, when a photopolymerization initiator is used, the film containing the copolymer reacts with the reactive groups (allyl and (meth)acryloyl) of the side chains of the copolymer located in the film to achieve crosslinking.

[0094] There are no particular limitations on the photopolymerization initiator; known compounds can be cited. Preferably, the photopolymerization initiator is an ultraviolet-sensitive photopolymerization initiator. A single photopolymerization initiator can be used, or two or more can be used in combination.

[0095] Photopolymerization initiators include, for example, α-keto alcohols such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)one, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxyphenylacetone, and 1-hydroxycyclohexylphenyl ketone; acetophenone compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1; and phenoisin ethers such as benzoin ethyl ether, benzoin isopropyl ether, and anisoisin methyl ether. Compounds; ketal compounds such as benzyl dimethyl ketal; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-benzophenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; benzoic anhydride, 3,3'-dimethyl-4-methoxybenzophenone, etc.; thioxanthone compounds such as 2-chlorothioxanthone, 2-methylthioxanthone; camphorquinone and other benzophenone compounds; haloketones, acylphosphine oxides, acylphosphonates and oligomers [2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone], etc.

[0096] The content of the photopolymerization initiator relative to 100 parts by weight of the copolymer is preferably 0.1 parts by weight or more and 10 parts by weight or less, more preferably 0.5 parts by weight or more and 7.5 parts by weight or less, and even more preferably 1 part by weight or more and 5 parts by weight or less.

[0097] By irradiating an article obtained by molding the resin composition of this embodiment into a given shape with energy rays, the copolymer is crosslinked, and a film as the crosslinked product of the copolymer can be obtained. The type of energy ray is not particularly limited, but ultraviolet light is preferred from the perspectives of reactivity and operability. The device for irradiating the article with ultraviolet light is not particularly limited; for example, it can be a device equipped with an ultraviolet LED lamp, a device equipped with a high-pressure mercury lamp, or a device equipped with a metal halide lamp.

[0098] There are no particular limitations on the conditions for irradiating the molded article with ultraviolet light. For example, the maximum illuminance and cumulative light intensity during ultraviolet irradiation can be described under the following conditions: The maximum illuminance is preferably 5 mW / cm². 2 Above and 1000mW / cm 2 The following is a preferred cumulative light intensity: 50 mJ / cm². 2 Above 5000mJ / cm 2 the following.

[0099] [Adhesive Resin]

[0100] The adhesive resin of this embodiment comprises the resin composition of this embodiment. When the adhesive resin of this embodiment is used as a material for the binder layer in the electrode of a secondary battery, the adhesive resin of this embodiment exhibits excellent swelling properties with the electrolyte, and also excellent adhesion to metal foils and inorganic materials. The reasons for this are not yet clear, but are considered as follows.

[0101] Existing adhesive resins, when used in the compound layer of secondary batteries such as lithium-ion batteries, can achieve good adhesion between the compound layer and the current collector and good adhesion between the active materials in the compound layer by suppressing the swelling of the electrolyte to a low level, even if the adhesive resin swells due to the electrolyte.

[0102] It can be considered that the binder layer in contact with the electrolyte has contact areas between the binder resin and the active material, and between the active material and the electrolyte, due to the electrolyte penetrating into the binder layer. Existing binder resins have low swelling capacity to electrolytes, thus exhibiting poor ionic conductivity; in the contact area between the binder resin and the active material, the ionic conductivity of lithium ions and the like contained in the electrolyte is low. On the other hand, in the contact area between the active material and the electrolyte, the ionic conductivity of lithium ions and the like contained in the electrolyte is improved. Furthermore, because existing binder resins have low swelling capacity to electrolytes, the contact area between the binder resin and the active material is not significantly expanded, resulting in a small contact area; conversely, the contact area between the active material and the electrolyte is large.

