Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
  • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
  • C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L79/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen or carbon only, not provided for in groups C08L61/00 - C08L77/00
  • C08L79/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
  • C08L79/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the present invention is a lithium ion secondary composed of a solvent-soluble polyimide compound, a resin composition for producing a negative electrode of a lithium ion secondary battery containing the solvent-soluble polyimide compound, and a resin composition for producing a negative electrode of a lithium ion secondary battery.
• the present invention relates to a negative electrode for a battery and a lithium ion secondary battery including the negative electrode for a lithium ion secondary battery.
• lithium ion secondary batteries As the negative electrode active material contained in the lithium ion secondary battery, a silicon (Si) material having a high discharge capacity and excellent initial charge / discharge efficiency and cycle characteristics is used, but silicon has a large expansion / contraction during charge / discharge. Repeated use may cause cutting of the conductive path between the negative electrode active materials and peeling of the current collector and the negative electrode active material layer.
• Si silicon
• the present invention has been made in view of the above problems, and the problem to be solved is a solvent-soluble polyimide compound capable of remarkably improving the initial charge / discharge efficiency and cycle characteristics of the lithium ion secondary battery. Is to provide. Another object of the present invention is to provide a resin composition for producing a negative electrode of a lithium ion secondary battery containing the solvent-soluble polyimide compound. Another object of the present invention is to provide a negative electrode for a lithium ion secondary battery constructed by using the resin composition for producing a negative electrode for a lithium ion secondary battery. Further, the present invention provides a lithium ion secondary battery including the negative electrode for the lithium ion secondary battery.
• the solvent-soluble polyimide compound of the present invention is a solvent-soluble polyimide used as an electrode material for a lithium ion secondary battery. It is a reaction product of a carboxyl group-containing diamine and an acid anhydride. It is characterized by having an elastic modulus of 3.4 GPa or more.
• the carboxyl group-containing diamine compound is represented by the following general formula (1) or (2).
• R 1 is represented by a single bond or (CH 2 ) p
• p is an integer of 1 to 6
• n and o are integers of 1 to 5, respectively. Is.
• the solvent-soluble polyimide compound of the present invention contains an aromatic diamine compound as a polymerization component.
• the solvent-soluble polyimide compound of the present invention contains, as an aromatic diamine compound, a diamine compound represented by the following general formula (3).
• R 2 ⁇ R 9 are each independently hydrogen, fluorine, selected from the group consisting of substituted or unsubstituted alkyl group and a substituted or unsubstituted aromatic group, R 2 ⁇ At least one of R 9 is an aromatic group.
• the solvent-soluble polyimide compound of the present invention is a reaction product of (a) a carboxyl group-containing diamine compound, (b) an aromatic diamine compound, and (c) an aromatic acid anhydride.
• aromatic acid anhydride is represented by the following general formula (4).
• X is selected from a single bond, an alkyl group having 1 to 6 carbon atoms, (CF 3 ) 2 C, SO 2 and an oxygen atom.
• the solvent-soluble polyimide compound of the present invention is a reaction product of (d) a carboxyl group-containing diamine compound and (e) an alicyclic acid anhydride.
• the resin composition for producing a negative electrode of a lithium ion secondary battery of the present invention is characterized by containing the solvent-soluble polyimide compound and a negative electrode active material.
• the negative electrode for a lithium ion secondary battery of the present invention includes a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector.
• the negative electrode active material layer is characterized by being composed of the resin composition for producing a negative electrode of a lithium ion secondary battery.
• the lithium ion secondary battery of the present invention is characterized by including the above-mentioned negative electrode for a lithium ion secondary battery and a positive electrode.
• a solvent-soluble polyimide compound capable of significantly improving the initial charge / discharge efficiency and cycle characteristics of a lithium ion secondary battery. Further, it is possible to provide a resin composition for producing a negative electrode of a lithium ion secondary battery containing the solvent-soluble polyimide compound. Further, it is possible to provide a negative electrode for a lithium ion secondary battery constructed by using the resin composition for producing a negative electrode for a lithium ion secondary battery. Further, it is possible to provide a lithium ion secondary battery including the negative electrode for the lithium ion secondary battery.
• the solvent-soluble polyimide compound of the present invention is characterized by being a reaction product of a carboxyl group-containing diamine compound and an acid anhydride.
