Resin composition, electrode using the same, secondary battery including electrodes, and capacitor

Abstract

To provide a resin composition on which low-temperature treatment can be performed and in which a treated film has high mechanical characteristics and adhesiveness, an electrode using the same, a secondary battery including the electrodes, and a capacitor.SOLUTION: A resin composition contains components (a) and (b); (a) at least one resin ("resin (a)" hereafter) selected from among polyimide, polyamide-imide, polyether, polyether ketone, polyether ether ketone, polysulfone, polyether sulfone, polyamide and precursor thereof; and (b) a solvent ("solvent (b)" hereafter) of which the Hansen solubility parameter is 16 (MPa)1 / 2 or more to 20 (MPa)1 / 2 or less. In the resin composition, the content of the solvent (b) is 50 mass% or more of all the solvents contained in the composition.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition, an electrode using the same, and a secondary battery and a capacitor including the electrode. [Background technology]

[0002] In recent years, with the explosive spread of notebook personal computers and small portable terminals, there has been an increasing demand for rechargeable secondary batteries that are small, lightweight, high capacity, high energy density, and highly reliable.

[0003] Additionally, the automotive industry is looking to reduce carbon dioxide emissions through the introduction of electric vehicles (EVs) and hybrid electric vehicles (HEVs), and there is active development of secondary batteries for motor drive, which hold the key to making these vehicles practical.

[0004] Lithium-ion secondary batteries, which are said to have the highest theoretical energy of all batteries, have attracted particular attention and are currently being rapidly developed. The currently widely used lithium-ion battery consists of a positive electrode, formed by applying a paste containing a positive electrode active material (such as lithium cobalt oxide or other lithium-containing composite oxides) and a binder (such as polyvinylidene fluoride (PVDF)) to aluminum foil, and a negative electrode, formed by applying a paste containing a carbon-based negative electrode active material (capable of absorbing and releasing lithium ions) and a binder (such as PVDF or styrene-butadiene rubber (SBR)) to copper foil, connected by a separator and an electrolyte layer and sealed.

[0005] To further increase the capacity of lithium-ion batteries, the use of silicon, germanium, or tin as the negative electrode active material has been investigated (see, for example, Patent Document 1). Because negative electrode active materials using silicon, germanium, tin, etc. can absorb large amounts of lithium ions, they undergo a large change in volume between full charge and full discharge. Conventional binders cannot keep up with the volume change of the active material, resulting in a decrease in capacity retention during charge-discharge cycles. For this reason, binders suitable for negative electrodes with large volume expansion have been investigated (see, for example, Patent Documents 2 and 3). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-199761 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-245773 [Patent Document 3] International Publication No. 2017 / 099172 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the sodium salt of carboxymethyl cellulose, which is described in Patent Document 1 as a specific binder for negative electrodes that have a large volume expansion, still lacks strength and has the problem of not being able to achieve a sufficient capacity retention rate during charge-discharge cycles.

[0008] The polyimide binder described in Patent Document 2 has high binder strength, but has problems such as oxidation degradation of the electrode because high-temperature treatment at 300°C or higher is required during electrode production to convert the polyimide precursor into a polyimide structure.

[0009] The binder described in Patent Document 3 has high strength even when the processing temperature is lowered, and sufficient film properties are obtained to suppress electrode deterioration due to volume changes during charging and discharging and obtain a high capacity retention rate. However, when the processing temperature is lowered to 150°C or lower, which is the processing temperature for general-purpose batteries, there is a problem in that the mechanical properties (strength, elongation) and adhesiveness of the film cannot be fully demonstrated.

[0010] Therefore, an object of the present invention is to provide a resin composition that can be treated at low temperatures and that produces a film having high mechanical properties and adhesiveness after treatment, an electrode using the same, and a secondary battery and a capacitor that include these electrodes. [Means for solving the problem]

[0011] In order to solve the above problems, the present invention has the following configuration. <1> The following ingredients (a) and (b): (a) at least one resin selected from the group consisting of polyimide, polyamideimide, polyether, polyetherketone, polyetheretherketone, polysulfone, polyethersulfone, polyamide, and any precursor thereof (hereinafter referred to as "(a) resin"); (b) Hansen solubility parameter is 16 (MPa) 1 / 2 Over 20 (MPa) 1 / 2 A solvent that is one of the following (hereinafter referred to as "(b) solvent") A resin composition comprising: A resin composition, wherein the content of the (b) solvent is 50 mass % or more of the total solvent contained in the composition. <2> The (a) resin is a polyimide resin containing a structural unit represented by formula (1). <1> The resin composition according to claim 1.

[0012] [ka]

[0013] (In formula (1), R 1 represents a divalent organic group having 2 to 50 carbon atoms, and R 2 represents a tetravalent organic group having 2 to 50 carbon atoms. <3> In the formula (1), R 1 is a structure represented by formula (2), <2> The resin composition according to claim 1.

[0014] [ka]

[0015] (In formula (2), X1 is an ether group, a thioether group, a ketone group, a sulfonyl group, a fluorene group, or a single bond. R 3 and R 4 each independently represents a halogen atom or a monovalent organic group having 1 to 3 carbon atoms. 1 and a 2 are each independently an integer of 0 to 4. m is an integer of 0 to 3. <4> Of 100 mol % of the structural units represented by the formula (1), 70 mol % or more of R 1 is a structure represented by formula (3), <3> The resin composition according to claim 1.

[0016] [ka]

[0017] (In formula (3), R 5 and R 6 R each independently represents a halogen atom or a monovalent organic group having 1 to 3 carbon atoms. 7 and R 8 each independently represents a halogen atom or a monovalent organic group having 1 to 3 carbon atoms. 3 and a 4 are each independently an integer of 0 to 3. <5> The (b) solvent is a solvent consisting of an aromatic compound having a dipole term (δp) of the Hansen solubility parameter of 7.5 or less and a hydrogen bond term (δh) of 0.5 or more and 7.5 or less. <1> ~ <4> The resin composition according to any one of the preceding claims. <6> Further, (c) a filler containing at least one element selected from the group consisting of silicon, cobalt, manganese, nickel, tin, germanium, iron, and titanium (hereinafter referred to as "(c) filler"); <1> ~ <5> The resin composition according to any one of the preceding claims. <7> In the formula (1), R 2 is a structure selected from at least one of general formulas (4) and (5), <2> The resin composition according to claim 1.

[0018] [ka]

[0019] (In formula (4), R 9 is an aliphatic hydrocarbon group having 1 to 30 carbon atoms, and some or all of the hydrogen atoms of the group are replaced with halogen atoms.

[0020] [ka]

[0021] (In formula (5), R 10 is an ether group, a ketone group, a single bond, a sulfone group, or a thioether group. <8> The structural unit represented by the formula (1) is R 2 is a structure represented by the formula (4), and R 2 is a structure represented by the formula (5), <7> The resin composition according to claim 1. <9> In 100 mol % of the structural units represented by the formula (1), R 2 is a structural unit represented by the formula (4), and R 2 and the structural unit represented by the formula (5) have a molar ratio ((4):(5)) of 90:10 to 10:90. <8> The resin composition according to claim 1. <10> (a) the terminal structure of the resin has an unsaturated group; <1> ~ <9> The resin composition according to any one of the preceding claims. <11> the structure having an unsaturated group is a structure having a maleimide group or a structure having a styryl group; <10> The resin composition according to claim 1. <12> (b') Hansen solubility parameter is 20 (MPa) 1 / 2 The content of solvents exceeding this is less than 5% by mass of the total solvents contained in the composition, <1> ~ <11> The resin composition according to any one of the preceding claims. <13> (c) the theoretical capacity of the filler is 160 mAh / g or more; <6> The resin composition according to claim 1. <14> further comprising (d) a solid electrolyte; <1> ~ <13> The resin composition according to any one of the preceding claims. <15> further comprising (e) a thermal radical generator; <1> ~ <14> The resin composition according to any one of the preceding claims. <16> Further, (f) at least one of a bismaleimide compound having a molecular weight of 700 or less and a bisstyryl compound having a molecular weight of 700 or less is contained. <1> ~ <15> The resin composition according to any one of the preceding claims. <17> At least one surface of a conductive substrate or an insulating substrate having conductive wiring, <1> ~ <16> 1. An electrode having a lithium charge / discharge layer made of the resin composition according to any one of claims 1 to 9, or a thermoset product thereof. <18> <17> A secondary battery comprising the electrode according to claim 1. <19> <17> A capacitor comprising the electrode according to claim 1. [Effects of the Invention]

[0022] The resin of the present invention makes it possible to provide a resin composition that can be processed at low temperatures and that produces a film having high mechanical properties and adhesiveness after the processing, an electrode using the resin, and a secondary battery and a capacitor that include the electrode. DETAILED DESCRIPTION OF THE INVENTION

[0023] The following describes in detail the embodiments of the present invention, but the present invention is not limited to the following embodiments and can be modified in various ways depending on the purpose and application.