[0103] It can be considered that although the electrolyte is not easily decomposed in the contact area between the adhesive resin and the active material, a decomposed electrolyte layer called an SEI (Solid Electrolyte Interphase) layer is easily formed in the contact area between the active material and the electrolyte. When using existing adhesive resins as the binder layer, as mentioned above, because the contact area between the active material and the electrolyte is large, the area where the SEI layer can be formed also increases, thereby easily reducing the electrolyte's lifespan.

[0104] In contrast, when the adhesive resin of this embodiment is used in the compound layer of secondary batteries such as lithium-ion batteries, the adhesive resin of this embodiment contains a copolymer with a carbonate backbone as the main polymer backbone. This improves compatibility with the electrolyte and thus exhibits high swelling capacity with respect to the electrolyte. Furthermore, the adhesive resin of this embodiment swells significantly upon contact with the electrolyte, thereby exhibiting ionic conductivity. Additionally, because the adhesive resin of this embodiment has high swelling capacity with respect to the electrolyte, the contact area between the adhesive resin and the active material becomes larger, while the contact area between the active material and the electrolyte becomes smaller. Therefore, it can be considered that when the adhesive resin of this embodiment is used, ionic conductivity is exhibited in the contact area between the adhesive resin and the active material, and the electrolyte is less prone to decomposition. It can be considered that the area of ​​SEI layer formation in the contact area between the active material and the electrolyte is suppressed. Therefore, it can be considered that when the adhesive resin of this embodiment is used in the compound layer of secondary batteries such as lithium-ion batteries, it contributes to improving electrolyte lifespan, resulting in improved battery performance. However, if the swelling capacity of the electrolyte is too high, the adhesion between the electrolyte and the metal foil and the inorganic materials can easily be reduced.

[0105] The adhesive resin of this embodiment exhibits excellent adhesion to metal foil and inorganic materials, thus making it suitable for applications requiring such properties. The adhesive resin of this embodiment is preferably applicable to batteries, for example. In this case, the adhesive resin of this embodiment is preferably an adhesive resin for battery electrodes, and also preferably an adhesive resin for electrodes of secondary batteries such as lithium-ion batteries. The adhesive resin of this embodiment can also be used as an adhesive resin for the flux layer in the positive electrode, or as an adhesive resin for the flux layer in the negative electrode.

[0106] [Polymer Films]

[0107] The polymer film of this embodiment comprises the resin composition of this embodiment. According to the polymer film of this embodiment, a polymer film with high swelling capacity to electrolytes and the like can be obtained. The reason for this is not yet determined, but can be considered as follows. The copolymer used in the polymer film of this embodiment improves compatibility with electrolytes by setting the main polymer backbone as a carbonate backbone. Therefore, when assembling a battery, the polymer film serving as a separator can swell after the electrolyte is injected. Moreover, the crosslinking reaction is carried out moderately by using structural units represented by general formula (2) containing a given amount of reactive groups, thus achieving both high swelling capacity and low dissolution.

[0108] The polymer film of this embodiment exhibits high swelling capacity in electrolytes and the like, and therefore can be applied to applications requiring such properties. The polymer film of this embodiment is preferably used in batteries, for example. In this case, the polymer film of this embodiment is preferably a battery separator, and more preferably a separator for secondary batteries such as lithium-ion batteries. Furthermore, the polymer film of this embodiment is preferably a negative electrode protective film covering at least a portion of the negative electrode of a battery, and more preferably a negative electrode protective film for secondary batteries such as lithium-ion batteries.

[0109] [Battery]

[0110] Next, a preferred example of the battery in this embodiment will be described.

[0111] The battery of this embodiment utilizes the resin composition of this embodiment. The battery of this embodiment includes the binder resin of this embodiment as the material constituting the battery electrodes. Additionally, the battery of this embodiment includes, for example, the polymer film of this embodiment as a battery separator. The battery consists of a positive electrode, a negative electrode, and an electrolyte layer disposed between the positive and negative electrodes. With this configuration, a battery with excellent characteristics can be obtained. Furthermore, as the battery, a secondary battery is preferred, and a lithium-ion secondary battery is more preferred. The structure of the battery of this embodiment is not particularly limited; it can be a laminated structure or a wound structure.