• the solvent-soluble polyimide compound of the present invention may be obtained by reacting two or more kinds of a carboxyl group-containing diamine compound and an acid anhydride.
• the "solvent-soluble polyimide compound” means a polyimide compound that dissolves 5 g or more in 100 g of an organic solvent.
• the solvent-soluble polyimide compound of the present invention is characterized by having an elastic modulus of 3.4 GPa or more. More preferably, the elastic modulus of the solvent-soluble polyimide compound is 3.6 GPa or more and 10 GPa or less.
• the elastic modulus of the polyimide compound is such that after preparing a polyimide single film having a thickness of about 15 ⁇ m, a test piece having a size of 10 mm ⁇ 80 mm is used as a tensile tester (manufactured by Shimadzu Corporation, trade name: AG-Xplus 50 kN). ) was used to measure the elastic modulus in the MD direction and the TD direction at a tensile speed of 10 mm / min. The average value of the elastic modulus in the MD direction and the elastic modulus in the TD direction was calculated.
• the tensile strength of the solvent-soluble polyimide compound of the present invention is preferably 90 MPa or more, more preferably 110 MPa or more.
• the tensile strength of the solvent-soluble polyimide compound is such that after preparing a polyimide single film having a thickness of about 15 ⁇ m, a test piece having a size of 10 mm ⁇ 80 mm is used as a tensile tester (manufactured by Shimadzu Corporation, trade name: AG-Xplus 50 kN).
• the number average molecular weight of the solvent-soluble polyimide compound of the present invention is preferably 20,000 to 150,000, more preferably 30,000 to 100,000.
• the number average molecular weight is a polystyrene-equivalent value based on a calibration curve prepared by using a standard polystyrene by a gel permeation chromatography (GPC) apparatus.
• GPC gel permeation chromatography
• the carboxyl group-containing diamine compound is represented by the following general formula (1) or (2).
• the carboxyl group-containing diamine compound represented by such a general formula the initial charge / discharge efficiency and cycle characteristics of the lithium ion secondary battery can be further improved.
• the carboxyl group-containing diamine compound is represented by the following general formula (1).
• the diamine compound represented by the general formula (1) and the diamine compound represented by the general formula (2) may be used in combination.
• R 1 is represented by a single bond or (CH 2 ) p
• p is an integer of 1 to 6, preferably 1 to 3.
• n and o are integers of 1 to 5, respectively, more preferably 1 to 3, and particularly preferably 1.
• Examples of the diamine compound satisfying the above general formula (1) or (2) include, but are not limited to, the following compounds. Moreover, you may use these together.
• the following diamine compounds are preferable.
• the initial charge / discharge efficiency and cycle characteristics of the lithium ion secondary battery can be further improved. Moreover, you may use these together.
• carboxyl group-containing diamine compound a compound other than the diamine compound represented by the general formula (1) or (2) (hereinafter, referred to as other carboxyl group-containing diamine compound) may be used, and the general formula (1) may be used. Alternatively, it may be used in combination with the diamine compound represented by (2).
• Examples of other carboxyl group-containing diamine compounds include 1,3-bis (4-amino-2-carboxyphenoxy) benzene, 3,5-bis (4-aminophenoxy) benzoic acid, and 5-amino-2- ( Aminophenoxy) Benzoic acid, 3,5-diaminobenzoic acid and the like can be mentioned.
• the acid anhydride is not particularly limited, and an aromatic acid anhydride may be used, an aliphatic acid anhydride may be used, or these may be used in combination. Further, the aliphatic acid anhydride may be a linear type, a branched chain type, or an alicyclic type.
• aromatic acid anhydride examples include 4,4'-oxydiphthalic acid dianhydride (ODPA), 3,3', 4,4'-biphenyltetracarboxylic acid hydride (BPDA), and 2,3-naphthalene.
• ODPA 4,4'-oxydiphthalic acid dianhydride
• BPDA 4,4'-biphenyltetracarboxylic acid hydride
• 2,3-naphthalene 2,3-naphthalene.
• aliphatic acid anhydride examples include norbornan-2-spiro- ⁇ -cyclopentanone- ⁇ '-spiro-2''-norbornan-5,5'', 6,6''-tetracarboxylic acid dianhydride.
