Lithium secondary battery composition, electrode, lithium secondary battery, method for producing lithium secondary battery electrode, and block isocyanate

Abstract

A lithium secondary battery composition according to the present disclosure contains a polyisocyanate compound.

Description

Composition for lithium secondary batteries, electrodes, lithium secondary batteries, methods for manufacturing electrodes for lithium secondary batteries, and blocked isocyanates 【0001】 This disclosure relates to compositions for lithium secondary batteries, electrodes, lithium secondary batteries, methods for manufacturing electrodes for lithium secondary batteries, and blocked isocyanates. 【0002】 Lithium-ion batteries are attracting attention as high-energy-density batteries. 【0003】 When an electrolyte containing a cyclic carbonate containing fluorine atoms is used, a reaction occurs in which the cyclic carbonate containing fluorine atoms decomposes, resulting in the generation of a large amount of gas within the battery. For example, when fluoroethylene carbonate (FEC) is used, it is known that FEC undergoes oxidative decomposition on the positive electrode, producing carbon dioxide. 【0004】 It is known that the electrolyte can degrade due to the influence of trace amounts of water contained in the materials of the electrolyte. For example, LiPF4 ６ When used, the electrolyte decomposes, producing acid. 【0005】 Patent Document 1 discloses an acid or water-reducing agent (hereinafter also referred to as "reducing agent") for a non-aqueous electrolyte that can reduce gas generation even under high-temperature conditions and suppress deterioration of battery characteristics. The reducing agent contains a diisocyanate compound represented by the following formulas (Z1), (Z2), or (Z3). The non-aqueous electrolyte contains a cyclic carbonate containing a fluorine atom. 【0006】 【0007】 In equation (Z1), R １ ~R ４ Each of these is independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a halogen atom. ５ and R ６ Each of these is independently a bond or an alkylene group having 1 to 4 carbon atoms. In formula (Z2), R' １ ~R' ４is, independently of each other, hydrogen, an alkyl group having 1 to 4 carbon atoms, or a halogen atom. R' ５ and R' ６ are, independently of each other, a bond or an alkylene group having 1 to 4 carbon atoms. In formula (Z3), R'' １ to R'' ４ are, independently of each other, hydrogen, an alkyl group having 1 to 4 carbon atoms, or a halogen atom. R'' ５ and R'' ６ are, independently of each other, a bond or an alkylene group having 1 to 4 carbon atoms. 【0008】 Patent Document 1: Japanese Patent Application Laid-Open No. 2024-93864 【0009】 The capacity of a lithium secondary battery may decrease when charging is performed and then discharging is performed (hereinafter, also referred to as "charge-discharge") repeatedly. Therefore, there is a demand for a composition for a lithium secondary battery that can suppress a decrease in battery capacity even when charge-discharge is repeated. 【0010】 A lithium secondary battery may be used not only in a warm region (for example, 25°C) but also in a cold region (for example, -10°C). In a cold region, the battery performance of a lithium secondary battery may decrease. Therefore, there is a demand for a composition for a lithium secondary battery that can suppress an increase in battery resistance at normal temperature (for example, 25°C) and low temperature (for example, -10°C). 【0011】 In view of the above circumstances, the present disclosure aims to provide a composition for a lithium secondary battery, an electrode, a lithium secondary battery, a method for manufacturing an electrode for a lithium secondary battery, and a blocked isocyanate that can suppress a decrease in battery capacity and an increase in battery resistance at normal temperature and low temperature even when charge-discharge is repeated. 【0012】 Means for solving the above problems include the following embodiments. 【0013】<1> A composition for a lithium secondary battery comprising a polyisocyanate compound. <2> The composition for a lithium secondary battery according to <1>, wherein the polyisocyanate compound comprises at least one of an isocyanurate derivative of 1,3-bis(isocyanatomethyl)cyclohexane and an isocyanurate derivative of xylylene diisocyanate. <3> The composition for a lithium secondary battery according to <1> or <2>, wherein the polyisocyanate compound is a blocked isocyanate obtained by blocking the isocyanate group of the polyisocyanate compound with a blocking agent, and the blocking agent comprises at least one of a guanidino group-containing compound and a compound having a five-membered or six-membered nitrogen-containing heterocyclic structure. <4> The composition for a lithium secondary battery according to any one of <1> to <3>, wherein the content of the polyisocyanate compound is 0.1 parts by mass to 3.0 parts by mass per 100 parts by mass of the solid content of the composition for a lithium secondary battery. <5> The lithium secondary battery composition according to any one of <1> to <4>, wherein the isocyanate group content (NCO%) in the polyisocyanate compound is 5% by mass to 30% by mass. <6> The lithium secondary battery composition according to any one of <1> to <5>, further comprising an active material. <7> The lithium secondary battery composition according to <6>, wherein the active material is a carbon material. <8> The lithium secondary battery composition according to any one of <1> to <7>, used as an electrode for a lithium secondary battery. <9> An electrode comprising a dried product of the lithium secondary battery composition according to any one of <1> to <8>. <10> A lithium secondary battery comprising the electrode according to <9>.<11> Preparing a composition for a lithium secondary battery containing a blocked isocyanate; mixing the composition for the lithium secondary battery and an active material to prepare a mixture; and applying the mixture to a current collector and drying it to prepare an electrode for a lithium secondary battery, the blocked isocyanate being formed by blocking isocyanate groups of a polyisocyanate compound with a blocking agent, the blocking agent containing at least one of a guanidinogroup-containing compound and a compound having a five- or six-membered nitrogen-containing heterocyclic structure. A method for manufacturing an electrode for a lithium secondary battery. <12> A blocked isocyanate in which isocyanate groups of a polyisocyanate compound are blocked by a blocking agent, the blocking agent containing at least two compounds having a five- or six-membered nitrogen-containing heterocyclic structure. 