Polyamide-imide and material for electrode formation

Abstract

To provide polyamide-imide which enables production of an electrode for an energy device having excellent charge-discharge characteristics.SOLUTION: Polyamide-imide has a structure represented by the following formula (1-1) (where, R1 represents an organic group; R represents a carboxyl group; n represents an integer of 1-5; and * represents a bond position with other atoms).SELECTED DRAWING: None

Description

Technical Field

[0001] Embodiments of the present invention relate to polyamideimide, a material for forming an electrode, an electrode binder, an electrode for an energy device, and an energy device.

Background Art

[0002] Lithium-ion secondary batteries are widely used as power sources for portable information terminals such as notebook computers, mobile phones, and PDAs (Personal Digital Assistants), and as power sources for electric vehicles. A lithium-ion secondary battery is a non-aqueous electrolyte-based energy device having a high energy density. Electrodes of a lithium-ion secondary battery are produced, for example, using a slurry-like electrode binder containing an active material, a binder, and a solvent.

[0003] Patent Document 1 describes a composition containing a copolymer containing a structural unit derived from (meth)acrylonitrile and a structural unit derived from a compound having two or more ethylenically unsaturated bonds, for an electrode binder resin material for an energy device. Patent Document 2 also describes a composition containing a copolymer containing a structural unit derived from (meth)acrylonitrile and a structural unit derived from (meth)acrylate, and having a swelling degree of 200 to 400% with respect to an electrolytic solution, for a copolymer for an electrode of an energy device.

[0004] With the background of expanding the applications of lithium-ion secondary batteries to electric vehicles and the like, further improvement of battery characteristics is expected.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] An embodiment of the present invention aims to provide a polyamideimide, a material for forming an electrode, and an electrode binder that can manufacture an electrode of an energy device having excellent charge and discharge characteristics. Another embodiment of the present invention aims to provide an electrode that can manufacture an energy device having excellent charge and discharge characteristics. Still another embodiment of the present invention aims to provide an energy device having excellent charge and discharge characteristics.

Means for Solving the Problems

[0007] The present invention includes the following embodiments. The present invention is not limited to the following embodiments. [1] A polyamideimide containing a structure represented by the following formula (1-1).

Chemical Formula

Chemical Formula

[0008] According to an embodiment of the present invention, it is possible to provide a polyamideimide, a material for forming an electrode, and an electrode mixture that can manufacture an electrode of an energy device having excellent charge and discharge characteristics. Further, according to an embodiment of the present invention, it is possible to provide an electrode that can manufacture an energy device having excellent charge and discharge characteristics. Furthermore, according to an embodiment of the present invention, it is possible to provide an energy device having excellent charge and discharge characteristics. [Embodiments for Carrying Out the Invention]

[0009] Embodiments of the present invention will be described. The present invention is not limited to the following embodiments. In the present disclosure, a numerical range indicated by "~" means a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in the present disclosure, the upper limit value or the lower limit value of a certain numerical range may be replaced with the upper limit value or the lower limit value of another numerical range. The upper limit value or the lower limit value of the numerical range described in the present disclosure may be replaced with the value shown in the examples. From the upper limit numerical value and the lower limit numerical value described stepwise in the present disclosure, a certain numerical value may be selected respectively to form a stepwise numerical range. The upper limit numerical value and the lower limit numerical value described in the present disclosure may be replaced with the values shown in the examples. In the present disclosure, each component may include a plurality of corresponding substances. When there are a plurality of substances corresponding to each component in the composition, the content rate or content of each component means the total content rate or content of the plurality of substances present in the composition, unless otherwise specified. In the present disclosure, each structure in the polymer may include a plurality of types of corresponding structures. When there are a plurality of types of structures corresponding to each structure in the polymer, the content ratio or content of each structure means the total content ratio or content of the plurality of types of structures present in the polymer, unless otherwise specified. In the present disclosure, the "layer" includes a continuous layer and a discontinuous layer. The thickness of the "layer" may be uniform or non-uniform. The outer edge in the plane direction and the outer edge in the thickness direction of the "layer" may each be clear or unclear. The same applies to the "film".

[0010] <Polyamideimide> The polyamideimide according to an embodiment of the present invention includes at least a structure represented by the following formula (1-1). The polyamideimide may include the structure represented by the following formula (1-1) alone or in combination of two or more. [Chemical formula] (In the formula, R 1 represents an organic group, R represents a carboxy group, n represents an integer of 1 to 5. * represents the bonding position with other atoms.)

[0011] The polyamideimide may further include a structure represented by the following formula (1-2). The polyamideimide may include the structure represented by the following formula (1-2) alone or in combination of two or more. [Chemical formula] (In the formula, R 1 represents an organic group, R represents a carboxy group, n represents an integer of 1 to 5. * represents the bonding position with other atoms.)

[0012] In Formula (1-1) and Formula (1-2), the organic group is, for example, a group containing at least one selected from the group consisting of a saturated aliphatic hydrocarbon group, an unsaturated aliphatic hydrocarbon group, a saturated alicyclic hydrocarbon group, an unsaturated alicyclic hydrocarbon group, an aromatic hydrocarbon group, an aromatic heterocyclic compound group, and a group composed of two or more selected from these. These groups may or may not have a substituent (excluding a carboxy group). In some embodiments, these groups do not have a substituent (excluding a carboxy group). The organic group may be a group containing an aromatic hydrocarbon group, and preferably may be a group containing a benzene ring. n may be, for example, 1 to 4, and may be 1 or 2.