[0024] The resin composition according to the present invention comprises the following components (a) and (b): (a) at least one resin selected from polyimide, polyamideimide, polyether, polyetherketone, polyetheretherketone, polysulfone, polyethersulfone, polyamide, and any precursor thereof (hereinafter referred to as "(a) resin"); (b) Hansen solubility parameter is 16 (MPa) 1 / 2 Over 20 (MPa) 1 / 2 A solvent that is one of the following (hereinafter referred to as "(b) solvent") A resin composition comprising: (b) A resin composition in which the content of the solvent is 50% by mass or more of the total solvent contained in the composition.

[0025] <(a) Resin> The resin (a) used in the present invention is at least one resin selected from the group consisting of polyimide, polyamideimide, polyether, polyether ketone, polyether ether ketone, polysulfone, polyethersulfone, polyamide, and any precursor thereof.

[0026] From the viewpoint of improving the mechanical properties and adhesiveness of the resin composition, the (a) resin is preferably a polyimide resin, and more preferably a polyimide resin containing a structural unit represented by formula (1).

[0027] [ka]

[0028] From the viewpoint of improving the mechanical properties and adhesiveness of the resin composition, it is more preferable that the (a) resin contains the structural unit represented by formula (1) as the main component.

[0029] The term "main component" as used herein refers to 70% by weight or more, preferably 80% by weight or more of the total resin.

[0030] (diamine residue) In formula (1), R 1 represents a diamine residue, and represents a divalent organic group having 2 to 50 carbon atoms.

[0031] From the viewpoint of improving the mechanical properties of the resin composition, R 1 is preferably an organic group containing an aromatic ring or a cycloaliphatic group, and more preferably an organic group containing two or more aromatic rings, an organic group containing two or more cycloaliphatic groups, or an organic group containing one or more aromatic rings and one or more cycloaliphatic groups.

[0032] Preferred R 1 Specific examples of include, but are not limited to, residues of the following diamines:

[0033] 3,4'-Diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 1,4-bis(4-aminophenoxy)benzene, 1,3- Bis(4-aminophenoxy)benzene, m-phenylenediamine, p-phenylenediamine, 1,5-naphthalenediamine, 2,6-naphthalenediamine, bis(4-aminophenoxyphenyl)sulfone, bis(3-aminophenoxyphenyl)sulfone, bis(4-aminophenoxy)biphenyl, bis{4-(4-aminophenoxy)phenyl}ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-diethyl-4,4'-diaminobiphenyl, 2,2' ,3,3'-tetramethyl-4,4'-diaminobiphenyl, 3,3',5,5'-tetramethyl-4,4'-diaminobiphenyl, 3,5-diaminobenzoic acid, 3-carboxy-4,4'-diaminodiphenyl ether, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane, 3-sulfonic acid-4,4'-diaminodiphenyl ether, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, 2,2-bis(3-amino-4-hydroxyphenyl) bis(3-amino-4-hydroxyphenyl)propane, bis(3-amino-4-hydroxyphenyl)ether, bis(3-amino-4-hydroxyphenyl)sulfone, 1,1-bis(3-amino-4-hydroxyphenyl)fluorene, 1,1-bis(3-amino-4-hydroxyphenyl)cyclohexane, 3,3'-dihydroxybenzidine, 2,2'-dimethylbenzidine, 3,3'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)benzidine, 3,3'-bis(trifluoromethyl)benzidine.

[0034] Other examples include residues of compounds in which some of the hydrogen atoms on the aromatic rings of the above diamines have been substituted with alkyl groups or halogen atoms, and residues of aliphatic diamines in which the aromatic rings of the above diamines have been hydrogenated, such as cyclohexyldiamine and methylenebiscyclohexylamine.

[0035] In addition to diamines, raw materials that provide these diamine residues include diisocyanate compounds in which isocyanate groups are bonded to the diamine residue structure instead of amino groups, and tetratrimethylsilylated diamines in which two hydrogen atoms of the amino groups of diamines are substituted with trimethylsilyl groups.

[0036] From the viewpoint of improving the mechanical properties of the resin composition, R 1 is preferably a structure represented by formula (2).

[0037] [ka]

[0038] In formula (2), X1 is an ether group, a thioether group, a ketone group, a sulfonyl group, a fluorene group, or a single bond.

[0039] In formula (2), R 3 and R 4 Each independently represents a halogen atom or a monovalent organic group having 1 to 3 carbon atoms. Preferred halogen atoms include, but are not limited to, fluorine, chlorine, and bromine. Preferred monovalent organic groups having 1 to 3 carbon atoms include, but are not limited to, substituted or unsubstituted alkyl groups such as methyl, ethyl, n-propyl, isopropyl, trifluoromethyl, and pentafluoroethyl. From the viewpoint of improving the mechanical properties of the resin composition, R 3 and R 4 are each independently fluorine, a methyl group, an ethyl group, a trifluoromethyl group or a pentafluoroethyl group.

[0040] In formula (2), a1 and a 2 are each independently an integer of 0 to 4. From the viewpoint of improving the mechanical properties of the resin composition, 1 and a 2 is preferably an integer of 0 to 1, and more preferably 0.

[0041] In formula (2), m is an integer of 0 to 3. From the viewpoint of improving the mechanical properties of the resin composition, m is preferably an integer of 0 to 1, and more preferably 1.

[0042] Preferred specific examples of formula (2) include, but are not limited to, the following diamine residues:

[0043] 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-diethyl-4,4'-diaminobiphenyl, 2,2',3,3'-tetramethyl-4,4'-diaminobiphenyl, 3,3',5,5'-tetramethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, 2,2'-dimethylbenzidine, 3,3'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)benzidine, 3,3'-bis(trifluoromethyl)benzidine.

[0044] From the viewpoint of improving the mechanical properties and adhesiveness of the resin composition and improving the capacity retention rate of the battery, 70 mol % or more of 100 mol % of the structural units represented by formula (1) are R 1 is preferably a structure represented by formula (3). More preferably, 75 mol % or more, and even more preferably 80 mol % or more of R 1 is a structure represented by formula (3).

[0045] [ka]

[0046] The rigid structure represented by formula (3), in which aromatic rings are linked by single bonds, allows the polyimide main chain to easily orient, even during low-temperature curing, strengthening intermolecular forces and enabling the material to exhibit high strength, elongation, and adhesiveness.

[0047] In formula (3), R 5 and R 6 Each independently represents a halogen atom or a monovalent organic group having 1 to 3 carbon atoms. 3 and R 4 The same things can be mentioned as mentioned above.

[0048] In formula (3), R 7 and R 8 Each independently represents a halogen atom or a monovalent organic group having 1 to 3 carbon atoms. 3 and R 4 The same things can be mentioned as mentioned above.

[0049] In formula (3), a 3 and a 4 are each independently an integer of 0 to 3. Preferred examples include 1 and a 2 The same things can be mentioned as mentioned above.

[0050] More preferred specific examples of the structure represented by formula (3) include, but are not limited to, the following structures:

[0051] [ka]

[0052] (a) Resin is R 1The structural unit R that gives a structure other than the structure represented by formula (3) may be contained in an amount of less than 30 mol % of 100 mol % of the structural unit represented by formula (1). 1 Examples of the diamine include, but are not limited to, the residues of the diamines listed below.