【0014】 According to the present disclosure, there are provided a composition for a lithium secondary battery, an electrode, a lithium secondary battery, a method for manufacturing an electrode for a lithium secondary battery, and a blocked isocyanate, which can suppress a decrease in battery capacity and suppress an increase in battery resistance at normal temperature and low temperature even when charge and discharge are repeated. 【0015】 FIG. 1 is a schematic cross-sectional view showing a laminated battery, which is an example of the lithium secondary battery of the present disclosure. FIG. 2 is a schematic cross-sectional view showing a coin-type battery, which is another example of the lithium secondary battery of the present disclosure. 【0016】 In the present specification, a numerical range represented using "to" means a range including the numerical values described before and after "to" as a lower limit value and an upper limit value. In the present specification, the term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps as long as the intended purpose of the step is achieved. In the present specification, (meth)acrylate means acrylate or methacrylate. 【0017】 Hereinafter, embodiments of a composition for a lithium secondary battery, an electrode, a method for manufacturing an electrode for a lithium secondary battery, and a blocked isocyanate of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and the description will not be repeated. 【0018】 (1) Composition for lithium secondary battery The composition for lithium secondary battery of the present disclosure (hereinafter also simply referred to as "composition") comprises a polyisocyanate compound. 【0019】 A "polyisocyanate compound" refers to a compound having at least two isocyanate groups in one molecule. 【0020】 Because the lithium secondary battery composition of this disclosure has the above-described structure, it can suppress the decrease in battery capacity and the increase in battery resistance at room temperature and low temperature, even when repeated charging and discharging is performed. This effect is presumed to be due to, but is not limited to, the following reasons: The polyisocyanate forms a protective film on the surface of the active material, thereby suppressing the progress of side reactions (e.g., decomposition of the non-aqueous electrolyte). As a result, it is presumed that the decrease in battery capacity and the increase in battery resistance at room temperature and low temperature are suppressed even when repeated charging and discharging is performed. 【0021】 The lithium secondary battery composition disclosed herein is used in lithium secondary batteries, and is preferably used in the electrodes of the lithium secondary battery. Examples of materials for the electrodes of a lithium secondary battery include raw materials for the electrode composite layer and coating layers for the electrode surface. The lithium secondary battery composition disclosed herein is suitably used as a raw material for the electrode composite layer. Details of the electrodes will be described later. 【0022】 (1.1) The polyisocyanate compound composition contains a polyisocyanate compound. The polyisocyanate compound may be used alone or in combination of two or more types. 【0023】 The average number of functional groups of isocyanate groups in a polyisocyanate compound may be 2 or more, 2.5 or more, 4 or less, or 3.5 or less. 【0024】The isocyanate group content (NCO%) in the polyisocyanate compound may be 5% by mass or more, 7% by mass or more, 10% by mass or more, 13% by mass or more, 30% by mass or less, 25% by mass or less, 20% by mass or less, 15% by mass or less, or 14% by mass or less. The isocyanate group content (NCO%) in the polyisocyanate compound may be between 5% by mass and 30% by mass. 【0025】 Examples of polyisocyanate compounds include polyisocyanate monomers and polyisocyanate derivatives. 【0026】 The content of the polyisocyanate compound is not particularly limited, but is preferably 0.1 to 3.0 parts by mass, more preferably 0.1 to 2.0 parts by mass, even more preferably 0.2 to 1.0 parts by mass, particularly preferably 0.2 to 0.8 parts by mass, and even more preferably 0.3 to 0.5 parts by mass, per 100 parts by mass of the solid content of the composition. 【0027】 (1.1.1) Polyisocyanate monomers Examples of polyisocyanate monomers include aliphatic polyisocyanates (e.g., acyclic aliphatic polyisocyanates and cyclic aliphatic polyisocyanates), aromatic polyisocyanates, and aromatic aliphatic polyisocyanates. 【0028】 Examples of acyclic aliphatic polyisocyanates include ethylene diisocyanate, trimethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and 2,6-diisocyanate methyl caproate. 【0029】Examples of cyclic aliphatic polyisocyanates include 1,3-cyclopentane diisocyanate, 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, methylenebis(cyclohexyl isocyanate), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, norbornane diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, and 1,4-bis(isocyanatomethyl)cyclohexane. 【0030】 Examples of aromatic polyisocyanates include tolylene diisocyanate, phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, diphenylmethane diisocyanate, 4,4'-toluidine diisocyanate, and 4,4'-diphenyl ether diisocyanate. 【0031】 Examples of aromatic aliphatic polyisocyanates include xylylene diisocyanate, tetramethyl xylylene diisocyanate, and ω,ω'-diisocyanate-1,4-diethylbenzene. 【0032】 (1.1.2) Polyisocyanate derivatives Polyisocyanate derivatives are derived from polyisocyanate monomers. Examples of polyisocyanate derivatives include isocyanurate derivatives, iminooxadiazinedione derivatives, triol adducts, allophanate derivatives, biuret derivatives, urea derivatives, oxadiazinetrione derivatives, carbodiimide derivatives, uretodione derivatives, and uretonimine derivatives. 