[0013] * represents the bonding position with another atom. * may be, for example, the bonding position with a carbon atom, and * may each independently be the bonding position with a carbon atom contained in the structure represented by Formula (2-1) (the C atom in “-CO-*”) or a carbon atom contained in another structure.

[0014] R 1 and (R) n Examples of the group represented by and include the groups represented by the following formulae.

Chemical formula

[0015] The linking group may be, for example, an alkylene group (such as -CH2-, -C(CH3)2-), -CO-, -SO2-, or -O-.

[0016] Specific examples of the group represented by Formula (1-3) include the groups represented by the following formulae.

Chemical formula

Chemical formula

[0017] In some embodiments, the polyamideimide contains a structure represented by formula (1-1) (wherein R 1 and (R) n and the group represented by is a group represented by formula (1-3).), and preferably, the polyamideimide contains a structure represented by formula (1-1) (wherein R 1 and (R) n and the group represented by is a group represented by formula (1-4).). In some embodiments, the polyamideimide further contains a structure represented by formula (1-2) (wherein R 1 and (R) n and the group represented by is a group represented by formula (1-3).), and preferably, the polyamideimide further contains a structure represented by formula (1-2) (wherein R 1 and (R) n and the group represented by is a group represented by formula (1-4).).

[0018] The structure represented by formula (1-1) and the structure represented by formula (1-2) can be introduced into the polyamideimide using a diisocyanate compound having a carboxy group, a diamine compound having a carboxy group, or both of them, which will be described later.

[0019] The polyamideimide may further contain a structure represented by the following formula (2-1). The polyamideimide may contain the structure represented by the following formula (2-1) alone or in combination of two or more kinds.

[0020]

Chemical formula

[0021] In formula (2-1), the organic group is, for example, a group containing at least one selected from the group consisting of a saturated aliphatic hydrocarbon group, an unsaturated aliphatic hydrocarbon group, a saturated alicyclic hydrocarbon group, an unsaturated alicyclic hydrocarbon group, an aromatic hydrocarbon group, an aromatic heterocyclic compound group, and a group consisting of two or more selected from these. These groups may or may not have a substituent. Examples of the substituent include an alkyl group (e.g., having 1 to 20 or 1 to 6 carbon atoms), a hydroxy group, an alkoxy group (e.g., having 1 to 20 or 1 to 6 carbon atoms), and the like. The organic group may be a group containing an aromatic hydrocarbon group, and preferably may be a group containing a benzene ring. The aromatic hydrocarbon group and the benzene ring may each have or may not have a substituent.

[0022] * represents the bonding position with another atom. * may be, for example, the bonding position with a nitrogen atom, and each * may independently be the bonding position with a nitrogen atom contained in the structure represented by formula (1-1), a nitrogen atom contained in the structure represented by formula (1-2) (the N atom in “-N(-*)-*”), or a nitrogen atom contained in another structure.

[0023] R 2 Examples of R include groups represented by the following formulas.

Chemical formula

Chemical formula

[0024] The linking group may be, for example, an alkylene group (-CH2-, -C(CH3)2-, etc.), -CO-, -SO2-, or -O-.

[0025] Preferably, the polyamideimide contains a structure represented by formula (2-1) (wherein R 2 is a group represented by formula (2-3).).

[0026] The structure represented by formula (2-1) can be introduced into the polyamideimide using a tricarboxylic acid compound described later.

[0027] The polyamideimide may further contain at least one structure selected from the group consisting of the structure represented by the following formula (3-1) and the structure represented by the following formula (3-2). The polyamideimide may contain the structure represented by the following formula (3-1) and the structure represented by the following formula (3-2) alone or in combination of two or more. The structure represented by the following formula (3-1) and the structure represented by the following formula (3-2) are different from the structure represented by formula (1-1) and the structure represented by formula (1-2), respectively, and do not have a carboxy group in the structure. [Chemical formula] (wherein R 3 represents an organic group. * represents the bonding position with another atom.) [Chemical formula] (wherein R 3 represents an organic group. * represents the bonding position with another atom.)

[0028] In formulas (3-1) and (3-2), the organic group is, for example, a group selected from the group consisting of at least one group selected from saturated aliphatic hydrocarbon groups, unsaturated aliphatic hydrocarbon groups, saturated alicyclic hydrocarbon groups, unsaturated alicyclic hydrocarbon groups, aromatic hydrocarbon groups, aromatic heterocyclic compound groups, and groups composed of two or more selected from these. These groups may or may not have a substituent (except for a carboxy group). Examples of the substituent include an alkyl group (e.g., having 1 to 20 or 1 to 6 carbon atoms), a hydroxy group, an alkoxy group (e.g., having 1 to 20 or 1 to 6 carbon atoms), etc. The substituent may be an alkyl group and may be a methyl group. The organic group may be a group containing an aromatic hydrocarbon group, and preferably may be a group containing a benzene ring. The aromatic hydrocarbon group and the benzene ring may each have or may not have a substituent.