[0112] Here, an example of a battery using the polymer film of this embodiment will be described with reference to the accompanying drawings. In the drawings, some parts are shown in enlarged or reduced form for ease of explanation.

[0113] Figure 1 An example of a battery using the polymer film of this embodiment is shown. Figure 1 The battery 100 shown is a lithium-ion secondary battery. For example... Figure 1 As shown, the battery 100 includes a positive electrode 10, a negative electrode 20, and an electrolyte layer 30 disposed between the positive electrode 10 and the negative electrode 20. The positive electrode 10 is composed of a positive current collector 13 and a positive electrode flux layer 11 stacked on the positive current collector 13, and the negative electrode 20 is composed of a negative current collector 23 and a negative electrode flux layer 21 stacked on the negative current collector 23. The electrolyte layer 30 is composed of an electrolyte 33 and a separator 31 impregnated with the electrolyte 33, which separates the positive electrode 10 side and the negative electrode 20 side from each other. The battery 100 has a stacked structure in which the positive current collector 13, the positive electrode flux layer 11, the electrolyte layer 30, the negative electrode flux layer 21, and the negative current collector 23 are stacked sequentially from the positive current collector 13 to the negative current collector 23, and this stacked structure is housed inside a container (not shown).

[0114] In the battery 100, the positive electrode binder layer 11 and the negative electrode binder layer 21 preferably contain the binder resin (not shown) of this embodiment. In this case, the positive electrode binder layer 11 and the negative electrode binder layer 21 contain the electrolyte 33 by impregnating the electrolyte layer 30 with the electrolyte 33, and the binder resin (not shown) of this embodiment swells due to the electrolyte 33.

[0115] In the battery 100, a polymer film of this embodiment is preferably used as the separator 31.

[0116] In the battery 100, it is preferable to use a polymer film of this embodiment as a negative electrode protective film (not shown) covering at least a portion of the negative electrode binder layer 21.

[0117] According to the battery using the polymer film of this embodiment, the formation of dendritic crystals can be suppressed by having the above-described configuration. The reason for this is not yet determined, but it can be considered as follows: When the polymer film of this embodiment is used as the separator 31, after the electrolyte is injected during battery assembly, as... Figure 2As shown in (A), the separator 31 is separated from the electrolyte 33. In this state, a gap caused by fine irregularities exists between the negative electrode binder layer 21 and the separator 31. Furthermore, the inventors deduced that dendritic crystals would be formed in this area. On the other hand, the separator 31 using the polymer film of this embodiment has high swelling capacity for the electrolyte 33; therefore, after a period of time following the injection of the electrolyte, as... Figure 2 As shown in (B), the diaphragm 31 will swell. Furthermore, through this swelling of the diaphragm 31, as... Figure 2 As shown in (C), the gap between the negative electrode binder layer 21 and the separator 31 disappears. Therefore, when the polymer film of this embodiment is used as the separator 31, the formation of dendritic crystals can be suppressed.

[0118] Above, refer to Figure 1 and Figure 2 An example of the battery according to this embodiment has been described, but the examples of the battery according to this embodiment are not limited to this. The battery according to this embodiment can be made in various ways as long as the polymer film of this embodiment is used.

[0119] Materials used for the positive and negative current collectors include, for example, metal foils or plates made of copper, aluminum, nickel, titanium, and stainless steel, as well as carbon sheets and carbon nanotube sheets.

[0120] The positive electrode binder layer is preferably composed of positive electrode active materials such as lithium-containing composite oxides, conductive additives such as carbon materials, and the adhesive resin of this embodiment.

[0121] The negative electrode binder layer is preferably composed of negative electrode active materials such as acetylene black, carbon nanotubes, carbon nanofibers, and graphene, as well as the binder resin of this embodiment.