【0033】 The polyisocyanate compound preferably contains a polyisocyanate derivative, and more preferably consists of a polyisocyanate derivative. 【0034】Examples of polyisocyanate derivatives include aliphatic polyisocyanate derivatives derived from aliphatic polyisocyanates, aromatic polyisocyanate derivatives derived from aromatic polyisocyanates, and aromatic aliphatic polyisocyanate derivatives derived from aromatic aliphatic polyisocyanates. 【0035】 As an aliphatic polyisocyanate derivative, isocyanurate derivatives of aliphatic polyisocyanates (for example, 1,3-bis(isocyanatomethyl)cyclohexane(1,3-H ６ Examples include isocyanurate derivatives of XDI, and isocyanurate derivatives of 1,6-hexamethylene diisocyanate, etc. 【0036】 Examples of aromatic polyisocyanate derivatives include isocyanurate derivatives of aromatic polyisocyanates (for example, isocyanurate derivatives of tolylene diisocyanate). 【0037】 Examples of aromatic aliphatic polyisocyanate derivatives include isocyanurate derivatives of aromatic aliphatic polyisocyanates (for example, isocyanurate derivatives of xylylene diisocyanate (XDI)). 【0038】 The polyisocyanate compound may be a commercially available product. 【0039】 The polyisocyanate compound preferably contains at least one isocyanurate derivative of 1,3-bis(isocyanatomethyl)cyclohexane and isocyanurate derivative of xylylene diisocyanate. This allows for the formation of an electrochemically stable protective film on the active material surface, thereby maintaining the battery capacity and suppressing resistance increases. 【0040】 (1.1.3) Modified polyisocyanate compounds may be modified with a hydrophilic compound containing an active hydrogen group. Modification of the polyisocyanate compound with a hydrophilic compound containing an active hydrogen group enables dispersion in water. Cationic hydrophilic groups and nonionic hydrophilic groups may be used in combination. 【0041】Hydrophilic compounds have both active hydrogen groups and hydrophilic groups. Examples of hydrophilic compounds include nonionic hydrophilic compounds (e.g., polyoxyethylene compounds). 【0042】 Polyoxyethylene compounds have at least three consecutive oxyethylene groups. Examples of polyoxyethylene compounds include polyols containing polyoxyethylene groups, polyamines containing polyoxyethylene groups, single-ended polyoxyethylene glycols, and single-ended polyoxyethylenediamines. Polyoxyethylene compounds may be used individually or in combination of two or more. 【0043】 The polyoxyethylene compound preferably contains a single-ended polyoxyethylene glycol, and more preferably contains a monoalkoxy polyoxyethylene glycol. 【0044】 One end of the monoalkoxypolyoxyethylene glycol may be encapsulated with, for example, an alkyl group having 1 to 20 carbon atoms. The other end of the monoalkoxypolyoxyethylene glycol has a hydroxyl group. 【0045】 Examples of monoalkoxypolyoxyethylene glycols include methoxypolyoxyethylene glycol and ethoxypolyoxyethylene glycol. 【0046】 The number-average molecular weight of the polyoxyethylene compound may be 200 or more, 400 or more, 2000 or less, or 1500 or less. The number-average molecular weight of the polyoxyethylene compound can be measured by gel permeation chromatography. 【0047】 When the polyisocyanate compound is modified with a hydrophilic compound, at least one of the polyisocyanate monomer and / or polyisocyanate derivative is reacted with the hydrophilic compound in a proportion that leaves free isocyanate groups intact. 【0048】The proportion of active hydrogen groups in the hydrophilic compound may be 0.5 moles or more, 1 mole or more, 3 moles or more, 10 moles or less, 8 moles or less, or 5 moles or less, per 100 moles of isocyanate groups in the polyisocyanate compound before modification. 【0049】 (1.1.4) Blocked isocyanate polyisocyanate compounds may be blocked isocyanates obtained by blocking the isocyanate groups of a polyisocyanate compound with a blocking agent. The fact that the polyisocyanate compound is a blocked isocyanate extends the pot life in water. That is, it can maintain a dispersed state in water for a long period of time and has excellent storage stability. 【0050】 The blocking agent is a compound having an active group that can react with isocyanate groups. The blocking agent is deactivated by reacting with the free isocyanate groups of the polyisocyanate compound, forming "latent isocyanate groups." A "latent isocyanate group" is a group that can be dissociated from the blocked isocyanate by heating or other conditions, thereby generating free isocyanate groups again. In other words, the blocked isocyanate contains "latent isocyanate groups" derived from the polyisocyanate compound, rather than free isocyanate groups. Furthermore, the isocyanate group content in the blocked isocyanate refers to the amount of latent isocyanate groups derived from the polyisocyanate compound. 【0051】 The blocking agent may contain a first blocking agent, a second blocking agent, a first and second blocking agent, a first blocking agent alone, a second blocking agent alone, or a first blocking agent and a second block. 【0052】 The first blocking agent is a guanidino group-containing compound. The first blocking agent has catalytic activity that blocks and inactivates the isocyanate group, and also activates the isocyanate group in both the blocked and unblocked states. 【0053】The second blocking agent is different from the first blocking agent. The second blocking agent blocks and inactivates the isocyanate group, and regenerates the isocyanate group in the deblocked state. The second blocking agent either does not have enough catalytic activity to activate the regenerated isocyanate group, or if it does have enough catalytic activity to activate the regenerated isocyanate group, its catalytic activity is weaker than that of the first blocking agent. 【0054】 (1.1.4.1) The first blocking agent may contain a guanidino group-containing compound which is the first blocking agent. That is, the polyisocyanate compound may contain a first latent isocyanate group in which the isocyanate group of the polyisocyanate compound is blocked by the first blocking agent. By including a guanidino group-containing compound in the blocking agent, the polyisocyanate compound can exhibit curability at low temperatures. 