[0029] * represents the bonding position with another atom. * may be, for example, the bonding position with a carbon atom, and * may each independently be the bonding position with a carbon atom contained in the structure represented by formula (2-1) (the C atom in “-C(O)-*”) or a carbon atom contained in another structure.

[0030] R 3 Examples of the group represented by include the groups represented by the following formulas.

Chemical formula

[0031] The linking group may be, for example, an alkylene group (-CH2-, -C(CH3)2-, etc.), -CO-, -SO2-, or -O-.

[0032] Specific examples of the group represented by formula (3-3) include the groups represented by the following formulas.

Chemical formula

Chemical formula

[0033] In some embodiments, the polyamideimide contains at least one structure selected from the group consisting of the structure represented by formula (3-1) (wherein R 3 is a group represented by formula (3-3)) and the structure represented by formula (3-2) (wherein R 3 is a group represented by formula (3-3)). Preferably, the polyamideimide contains at least one structure selected from the group consisting of the structure represented by formula (3-1) (wherein R 3 is a group represented by formula (3-4)) and the structure represented by formula (3-2) (wherein R 3 is a group represented by formula (3-4)).

[0034] The structure represented by formula (3-1) and the structure represented by formula (3-2) can be introduced into the polyamideimide using a diisocyanate compound, a diamine compound, or both described below.

[0035] When the polyamideimide contains at least one structure selected from the group consisting of the structure represented by the formula (3-1) and the structure represented by the formula (3-2), based on the total of the structure represented by the formula (1-1), the structure represented by the formula (1-2), the structure represented by the formula (3-1), and the structure represented by the formula (3-2), the content rate (when only one of them is included, the content rate of that one only) of the total of the structure represented by the formula (1-1) and the structure represented by the formula (1-2) is, from the viewpoint of improving charge-discharge characteristics, for example, 10 to 60% by mass, 15 to 50% by mass, or 20 to 45% by mass. The content rate (when only one of them is included, the content rate of that one only) of the total of the structure represented by the formula (3-1) and the structure represented by the formula (3-2) is, for example, 40 to 90% by mass, 50 to 85% by mass, or 55 to 80% by mass.

[0036] When the polyamideimide contains at least one structure selected from the group consisting of the structure represented by the formula (3-1) and the structure represented by the formula (3-2), based on the total of the structure represented by the formula (1-1), the structure represented by the formula (1-2), the structure represented by the formula (3-1), and the structure represented by the formula (3-2), the content rate (molar ratio) of the total of the structure represented by the formula (1-1) and the structure represented by the formula (1-2) (when only one of them is included, the content rate of that one only) is, from the viewpoint of improving charge-discharge characteristics, for example, 0.05 to 0.60, 0.10 to 0.50, or 0.15 to 0.45. The content rate (molar ratio) of the total of the structure represented by the formula (3-1) and the structure represented by the formula (3-2) (when only one of them is included, the content rate of that one only) is, for example, 0.40 to 0.95, 0.50 to 0.90, or 0.55 to 0.85.

[0037] Polyamideimide is a polymer having an amide bond and an imide bond in the molecule. Polyamideimide can be obtained using at least a diisocyanate compound and / or a diamine compound and a tricarboxylic acid compound (excluding compounds having an isocyanate group and / or an amino group).

[0038] For example, as the diisocyanate compound and the diamine compound, compounds represented by the following formula (1-6) and compounds represented by the following formula (3-6) can be mentioned. The diisocyanate compound and the diamine compound are used alone or in combination. The diisocyanate compound and the diamine compound contain at least a compound represented by the following formula (1-6).

[0039] [Chemical formula] (In the formula, R 1 represents an organic group, R represents a carboxy group, Z represents an isocyanate group or an amino group. n represents an integer of 1 to 5.) [Chemical formula] (In the formula, R 3 represents an organic group, Z represents an isocyanate group or an amino group.)

[0040] R 1 、R, n, and R 3 are as described above, and preferred embodiments, specific examples, etc. are also as described above.

[0041] As the compound represented by formula (1-6) (wherein the group represented by R 1 and (R) n is a group represented by formula (1-3) or a group represented by formula (1-4).), for example, 4,4'-diisocyanato-3,3'-dicarboxybiphenyl, 4,4'-diisocyanato-2,2'-dicarboxybiphenyl, bis(4-isocyanato-3-carboxyphenyl)methane, bis(4-isocyanato-2-carboxyphenyl)methane, 4,4'-diamino-3,3'-dicarboxybiphenyl, 4,4'-diamino-2,2'-dicarboxybiphenyl, bis(4-amino-3-carboxyphenyl)methane, bis(4-amino-2-carboxyphenyl)methane, etc. can be mentioned.