[0053] 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, m-phenylenediamine, p-phenylenediamine, 1,5-naphthalenediamine, 2,6-naphthalenediamine, bis(4-aminophenoxyphenyl)sulfone, bis(3-aminophenoxyphenyl)sulfone, bis(4-aminophenoxy)biphenyl, bis{4-(4-aminophenoxy)phenyl} ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-diethyl-4,4'-diaminobiphenyl, 3,3',5,5'-tetramethyl-4,4'-diaminobiphenyl, 3,5-diaminobenzoic acid, 3-carboxy-4,4'-diaminodiphenyl ether, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane, 3-sulfonic acid-4,4'-diaminodiphenyl ether, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, 2,2-bis(3-amino-4-hydroxyphenyl)propane, bis(3-amino-4-hydroxyphenyl)ether, bis(3-amino-4-hydroxyphenyl)sulfone, 1,1-bis(3-amino-4-hydroxyphenyl)fluorene, 1,1-bis(3-amino-4-hydroxyphenyl)cyclohexane.

[0054] Other examples include residues of compounds in which some of the hydrogen atoms on the aromatic rings of the above diamines have been substituted with alkyl groups or halogen atoms, and residues of aliphatic diamines in which the aromatic rings of the above diamines have been hydrogenated, such as cyclohexyldiamine and methylenebiscyclohexylamine.

[0055] In addition to diamines, raw materials that provide these diamine residues include diisocyanate compounds in which isocyanate groups are bonded to the diamine residue structure instead of amino groups, and tetratrimethylsilylated diamines in which two hydrogen atoms of the amino groups of diamines are substituted with trimethylsilyl groups.

[0056] (acid residue) In formula (1), R 2 represents a tetracarboxylic acid residue (hereinafter referred to as "acid residue"), which is a tetravalent organic group having 2 to 50 carbon atoms.

[0057] From the viewpoint of improving the mechanical properties of the resin composition, R 2 is preferably an organic group containing an aromatic ring or a cycloaliphatic group, and more preferably an organic group containing two or more aromatic rings, an organic group containing two or more cycloaliphatic groups, or an organic group containing one or more aromatic rings and one or more cycloaliphatic groups.

[0058] Preferred R 2 Specific examples of include, but are not limited to, the residues of the following tetracarboxylic acids: Pyromellitic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 2,3,3',4'-biphenyltetracarboxylic acid, 2,2',3,3'-biphenyltetracarboxylic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, 2,2',3,3'-benzophenonetetracarboxylic acid, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane, 2,2-bis(2,3-dicarboxyphenyl)hexafluoropropane, 1,1-bis(3,4-dicarboxyphenyl)ethane, 1,1-bis(2,3-dicarboxyphenyl)ethane, bis(3,4-dicarboxyphenyl)methane, bis(2,3-dicarboxyphenyl)methane, bis(3,4-dicarboxyphenyl) ) sulfone, bis(3,4-dicarboxyphenyl) ether, aromatic tetracarboxylic acids such as 1,2,5,6-naphthalenetetracarboxylic acid, 2,3,6,7-naphthalenetetracarboxylic acid, 2,3,5,6-pyridinetetracarboxylic acid, and 3,4,9,10-perylenetetracarboxylic acid; and aliphatic tetracarboxylic acids such as cyclobutanetetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, cyclohexanetetracarboxylic acid, bicyclo[2.2.1.]heptanetetracarboxylic acid, bicyclo[3.3.1.]tetracarboxylic acid, bicyclo[3.1.1.]hept-2-enetetracarboxylic acid, bicyclo[2.2.2.]octanetetracarboxylic acid, and adamantanetetracarboxylic acid.

[0059] From the viewpoint of improving the mechanical properties and adhesiveness of the resin composition and improving the capacity retention rate of the battery, R 2 is preferably a structure selected from at least one of formula (4) and formula (5). From the viewpoint of improving adhesiveness, it is more preferable that the structural unit of formula (1) is 2 is a structural unit represented by formula (4), and R 2 and the structural unit represented by formula (5).

[0060] [ka]

[0061] [ka]

[0062] In formula (4), R 9 is an aliphatic hydrocarbon group having 1 to 6 carbon atoms, and is an organic group in which some or all of the hydrogen atoms have been replaced with halogen atoms.

[0063] R 9 Preferred specific examples of the above include, but are not limited to, a methylene group, an ethylene group, an ethylidene group, a vinylene group, a propenylene group, a propylene group, a trimethylene group, a propylidene group, an isopropylidene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, a cyclohexylene group, a cyclohexylidene group, a cyclobutylene group, a cyclobutylidene group, a cyclopentylene group, or an organic group in which some or all of the hydrogen atoms in the cyclopentylidene group have been replaced with halogen.

[0064] More preferred examples of formula (4) include, but are not limited to, the following structures:

[0065] [ka]

[0066] In formula (5), R 10 is an ether group, a ketone group, a single bond, a sulfone group, or a thioether group.

[0067] From the viewpoint of improving adhesiveness, R 10 is preferably an ether group.

[0068] By containing an aliphatic hydrocarbon group, at least a portion of which is replaced by a halogen atom, or an acid residue containing a flexible organic group such as an ether group, the polyimide can exhibit high adhesion to substrates that come into contact with the polyimide, even when cured at low temperatures.

[0069] From the viewpoint of improving the mechanical properties and adhesiveness of the resin composition, it is most preferable that R 2 is a structural unit represented by the formula (4) and R 2 The molar ratio ((4):(5)) of the structural unit represented by the formula (5) is 90:10 to 10:90.

[0070] In formula (1), in order to improve the adhesion of the coating film to the silicon substrate or glass substrate after heat treatment, or to increase the resistance to oxygen plasma or UV ozone treatment used for cleaning, R is set within a range that does not reduce the heat resistance. 1 Or, R 2 A siloxane structure may be copolymerized with the siloxane structure. 1 Examples of R include residues of bis(3-aminopropyl)tetramethyldisiloxane and bis(p-aminophenyl)octamethylpentasiloxane. 1 It is preferable that 1 to 10 mol % of the total is copolymerized. 2 Examples of R include residues of dimethylsilane diphthalic dianhydride, 1,3-bis(phthalic acid)tetramethyldisiloxane dianhydride, and 1-(p-carboxyphenyl)-3-phthalic acid-1,1,3,3-tetramethyldisiloxane. 2 It is preferable that 1 to 10 mol % of the total is copolymerized.

[0071] In formula (1), in order to improve the adhesion of the coating to the metal substrate after heat treatment, R 1 An aliphatic structure having a polyalkylene oxide group may be copolymerized with the above. Specific examples of the structure include residues of "JEFFAMINE" (registered trademark) KH-511, JEFFAMINE ED-600, JEFFAMINE ED-900, JEFFAMINE ED-2003, JEFFAMINE EDR-148, JEFFAMINE EDR-176, JEFFAMINE D-200, JEFFAMINE D-400, JEFFAMINE D-2000, and JEFFAMINE D-4000 (all trade names, manufactured by HUNTSMAN Co., Ltd.). These may be used alone or in combination of two or more types, and R1 It is preferable that 1 to 30 mol % of the total is copolymerized.

[0072] (a) The resin is synthesized by the following methods, but is not limited to these. Specifically, a typical method involves dissolving a diamine in a solvent such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), gamma-butyrolactone (GBL), or dimethyl sulfoxide (DMSO), and then adding a tetracarboxylic dianhydride to the solution to cause a reaction to obtain a polyimide precursor. The reaction temperature is typically between -20°C and 100°C, with 0°C to 50°C being preferred. The reaction time is typically between 1 minute and 100 hours, with 2 to 24 hours being preferred. It is preferable to prevent moisture from entering the system during the reaction by, for example, flushing nitrogen through the system.

[0073] The polyimide precursor is then subjected to heat treatment or chemical treatment to form an imide ring, thereby obtaining a polyimide having a structural unit represented by formula (1). Examples of chemical treatments include treatment with acetic anhydride and pyridine, treatment with a base such as triethylamine or dodecylundecene, and treatment with an acid anhydride such as acetic anhydride or succinic anhydride.

[0074] Alternatively, in the above-described method, the amino group of the diamine compound may be converted to an isocyanate, followed by reaction with a tetracarboxylic dianhydride or a tricarboxylic anhydride, optionally in the presence of a tin catalyst or a base catalyst, at a temperature ranging from room temperature to 200°C for 1 minute to 24 hours, to obtain a polyimide having a structural unit represented by formula (1). This method is preferable because it does not produce water as a by-product.

[0075] (a) In the polymerization reaction of the resin, the molar ratio of the acidic component to the diamine or diisocyanate is 100 mol % or less, preferably 95 mol % or less, more preferably 90 mol % or less, and most preferably 85 mol % or less, relative to 100 mol % of the diamine or diisocyanate. If the diamine or diisocyanate is in a higher proportion, the terminal amine or isocyanate group has the effect of increasing the adhesion between the resin and the filler, conductive substrate, and conductive wiring.