[0122] The electrolyte layer is preferably composed of an electrolyte and a membrane, which is a polymer film in this embodiment.

[0123] In the battery of this embodiment, the electrolyte preferably comprises a lithium salt and a carbonate solvent. From the viewpoint of easily improving the effect of suppressing the formation of dendrites, the molar ratio of lithium salt to carbonate solvent (lithium salt / carbonate solvent) is preferably 1 / 6 or more and 1 / 1 or less. This molar ratio is more preferably 1 / 4 or more and 1 / 1 or less, and even more preferably 1 / 3 or more and 1 / 1 or less.

[0124] Specific examples of lithium salts include: lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium 2-trifluoromethyl-4,5-dicyanoimidazolium, lithium 4,5-dicyano-1,2,3-triazole, lithium bis(pentafluoroethylsulfonyl)imide, lithium tetrafluoroborate, lithium dioxalatoborate, lithium nitrate, lithium chloride, lithium bromide, and lithium fluoride. One or more of the lithium salts listed above may be used.

[0125] Examples of carbonate solvents include dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, ethylene carbonate, propylene carbonate, and butyl carbonate. One or more of the carbonate solvents exemplified above can be used. Here, in this embodiment, carbonate solvent refers to a compound having a carbonate backbone in its molecular structure.

[0126] It should be noted that the present invention is not limited to the above embodiments, and variations and improvements that can achieve the purpose of the present invention are included in the present invention.

[0127] Example

[0128] The present invention will be described in more detail below with reference to specific embodiments, but the present invention is not limited to these embodiments in any way.

[0129] The measurements or evaluations in the following examples and comparative examples were performed using the methods shown below.

[0130] [Determination of weight-average molecular weight (Mw) and number-average molecular weight (Mn)]

[0131] The determination was performed using a gel permeation chromatography apparatus (manufactured by Tosoh Corporation, product name "HLC-8320GPC") under the following conditions, and the values ​​were obtained by conversion to standard polystyrene.

[0132] (Measurement conditions)

[0133] • Pillar: A pillar formed by sequentially connecting “TSKgel guardcolumn SuperH-H”, “TSKgel SuperHM-H”, “TSKgel SuperHM-H”, and “TSKgel SuperH2000” (all manufactured by Tosoh Corporation).

[0134] Column temperature: 40℃

[0135] • Elution solvent: Tetrahydrofuran (copolymer concentration 1% by mass)

[0136] • Standard material: Polystyrene

[0137] Injection volume: 20μL

[0138] • Flow rate: 0.60 mL / min

[0139] • Detector: Differential refractometer

[0140] [Dissolution rate determination]

[0141] The films obtained in the examples and comparative examples described below were weighed to approximately 300 mg. The mass of the film at this point is designated M0. The film was wrapped in a polyester sieve (mesh size 200). The mass of the film wrapped in the polyester sieve was weighed, and the mass of the film was subtracted to calculate the mass of the polyester sieve alone. Next, the film wrapped in the polyester sieve was immersed in ethyl acetate at 23°C for 48 hours. Then, the film wrapped in the polyester sieve was removed from the ethyl acetate, dried in an oven at 120°C for 2 hours, and further air-dried at 23°C and 50% relative humidity for 2 hours. The mass after air-drying was weighed, and the mass of the polyester sieve alone was subtracted to calculate the mass of the film after immersion only. This mass is designated M1. Then, the dissolution amount was calculated using the following mathematical formula (F1).

[0142] Dissolution rate (%) = {(M0-M1) / M0} × 100···(F1)

[0143] In the mathematical formula (F1), M0 represents the mass of the film weighed before being wrapped in a polyester screen, and M1 represents the mass of the film alone after being impregnated with ethyl acetate.