[0042] As the compound represented by formula (3-6) (wherein R 3The group represented by formula (3-3) or the group represented by formula (3-4) is a group represented by formula (3-3) or a group represented by formula (3-4).) As such, for example, 4,4'-diisocyanatodiphenylmethane, 4,4'-diisocyanatobiphenyl, 3,3'-diisocyanatobiphenyl, 3,4'-diisocyanatobiphenyl, 4,4'-diisocyanato-3,3'-dimethylbiphenyl, 4,4'-diisocyanato-2,2'-dimethylbiphenyl, 4,4'-diisocyanato-3,3'-diethylbiphenyl, 4,4'-diisocyanato-2,2'-diethylbiphenyl, 4,4'-diisocyanato-3,3'-dimethoxybiphenyl, 4,4'-diisocyanato-2,2'-dimethoxybiphenyl, 4,4'-diaminodiphenylmethane, 4,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 3,4'-diaminobiphenyl, 4,4'-diamino-3,3'-dimethylbiphenyl, 4,4'-diamino-2,2'-dimethylbiphenyl, 4,4'-diamino-3,3'-diethylbiphenyl, 4,4'-diamino-2,2'-diethylbiphenyl, 4,4'-diamino-3,3'-dimethoxybiphenyl, 4,4'-diamino-2,2'-dimethoxybiphenyl and the like can be mentioned.

[0043] As the compound represented by formula (3-6), other aromatic diisocyanate compounds and / or aromatic diamine compounds other than the above compounds can be used. Examples of other aromatic diisocyanate compounds or aromatic diamine compounds include 1,4-phenylene diisocyanate, 1,5-diisocyanatonaphthalene, 2,6-diisocyanatonaphthalene, tolylene diisocyanate, xylylene diisocyanate, 4,4'-diisocyanatodiphenyl ether, 2,2-bis[4-(4'-isocyanatophenoxy)phenyl]propane, 1,4-phenylenediamine, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, tolylene diamine, xylylene diamine, 4,4'-diaminodiphenyl ether, 2,2-bis[4-(4'-aminophenoxy)phenyl]propane and the like.

[0044] As the compound represented by formula (3-6), an aliphatic or alicyclic diisocyanate compound and / or an aliphatic or alicyclic diamine compound can be used. Together with the diisocyanate compound and / or diamine compound, a monofunctional isocyanate compound and / or amine compound, a polyfunctional isocyanate compound and / or amine compound having three or more functional groups, etc. can be used in combination as necessary. When necessary to avoid daily changes, a compound in which the isocyanate group is stabilized with a blocking agent may be used. Examples of the blocking agent include alcohol, phenol, oxime, etc., but there is no particular limitation.

[0045] The usage amount of the diisocyanate compound and diamine compound based on the mass of the isocyanate compound and amine compound is, for example, 90 to 100% by mass, 95 to 100% by mass, or 98 to 100% by mass. When using the compound represented by formula (1-6), the usage amount of the compound represented by formula (1-6) based on the mass of the diisocyanate compound and diamine compound is, from the viewpoint of improving charge-discharge characteristics, for example, 10 to 60% by mass, 15 to 50% by mass, or 20 to 45% by mass. When using the compound represented by formula (3-6), the usage amount of the compound represented by formula (3-6) based on the mass of the diisocyanate compound and diamine compound is, for example, 40 to 90% by mass, 50 to 85% by mass, or 55 to 80% by mass.

[0046] When using the compound represented by formula (1-6), the usage ratio (molar ratio) of the compound represented by formula (1-6) based on the diisocyanate compound and diamine compound is, from the viewpoint of improving charge-discharge characteristics, for example, 0.05 to 0.60, 0.10 to 0.50, or 0.15 to 0.45. When using the compound represented by formula (3-6), the usage ratio (molar ratio) of the compound represented by formula (3-6) based on the diisocyanate compound and diamine compound is, for example, 0.40 to 0.95, 0.50 to 0.90, or 0.55 to 0.85.

[0047] As the tricarboxylic acid compound, there is no particular limitation as long as it is a trivalent carboxylic acid having a carboxylic anhydride group capable of reacting with an isocyanate group or an amino group, including its derivatives. Examples of the derivatives include esters, halides, and the like. Considering heat resistance, compounds having an aromatic ring group are preferred. The aromatic ring group may be an aromatic hydrocarbon group, an aromatic heterocyclic compound group, or a group composed of two or more selected from these. For example, as the tricarboxylic anhydride, compounds represented by the following formula (2-4) and compounds represented by the following formula (2-5) can be mentioned. The tricarboxylic acid compound is used alone or in combination. Considering heat resistance, cost, etc., it is particularly preferable that the acid component contains trimellitic anhydride.

[0048] [Chemical formula] (In the formula, Y represents -CH2-, -CO-, -SO2-, -O-, or a direct bond. Each benzene ring may be independently substituted or unsubstituted.) [Chemical formula] (In the formula, the benzene ring may be substituted or unsubstituted.)

[0049] Together with the tricarboxylic acid compound, a dicarboxylic acid compound and / or a tetracarboxylic acid compound can be used in combination as necessary. The tricarboxylic acid compound, dicarboxylic acid compound, and tetracarboxylic acid compound may be collectively referred to as a carboxylic acid compound. In this specification, a compound having a carboxy group and an isocyanate group or an amino group shall be regarded as corresponding to an isocyanate compound or an amine compound.

[0050] The amount of the tricarboxylic acid compound based on the mass of the carboxylic acid compound is, for example, 90 to 100% by mass, 95 to 100% by mass, or 98 to 100% by mass. When using the compound represented by formula (2-5), the amount of the compound represented by formula (2-5) based on the mass of the tricarboxylic acid compound is, for example, 30 to 100% by mass, 70 to 100% by mass, or 95 to 100% by mass.