[0076] Alternatively, the (a) resin may be obtained by precipitating the resin in a poor solvent for the resin, such as methanol or water, after the polymerization is complete, followed by washing and drying. Reprecipitation has the advantage of improving heat resistance, since it can remove by-products of the esterifying agent, condensing agent, and acid chloride used in the polymerization, as well as low-molecular-weight components of the resin precursor.

[0077] From the viewpoint of improving the mechanical properties of the resin composition and improving the capacity retention rate of the battery, it is preferable that the (a) resin has a structure in which the resin terminal has an unsaturated group.

[0078] Specific examples of preferred unsaturated groups include, but are not limited to, vinyl groups, acrylic groups, methacrylic groups, ethynyl groups, cyclohexene groups, norbornene groups, and maleic acid groups.

[0079] (a) It is believed that the steric hindrance of the heterocyclic and aromatic rings at the resin terminals reduces the interaction with the electrolyte components, improving the capacity retention rate without interfering with the charge and discharge of lithium. From this perspective, the structure having an unsaturated group is preferably a structure selected from a maleimide group and a styryl group.

[0080] These are introduced as residues of monoamine, monocarboxylic acid, or acid anhydride into the terminals of polyimides having structural units represented by formula (1). Specific structures include, but are not limited to, the following structures:

[0081] [ka]

[0082] <(b) Solvent> The (b) solvent in the present invention refers to a solvent that dissolves the (a) resin at a resin concentration of 5% by mass or more. The (b) solvent used in the present invention has a Hansen solubility parameter (HSP value: δ) of 16 (MPa). 1 / 2 Over 20 (MPa) 1 / 2 The reason is as follows. By reducing the polarity of the solvent, it is thought that the interaction between the polar groups of the polyimide and the solvent is reduced, and the intermolecular forces between the polyimide molecules after low-temperature curing are strengthened. As a result, it leads to improved mechanical properties, adhesiveness, and capacity retention.

[0083] (b) Specific examples of solvents include, but are not limited to, methylene chloride (δ=19.8), dioxane (δ=19.8), anisole (δ=19.6), tetrahydrofuran (δ=19.5), propylene glycol monomethyl ether acetate (δ=19.3), methyl ethyl ketone (δ=19.1), chloroform (δ=18.9), toluene (δ=18.2), xylene (δ=18.1), benzene (δ=18.5), ethyl acetate (δ=18.2), butyl acetate (δ=17.4), methyl isobutyl ketone (δ=17.0), and cyclohexane (δ=16.8).

[0084] From the viewpoint of improving the mechanical properties and adhesiveness of the resin composition and improving the capacity retention rate of the battery, it is preferable that the (b) solvent is a solvent made of an aromatic compound whose Hansen solubility parameter dipole term (δp) is 7.5 or less and whose hydrogen bond term (δh) is 0.5 or more and 7.5 or less.

[0085] The Hansen Solubility Parameter (HSP value: δ) in this invention is a value used to predict the solubility of a substance, which was published by Charles M. Hansen in 1967, and is calculated from the energies of δd (dispersion force term), δp (dipole term), and δh (hydrogen bond term). δ 2 =(δd) 2 +(δp) 2 +(δh) 2 This is the value calculated as follows.

[0086] As the polarity of a solvent decreases, the value of δ tends to decrease. In particular, small values ​​of δp (dipole term) and δh (hydrogen bond term) are thought to contribute significantly to reducing the polarity of the solvent and reduce the interaction with the polar groups of the polyimide. As a result, the intermolecular forces between polyimides during low-temperature curing become stronger, leading to improved mechanical properties, adhesion, and capacity retention.

[0087] Specific examples of solvents consisting of aromatic compounds in which the dipole term (δp) of the Hansen solubility parameter is 7.5 or less and the hydrogen bond term (δh) is 0.5 to 7.5 or less include, but are not limited to, toluene (δ=18.2, δp=1.4, δh=2.0), xylene (δ=18.1, δp=1.0, δh=3.1), anisole (δ=19.6, δp=4.4, δh=6.9), and benzene (δ=18.5, δp=0.0, δh=2.0).

[0088] The Hansen solubility parameters here can be obtained by using the values ​​listed in Hansen, Charles (2007). Hansen Solubility Parameters: A user's handbook, Second Edition. Boca Raton, Fla.: CRC Press. Calculations can be performed using software for calculating Hansen solubility parameters, such as HSPiP (Hansen Solubility Parameter in Practice) (manufactured by HSP Science). The HSP value calculation results published by Professor Steven Abbott (1,218 substances; published by: https: / / www.stevenabbott.co.uk / practical-solubility / hsp-basics.php) can also be obtained.

[0089] Hansen solubility parameter in resin composition is 20 (MPa) 1 / 2If the content of the solvent exceeding 20 (MPa) is small, the interaction with the electrolyte component is small, and it is thought that the capacity retention rate of the battery is further improved without interfering with the charge and discharge of lithium. From this viewpoint, the resin composition according to the embodiment of the present invention is 1 / 2 The content of solvents exceeding this range is preferably less than 5% by mass, more preferably less than 1% by mass, and even more preferably less than 0.1% by mass of the total solvents contained in the composition.

[0090] Hansen solubility parameter is 20 (MPa) 1 / 2 Specific examples of solvents exceeding this range include, but are not limited to, N-methyl-2-pyrrolidone (δ=23.0), gamma-butyrolactone (δ=25.6), N,N-dimethylacetamide (δ=22.4), dimethyl sulfoxide (δ=26.7), 1,3-dimethyl-2-imidazolidinone (δ=22.1), and diacetone alcohol (δ=20.8).

[0091] <(c) Filler> The resin composition according to the embodiment of the present invention includes (c) a filler containing at least one element selected from the group consisting of silicon, cobalt, manganese, nickel, tin, germanium iron, and titanium. The resin composition according to the embodiment of the present invention is capable of absorbing and releasing lithium ions by including (c) the filler.

[0092] (c) Preferred specific examples of the filler include lithium iron phosphate, manganese iron phosphate, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, ternary lithium compounds of nickel-manganese-cobalt, ternary lithium compounds of nickel-aluminum-cobalt, lithium titanate, compounds containing silicon atoms, compounds containing tin atoms, compounds containing germanium atoms, and the like. In particular, for a storage battery using a compound containing a silicon atom, a compound containing a tin atom, or a compound containing a germanium atom as a filler, since the volume expansion of the active material is large during charging, it is preferable to use a resin with high strength such as the resin of the present invention as a binder in order to reduce the deterioration of the active material and thus the capacity deterioration during charge and discharge.

[0093] Examples of the compound containing a silicon atom include, for example, (1) silicon fine particles, (2) alloys of tin, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony or chromium and silicon, (3) compounds of boron, nitrogen, oxygen or carbon and silicon, and those further having the metals exemplified in (2) above. Examples of the alloy or compound of silicon include SiB4, SiB6, Mg2Si, Ni2Si, TiSi2, MoSi2, CoSi2, NiSi2, CaSi2, CrSi2, Cu5Si, FeSi2, MnSi2, NbSi2, TaSi2, VSi2, WSi2, ZnSi2, SiC, Si3N4, Si2N2O, SiOv (0 < v ≦ 2) or LiSiO.

[0094] Examples of the compound containing a tin atom include, for example, (1) alloys of silicon, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony or chromium and tin, (2) compounds of oxygen or carbon and tin, and those further having the metals exemplified in (1) above. Examples of the alloy or compound of tin include SnOw (0 < w ≦ 2), SnSiO3, LiSnO or Mg2Sn.

[0095] Examples of compounds containing germanium atoms include alloys of germanium with silicon or tin.

[0096] From the viewpoint of improving charge / discharge characteristics, it is more preferable that the resin composition according to the embodiment of the present invention contains a filler having a theoretical capacity of 160 mAh / g or more, and it is most preferable that the resin composition according to the embodiment of the present invention contains a filler having a theoretical capacity of 1500 mAh / g or more.

[0097] The theoretical capacity here is the amount of lithium that the electrode material can tolerate in the charge-discharge reaction shown in the electrochemical reaction formula, converted into electric charge. It is expressed per unit weight of the electrode material, and is expressed as mAh / g or Ah / kg.