[0144] [Swelling Degree Measurement]

[0145] The films obtained in the examples and comparative examples described below were cut into pieces of approximately 3 cm (length) × approximately 3 cm (width) and weighed to obtain approximately 1 g. This mass is designated W0. The film sheet was wrapped in a polyester sieve (mesh size 200), and the mass of the film sheet wrapped in the sieve was weighed. The mass of the sieve alone was calculated by subtracting the mass of the film sheet. The film sheet was then immersed in a carbonate solvent [a mixed solvent of ethylene carbonate and dimethyl carbonate in a 1 / 1 (volume ratio)] for 24 hours to allow it to swell. The film sheet wrapped in the sieve was then lifted, the solvent on the surface was wiped off with a wiping paper, and its mass was measured. The mass of the swollen film sheet was calculated by subtracting the mass of the sieve alone. This mass is designated W1. The degree of swelling was then calculated using the following mathematical formula (F2).

[0146] Swelling degree (%) = {(W1-W0) / W0} × 100···(F2)

[0147] In the mathematical formula (F2), W0 represents the mass of the film sheet before it is wrapped in a polyester screen, and W1 represents the mass of the film sheet after it has swelled.

[0148] [Ionic Conductivity Measurement]

[0149] For the lithium half-cells obtained in the examples and comparative examples described below, the resistivity was measured using AC impedance spectroscopy, which involves applying an alternating current (10 mV) between the electrodes. The ionic conductivity was calculated from the real impedance intercept of the resulting Cole-Cole plot. It should be noted that a potentiostat / galvanostat (VMP-300, manufactured by Biologic) was used for the measurements.

[0150] Ionic conductivity (σ) A It can be obtained through the following mathematical expression (F3).

[0151] σ A =L A / (R A ×S A (F3)

[0152] In mathematical expression (F3), σ A Ionic conductivity (unit: S·cm) -1 ), R A Represents resistance (unit: Ω), S A The cross-sectional area of ​​the solid electrolyte membrane during measurement (unit: cm²) 2 ), L A Indicates the distance between electrodes (unit: cm).

[0153] The measurement temperature was 25℃. Additionally, the ionic conductivity (σ) was calculated based on the results of the complex impedance measurement. A ).

[0154] [Example 1]

[0155] (Synthesis of polymerization catalysts)

[0156] (R,R)-N,N'-bis(3,5-di-tert-butylsalicyl)-1,2-diaminocyclohexanecobalt(II) and pentafluorobenzoic acid were weighed in a molar ratio of 1:1.1 and placed in a flask. Dehydrated toluene was added. The flask was shielded from light with aluminum foil and allowed to react at room temperature for 20 hours. The chemical reaction equation is shown below. After the reaction was complete, the solvent was removed under reduced pressure, and the mixture was washed several times with excess hexane. Then, it was dried under vacuum at room temperature to obtain the cobalt Salen complex.

[0157] [Chemical Formula 9]

[0158]

[0159] (Synthesis of copolymer A)

[0160] As the epoxide monomer, a mixture of propylene oxide and allyl glycidyl ether at a molar ratio of 97:3 was used. Cobalt Salen complex, synthesized as a polymerization catalyst, and bis(triphenylphosphine)ammonium chloride, as a co-catalyst, were weighed at a molar ratio of epoxide monomer:catalyst:co-catalyst = 2000:1:1 and placed in a pressure vessel. After adding 200 ppm of phenothiazine, ethyl acetate was added at a monomer:ethyl acetate ratio of 50:50 (mass ratio). All the above operations were performed by purging the pressure vessel with argon gas. Then, after purging the pressure vessel, carbon dioxide was introduced into the pressure vessel using a pump to bring the pressure inside to 2.0 MPa, and the polymerization reaction was carried out at 25°C for 20 hours.

[0161] After the reaction was complete, chloroform was added to the contents of the pressure vessel to prepare a chloroform solution, and 1M hydrochloric acid was added. Next, the chloroform solution was added dropwise to stirred methanol to precipitate the product. Then, the product was dried under reduced pressure using a diaphragm pump in a desiccator, followed by vacuum drying at 60°C to obtain copolymer A.