[0051] When the carboxylic acid compound, the isocyanate compound, and the amine compound (when only one of them is used, the said one compound) have a carboxy group, an acid anhydride group, and a reactive hydroxy group, it is preferable to react them so that the ratio of the total number of isocyanate groups and amino groups to the total number of those functional groups is preferably 0.6 to 1.4, more preferably 0.7 to 1.3, and still more preferably 0.8 to 1.2. When this ratio is 0.6 or more, there is a tendency that it becomes easy to increase the molecular weight of the polyamideimide. When this ratio is 1.4 or less, it is possible to prevent the reaction accompanied by foaming from becoming intense and the remaining amount of unreacted substances from increasing, and there is a tendency that good stability of the polyamideimide is easily obtained. In the polyamideimide, an amide group and an imide group are introduced by the reaction of the tricarboxylic acid compound with the diisocyanate compound and / or the diamine compound. Since the compound represented by formula (1-6) has a carboxy group and an isocyanate group or an amino group, an amide bond may be introduced into the polyamideimide by the reaction of the compounds represented by formula (1-6) with each other. When using the compound represented by formula (3-6), an amide bond may be introduced by the reaction of the compound represented by formula (1-6) and the compound represented by formula (3-6).

[0052] The amount of the solvent used during the reaction is preferably 100 to 300 parts by mass, more preferably 150 to 250 parts by mass, based on 100 parts by mass of the total amount of the carboxylic acid compound, the isocyanate compound, and the amine compound. When the amount of the solvent used is 100 parts by mass or more, the reaction accompanied by foaming can be easily prevented. When the amount of the solvent used is 300 parts by mass or less, the synthesis time can be prevented from becoming too long, and the concentration of the polyamideimide contained in the solution obtained after the synthesis tends to be sufficient. Examples of the solvent include polar solvents such as N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone (NEP), γ-butyrolactone (GBL), 3-methoxy-N,N-dimethylpropanamide (MPA), N,N'-dimethylformamide, N,N'-dimethylpropyleneurea [1,3-dimethyl-3,4,5,6-tetrahydropyrimidin-2(1H)-one], dimethyl sulfoxide, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, and sulfolane; aromatic hydrocarbon solvents such as xylene and toluene; and ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone. The solvent preferably contains at least one selected from the group consisting of N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone (NEP), γ-butyrolactone (GBL), and 3-methoxy-N,N-dimethylpropanamide (MPA), and more preferably contains at least one selected from the group consisting of N-methyl-2-pyrrolidone (NMP), γ-butyrolactone (GBL), and 3-methoxy-N,N-dimethylpropanamide (MPA).

[0053] For the reaction, a catalyst may or may not be used from the viewpoint of reaction efficiency or from the viewpoint of reducing residual impurities. For example, when a fluorine-based catalyst such as potassium fluoride is not used, contamination by fluorine is prevented, and thus a polyamideimide excellent in properties such as electrochemical stability can be obtained.

[0054] The synthesis conditions of polyamide-imide are diverse and cannot be specified generally. For example, it can be carried out at a temperature of 80 to 180 °C. The synthesis is preferably carried out under an atmosphere such as nitrogen in order to reduce the influence of moisture in the air.

[0055] The synthesized polyamide-imide can be obtained, for example, as a polyamide-imide solution dissolved in the solvent used in the reaction.

[0056] The polyamide-imide preferably has a number average molecular weight of 3,000 to 100,000. When the number average molecular weight is 3,000 or more, various properties such as viscosity and strength tend to improve. The number average molecular weight of the polyamide-imide may be 5,000 or more, 7,000 or more, 8,000 or more, or 8,500 or more. When the number average molecular weight is 100,000 or less, good adhesion to the current collector is likely to be obtained. The number average molecular weight of the polyamide-imide may be 50,000 or less, 30,000 or less, 20,000, or 18,000 or less.

[0057] The polyamide-imide preferably has a dispersity (Mw / Mn) of 2.8 or less. The smaller the dispersity, the more likely it is to form an electrode with excellent properties. The lower limit of the dispersity may be 1.0 or more. The dispersity of the polyamide-imide is more preferably 1.1 to 2.5, and even more preferably 1.1 to 2.3.

[0058] The number average molecular weight and weight average molecular weight of the polyamide-imide can be measured by gel permeation chromatography (GPC) using a calibration curve of standard polystyrene. The number average molecular weight and weight average molecular weight of the polyamide-imide can be controlled and adjusted by repeating sampling and measurement during synthesis and continuing the synthesis until the target number average molecular weight is reached.

[0059] The polyamideimide has an acid value of, for example, 15 to 70 mgKOH / g, 20 to 65 mgKOH / g, or 25 to 60 mgKOH / g. When the acid value is 15 mgKOH / g or more, the adhesion to the active material, current collector, etc. and the strength of the electrode binder layer tend to improve. When the acid value is 70 mgKOH / g or less, the decrease in adhesion can be prevented. The acid value may be 30 mgKOH / g or more, 40 mgKOH / g or more, or 50 mgKOH / g or more.

[0060] The acid value of the polyamideimide can be measured by the potentiometric titration method. For the titration, for example, a 0.05 mol / L aqueous potassium hydroxide solution can be used.