• CpODA Bicyclo [2,2,2] Octo-ene-2,3,5,6-tetracarboxylic acid dianhydride
• BTA 1,2,4,5-Cyclohexanetetracarboxylic acid dianhydride
• 1,2,3,4-butanetetracarboxylic acid dianhydride 3,3', 4,4'-bicyclohexyltetracarboxylic acid dioanoxide, carbonyl-4,4'-bis (cyclohexane-1,2) -Dicarboxylic acid) dianhydride, methylene-4,4'-bis (cyclohexane-1,2-dicarboxylic acid) dianhydride, 1,2-ethylene-4,4'-bis (cyclohexane-1,2-dicarboxylic acid) Acid) dianhydride, oxy-4,4'-bis (cyclohexane-1,2-dicarboxylic acid) dianhydride, thio-4,4'-bis (cyclohehex
• the polyimide compound of the present invention contains an aromatic diamine compound as a polymerization component.
• the aromatic diamine compound means an aromatic diamine compound having no carboxyl group.
• aromatic diamine compound examples include bis [4- (4-aminophenoxy) phenyl] sulfone (BAPS), 2,2'-bis (trifluoromethyl) benzidine, m-phenylenediamine, p-phenylenediamine, 2 , 4-Diaminotoluene, 2,4 (6) -diamino-3,5-diethyltoluene, 5 (6) -amino-1,3,3-trimethyl-1- (4-aminophenyl) indan, 4,4 '-Diamino-2,2'-dimethyl-1,1'-biphenyl, 4,4'-diamino-3,3'-dimethyl-1,1'-biphenyl, 3,4'-diaminodiphenyl ether, 4,4 '-Diaminodiphenyl ether, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenyls
• BAPS bis [4- (4-aminophenoxy) phenyl] sulfone
• TPE-R 1,3-bis (4-aminophenoxy) benzene
• a diamine compound represented by the following general formula (3) can also be used.
• the initial charge / discharge efficiency and the cycle characteristics of the lithium ion secondary battery can be further improved.
• the solvent solubility of the polyimide compound can be further improved.
• R 2 ⁇ R 9 are each independently hydrogen, fluorine, selected from the group consisting of substituted or unsubstituted alkyl group and a substituted or unsubstituted aromatic group, R 2 ⁇ At least one of R 9 is an aromatic group.
• R 9 is an aromatic group.
• one or two of R 2 to R 9 are aromatic groups.
• one or two of R 6 to R 9 are substituted or unsubstituted aromatic groups, and more preferably at least R 6 or R 8 is an aromatic group.
• R 6 to R 9 are substituted or unsubstituted aromatic groups, and R 2 to R 9 other than the aromatic group are hydrogen, fluorine and a substituted or unsubstituted alkyl group. Selected from the group consisting of. Specific examples thereof include compounds represented by the following chemical formulas (a mode in which R 8 is an aromatic group and R 2 to R 7 and R 9 other than R 8 are hydrogen).
• the alkyl group includes a linear group, a branched chain group and a cyclic group, and further includes an alkoxy group and an alkylamino group which are bonded to the main skeleton via an oxygen atom or a nitrogen atom.
• the aromatic group also includes a substituent that binds to the main skeleton via an oxygen atom, a nitrogen atom or a carbon atom.
• the aromatic group includes a heteroaromatic group such as a pyrrole group.
• the alkyl group and aromatic group are preferably unsubstituted, but may have a substituent, for example, an alkyl group, a halogen group such as a fluoro group or a chloro group, an amino group, a nitro group, or a hydroxyl group. , Cyano group, carboxyl group, sulfonic acid group and the like.
• the alkyl group and aromatic group may have one or more or two or more of these substituents.
• the alkyl group preferably has 1 to 10 carbon atoms, and more preferably 1 to 3 carbon atoms.
• Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a tert-butyl group, an n-pentyl group, a sec-pentyl group, and n-.
• a methyl group, an ethyl group, a methoxy group, an ethoxy group and a trifluoromethyl group are preferable because of steric hindrance and heat resistance.
• the aromatic group preferably has 5 to 20 carbon atoms, and more preferably 6 to 10 carbon atoms.