[0162] By nuclear magnetic resonance spectroscopy ( 1 H-NMR (Biospin Avance 500, Bruker) was used to confirm the structure of the obtained copolymer A using (CDCl3 containing 0.03 vol% tetramethylsilane) as a solvent. The results showed that the molar ratio of structural units represented by general formula (1) (hereinafter also referred to as structural unit (1)), structural units represented by general formula (2) (hereinafter also referred to as structural unit (2)), structural units represented by general formula (3) (hereinafter also referred to as structural unit (3)) and structural units represented by general formula (4) (hereinafter also referred to as structural unit (4)) in copolymer A was structural unit (1): structural unit (2): structural unit (3): structural unit (4) = 94.5:2.9:2.5:0.1 (refer to...) Figure 3 ).

[0163] In addition, the number-average molecular weight Mn of the obtained copolymer A is 24,000, and the molecular weight distribution Mw / Mn is 1.1.

[0164] (Thin film fabrication)

[0165] For the obtained copolymer A, 1-hydroxycyclohexylphenyl ketone, as a photopolymerization initiator, was added in a ratio of copolymer:initiator = 97:3 by mass. The solution was further diluted with ethyl acetate and stirred to prepare a film-forming solution with a solid content concentration of 30 by mass. A first release film (manufactured by Lintec Corporation, product name "SP-PET381031") was prepared, and the prepared film-forming solution was coated on the release-treated surface of the release film. It was dried at 120°C for 1 minute to form a film layer with a thickness of 10 μm. A second release film (manufactured by Lintec Corporation, product name "SP-PET382150") was further prepared, and the release-treated surface of the release film was adhered to the surface of the film layer. Then, the film stack sandwiched between the first and second release films was placed on a stainless steel plate and subjected to ultraviolet irradiation at 50°C [irradiance used: 200 mW / cm²]. 2 Cumulative light intensity: 1000 mJ / cm 2 The illuminance was measured using an illuminometer manufactured by EYE GRAPHICS (control unit: EYE UVMETER UVPF-A2, light-receiving unit: EYE UV METER PD-365A2), resulting in a 10 μm thick film. The obtained film served as a negative electrode protective film. The dissolution rate and swelling degree of the obtained film were measured using the method described above.

[0166] [Example 2]

[0167] (Polymerization of copolymer B)

[0168] As the epoxide monomer, a substance prepared by mixing propylene oxide and allyl glycidyl ether in a molar ratio of 90:10 was used, and polymerization was otherwise performed in the same manner as in Example 1. The polymerization was carried out in the same manner as in Example 1. 1 H-NMR confirmed the structure of the obtained copolymer B. The results showed that the molar ratio of structural unit (1), structural unit (2), structural unit (3) and structural unit (4) in copolymer B was structural unit (1): structural unit (2): structural unit (3): structural unit (4) = 81.7:8.4:8.9:0.9.

[0169] In addition, the number-average molecular weight Mn of the obtained copolymer B is 25,000, and the molecular weight distribution Mw / Mn is 1.2.

[0170] (Thin film fabrication)

[0171] Copolymer B was used, and otherwise a film with a thickness of 10 μm was obtained by the same method as in Example 1.

[0172] [Example 3]

[0173] (Polymerization of copolymer C)

[0174] As the epoxide monomer, a mixture of propylene oxide and 4-hydroxybutyl acrylate glycidyl ether in a molar ratio of 98:2 was used. Otherwise, polymerization was performed in the same manner as in Example 1. The polymerization was carried out in the same manner as in Example 1. 1 H-NMR confirmed the structure of the obtained copolymer C. The results showed that the molar ratio of structural units (1), (2), (3), and (4) in copolymer C was structural unit (1): structural unit (2): structural unit (3): structural unit (4) = 95.0:2.1:2.8:0.1 (refer to...). Figure 4 ).

[0175] In addition, the number-average molecular weight Mn of the obtained copolymer C is 38,000, and the molecular weight distribution Mw / Mn is 1.2.