【0055】 Examples of guanidino group-containing compounds include guanidine, 1-alkylguanidines such as 1-methylguanidine, 1-arylguanidines such as 1-phenylguanidine, 1,3-dialkylguanidines such as 1,3-dimethylguanidine, 1,3-diarylguanidines such as 1,3-diphenylguanidine and 1,3-di(o-tolyl)-guanidine, 1,1-dialkylguanidines such as 1,1-dimethylguanidine and 1,1-diethylguanidine, 1,2,3-trialkylguanidines such as 1,2,3-trimethylguanidine, 1,2,3-triarylguanidines such as 1,2,3-triphenylguanidine, 1,1,3,3-tetraalkylguanidines such as 1,1,3,3-tetramethylguanidine, and 1,5,7-triazabicyclo[4.4.0]deca-5-ene. 【0056】 The first blocking agent preferably contains TMG, and more preferably TMG. By neutralizing TMG with an acid (e.g., acetic acid) to form a salt, the blocking isocyanate becomes water-dispersible. As a result, the polyisocyanate compound can be stably stored in a dispersed state in water, and curability at low temperatures can be achieved. 【0057】The dissociation temperature of the first blocking agent may be 60°C or higher, 80°C or higher, 150°C or lower, or 130°C or lower. The dissociation temperature of the blocking agent can be measured by the following method: The blocked isocyanate is coated onto a silicon wafer, and the temperature at which the isocyanate groups are regenerated is observed by IR (Infrared Spectroscopy) measurement while heating. If the catalytic activity of the blocking agent is high and the regenerated isocyanate groups cannot be observed, the blocking agent can be mixed with a polyol, the mixture is coated onto a silicon wafer, and the dissociation temperature of the blocking agent can be measured by observing the temperature at which the hydroxyl groups of the polyol compound react by IR measurement while heating. 【0058】 The content of the first blocking agent in the blocking agent is preferably 1 mol% or more, more preferably more than 2 mol%, even more preferably 4 mol% or more, and even more preferably 6 mol% or more. The content of the first blocking agent in the blocking agent is preferably 100 mol% or less, more preferably 90 mol% or less, even more preferably less than 80 mol%, particularly preferably 70 mol% or less, and even more preferably 25 mol% or less. If the content of the first blocking agent is within the above range, it is possible to stably ensure the water dispersibility of the blocked isocyanate while improving the storage stability of the water dispersion of the blocked isocyanate. 【0059】 (1.1.4.2) The second blocking agent may contain a second blocking agent different from the first blocking agent. That is, the polyisocyanate compound may contain a second latent isocyanate group in which the isocyanate group of the polyisocyanate compound is blocked by the second blocking agent. By including the second blocking agent in the blocking agent, the curing temperature of the polyisocyanate compound can be adjusted. 【0060】Examples of the second blocking agent include compounds having a five-membered or six-membered ring nitrogen-containing heterocyclic structure, alcohol compounds, phenolic compounds, active methylene compounds, amine compounds, imine compounds, oxime compounds, carbamic acid compounds, urea compounds, acid amide compounds, acid imide compounds, mercaptan compounds, bisulfites, and tetrabutylphosphonium acetate. The second blocking agent may be used alone or in combination of two or more. 【0061】 Examples of compounds having a five-membered ring nitrogen-containing heterocyclic structure include imidazole compounds, pyrazole compounds, triazole compounds, imidazoline compounds, and benzoxazolone. Examples of imidazole compounds include imidazole, benzimidazole, 2-methylimidazole, 4-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, and 2-amine-imidazole. Examples of pyrazole compounds include pyrazole, 3-methylpyrazole, 3-methyl-5-phenylpyrazole, 3,5-diphenylpyrazole, 4-benzyl-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3,5-dimethylpyrazole, and 3,5-dialkylpyrazole. 3,5-dialkylpyrazoles do not have substituents at the 4-position of the pyrazole ring. Examples of 3,5-dialkylpyrazoles include 3,5-dimethylpyrazole, 3,5-diisopropylpyrazole, and 3,5-di-t-butylpyrazole. Examples of triazole compounds include 1,2,4-triazole and benzotriazole. Examples of imidazoline compounds include 2-methylimidazoline and 2-phenylimidazoline. 【0062】 Examples of compounds having a six-membered ring nitrogen-containing heterocyclic structure include pyrimidine compounds and isatoic anhydride. Examples of pyrimidine compounds include 2-methyl-1,4,5,6-tetrahydropyrimidine. 【0063】Examples of alcohol compounds include methanol, ethanol, 2-propanol, n-butanol, s-butanol, 2-ethylhexyl alcohol, 1-octanol, 2-octanol, cyclohexyl alcohol, ethylene glycol, benzyl alcohol, 2,2,2-trifluoroethanol, 2,2,2-trichloroethanol, 2-(hydroxymethyl)furan, 2-methoxyethanol, methoxypropanol, 2-ethoxyethanol, n-propoxyethanol, 2-butoxyethanol, and 2-ethoxyethoxyethanol. Examples include ioethanol, 2-ethoxybutoxyethanol, butoxyethoxyethanol, 2-butoxyethylethanol, 2-butoxyethoxyethanol, N,N-dibutyl-2-hydroxyacetamide, N-hydroxysuccinimide, N-morpholineethanol, 2,2-dimethyl-1,3-dioxolane-4-methanol, 3-oxazolidineethanol, 2-hydroxymethylpyridine, furfuryl alcohol, 12-hydroxystearic acid, triphenylsilanol, and 2-hydroxyethyl methacrylate. 【0064】Examples of phenolic compounds include phenol, cresol, ethylphenol, n-propylphenol, isopropylphenol, n-butylphenol, s-butylphenol, t-butylphenol, n-hexylphenol, 2-ethylhexylphenol, n-octylphenol, n-nonylphenol, di-n-propylphenol, diisopropylphenol, isopropyl cresol, di-n-butylphenol, di-s-butylphenol, di-t-butylphenol, di-n-octylphenol, di-2-ethylhexylphenol, and di-n-nonyl Examples include phenols, nitrophenols, bromophenols, chlorophenols, fluorophenols, dimethylphenols, styrene-phenols, methyl salicylates, methyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, 2-ethylhexyl hydroxybenzoate, 4-[(dimethylamino)methyl]phenol, 4-[(dimethylamino)methyl]nonylphenol, bis(4-hydroxyphenyl)acetic acid, 2-hydroxypyridine, 2-hydroxyquinoline, 8-hydroxyquinoline, 2-chloro-3-pyridinol, and pyridine-2-thiol. 