[0098] Specific examples of fillers with a theoretical capacity of 160 mAh / g or more include, but are not limited to, LiFePO4 (170 mAh / g), LiMnPO4 (171 mAh / g), LiCoO2 (274 mAh / g), LiNiO2 (274 mAh / g), Li2TiO3 (175 mAh / g), silicon (4200 mAh / g), tin (994 mAh / g), a composite of silicon and silicon oxide (1500 mAh / g), and a composite of silicon and graphite or graphite (400 to 3500 mAh / g).

[0099] The median diameter (d50) in the particle size distribution of the filler is preferably 0.01 to 20 μm. The surface of the filler may be treated with a silane coupling agent or the like.

[0100] Here, the median diameter was measured using a Horiba, Ltd. laser diffraction / scattering particle size distribution analyzer LA-920. Prior to measurement, an appropriate amount of sample was added to an aqueous solution of sodium hexametaphosphate, dispersed in an ultrasonic cleaner for approximately 10 minutes, and then the measurement was carried out. This breaks down agglomerations in samples where the powder has aggregated, and prevents the settling of large particle diameter powders, enabling accurate measurement of particle size distribution.

[0101] In the resin composition according to the embodiment of the present invention, the content of the resin (resin + additive if an additive is added) is preferably 1 part by weight or more, more preferably 3 parts by weight or more, and even more preferably 5 parts by weight or more per 100 parts by weight of the (c) filler, from the viewpoint of further improving adhesiveness.

[0102] Furthermore, when the resin composition according to the embodiment of the present invention is used for an electrode of a secondary battery or a capacitor, from the viewpoint of reducing electrical resistance and increasing the amount of filler filled, the content of the resin is preferably 20 parts by weight or less, more preferably 15 parts by weight or less, and most preferably 12 parts by weight or less, per 100 parts by weight of the (c) filler.

[0103] <(d) Solid electrolyte> The resin composition according to the embodiment of the present invention preferably further contains (d) a solid electrolyte.

[0104] (d) The solid electrolyte may be any one that has ionic conductivity for ions of Group 1 or Group 2. Examples of the solid electrolyte that can be used include sulfide-based solid electrolytes, oxide-based solid electrolytes, hydride-based solid electrolytes, and polymer electrolytes.

[0105] Examples of sulfide-based solid electrolytes include argyrodite-based Li6PS5Cl and LGPS-based Li 10 GeP2S 12 and LiS-P2S5, a glass-based solid electrolyte.

[0106] Examples of oxide-based solid electrolytes include phosphate compounds having a Nasicon structure or substituted compounds in which a part of the phosphate compound is substituted with another element, such as Li7La3Zr2O 12 Examples of suitable oxide solid electrolytes include lithium ion conductors having a garnet structure or a garnet-like structure, such as Li-La-Ti-O-based lithium ion conductors. Also usable are oxide solid electrolytes having a perovskite structure or a perovskite-like structure, such as Li-La-Ti-O-based lithium ion conductors. Specific examples of oxide solid electrolytes include Li7La3Zr2O 12, LiTi(PO4)3, LiGe(PO4)3, LiLaTiO3, etc.

[0107] Examples of hydride-based solid electrolytes include LiBH4 alone and solid solutions of LiBH4 and alkali metal halides, such as lithium halides, rubidium halides, and cesium halides.

[0108] Examples of the polymer electrolyte include polyethylene oxide, polypropylene oxide, and polypropylene glycol.

[0109] These (d) solid electrolytes may be used alone or in combination of two or more.

[0110] From the viewpoint of the capacity retention rate of the battery, (d) the solid electrolyte is preferably a sulfide-based solid electrolyte.

[0111] When the resin composition contains (d) solid electrolyte, its content is preferably 20 parts by weight or more, more preferably 30 parts by weight or more, and preferably 90 parts by weight or less, more preferably 80 parts by weight or less, per 100 parts by weight of (c) filler. When the content of (d) solid electrolyte is equal to or greater than the above-mentioned lower limit, ion conduction paths can be formed more easily, and the output characteristics of the solid battery can be further improved. On the other hand, when the content of (d) solid electrolyte is equal to or less than the above-mentioned upper limit, the amount of active material in the electrode can be further increased, and the battery capacity of the solid battery can be further increased.

[0112] <(e) Thermal Radical Generator> The resin composition according to the embodiment of the present invention preferably further contains (e) a thermal radical generator, from the viewpoint of (a) promoting low-temperature curing of the unsaturated groups at the resin terminals, thereby improving the mechanical properties of the resin composition and improving the capacity retention rate of the battery.

[0113] (e) The thermal radical generator may be a radical polymerization initiator used in a radical polymerization method, such as, but not limited to, 2,2'-azobisisobutyronitrile, 2,2'-azobis(isobutyric acid) dimethyl, 2,2'-azobis-(2,4-dimethylvaleronitrile), and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile).

[0114] When the resin composition contains (e) a thermal radical generator, the content thereof is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and particularly preferably 0.5% by mass or more, and is preferably 30% by mass or less, more preferably 15% by mass or less, and particularly preferably 10% by mass or less, when (a) the resin is taken as 100% by mass.

[0115] <(f) Bismaleimide compounds, bisstyryl compounds> From the viewpoint of (a) promoting low-temperature curing of the unsaturated groups at the resin terminals and improving adhesiveness, the resin composition according to the embodiment of the present invention preferably contains at least one ((f) compound) of (f) a bismaleimide compound having a molecular weight of 700 or less and a bisstyryl compound having a molecular weight of 700 or less.

[0116] As with (a) when introduced into the terminal structure of the resin, these have the effect of reducing the interaction with the electrolyte containing lithium due to the steric hindrance of the heterocyclic and aromatic rings, which is thought to improve the charge / discharge characteristics (capacity retention rate) of the battery.

[0117] Examples of bismaleimide compounds having a molecular weight of 700 or less include 4,4'-diphenylmethane bismaleimide, polyphenylmethane maleimide, phenylene bismaleimide, bisphenol A diphenyl ether bismaleimide, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, 1,6'-bismaleimide-(2,2,4-trimethyl)hexane, 4,4'-diphenyl ether bismaleimide, 4,4'-diphenylsulfone bismaleimide, 1,3-bis(3-maleimidophenoxy)benzene, and 1,3-bis(4-maleimidophenoxy)benzene.

[0118] Specific examples of bismaleimide compounds having a molecular weight of 700 or less include "BMI-1000" manufactured by Daiwa Chemical Industry Co., Ltd., "BMI" (4,4'-diphenylmethane bismaleimide) manufactured by K.I. Chemical Industry Co., Ltd., "BMI-2000" (polyphenylmethane maleimide) manufactured by Daiwa Chemical Industry Co., Ltd., "BMI-3000" (m-phenylene bismaleimide) manufactured by Daiwa Chemical Industry Co., Ltd., "BMI4000" manufactured by Daiwa Chemical Industry Co., Ltd., and "BMI-80" (bisphenol A diphenyl ether bismaleimide); "BMI5100" manufactured by Daiwa Chemical Industry Co., Ltd., "BMI-70" (3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide) manufactured by K.I. Chemical Industry Co., Ltd.; "BMI-7000" (4-methyl-1,3-phenylene bismaleimide) manufactured by Daiwa Chemical Industry Co., Ltd.; "BMI-TMH" (1,6'-bismaleimide-(2,2,4-trimethyl)hexamethyl bismaleimide) manufactured by Daiwa Chemical Industry Co., Ltd. "BMI-6000" (4,4'-diphenyletherbismaleimide) manufactured by Daiwa Chemical Industry Co., Ltd.; "BMI-8000" (4,4'-diphenylsulfonebismaleimide) manufactured by Daiwa Chemical Industry Co., Ltd.; 1,3-bis(3-maleimidophenoxy)benzene manufactured by Daiwa Chemical Industry Co., Ltd.; 1,3-bis(4-maleimidophenoxy)benzene manufactured by Daiwa Chemical Industry Co., Ltd.; "ANILIX-MI" manufactured by Mitsui Chemicals Fine Co., Ltd., and the like. One type of maleimide compound may be used alone, or two or more types may be used in combination.

[0119] Examples of bisstyryl compounds having a molecular weight of 700 or less include those obtained by reacting 100 moles of an acid dianhydride compound with 200 moles of 4-aminostyrene, or those obtained by imidizing these compounds to form bisimides.