• Examples of the aromatic group having 5 to 20 carbon atoms include a phenyl group, a trill group, a methylphenyl group, a dimethylphenyl group, an ethylphenyl group, a diethylphenyl group, a propylphenyl group, a butylphenyl group, a fluorophenyl group, and a pentafluoro.
• Phenyl group chlorphenyl group, bromophenyl group, methoxyphenyl group, dimethoxyphenyl group, ethoxyphenyl group, diethoxyphenyl group, benzyl group, methoxybenzyl group, dimethoxybenzyl group, ethoxybenzyl group, diethoxybenzyl group, aminophenyl Group, aminobenzyl group, nitrophenyl group, nitrobenzyl group, cyanophenyl group, cyanobenzyl group, phenethyl group, phenylpropyl group, phenoxy group, benzyloxy group, phenylamino group, diphenylamino group, biphenyl group, naphthyl group, Phenylnaphthyl group, diphenylnaphthyl group, anthryl group, anthrylphenyl group, phenylanthryl group, naphthacenyl group, phenanthryl
• the polyimide compound is a reaction of (a) a carboxyl group-containing diamine compound, (b) an aromatic diamine compound, and (c) an aromatic acid anhydride. It is a thing.
• (A) As the carboxyl group-containing diamine compound it is preferable to use the diamine compound represented by the above general formula (1) or (2).
• the more preferable embodiment in the diamine compound satisfying the general formula (1) or (2) is as described above.
• the content of the (a) carboxyl group-containing diamine compound in the polyimide compound is preferably 10 mol% or more and 90 mol% or less, preferably 20 mol% or more and 80 mol% or less, based on 100 mol% of the total diamine amount. More preferably. Within the above numerical range, the initial charge / discharge efficiency and cycle characteristics of the lithium ion secondary battery can be further improved. Further, it is possible to prevent the varnish containing the polyimide compound from gelling.
• aromatic diamine compound As the aromatic diamine compound, the above-mentioned one can be appropriately selected and used. Among the above-mentioned aromatic diamine compounds, bis [4- (4-aminophenoxy) phenyl] sulfone (BAPS), 1,3-bis (4-aminophenoxy) benzene (TPE-R) and the above general formula (3) Aromatic diamine compounds satisfying the above conditions are preferable. Moreover, you may use these together.
• the content of the aromatic diamine compound (b) in the polyimide compound is preferably 10 mol% or more and 90 mol% or less, preferably 20 mol% or more and 80 mol% or less, based on 100 mol% of the total diamine amount. Is more preferable. Thereby, the initial charge / discharge efficiency and the cycle characteristics of the lithium ion secondary battery can be further improved.
• aromatic acid anhydride (c) it is preferable to use one represented by the following general formula (4).
• aromatic acid anhydride By using such an aromatic acid anhydride, the initial charge / discharge efficiency and cycle characteristics of the lithium ion secondary battery can be further improved.
• X is selected from a single bond, an alkyl group having 1 to 6 carbon atoms, (CF 3 ) 2 C, SO 2 and an oxygen atom.
• aromatic acid anhydride satisfying the above general formula (4) examples include 4,4'-oxydiphthalic acid dianhydride (ODPA) and 3,3', 4,4'-biphenyltetracarboxylic dianhydride (BPDA). , 3,3', 4,4'-biphenylsulfonetetracarboxylic dianhydride, 2,3,3', 4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetra Examples thereof include carboxylic acid dianhydride.
• aromatic acid anhydride (c) is not limited to this, and the above-mentioned aromatic acid anhydride that does not satisfy the general formula (4) may be used.
• the polyimide compound according to a particularly preferable embodiment is a polymerization component other than (a) a carboxyl group-containing diamine compound, (b) an aromatic diamine compound, and (c) an aromatic acid anhydride, as long as the characteristics of the present invention are not impaired. May include.
• One of the particularly preferable embodiments of the polyimide compound according to the present invention is a reaction product of (d) a carboxyl group-containing diamine compound and (e) an alicyclic acid anhydride.
• the diamine compound represented by the above general formula (1) or (2) it is preferable to use the diamine compound represented by the above general formula (1) or (2).
• the more preferable embodiment in the diamine compound satisfying the general formula (1) or (2) is as described above.