[0061] <Material for electrode formation> The material for electrode formation according to an embodiment of the present invention is used for forming an electrode. The material for electrode formation contains at least the polyamideimide of the above embodiment.

[0062] The material for electrode formation contains at least polyamideimide, and may further contain materials known as binders for electrodes such as polyolefins and acrylic polymers. Since the polyamideimide of the above embodiment has a carboxy group, a crosslinked structure is introduced by heating, and it is presumed that a stronger polymer network can be formed and the charge and discharge characteristics of the battery can be improved. However, the present invention is not limited by this presumption. When the active material contains a silicon-based active material, the polyamideimide of the above embodiment can prevent deformation of the electrode because it is difficult to follow the volume change of the silicon-based active material, and can improve the reliability of the electrode because it exhibits excellent adhesiveness. In addition, since polyamideimide has good chemical resistance, it is hardly affected by the electrolyte.

[0063] <Electrode binder> The electrode binder according to an embodiment of the present invention contains at least an active material and the material for electrode formation of the above embodiment. The electrode binder may be a slurry containing a solvent. The electrode binder may contain any components such as conductive materials and additives.

[0064] The active material contains at least a carbon-based active material, and may contain a carbon-based active material and a silicon-based active material. The carbon-based active material may be a carbon material, for example, an amorphous carbon material, natural graphite, a composite carbon material formed by forming a coating of an amorphous carbon material on natural graphite, artificial graphite (graphite obtained by firing a resin raw material such as an epoxy resin or a phenol resin, or a pitch-based raw material obtained from petroleum, coal, etc.), and the like. The carbon-based active material preferably contains natural graphite and / or artificial graphite. The silicon-based active material contains at least silicon, and examples thereof include a silicon-containing alloy, a silicon-containing oxide, a silicon-containing nitride, or a silicon-containing carbide. Examples of the silicon-containing alloy include an alloy containing silicon and at least one selected from the group consisting of tin, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony, and chromium. Specific examples of the silicon-containing oxide include SiO, SiO2, LiSiO, etc., specific examples of the silicon-containing nitride include Si3N4, Si2N2O, etc., and examples of the silicon-containing carbide include SiC, etc.

[0065] When the active material contains a carbon-based active material and a silicon-based active material, the content of the silicon-based active material is preferably 10% by mass or more based on the mass of the active material. When the content of the silicon-based active material is 10% by mass or more, the discharge capacity tends to be larger. The content of the silicon-based active material may be 15% by mass or more, 20% by mass or more, 25% by mass or more, or 30% by mass or more. The content of the silicon-based active material may be less than 100% by mass based on the mass of the active material. By the active material containing a carbon-based active material, a decrease in cycle characteristics can be prevented, and the handleability tends to be excellent. The content of the silicon-based active material may be 80% by mass or less, 70% by mass or less, 50% by mass or less, 45% by mass or less, 40% by mass or less, 35% by mass or less, or 30% by mass or less.

[0066] Examples of the solvent include the solvents exemplified as solvents that can be used for the synthesis of polyamideimide. The solvent used for the synthesis of polyamideimide and the solvent contained in the electrode binder may be the same. The content of the active material is preferably 80% by mass or more based on the total mass of the components other than the solvent contained in the electrode binder. When the content of the active material is 80% by mass or more, the discharge capacity tends to be further improved. The content of the active material may be 85% by mass or more, 88% by mass or more, 90% by mass or more, 93% by mass or more, or 95% by mass or more. Considering the content of the binder, the content of the active material may be, for example, 99% by mass or less, 98% by mass or less, 97% by mass or less, 96% by mass or less, or 95% by mass or less based on the total mass of the components other than the solvent contained in the electrode binder.

[0067] Examples of the conductive material include carbon blacks such as acetylene black and ketjen black, carbon materials such as graphite, graphene, and carbon nanotubes. As the active material, a material that can function as an active material, for example, a material having a structure capable of occluding and releasing an electrolyte such as lithium ions can be selected and used, while as the conductive material, a material that cannot function as an active material, for example, a material not having a structure capable of occluding and releasing an electrolyte such as lithium ions can be selected and used. When the electrode binder contains a conductive material, the content of the conductive material may be, for example, 0.01% by mass or more, 0.1% by mass or more, or 1% by mass or more based on the total mass of the components other than the solvent contained in the electrode binder. The content of the conductive material may be, for example, 50% by mass or less, 30% by mass or less, or 15% by mass or less based on the total mass of the components other than the solvent contained in the electrode binder.

[0068] <Electrode for Energy Device> The electrode for an energy device according to an embodiment of the present invention includes at least a current collector and an electrode binder layer formed on at least a part of the surface of the current collector. The electrode binder layer can be formed using the electrode binder of the above embodiment.

[0069] Examples of the material of the current collector include copper, stainless steel, nickel, aluminum, titanium, fired carbon, conductive polymer, conductive glass, aluminum-cadmium alloy, etc. From the viewpoint of improving adhesiveness, conductivity, and reduction resistance, the surface of the current collector may be treated with carbon, nickel, titanium, silver, etc. Examples of the shape of the current collector include a plate, a film, etc.