[0120] Specific examples of the acid dianhydride used in this case include pyromellitic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)hexafluoropropane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, and bis(3,4-dicarboxyphenyl)sulfonyl. Examples of suitable tetracarboxylic dianhydrides include aromatic tetracarboxylic dianhydrides such as phenylene dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 2,3,5,6-pyridinetetracarboxylic dianhydride, and 3,4,9,10-perylenetetracarboxylic dianhydride; and aliphatic tetracarboxylic dianhydrides such as cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, cyclohexanetetracarboxylic dianhydride, bicyclo[2.2.1.]heptanetetracarboxylic dianhydride, bicyclo[3.3.1.]tetracarboxylic dianhydride, bicyclo[3.1.1.]hept-2-enetetracarboxylic dianhydride, bicyclo[2.2.2.]octanetetracarboxylic dianhydride, and adamantanetetracarboxylic dianhydride.

[0121] When the resin composition contains the (f) compound, the content thereof is preferably 1% by mass or more, more preferably 3% by mass or more, and particularly preferably 5% by mass or more, and is preferably 40% by mass or less, more preferably 30% by mass or less, and particularly preferably 20% by mass or less, when the (a) resin is taken as 100% by mass.

[0122] <Other ingredients> When the resin composition according to the embodiment of the present invention is used for an electrode of a secondary battery or a capacitor, it may contain a conductive carbon compound such as graphite, ketjen black, carbon nanotubes, acetylene black, etc., in order to reduce electrical resistance. The content of these compounds is preferably 0.1 parts by weight or more and 20 parts by weight or less per 100 parts by weight of the negative electrode active material.

[0123] The resin composition according to the embodiment of the present invention may contain a silane coupling agent, a titanium chelating agent, an aluminum chelating agent, etc. in order to further improve adhesion to the conductive substrate and filler after heat treatment. Specific examples of preferred silane coupling agents include N-phenylaminoethyltrimethoxysilane, N-phenylaminoethyltriethoxysilane, N-phenylaminopropyltrimethoxysilane, N-phenylaminopropyltriethoxysilane, N-phenylaminobutyltrimethoxysilane, N-phenylaminobutyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltrichlorosilane, vinyltris(β-methoxyethoxy)silane, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-methacryloxypropylmethyldiethoxysilane.

[0124] When these adhesion improvers are contained, the content thereof is preferably 0.01 to 15 parts by weight per 100 parts by weight of the (a) resin.

[0125] Adhesion can also be further improved by pretreating the substrate surface to which the resin composition is applied. Examples of pretreatment methods include the following: Surface treatment is performed by spin coating, immersion, spray coating, or vapor treatment using a solution prepared by dissolving 0.5 to 20 parts by weight of the above-mentioned adhesion promoter in a solvent such as isopropanol, ethanol, methanol, water, tetrahydrofuran, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, ethyl lactate, or diethyl adipate. Alternatively, treatment may be performed by directly spraying hexamethyldisilazane vapor. Thereafter, a vacuum drying treatment is performed as needed, and a temperature of 50 to 300°C is applied to promote the reaction between the silicon-based material surface and the adhesion promoter.

[0126] The resin composition according to the embodiment of the present invention may contain a surfactant, which can improve the wettability with the substrate and the defoaming property during printing.

[0127] Examples of surfactants include fluorine-based surfactants such as "Fluorad" (registered trademark) (trade name, manufactured by Sumitomo 3M Co., Ltd.), "Megafac" (registered trademark) (trade name, manufactured by DIC Corporation), and "Sulfuron" (registered trademark) (trade name, manufactured by Asahi Glass Co., Ltd.); organic siloxane surfactants such as KP341 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), DBE (trade name, manufactured by Chisso Corporation), "Granol" (registered trademark) (trade name, manufactured by Kyoeisha Chemical Co., Ltd.), and BYK (manufactured by BYK-Chemie Co., Ltd.); and acrylic polymer surfactants such as "Polyflow" (registered trademark) (trade name, manufactured by Kyoeisha Chemical Co., Ltd.).

[0128] <Method of manufacturing resin composition> The resin composition according to an embodiment of the present invention can be obtained by mixing and kneading (a) resin, (b) solvent, (c) filler, and other necessary components. Examples of mixing methods include placing the components in a glass flask or stainless steel container and stirring and dissolving them with a mechanical stirrer, ultrasonic dissolving, or stirring and dissolving them with a planetary stirring and degassing device. Examples of kneading methods include using a planetary mixer, a three-roll mill, a ball mill, a homogenizer, or the like. The conditions for mixing and kneading are not particularly limited.

[0129] To remove foreign matter, the resin solution, resin composition, or slurry after mixing and kneading may be filtered through a filter with a pore size of 0.01 μm to 100 μm. Filter materials include polypropylene (PP), polyethylene (PE), nylon (NY), and polytetrafluoroethylene (PTFE), with polyethylene and nylon being preferred. When the resin composition contains fillers or organic pigments, it is preferable to use a filter with a pore size larger than the particle size of these particles.

[0130] <Electrode> Next, a method for manufacturing an electrode using the resin composition according to an embodiment of the present invention will be described using an electrode for a lithium ion battery or an electrode for an electric double layer capacitor as examples. These electrodes have a lithium charge / discharge layer made of the resin composition according to an embodiment of the present invention or a thermoset thereof on at least one side of a conductive substrate or an insulating substrate having conductive wiring.

[0131] In the case of a negative electrode of a lithium ion battery (hereinafter sometimes referred to as a negative electrode), the resin composition according to the embodiment of the present invention is applied to a metal foil in a thickness of 1 to 100 μm. Copper foil is generally used as the metal foil. For application, methods such as screen printing, roll coating, and slit coating can be used.

[0132] When polyimide is used as the binder, it is preferable to remove the solvent after application by heat treatment at 80°C to 500°C for 1 minute to 24 hours. Since imidization is not particularly required, it is more preferable to treat at 100°C to 250°C for 10 minutes to 24 hours. In either case, it is preferable to heat in an inert gas such as nitrogen gas or in a vacuum to prevent moisture from being mixed in.

[0133] In the case of a positive electrode of a lithium battery (hereinafter sometimes referred to as a positive electrode) or a positive or negative electrode of an electric double layer capacitor, the slurry of the present invention is applied to a metal foil in a thickness of 1 to 500 μm. Examples of the metal foil include aluminum foil, nickel foil, titanium foil, and copper foil, with aluminum foil being commonly used. The application method and heat treatment method are the same as those for a lithium battery negative electrode.

[0134] <Secondary batteries and capacitors> Next, a secondary battery and a capacitor according to an embodiment of the present invention will be described. For example, a secondary battery or an electric double layer capacitor can be obtained by stacking a plurality of positive electrodes and negative electrodes obtained using the resin composition according to an embodiment of the present invention with a separator interposed therebetween, and placing the stacked electrodes together with an electrolyte in an exterior material such as a metal case and sealing the case.

[0135] Examples of the separator include polyolefins such as polyethylene and polypropylene, and microporous films and nonwoven fabrics such as cellulose, polyphenylene sulfide, aramid, and polyimide.

[0136] To improve heat resistance, the surface of the separator may be coated with ceramic or the like.

[0137] The solvent used in the electrolyte serves as a medium through which ions involved in the electrochemical reaction of the battery can migrate. Preferred solvents include carbonates, esters, ethers, ketones, alcohols, and aprotic solvents. Examples of carbonate solvents include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC). Examples of ester solvents include methyl acetate, ethyl acetate, n-propyl acetate, methyl propionate, ethyl propionate, γ-butyrolactone, tetradecanolide, valerolactone, mevalonolactone, and caprolactone. Examples of ether-based solvents include dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, and tetrahydrofuran. Examples of ketone-based solvents include cyclohexanone. Examples of alcohol-based solvents include ethyl alcohol and isopropyl alcohol. Examples of aprotic solvents include amides such as tolyls and dimethylformamide, dioxolanes such as 1,3-dioxolane, and sulfolanes. Two or more of these may be used, and the content ratio can be appropriately selected depending on the desired battery performance. For example, in the case of carbonate-based solvents, it is preferable to combine a cyclic carbonate and a chain carbonate in a volume ratio of 1:1 to 1:9, which can improve the performance of the electrolyte.