• the content of the (d) carboxyl group-containing diamine compound in the polyimide compound is preferably 10 mol% or more and 90 mol% or less, preferably 20 mol% or more and 80 mol% or less, based on 100 mol% of the total diamine amount. More preferably. Thereby, the initial charge / discharge efficiency and the cycle characteristics of the lithium ion secondary battery can be further improved.
• (E) As the alicyclic acid anhydride, the above-mentioned one can be appropriately selected and used.
• norbornane-2-spiro- ⁇ -cyclopentanone- ⁇ '-spiro-2''-norbornane-5 from the viewpoint of initial charge / discharge efficiency of the lithium ion secondary battery.
• 5 ′′, 6,6''-tetracarboxylic dianhydride (CpODA) and bicyclo [2,2,2] octo-ene-2,3,5,6-tetracarboxylic dianhydride (BTA) Is preferable.
• the polyimide compound according to a particularly preferable embodiment may contain a polymerization component other than (d) a carboxyl group-containing diamine compound and (e) an alicyclic acid anhydride as long as the characteristics of the present invention are not impaired.
• the polyimide compound of the present invention can be produced by a conventionally known method using the diamine compound and the acid anhydride. Specifically, it can be obtained by reacting a diamine compound with an acid anhydride to obtain a polyamic acid, and then performing a cyclization dehydration reaction to convert it into a polyimide compound.
• the mixing ratio of the acid anhydride and the diamine compound is preferably 0.5 mol% to 1.5 mol%, preferably 0.9 mol%, based on the total amount of the acid anhydride of 1 mol%. More preferably, it is ⁇ 1.1 mol%.
• the reaction between the diamine compound and the acid anhydride is preferably carried out in an organic solvent.
• the organic solvent is not particularly limited as long as it does not react with the diamine compound and acid anhydride of the present invention and can dissolve the reaction product of the diamine compound and acid anhydride.
• the reaction temperature of the diamine compound and the acid anhydride is preferably 40 ° C. or lower in the case of chemical imidization. Further, in the case of thermal imidization, the temperature is preferably 150 to 220 ° C, more preferably 170 to 200 ° C.
• An imidization catalyst may be used during the cyclization dehydration reaction, for example, methylamine, ethylamine, trimethylamine, triethylamine, propylamine, tripropylamine, butylamine, tributylamine, tert-butylamine, hexylamine, triethanolamine, etc.
• N, N-dimethylethanolamine, N, N-diethylethanolamine, triethylenediamine, N-methylpyrrolidin, N-ethylpyrrolidin, aniline, benzylamine, toluidine, trichloroaniline, pyridine, colidin, lutidine, picolin, quinoline, isoquinolin , Valerolactone and the like can be used.
• an azeotropic dehydrating agent such as toluene, xylene, or ethylcyclohexane
• an acid catalyst such as acetic anhydride, propionic anhydride, butyric anhydride, and benzoic anhydride can be used.
• a sealing agent such as benzoic acid, phthalic anhydride, or hydrogenated phthalic anhydride can be used.
• a sealing agent such as benzoic acid, phthalic anhydride, or hydrogenated phthalic anhydride
• the polyimide compound can be prepared. Double or triple bonds can also be introduced at the ends.
• the resin composition for producing a negative electrode of a lithium ion secondary battery of the present invention contains the above-mentioned polyimide compound and a negative electrode active material. Also, in one embodiment, the resin composition comprises a conductive agent.
• the content of the polyimide compound in the resin composition is preferably 1% by mass or more and 20% by mass or less, and more preferably 3% by mass or more and 18% by mass or less.
• a silicon material as the negative electrode active material because the volume change of silicon can be effectively prevented.
• the silicon material include alloys of silicon with metals such as silicon particles, tin, nickel, iron, copper, silver, cobalt, manganese and zinc, and compounds of silicon with boron, nitrogen, oxygen and carbon. Be done.
• silicon materials include SiO, SiO 2 , SiB 4 , Mg 2 Si, Ni 2 Si, CoSi 2 , NiSi 2 , Cu 5 Si, FeSi 2 , MnSi 2 , ZnSi 2 , SiC, Si 3 N 4 and Si. 2 N 2 O and the like can be mentioned.
• a material other than a silicon material may be used, and examples thereof include metallic lithium, metal oxide, and graphite.
• the resin composition may contain two or more types of negative electrode active materials.