[0070] When the current collector is in the shape of a plate or a film, the electrode has at least the current collector and an electrode binder layer formed on one surface or both surfaces of the current collector. The electrode binder layer can be formed, for example, according to the following method. First, a binder is prepared by mixing at least an active material containing a silicon-based active material and a carbon-based active material, a material for forming an electrode, and a solvent. Next, the electrode binder is applied to at least one surface of the current collector to form a coating film. Then, the solvent contained in the coating film is volatilized. After volatilizing the solvent, the coating film is compression molded. Examples of the coating method include the doctor blade method, the dipping method, the spraying method, the transfer roll method, etc. Examples of the compression molding method include the method of roll pressing.

[0071] The compression molding can be performed while heating the coating film. After performing the compression molding at room temperature or under heating, the coating film may be heated. The heating temperature may be, for example, 200 °C or higher, 250 °C or higher, or 260 °C or higher. The heating temperature may be 300 °C or lower, 290 °C or lower, or 280 °C or lower. By using the material for forming an electrode of the above embodiment, even when the heating temperature is low, an electrode binder layer with good adhesion between the active materials and between the active material and the current collector can be formed. For example, the heating temperature can be about 30 to 100 °C lower than the case of using polyimide as the binder.

[0072] <Energy device> An energy device according to an embodiment of the present invention has a positive electrode and a negative electrode, and at least one of the positive electrode and the negative electrode includes an electrode for an energy device of the embodiment. Examples of the energy device include a non-aqueous electrolyte secondary battery, a capacitor, and the like. The non-aqueous electrolyte secondary battery is preferably a lithium-ion secondary battery.

[0073] The non-aqueous electrolyte secondary battery includes, for example, an electrode group including a positive electrode, a negative electrode, and a separator, and a battery exterior body that houses the electrode group. The battery exterior body is filled with an electrolytic solution. The non-aqueous electrolyte secondary battery may be a so-called laminate-type battery or a battery having a shape other than the laminate type (coin type, cylindrical type, laminated type, etc.).

[0074] Examples of the separator include, but are not particularly limited to, a polyethylene nonwoven fabric, a polypropylene nonwoven fabric, a polyamide nonwoven fabric, and a nonwoven fabric obtained by subjecting these to a hydrophilic treatment. The battery exterior body may be, for example, a container formed of a laminate film. Examples of the laminate film include a laminate film in which a resin film such as a polyethylene terephthalate (PET film), a metal foil such as aluminum, copper, or stainless steel, and a sealant layer such as polypropylene are laminated in this order.

[0075] The electrolytic solution contains, for example, an electrolyte salt and a non-aqueous solvent. The electrolyte salt may be a lithium salt. Examples of the lithium salt may include at least one selected from the group consisting of LiPF6, LiBF4, LiClO4, LiB(C6H5)4, LiCH3SO3, CF3SO2OLi, LiN(SO2F)2 (Li[FSI], lithium bis(fluorosulfonyl)imide), LiN(SO2CF3)2 (Li[TFSI], lithium bis(trifluoromethanesulfonyl)imide), and LiN(SO2CF2CF3)2. The non-aqueous solvent may be, for example, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, γ-butyrolactone, acetonitrile, 1,2-dimethoxyethane, dimethoxymethane, tetrahydrofuran, dioxolane, methylene chloride, methyl acetate, etc. The electrolytic solution may contain additives such as vinylene carbonate.

[0076] The energy device includes, as at least one of the positive electrode and the negative electrode, the electrode for an energy device of the above embodiment. Preferably, at least the negative electrode is the electrode for an energy device of the above embodiment. When the energy device includes an electrode other than the electrode for an energy device of the above embodiment, the electrode may be a general electrode used in the field of energy devices. For example, a general positive electrode has at least a current collector and a positive electrode mixture layer formed on at least a part of the surface of the current collector. The positive electrode mixture layer contains at least a positive electrode active material and a binder, and may further contain a conductive material or the like.

[0077] The positive electrode active material may be, for example, nickel cobalt manganese oxide (NCM), lithium cobalt dioxide (LCO), nickel cobalt aluminum oxide (NCA), lithium manganese oxide (LMO), etc. Examples of the current collector and the conductive material include the current collector and the conductive material exemplified in the electrode for an energy device of the above embodiment.

Examples

[0078] Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto.

[0079] <Preparation of Electrode-Forming Material (Polyamide Imide)> [Example 1] 192.0 g of trimellitic anhydride, 114.5 g of bis(4-amino-3-carboxyphenyl)methane, 150.0 g of bis(4-isocyanatophenyl)methane, and 760 g of N-methyl-2-pyrrolidone (NMP) were placed in a flask equipped with a thermometer, a stirrer, and a condenser tube, and while stirring in a dried nitrogen stream, the temperature was gradually raised to 130°C over 2 hours. While paying attention to the rapid foaming of carbon dioxide gas generated by the reaction, the temperature was maintained at 130°C, and heating was continued for 6 hours as it was, and then the reaction was stopped to obtain a polyamide imide solution.

[0080] The nonvolatile content (200°C - 2 h) of the obtained polyamide imide solution was 32% by mass. The number average molecular weight of the polyamide imide was measured using a calibration curve of standard polystyrene under the following conditions by gel permeation chromatography (GPC). The acid value of the polyamide imide was measured by potentiometric titration. For the titration, a 0.05 mol / L aqueous potassium hydroxide solution was used. The number average molecular weight and the acid value are shown in Table 1. The "MBAA ratio" in Table 1 is the molar ratio obtained from (MBAA) / (MBAA + MDI + MDA).