[0138] Examples of electrolytes used in the electrolytic solution include lithium salts such as lithium hexafluorophosphate, lithium borofluoride, and lithium perchlorate, and ammonium salts such as tetraethylammonium tetrafluoroborate and triethylmethylammonium tetrafluoroborate.

[0139] When a solid-state battery is made using a solid electrolyte, a secondary battery or an electric double-layer capacitor can be obtained by stacking a positive electrode, a solid electrolyte, and a negative electrode in that order. [Example]

[0140] The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The names of the compounds used, for which abbreviations are used, are shown below. TFMB: 2,2'-bis(trifluoromethyl)benzidine 3,3'-DDS: 3,3'-diaminodiphenyl sulfone SiDA: bis(3-aminopropyl)tetramethyldisiloxane PMDA: Pyromellitic dianhydride 6FDA: 4,4'-(hexafluoroisopropylidene)diphthalic anhydride ODPA: 4,4'-oxydiphthalic anhydride TDA-100: 1,3,3a,4,5,9b-hexahydro-5(tetrahydro-2,5-dioxo-3-furanyl)naphtho[1,2-c]furan-1,3-dione PA: Phthalic anhydride MA: Maleic anhydride 4Ast: 4-aminostyrene DMAc: N,N'-dimethylacetamide NMP: N-methyl-2-pyrrolidone GBL: gamma butyrolactone DAA: Diacetone alcohol ABMDMV: 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) BMI-TMH: 1,6'-bismaleimide-(2,2,4-trimethyl)hexane (manufactured by Daiwakasei Kogyo Co., Ltd.) The compositions in the examples were evaluated by the following methods.

[0141] 1) Method for measuring the mechanical properties (strength, elastic modulus, elongation) of resin compositions Polyimide solutions 1 to 21 prepared in Synthesis Examples 12 to 32 were spin-coated onto an 8-inch silicon wafer and then heat-treated for 7 minutes on a hot plate (Act-8, manufactured by Tokyo Electron Limited) at 120°C to obtain a resin film. The thickness of the resin film was measured with an optical interference film thickness meter (Lambda Ace STM602, manufactured by SCREEN Holdings Co., Ltd.), and the rotation speed during spin-coating was adjusted so that the film thickness after heat treatment would be 10 μm.

[0142] The film was then immersed in hydrofluoric acid for 1 to 4 minutes to peel it off from the substrate, air-dried, and cut into strips 1 cm wide and approximately 9 cm long to be used as measurement samples. Measurements were performed using a "Tensilon" (RTM-100; manufactured by Orientec), and the average of the top five measurement results was calculated.

[0143] A strength of 90 MPa or more and an elongation of 15% or more was deemed acceptable.

[0144] 2) Adhesion to the substrate A 30 μm thick electrolytic copper foil with a carbon-coated surface was used as the substrate. Resin compositions 1 to 24 prepared in Synthesis Examples 36 to 59 were applied to this substrate using a doctor blade, and then the substrate was heat-treated in a ventilated oven at 120°C for 1 hour. The clearance between the blade and the substrate was adjusted so that the resin composition film thickness after heat treatment was 30 μm.

[0145] The copper foil with the resin composition film after heat treatment was cut into strips with a width of 1 cm and a length of approximately 9 cm to be used as measurement samples. A Tensilon (RTM-100, manufactured by Orientec) was used for measurement, and a peel test was performed at 180°C to determine the adhesive strength. An adhesive strength of 40 N / m or more was considered acceptable.

[0146] 3) Battery capacity retention rate The resin compositions 1 to 24 prepared in Synthesis Examples 36 to 59 were used in the following procedure.

[0147] 3-1) Preparation of the positive electrode The positive electrode composition synthesized in Synthesis Example 35 was applied to an aluminum current collector foil using a doctor blade, dried at 60 °C for 1 hour, and pressed using a roll press to form an electrode. The coated portion of this electrode was then punched into a circle with a diameter of 16 mm to prepare a positive electrode. The clearance between the blade and the substrate was adjusted so that the resin composition film thickness before pressing was 30 μm.

[0148] 3-2) Preparation of the negative electrode Resin compositions 1 to 24 were applied to electrolytic copper foil using a doctor blade, dried at 120°C for 1 hour, and pressed using a roll press to form an electrode. The coated area of ​​this electrode was then punched out into a circle with a diameter of 16 mm, and vacuum dried at 120°C for 24 hours to form a negative electrode. The clearance between the blade and the substrate was adjusted so that the resin composition film thickness before pressing was 30 μm.

[0149] 3-3) Capacity retention rate evaluation To measure the charge-discharge characteristics, an HS cell (manufactured by Hosen Co., Ltd.) was used, and the lithium-ion battery was assembled in a glove box under an argon atmosphere with a dew point of -60°C or less. The negative electrode prepared in the cell was placed, and the solid electrolyte synthesized in Synthesis Example 34 was filled on top of it to a thickness of 24 μm. A positive electrode was placed on top of that and sealed to obtain a lithium-ion battery.

[0150] The lithium-ion battery prepared as described above was charged at a constant current of 6 mA until the battery voltage reached 3.7 V, and then further charged at a constant voltage of 3.7 V for a total of 2 hours and 30 minutes from the start of charging, after which it was rested for 30 minutes and then discharged at a constant current of 6 mA until the battery voltage reached 2.4 V, completing the first charge-discharge cycle. After this, the battery was charged and discharged 19 times under the same conditions, and the charge and discharge capacities were measured for each cycle for a total of 20 cycles.

[0151] The capacity retention rate was calculated according to the following formula: A capacity retention rate of 40% or more was considered acceptable. Capacity retention rate (%) = (discharge capacity at 20th cycle / discharge capacity at 1st cycle) x 100 (Synthesis Examples 1 to 11: Synthesis of Polyimides) Synthesis Example 1 Under a dry nitrogen stream, 22.4 g (0.07 mol: 70 mol%) of TFMB and 7.45 g (0.03 mol: 30 mol%) of 3,3'-DDS were dissolved in 140 g of N-methyl-2-pyrrolidone (NMP). To this solution, 21.4 g (0.098 mol: 98 mol%) of PMDA were added as an acid component along with 15.6 g of NMP, and the mixture was allowed to react at 60°C for 2 hours. 0.592 g (0.004 mol, 4 mol%) of PA was then added, and the mixture was allowed to react at 60°C for 2 hours, then at 200°C for 6 hours, after which the temperature was lowered to room temperature. The resulting solution was poured into 4 L of purified water, and the precipitate was filtered off. The filtered precipitate was dispersed in 2 L of water and filtered off, and this process was repeated three times. Thereafter, the precipitate separated by filtration was dried at normal pressure at 50° C. for 96 hours, and then in vacuum at 200° C. for 8 hours, to obtain Polyimide A.

[0152] Synthesis Examples 2-7, 10-11 Polyimides B to G and J to K were obtained in the same manner as in Synthesis Example 1 using the amine components and acid components shown in Table 1.

[0153] Synthesis Example 8 Under a dry nitrogen stream, 30.4 g (0.095 mol: 95 mol%) of TFMB and 1.24 g (0.005 mol: 5 mol%) of SiDA were dissolved in 140 g of N-methyl-2-pyrrolidone (NMP). To this solution, 13.3 g (0.03 mol: 30 mol%) of 6FDA and 18.6 g (0.06 mol: 60 mol%) of ODPA were added as acid components along with 15.6 g of NMP, and the mixture was allowed to react at 60°C for 2 hours. 1.96 g (0.02 mol, 20 mol%) of MA was then added and the mixture was allowed to react at 60°C for 2 hours. After this, 7.91 g of pyridine and 25.5 g of acetic anhydride were added, and the imidization reaction was carried out at room temperature for 24 hours. This solution was poured into 4 L of purified water, and the precipitate was filtered off. The filtered precipitate was dispersed in 2 L of water and filtered off, and this process was repeated three times. Thereafter, the precipitate separated by filtration was dried at 50° C. under atmospheric pressure for 96 hours, and then at 80° C. under vacuum for 96 hours, to obtain polyimide H.

[0154] Synthesis Example 9 Polyimide I was obtained in the same manner as in Synthesis Example 8 using the amine components and acid components shown in Table 1.

[0155] In Table 1, TFMB is R 1 is a diamine that gives a structure represented by general formula (2), and the polyimides obtained in Synthesis Examples 1 to 9 contain structural units represented by general formula (1), and 70 mol % or more of 100 mol % of the structural units represented by general formula (1) are represented by R 1 corresponds to the polyimide having the structure represented by general formula (2).