• the content of the negative electrode active material in the resin composition is preferably 70% by mass or more and 99% by mass or less, and more preferably 75% by mass or more and 95% by mass or less.
• the resin composition of the present invention contains a conductive agent and includes, for example, carbon black (acetylene black, ketjen black, furnace black, etc.), graphite, carbon fiber, carbon flakes, metal fiber, foil and the like. Be done. Among these, carbon black is preferable, and acetylene black is more preferable.
• the resin composition may contain two or more kinds of conductive agents.
• the content of the conductive agent in the resin composition is preferably 0.1% by mass or more and 25% by mass or less, and more preferably 1% by mass or more and 20% by mass or less.
• the resin composition of the present invention may contain additives as long as the characteristics of the present invention are not impaired, and examples thereof include thickeners and fillers.
• the negative electrode for a lithium ion secondary battery of the present invention includes a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector, and the negative electrode active material layer is composed of the above resin composition. It is characterized by being done.
• the current collector that can be used is not particularly limited, and examples thereof include copper, nickel, stainless steel, gold, iron, aluminum and alloys thereof, nickel-plated steel, and chrome-plated steel.
• the thickness of the negative electrode active material layer is preferably 15 ⁇ m or more and 150 ⁇ m or less, and more preferably 30 ⁇ m or more and 120 ⁇ m or less.
• the negative electrode for a lithium ion secondary battery of the present invention can be produced by applying an organic solvent in which the above resin composition is dissolved or dispersed on a current collector and drying it.
• organic solvent those described above can be used, and from the viewpoint of solubility or dispersibility of the resin composition, N-methyl-2-pyrrolidone, N, N'-dimethylimidazolidinone and ⁇ -butyrolactone Is preferable.
• the coating method is not particularly limited, and examples thereof include a die coater method, a three-roll transfer coater method, a doctor blade method, a dip method, a direct roll method, and a gravure method.
• the lithium ion secondary battery of the present invention is characterized by including the above-mentioned negative electrode and a positive electrode. Further, in one embodiment, the lithium ion secondary battery of the present invention includes a separator arranged between the negative electrode and the positive electrode.
• a separator arranged between the negative electrode and the positive electrode.
• the positive electrode As the positive electrode, those conventionally used for the positive electrode of the lithium ion secondary battery can be appropriately used.
• the positive electrode can be produced by applying a resin composition for producing a positive electrode of a lithium ion secondary battery on a current collector and drying it.
• the resin composition for producing a positive electrode of a lithium ion secondary battery can include a positive electrode active material and a binder resin. Further, the resin composition for producing a positive electrode of a lithium ion secondary battery may contain the above-mentioned conductive agent and additive.
• the positive electrode active material examples include lithium cobalt oxide, lithium nickel oxide, lithium manganate, lithium iron phosphate and the like.
• the binder resin the above-mentioned polyimide compound may be used, or polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, polyethylene or the like may be used.
• the present invention is not limited to the above, and a lithium foil or the like can be used as the positive electrode.
• separator conventionally known ones can be used, and examples thereof include a paper separator, a resin separator such as polyethylene and polypropylene, and a glass fiber separator.
• the positive electrode and the negative electrode are arranged in a battery container, and the container is filled with an organic solvent (electric field solution) in which an electrolyte is dissolved.
• the electrolyte is not particularly limited, for example, LiPF 6, LiClO 4, LiBF 4, LiClF 4, LiAsF 6, LiSbF 6, LiAlO 4, LiAlCl 4, CF 3 SO 3 Li, LiN (CF 3 SO 2) 3 , LiCl, LiI and the like can be mentioned.
• LiPF 6 , LiClO 4 and CF 3 SO 3 Li are preferable because they have a high degree of dissociation.
• the organic solvent is also not particularly limited, and examples thereof include carbonate compounds, lactone compounds, ether compounds, sulfolane compounds, dioxolane compounds, ketone compounds, nitrile compounds, and halogenated hydrocarbon compounds.
• carbonates such as dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, ethylene glycol dimethyl carbonate, propylene glycol dimethyl carbonate, ethylene glycol diethyl carbonate and vinylene carbonate, and lactones such as ⁇ -butyl lactone.