[0176] (Thin film fabrication)

[0177] Copolymer C was used, and otherwise a film with a thickness of 10 μm was obtained by the same method as in Example 1.

[0178] [Example 4]

[0179] (Polymerization of copolymer D)

[0180] As the epoxide monomer, a mixture of propylene oxide and 4-hydroxybutyl acrylate glycidyl ether in a molar ratio of 95:5 was used, and polymerization was performed in the same manner as in Example 1. The polymerization was carried out in the same manner as in Example 1. 1 H-NMR confirmed the structure of the obtained copolymer D. The results showed that the molar ratio of structural unit (1), structural unit (2), structural unit (3) and structural unit (4) in copolymer D was structural unit (1): structural unit (2): structural unit (3): structural unit (4) = 92.3:5.1:2.5:0.1.

[0181] In addition, the number-average molecular weight Mn of the obtained copolymer D is 41,000, and the molecular weight distribution Mw / Mn is 1.1.

[0182] (Thin film fabrication)

[0183] Copolymer D was used, and otherwise a film with a thickness of 10 μm was obtained by the same method as in Example 1.

[0184] [Comparative Example 1]

[0185] (Thin film fabrication)

[0186] A solution with a solid content of 30% by mass was prepared by diluting polyethylene carbonate (trade name "QPAC25", manufactured by EMPOWER MATERIALS) with chloroform. The prepared solution was coated onto the release-treated side of a release film (manufactured by Lintec Corporation, product name "SP-PET381031") and dried at 90°C for 1 minute to obtain a film with a thickness of 10 μm.

[0187] [Comparative Example 2]

[0188] (Thin film fabrication)

[0189] A solution of polypropylene carbonate (trade name "QPAC40", manufactured by EMPOWER MATERIALS) with a solid content of 30% by mass was prepared by diluting it with ethyl acetate. The prepared solution was coated onto the release surface of a release film (manufactured by Lintec Corporation, product name "SP-PET381031") and dried at 120°C for 1 minute to obtain a film with a thickness of 10 μm.

[0190]

[0191]

[0192] As shown in Table 2, the films obtained in Examples 1-4, despite having high swelling degree, exhibited low dissolution. This confirms that the copolymers obtained in Examples 1-4 possess crosslinking properties.

Claims

1. A resin composition comprising a copolymer containing structural units represented by general formula (1), general formula (2), general formula (3), and general formula (4). Relative to all structural units, the ratio of structural units represented by general formula (1) is 60.0 mol% or more and 98.0 mol% or less, the ratio of structural units represented by general formula (2) is 0.3 mol% or more and 12.0 mol% or less, and the combined ratio of structural units represented by general formula (3) and general formula (4) is 1.0 mol% or more and 10.0 mol% or less. In general formulas (1) and (2), R 1 It is an alkyl group having 1 or more hydrogen atoms and less than 3 carbon atoms, L 1 and L 2 Each is independently a single bond or an alkylene group having 1 or more but less than 3 carbon atoms, X 1 The reactive group is represented by the following structural formula (2-2). In general formulas (3) and (4), R 2 It is an alkyl group having 1 or more hydrogen atoms and less than 3 carbon atoms, L 3 and L 4 Each is independently a single bond or an alkylene group having 1 or more but less than 3 carbon atoms, X 2 The reactive group is represented by the following structural formula (4-2). 。 2. The resin composition according to claim 1, wherein, In the crosslinked form of the resin composition, The copolymer has a dissolution rate of less than 10% in ethyl acetate. The copolymer exhibits a swelling rate of over 100% in a mixed solvent of ethylene carbonate and dimethyl carbonate in a volume ratio of 1:

1.

3. An adhesive resin comprising the resin composition of claim 1 or 2.

4. A battery comprising the adhesive resin of claim 3.

5. A polymer film comprising the resin composition of claim 1 or 2.

6. A battery comprising the polymer film of claim 5.

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