【0065】 Examples of active methylene compounds include meldramic acid, dialkyl malonate, alkyl acetoacetate, 2-acetoacetoxyethyl methacrylate, acetylacetone, and ethyl cyanoacetate. Examples of dialkyl malonates include dimethyl malonate, diethyl malonate, di-n-butyl malonate, di-t-butyl malonate, di-2-ethylhexyl malonate, methyl n-butyl malonate, ethyl n-butyl malonate, methyl s-butyl malonate, ethyl s-butyl malonate, methyl t-butyl malonate, ethyl t-butyl malonate, diethyl methylmalonate, dibenzyl malonate, diphenyl malonate, benzylmethyl malonate, ethylphenyl malonate, t-butylphenyl malonate, and isopropylidene malonate. Examples of alkyl acetoacetates include methyl acetoacetate, ethyl acetoacetate, n-propyl acetoacetate, isopropyl acetoacetate, n-butyl acetoacetate, t-butyl acetoacetate, benzyl acetoacetate, and phenyl acetoacetate. 【0066】 Examples of amine compounds include dibutylamine, diphenylamine, aniline, N-methylaniline, carbazole, bis(2,2,6,6-tetramethylpiperidinyl)amine, di-n-propylamine, diisopropylamine, isopropylethylamine, 2,2,4-trimethylhexamethyleneamine, 2,2,5-trimethylhexamethyleneamine, N-isopropylcyclohexylamine, dicyclohexylamine, bis(3,5,5-trimethylcyclohexyl)amine, Examples include piperidine, 2,6-dimethylpiperidine, t-butylmethylamine, t-butylethylamine, t-butylpropylamine, t-butylbutylamine, t-butylbenzylamine, t-butylphenylamine, 2,2,6-trimethylpiperidine, 2,2,6,6-tetramethylpiperidine, (dimethylamino)-2,2,6,6-tetramethylpiperidine, 2,2,6,6-tetramethyl-4-piperidine, 6-methyl-2-piperidine, and 6-aminocaproic acid. 【0067】 Examples of imine compounds include ethyleneimine, polyethyleneimine, and 1,4,5,6-tetrahydropyrimidine. 【0068】 Examples of oxime compounds include formaldehyde oxime, acetaldehyde oxime, acetooxime, methyl ethyl ketoxime, cyclohexanone oxime, diacetyl monooxime, benzophenooxime, 2,2,6,6-tetramethylcyclohexanone oxime, diisopropyl ketone oxime, methyl t-butyl ketone oxime, diisobutyl ketone oxime, methyl isobutyl ketone oxime, methyl isopropyl ketone oxime, methyl 2,4-dimethylpentyl ketone oxime, methyl 3-ethylheptyl ketone oxime, methyl isoamyl ketone oxime, n-amyl ketone oxime, 2,2,4,4-tetramethyl-1,3-cyclobutanedione monooxime, 4,4'-dimethoxybenzophenone oxime, and 2-heptanone oxime. 【0069】Examples of carbamic acid compounds include phenyl N-phenylcarbamate. 【0070】 Examples of urea-based compounds include urea, thiourea, and ethyleneurea. 【0071】 Acid amide compounds are lactam compounds. Examples of acid amide compounds include acetanilide, N-methylacetamide, acetic acid amide, ε-caprolactam, δ-valerolactam, γ-butyrolactam, pyrrolidone, 2,5-piperazinedione, and laurolactam. 【0072】 Examples of acid-imide compounds include succinimide, maleimide, and phthalimide. 【0073】 Examples of mercaptan compounds include butyl mercaptan, dodecyl mercaptan, and hexyl mercaptan. 【0074】 Examples of bisulfites include sodium bisulfite. 【0075】 The dissociation temperature of the second blocking agent may be 150°C or lower, 140°C or lower, 130°C or lower, or 60°C or higher. 【0076】 The content ratio of the second blocking agent in the blocking agent may be 0 mol% or more, 10 mol% or more, more than 20 mol%, 30 mol% or more, 75 mol% or more, 99 mol% or less, less than 98 mol%, 96 mol% or less, or 94 mol% or less. 【0077】(1.1.4.3) Preferred Embodiments The polyisocyanate compound is preferably a blocked isocyanate in which the isocyanate groups of the polyisocyanate compound are blocked by a blocking agent, and the blocking agent preferably comprises at least one of a guanidino group-containing compound and a compound having a five-membered or six-membered nitrogen-containing heterocyclic structure. The polyisocyanate compound is a blocked isocyanate in which the isocyanate groups of the polyisocyanate compound are blocked by a blocking agent, and the blocking agent preferably comprises at least one of a guanidino group-containing compound and a compound having a five-membered or six-membered nitrogen-containing heterocyclic structure. The polyisocyanate compound having the above embodiment allows for the formation of an electrochemically stable protective film on the surface of the active material. 【0078】 (1.1.4.4) In an acid-blocked isocyanate, at least a portion of the first blocking agent blocking the isocyanate group may be neutralized by an acid. This causes the amino group of the first blocking agent to form an ammonium salt as a cationic group. If the blocking agent contains a second blocking agent, the acid may neutralize a portion of the second blocking agent. 【0079】 Examples of acids include organic acids and inorganic acids. The acid preferably contains an organic acid, and more preferably consists of an organic acid. The inclusion of an organic acid allows the polyisocyanate compound to be curable at low temperatures, disperse smoothly in water, maintain its dispersed state in water for a long period of time, and exhibit excellent storage stability. 【0080】 Examples of organic acids include carboxylic acids having 2 or 3 carbon atoms, and carboxylic acids having 4 or more carbon atoms. The acid may be used individually or in combination of two or more types. 【0081】 Examples of carboxylic acids having two or three carbon atoms include acetic acid, propionic acid, and lactic acid. 【0082】 To neutralize at least a portion of the first blocking agent with an acid, for example, a blocking isocyanate is reacted with an acid. 【0083】The equivalent ratio of the acid (acid / first blocking agent) to the first blocking agent blocking the isocyanate group may be 0.1 or greater, 0.5 or greater, 0.8 or greater, 5.0 or less, 3.0 or less, or 2.0 or less. 【0084】 The reaction between blocked isocyanates and acids is not particularly limited and can be carried out, for example, under air or in an inert gas atmosphere. Examples of inert gases include nitrogen gas and argon gas. 【0085】 The reaction temperature may be 0°C or higher, 20°C or higher, 80°C or lower, or 60°C or lower. The reaction pressure conditions are not particularly limited and include, for example, pressurized conditions and atmospheric pressure conditions. The reaction time may be 0.1 hours or more, 0.5 hours or more, 24 hours or less, or 12 hours or less. 