• ethers such as 1,4-dioxane, sulfolanes, sulfolanes such as 3-methylsulfolane, dioxolanes such as 1,3-dioxolane, 4-methyl- Ketones such as 2-pentanone, nitriles such as acetonitrile, pyropionitrile, valeronitrile, benzonitrile, halogenated hydrocarbons such as 1,2-dichloroethane, other methylformates, dimethylformamide, diethylformamide, dimethylsulfoxide.
• ethers such as 1,4-dioxane, sulfolanes, sulfolanes such as 3-methylsulfolane, dioxolanes such as 1,3-dioxolane, 4-methyl- Ketones such as 2-pentanone, nitriles such as acetonitrile, pyropionitrile, valeronitrile, benzon
• the carbonate compound is preferable because the solubility of the polyimide compound used for the negative electrode is low and the swelling of the polyimide can be suppressed.
• the form of the lithium ion secondary battery is not particularly limited, and can be appropriately changed depending on the application, such as paper type, button type, coin cell type, laminated type, cylindrical type and square type.
• Example 1 43.25 g (100 mmol) of the diamine compound (BAPS) represented by the following chemical formula and the diamine compound represented by the following chemical formula (100 mmol) in a 500 ml separable flask equipped with a synthetic nitrogen introduction tube for the solvent-soluble polyimide compound A and a stirrer.
• MBAA 28.63 g (100 mmol)
• acid anhydride (BPDA) 58.84 g (200 mmol) represented by the following chemical formula, N-methyl-2-pyrrolidone 700 g, pyridine 3.2 g (40 mmol) and toluene 70 g.
• Example 2 Synthesis of Solvent-Soluble Polyimide Compound B Using the same equipment as in Example 1, BAPS 43.25 g (100 mmol), MBAA 28.63 g (100 mmol), and diamine compound (PHBAAB) 15.22 g (50 mmol) represented by the following chemical formula. ), BPDA 44.13 g (150 mmol), acid anhydride (ODPA) 31.02 g (100 mmol) represented by the following chemical formula, N-methyl-2-pyrrolidone 868 g, pyridine 4.0 g (50 mmol) and toluene 87 g. was charged and reacted at 180 ° C. under a nitrogen atmosphere for 9 hours while looking out of the system on the way to obtain a 15 wt% polyimide solution.
• Example 3 Synthesis of Solvent-Soluble Polyimide Compound C Using the same equipment as in Example 1, 28.63 g (100 mmol) of MBAA, 15.22 g (50 mmol) of PHBAAB, and 29.23 g of diamine compound (TPE-R) represented by the following chemical formula (TPE-R).
• Example 4 Synthesis of Solvent-Soluble Polyimide Compound D Using the same equipment as in Example 1, 28.63 g (100 mmol) of MBAA, 38.44 g (100 mmol) of acid anhydride (CpODA) represented by the following chemical formula, N-methyl-2. -360 g of pyrrolidone, 1.6 g (20 mmol) of pyridine and 36 g of toluene were added, and the reaction was carried out at 180 ° C. under a nitrogen atmosphere for 12 hours while removing toluene from the system to obtain a 15 wt% polyimide solution. It was.
• CpODA acid anhydride
• An electrolytic copper foil having a thickness of 10 ⁇ m was prepared as a current collector for the negative electrode, and a resin composition for producing a negative electrode of a lithium ion secondary battery prepared as described above was applied to the surface of the electrolytic copper foil, and dried to obtain a thickness of 50 ⁇ m.
• a negative electrode active material layer was formed to obtain a negative electrode.
• a lithium foil as a positive electrode, ethylene carbonate and ethyl methyl carbonate as an electrolytic solution, and a polyolefin single-layer separator (Celguard Co., Ltd., Celguard (registered trademark) 2500) were prepared to prepare a coin-cell type lithium ion secondary battery.
• Cycle characterization The cycle characteristics were measured by the following method. After two cycles of initial charge / discharge efficiency measurement, CC (constant current) charging is performed up to 5 mV with a current density equivalent to 0.2 C, then switching to CV (constant voltage) charging at 5 mV, and a current density equivalent to 0.02 C. After charging until it becomes, CC discharge to 1.2V with a current density equivalent to 0.2C is performed for 3 cycles at 25 ° C., and then CC (constant current) charging is performed to 5mV with a current density equivalent to 0.5C.

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