[0156] [Table 1]

[0157] (Synthesis Examples 12 to 32: Synthesis of Polyimide Solutions) Synthesis Example 12 30 parts by mass of polyimide A was dissolved in 70 parts by mass of xylene to obtain polyimide solution 1 having a resin concentration of 30%.

[0158] Synthesis Examples 13-32 Polyimide solutions 2 to 21 were obtained in the same manner as in Synthesis Example 12 using polyimides B to K, thermal radical generators, crosslinkable low molecular weight compounds, and solvents shown in Table 2. For polyimide solution 19, the polyimide was insoluble in the solvent, so further measurements were discontinued.

[0159] [Table 2]

[0160] Synthesis Example 33: Synthesis of negative electrode active material 50 g of natural graphite (manufactured by Fuji Graphite Co., Ltd., CBF1) with a median diameter of 10 μm, 60 g of nanosilicon powder (manufactured by Aldrich Chemical Co., Ltd.), and 10 g of carbon black (manufactured by Mitsubishi Chemical Corporation, 3050) were mixed and thoroughly dispersed in a ball mill at 600 rpm for 12 hours. The mixture was then vacuum dried at 80°C for 12 hours to obtain a Si-C-based negative electrode active material (theoretical capacity: 2400 mAh / g). The median diameter was 10 μm.

[0161] Synthesis Example 34: Preparation of solid electrolyte The solid electrolyte was prepared by mechanochemical milling of Li2S powder and P2S5 powder. Li2S powder and P2S5 powder were weighed in a molar ratio of 80:20 and kneaded in a mortar. The mixture was then placed in an alumina container, and 10 mm diameter alumina balls and toluene were added. The container was then sealed. The above operation was carried out in an argon gas atmosphere. The container was then placed in a planetary ball mill and milled at 400 rpm for 40 hours. The resulting slurry was filtered under an argon gas atmosphere and vacuum dried to obtain a solid electrolyte.

[0162] Synthesis Example 35 Preparation of Positive Electrode Composition A positive electrode composition was prepared by adding acetylene black, LiNi5Mn3Co2O2 having an average particle size of 10 μm as an active material, and the solid electrolyte prepared in Synthesis Example 34 to a binder solution prepared by dispersing styrene-butadiene rubber (SBR) in anisole, and kneading the mixture. In the positive electrode composition, the active material, solid electrolyte, acetylene black, and SBR were mixed in a mass ratio of 67:29:3:1.

[0163] Synthesis Example 36: Preparation of negative electrode composition A negative electrode composition was prepared by adding the negative electrode active material obtained in Synthesis Example 33, acetylene black, the solid electrolyte produced in Synthesis Example 34, xylene, and NMP in the mass parts shown in Table 3 to polyimide solution 1 (resin concentration 30%) and kneading them. Resin composition 1 was obtained so that the mass ratio of the active material, solid electrolyte, acetylene black, and polyimide resin was 67:23:3:7 and the solid content concentration was 50%.

[0164] Synthesis Examples 37 to 59 Preparation of negative electrode compositions Resin compositions 2 to 25 were obtained in the same manner as in Synthesis Example 37 using polyimide solutions 2 to 18, 20, and 21 and solvents shown in Table 3, with the active material, solid electrolyte, acetylene black, and polyimide resin in a mass ratio of 67:23:3:7 and a solid content of 50%.

[0165] [Table 3]

[0166] Examples 1 to 17, Comparative Examples 1 to 4 Polyimide solutions 1 to 21 were evaluated for 1) mechanical properties of the resin composition, and the evaluation results are shown in Table 4-1.

[0167] Examples 18 to 38, Comparative Examples 5 to 7 Resin compositions 1 to 24 were evaluated for 2) adhesion to the substrate and 3) battery capacity retention rate. The evaluation results are shown in Table 4-2.

[0168] [Table 4-1]

[0169] [Table 4-2]

Claims

1. The following components (a) and (b): (a) at least one resin selected from the group consisting of polyimide, polyamideimide, polyether, polyetherketone, polyetheretherketone, polysulfone, polyethersulfone, polyamide, and any precursor thereof (hereinafter referred to as "(a) resin"); (b) Hansen solubility parameter is 16 (MPa) １／２ More than 20 (MPa) １／２ a solvent that is: A resin composition comprising: A resin composition, wherein the content of the (b) solvent is 50 mass % or more of the total solvent contained in the composition.

2. The resin composition according to claim 1, wherein the resin (a) is a polyimide resin containing a structural unit represented by formula (1). 【Chemical 1】 (In formula (1), R １ represents a divalent organic group having 2 to 50 carbon atoms, R ２ represents a tetravalent organic group having 2 to 50 carbon atoms.

3. In the formula (1), R １ The resin composition according to claim 2, wherein the structure is represented by formula (2): 【Chemistry 2】 (In formula (2), X １ R is an ether group, a thioether group, a ketone group, a sulfonyl group, a fluorene group, or a single bond. ３ and R ４ each independently represents a halogen atom or a monovalent organic group having 1 to 3 carbon atoms. １ and a ２ are each independently an integer of 0 to 4. m is an integer of 0 to 3.

4. Of 100 mol % of the structural units represented by the formula (1), 70 mol % or more of R １ The resin composition according to claim 3, wherein the structure is represented by formula (3): 【Chemistry 3】 (In formula (3), R ５ and R ６ R each independently represents a halogen atom or a monovalent organic group having 1 to 3 carbon atoms. ７ and R ８ each independently represents a halogen atom or a monovalent organic group having 1 to 3 carbon atoms. ３ and a ４ are each independently an integer of 0 to 3.

5. The (b) solvent is a solvent consisting of an aromatic compound having a dipole term (δp) of the Hansen solubility parameter of 7.5 or less and a hydrogen bond term (δh) of 0.5 or more and 7.5 or less. The resin composition according to any one of claims 1 to 4.

6. The resin composition according to any one of claims 1 to 4, further comprising: (c) a filler containing at least one element selected from the group consisting of silicon, cobalt, manganese, nickel, tin, germanium, iron, and titanium (hereinafter referred to as "(c) filler").

7. In the formula (1), R ２ The resin composition according to claim 2, wherein the structure is selected from at least one of general formulas (4) and (5). 【Chemistry 4】 (In formula (4), R ９ is an aliphatic hydrocarbon group having 1 to 30 carbon atoms, and some or all of the hydrogen atoms of the group are replaced by halogen atoms. 【Chemistry 5】 (In formula (5), R １０ is an ether group, a ketone group, a single bond, a sulfone group, or a thioether group.

8. The structural unit of the formula (1) is R ２ is a structural unit represented by the formula (4), and R ２ and a structural unit represented by formula (5).

9. In 100 mol % of the structural units represented by the formula (1), R ２ is a structural unit represented by the formula (4), and R ２ The resin composition according to claim 8, wherein the molar ratio ((4):(5)) of the structural unit represented by formula (5) to the structural unit represented by formula (5) is 90:10 to 10:

90.

10. The resin composition according to any one of claims 1 to 4, wherein the terminal structure of the resin (a) has an unsaturated group.

11. The resin composition according to claim 10, wherein the structure having an unsaturated group is a structure having a maleimide group or a structure having a styryl group.

12. (b') Hansen solubility parameter is 20 (MPa) １／２ The resin composition according to any one of claims 1 to 4, wherein the content of the solvent exceeding the above range is less than 5 mass % of the total solvent contained in the composition.

13. The resin composition according to claim 6, wherein the filler (c) has a theoretical capacity of 160 mAh / g or more.

14. The resin composition according to any one of claims 1 to 4, further comprising (d) a solid electrolyte.

15. The resin composition according to any one of claims 1 to 4, further comprising (e) a thermal radical generator.

16. 5. The resin composition according to claim 1, further comprising (f) at least one of a bismaleimide compound having a molecular weight of 700 or less and a bisstyryl compound having a molecular weight of 700 or less.

17. An electrode having a lithium charge / discharge layer made of the resin composition according to any one of claims 1 to 4 or a thermoset product thereof on at least one surface of a conductive substrate or an insulating substrate having conductive wiring.

18. A secondary battery comprising the electrode of claim 17.

19. A capacitor comprising the electrode of claim 17.

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