【0086】 The above reaction is preferably carried out in the presence of an organic solvent. When an organic solvent is used in the reaction between a blocked isocyanate and an acid, the blocked isocyanate is dissolved in a reaction solution containing the organic solvent. In this case, water is added to the reaction solution containing the blocked isocyanate, and the reaction solution and water are emulsified using a stirrer. Then, the organic solvent is removed by volatilization, for example, by heating the emulsion under reduced pressure. This produces an aqueous dispersion of the blocked isocyanate. 【0087】 The solid content concentration of the aqueous dispersion of blocked isocyanate may be 1% by mass or more, 10% by mass or more, 80% by mass or less, or 50% by mass or less. 【0088】 (1.2) The active material composition preferably further contains an active material. As a result, the dried product of the composition functions as an electrode composite layer. "Electrode composite layer" refers to at least one of the negative electrode composite layer and the positive electrode composite layer. 【0089】 The active material may be either the negative electrode active material or the positive electrode active material. 【0090】The shape of the active material is not particularly limited and can be fibrous, spherical, flake-shaped, etc. If the shape of the active material is particulate, the particle size of the active material is not particularly limited. The particle size of the negative electrode active material is preferably 5 μm to 20 μm. The particle size of the positive electrode active material is preferably 5 μm to 15 μm. The primary particle size of the particles of the positive electrode active material is preferably 2.0 μm or less, more preferably 0.2 μm to 1.0 μm. The particle size of the active material is the particle size (particle size distribution D50, median diameter) corresponding to the cumulative 50% by volume from the smallest particle size in the volume-based particle size distribution measured by a particle size distribution analyzer based on laser light diffraction scattering. 【0091】 If the composition contains an active substance, the amount of the active substance is not particularly limited, but is preferably 10% to 99.9% by mass, more preferably 30% to 99% by mass, even more preferably 50% to 99% by mass, and most preferably 70% to 99% by mass, relative to the solid content of the composition. 【0092】 The active material may be appropriately selected according to the intended use of the composition and may be a known active material. 【0093】 The following describes the active material when the battery is a lithium secondary battery and the solid component of the composition is used in the electrode composite layer. 【0094】 (1.2.1) Negative electrode active material The negative electrode active material is not particularly limited as long as it is a material capable of intercalating and releasing lithium ions. Examples of negative electrode active materials include carbon materials, silicon oxide, metals (e.g., silicon, tin, and lithium), alloys (e.g., silicon alloys, tin alloys, and lithium alloys), and lithium titanate. 【0095】 "Carbon material" refers to a carbon material having a volume resistivity of less than 40 Ω·cm, preferably less than 3 Ω·cm, at 20°C. "Silicon oxide" refers to a compound represented by the following formula (II). Formula (II): SiO Ｘ [In equation (II), X represents a value between 0.5 and less than 1.6.] 【0096】Examples of carbon materials include graphite and amorphous carbon materials. Examples of graphite include artificial graphite and natural graphite (e.g., flake graphite, lump graphite, and earthy graphite). Examples of amorphous carbon materials include hard carbon, coke, mesocarbon microbeads (MCMB), and mesophase pitch carbon fiber (MCF). Silicon oxide may be coated with amorphous carbon. Silicon oxide may be a known compound. Silicon oxide may be the silicon oxide described in International Publication No. 2013 / 094668 and Japanese Patent Publication No. 2016-143642, etc. The negative electrode active material may be used alone or in combination of two or more types. 【0097】 In particular, the active material preferably contains a carbon material, and more preferably is a carbon material. This improves the energy density of the lithium secondary battery compared to when the active material does not contain a carbon material. 【0098】 (1.2.2) Positive electrode active material The positive electrode active material is not particularly limited as long as it is a material capable of intercalating and releasing lithium ions, and can be appropriately adjusted depending on the application of the lithium secondary battery. 【0099】 Examples of positive electrode active materials include primary oxides and secondary oxides. Primary oxides consist of lithium (Li) and nickel (Ni) as constituent metal elements. Secondary oxides contain Li, Ni, and at least one other metal element besides Li and Ni as constituent metal elements. Examples of metal elements other than Li and Ni include transition metal elements and typical metal elements. In secondary oxides, the proportion of metal elements other than Li and Ni is preferably about the same as or less than the proportion of Ni in terms of the number of atoms. The metal elements other than Li and Ni may be at least one selected from the group consisting of Co, Mn, Al, Cr, Fe, V, Mg, Ca, Na, Ti, Zr, Nb, Mo, W, Cu, Zn, Ga, In, Sn, La, and Ce. The positive electrode active material may be used alone or in combination of two or more types. 【0100】The positive electrode active material preferably contains a lithium-containing composite oxide (hereinafter sometimes referred to as "NCM") represented by the following formula (X). The lithium-containing composite oxide (X) has the advantage of having a high energy density per unit volume and excellent thermal stability. 【0101】 LiNi ａ Co ｂ Mn ｃ O ２ ... Formula (X) 【0102】 In equation (X), a, b, and c are each independently greater than 0 and less than 1, and the sum of a, b, and c is 0.99 or greater and 1.00 or less. 【0103】 A concrete example of NCM is LiNi ０．３３ Co ０．３３ Mn ０．３３ O ２ LiNi ０．５ Co ０．３ Mn ０．２ O ２ LiNi ０．５ Co ０．２ Mn ０．３ O ２ LiNi ０．６ Co ０．２ Mn ０．２ O ２ , and LiNi ０．８ Co ０．１ Mn ０．１ O ２ These are some examples. 【0104】 The positive electrode active material may contain a lithium-containing composite oxide represented by the following formula (Y) (hereinafter sometimes referred to as "NCA"). 