[0081] Model: Manufactured by Hitachi, Ltd. Product name: L6000 Detector: Manufactured by Hitachi, Ltd. Product name: L4000 type UV Wavelength: 270 nm Data processor: ATT 8 Column: Manufactured by Hitachi High-Tech Corporation Product name: Gelpack GL-S300MDT-5×2 Column size: Diameter 8 mm × 300 mm Solvent: DMF / THF = 1 / 1 (liter) + 0.06 M phosphoric acid + 0.06 M lithium bromide Sample concentration: 5 mg / 1 mL Injection volume: 5 μL Pressure: 4.8×106 Pa (49 kgf / cm 2 ) Flow rate: 1.0 mL / min

[0082] [Examples 2, 3 and Comparative Examples 1, 2] A polyamideimide solution was obtained in the same manner as in Example 1, except that the types and amounts of the raw material monomers were changed as shown in Table 1. However, in Example 3, it was maintained at 130 °C and heating was continued for 8 hours as it was.

[0083] In Table 1, the abbreviations for the raw material monomers mean the following compounds. MBAA: 5,5'-methylenebis(2-aminobenzoic acid) (bis(4-amino-3-carboxyphenyl)methane) MDI: Diphenylmethane diisocyanate (bis(4-isocyanatophenyl)methane) MDA: 4,4'-Diaminodiphenylmethane TMAC: Trimellitic anhydride

[0084] [Fabrication and Evaluation of Lithium-Ion Secondary Batteries] [Fabrication of Negative Electrode] A silicon-based active material (Si alloy) and a carbon-based active material (graphite, "SMGYM2" manufactured by Hitachi Chemical Co., Ltd.) were used as the negative electrode active material. The negative electrode active material and the solution containing the polyamideimide and NMP obtained above (polyamideimide solution) were mixed so that the mass ratio of the solid content (carbon-based active material: silicon-based active material: polyamideimide) was 105:45:25 so that the volumetric density would be 600 mAh / kg, and NMP was further added for viscosity adjustment to obtain a slurry-like negative electrode mixture. The obtained negative electrode mixture was applied substantially evenly and homogeneously to one side of a current collector (metal foil (Cu, 10 μm)). Thereafter, the coating film was dried, compression molded by pressing, and then heated at 270 °C for 30 minutes for curing treatment to obtain a negative electrode.

[0085] [Fabrication of Secondary Battery] A positive electrode composite agent layer containing NCM111 (nickel cobalt manganese oxide, manufactured by BASF Toda Battery Materials Co., Ltd.) as a positive electrode active material and a current collector (metal foil (Al, 15 μm)) were used to obtain a positive electrode. Using this positive electrode and the negative electrode obtained above, a secondary battery containing an electrolytic solution (ethylene carbonate (EC) / ethyl methyl carbonate (EMC) (1 vol / 2 vol) + vinylene carbonate (VC) (1 wt%)) was fabricated.

[0086] (Measurement of the discharge rate characteristics of the battery) Regarding the obtained secondary battery, the discharge rate characteristics at 25 °C were measured using a charge-discharge device under the following charge-discharge conditions. After performing constant current constant voltage (CCCV) charging at a termination voltage of 4.2 V and 0.2 C, a cycle of discharging at a constant current (CC) to a termination voltage of 2.5 V at 0.2 C was performed once. The capacity during this discharge was defined as the discharge capacity at a current value of 0.2 C. Next, after performing constant current constant voltage (CCCV) charging at a termination voltage of 4.2 V and 1.5 C, a cycle of discharging at a constant current (CC) to a termination voltage of 2.5 V at 1.5 C was performed once. The capacity during this discharge was defined as the discharge capacity at a current value of 1.5 C. The discharge rate characteristics (%) = (discharge capacity at a current value of 0.5 C) / (discharge capacity at a current value of 0.2 C) × 100, and the discharge rate characteristics were determined. The results are shown in Table 1.

[0087]

Table 1

Claims

1. A polyamideimide containing a structure represented by the following formula (1-1). 【Chemical 1】 (wherein, R １ represents an organic group, R represents a carboxy group, n represents an integer of 1 to 5. * represents a bonding position with another atom.)

2. The polyamideimide according to Claim 1, having a number average molecular weight of 3,000 to 100,000.

3. R １ and (R) ｎ The polyamideimide according to claim 1, wherein the group represented by and is a group represented by the following formula (1-4). 【Chemical Formula 2】 (In the formula, * represents the bonding position with a nitrogen atom.)

4. A material for forming an electrode, containing the polyamideimide according to Claim 1.

5. An electrode binder, containing the material for forming an electrode according to Claim 4 and a carbon-based active material.

6. The electrode binder according to Claim 5, further containing a silicon-based active material.

7. An electrode for an energy device, having a current collector and an electrode binder layer formed on at least a part of the surface of the current collector using the electrode binder according to Claim 5 or 6.

8. An energy device, having a positive electrode and a negative electrode, wherein at least one of the positive electrode and the negative electrode includes the electrode for an energy device according to Claim 7.

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