【0105】 Li ｔ Ni １－ｘ－ｙ Co ｘ Al ｙ O ２ ... Formula (Y) 【0106】 In equation (Y), t is between 0.95 and 1.15, x is between 0 and 0.3, y is between 0.01 and 0.2, and the sum of x and y is less than 0.5. 【0107】 A concrete example of NCA is LiNi０．８ Co ０．１５ Al ０．０５ O ２ These are some examples. 【0108】 (1.3) The binder composition may contain a binder. In this case, if the composition contains an active material and forms an electrode composite layer on the current collector, the binder can bind the active material to the electrode current collector. 【0109】 Examples of binders include carboxymethylcellulose (CMC), polyvinyl acetate, polymethyl methacrylate, nitrocellulose, fluororesins, and rubber particles. Examples of fluororesins include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and vinylidene fluoride-hexafluoropropylene copolymer. Examples of rubber particles include styrene-butadiene rubber (SBR) particles and acrylonitrile rubber particles. Binders may be used individually or in combination of two or more types. 【0110】 If the composition contains a binder, the binder content is not particularly limited, but is preferably 0.1% to 4% by mass relative to the solid content of the battery composition. 【0111】 (1.4) The solvent composition may contain a solvent. 【0112】 Examples of solvents include water and water-compatible liquid media. Including a water-compatible liquid media in the solvent of the composition improves its coating properties on the electrode current collector. Examples of water-compatible liquid media include alcohols, glycols, cellosolves, amino alcohols, amines, ketones, amides (e.g., N-methylpyrrolidone), carboxylic acid amides, phosphate amides, sulfoxides, carboxylic acid esters, phosphate esters, ethers, and nitriles. When the composition contains a positive electrode active material and a solvent, N-methylpyrrolidone is preferably used as the solvent. 【0113】When the composition contains a solvent, the ratio of the total amount of solids to the total amount of the composition (hereinafter also referred to as "solids concentration") is not particularly limited, but is preferably 30% by mass or more, more preferably 35% by mass or more, and even more preferably 40% by mass or more. The solids concentration is preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 80% by mass or less, and particularly preferably 70% by mass or less. 【0114】 (1.5) The conductive additive composition may contain a conductive additive. 【0115】 The conductive additive may be a known conductive additive. Among known conductive additives, conductive carbon materials are preferred. Examples of conductive carbon materials include carbon black, conductive carbon fibers, and fullerenes. Examples of conductive carbon fibers include carbon nanotubes, carbon nanofibers, and carbon fibers. Examples of natural graphite include flake graphite, lumpy graphite, and earthy graphite. The conductive additive may be used alone or in combination of two or more types. 【0116】 The conductive additive may be a commercially available product. Examples of commercially available carbon black include "Super P" (manufactured by TIMCAL). Examples of commercially available flake graphite include "KS-6" (manufactured by TIMREX). 【0117】 The content of the conductive additive is not particularly limited, but is preferably 0.05% to 5% by mass relative to the solid content of the composition. 【0118】 (1.6) The additive composition may contain additives. Depending on the type of additive, various functions can be imparted to the composition. Examples of additives include thickeners, surfactants, dispersants, wetting agents, and defoaming agents. 【0119】 (2) Electrodes The electrodes of the present disclosure preferably include a dried product of the lithium secondary battery composition of the present disclosure. That is, the electrodes of the present disclosure preferably have a current collector and a dried product of the lithium secondary battery composition of the present disclosure. 【0120】"Electrode" refers to at least one of the positive and negative electrodes of a battery. "Dried composition" refers to the composition in a solid state at room temperature (23°C) and from which the solvent has been removed, if the composition contains a solvent. "Dried composition" refers to the composition in a solid state at room temperature (23°C) and consisting of the composition, if the composition does not contain a solvent. If the composition contains a solvent, the dried composition is formed, for example, by applying the composition to a current collector and drying it. If the composition does not contain a solvent, the dried composition is formed, for example, by applying the molten composition to a current collector and cooling it. 【0121】 Because the electrodes of this disclosure have the above configuration, even when charging and discharging are repeated, a decrease in battery capacity is suppressed, and an increase in battery resistance at room temperature and low temperature is suppressed. 【0122】 The dried electrode layer composition may be formed on at least one main surface of the current collector. 【0123】 The function of the dried composition depends on the raw materials of the composition. If the composition contains an active material, the dried composition may function as an electrode composite layer. If the composition does not contain an active material, the dried composition may function as an undercoat layer interposed between the current collector and the electrode composite layer. The following describes the case where the dried composition functions as an electrode composite layer. 【0124】 (2.1) The negative electrode comprises a current collector (hereinafter also referred to as the "negative electrode current collector") and a negative electrode composite layer. The negative electrode composite layer is formed on at least one main surface of the negative electrode current collector. 【0125】 Examples of materials for the negative electrode current collector include copper, aluminum, nickel, stainless steel (SUS), and nickel-plated steel. 【0126】The negative electrode composite layer is a dried product of the composition of this disclosure. More specifically, the negative electrode composite layer preferably contains a polyisocyanate compound, a negative electrode active material, and a binder. The negative electrode composite layer may optionally further contain at least one of a conductive additive and an additive. At least some of the isocyanate groups of the polyisocyanate compound in the negative electrode composite layer may or may not be blocked by a blocking agent. 【0127】 (2.2) Positive electrode The positive electrode comprises a current collector (hereinafter also referred to as the "positive electrode current collector") and a positive electrode composite layer. The positive electrode composite layer is formed on at least one main surface of the positive electrode current collector. 【0128】 Examples of materials for the positive electrode current collector include aluminum, nickel, stainless steel (SUS), and copper. "Aluminum" includes pure aluminum or aluminum alloys. 【0129】 The positive electrode composite layer is a dried product of the composition of this disclosure. More specifically, the positive electrode composite layer preferably contains a polyisocyanate compound, a positive electrode active material, and a binder. The positive electrode composite layer may optionally further contain at least one of a conductive additive and an additive. At least some of the isocyanate groups of the polyisocyanate compound in the positive electrode composite layer may or may not be blocked by a blocking agent. 【0130】 (3) Lithium secondary battery The lithium secondary battery of this disclosure comprises the electrodes of this disclosure. 【0131】 Because the lithium secondary battery of this disclosure has the above configuration, even when charging and discharging are repeated, the decrease in battery capacity is suppressed, and the increase in battery resistance at room temperature and low temperature is suppressed. 【0132】 In the lithium secondary battery of this disclosure, the electrode of this disclosure is at least one of a positive electrode and a negative electrode. 【0133】 (3.1) Lithium secondary battery The lithium secondary battery comprises the electrodes of the present disclosure. 【0134】A lithium secondary battery generally comprises an outer casing, a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte. The outer casing houses the positive electrode, negative electrode, separator, and non-aqueous electrolyte. The separator separates the positive electrode and the negative electrode. 【0135】 In the lithium secondary battery of this disclosure, at least one of the positive electrode and the negative electrode is the electrode of this disclosure. If one of the positive electrode and the negative electrode of the lithium secondary battery of this disclosure is the electrode of this disclosure, the other of the positive electrode and the negative electrode may be any known electrode used in lithium secondary batteries. The case in which the positive electrode and the negative electrode are the electrodes of this disclosure will be described below. 【0136】 (3.1.1) Outer casing The shape of the outer casing is not particularly limited and is selected as appropriate depending on the application of the lithium secondary battery. Examples of outer casings include an outer casing including a laminate film, and an outer casing consisting of a battery can and a battery can lid. 【0137】 (3.1.2) Positive and Negative Electrodes The positive electrode is the positive electrode described above. The negative electrode is the negative electrode described above. 【0138】 (3.1.3) Separator Examples of separators include porous resin plates. Materials for the porous resin plates include resins and nonwoven fabrics containing the resin. Examples of resins include polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polyester, cellulose, and polyamide. Among these, the separator is preferably a porous resin sheet with a single-layer or multi-layer structure. The porous resin sheet is mainly composed of one or more types of polyolefin resins. The thickness of the separator is preferably 5 μm to 30 μm. The separator is preferably placed between the positive electrode and the negative electrode. 【0139】 (3.1.4) Non-aqueous electrolyte The non-aqueous electrolyte contains an electrolyte and a non-aqueous solvent. 【0140】 (3.1.4.1) Electrolyte The electrolyte preferably contains at least one of a lithium salt containing fluorine (hereinafter also referred to as "fluorine-containing lithium salt") and a lithium salt that does not contain fluorine. 【0141】Examples of fluorinated lithium salts include inorganic acid anionic salts (for example, lithium hexafluoride phosphate (LiPF)). ６ ), lithium tetrafluoroborate (LiBF ４ )), and organic acid anionic salts (for example, lithium trifluoromethanesulfonate (LiCF) ３ SO ３ Examples include lithium salts that do not contain fluorine, such as lithium perchlorate (LiClO2). ４ ), lithium aluminum tetrachloride (LiAlCl ４ ), and lithium decachlorodecaborate (Li ２ B １０ Cl １０ ) are some examples. 【0142】 When the non-aqueous electrolyte contains an electrolyte, the concentration of the electrolyte in the non-aqueous electrolyte is preferably 0.1 mol / L to 3 mol / L, more preferably 0.5 mol / L to 2 mol / L. ６ ) If it contains lithium hexafluoride phosphate (LiPF) in a non-aqueous electrolyte, ６ The concentration of the substance is preferably 0.1 mol / L to 3 mol / L, more preferably 0.5 mol / L to 2 mol / L. 【0143】 (3.1.4.2) Non-aqueous solvents Non-aqueous electrolytes generally contain a non-aqueous solvent. 【0144】Examples of non-aqueous solvents include cyclic carbonates (e.g., ethylene carbonate (EC) and propylene carbonate (PC)), linear carbonates (e.g., dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC)), fluorinated cyclic carbonates, fluorinated linear carbonates, aliphatic carboxylic acid esters, fluorinated aliphatic carboxylic acid esters, γ-lactones, fluorinated γ-lactones, cyclic ethers, fluorinated cyclic ethers, linear ethers, fluorinated linear ethers, nitriles, amides, lactams, nitromethane, nitroethane, sulfolane, trimethyl phosphate, dimethyl sulfoxide, and dimethyl sulfoxide phosphate. Non-aqueous solvents may be used individually or in combination of two or more. 【0145】 The non-aqueous solvent preferably contains at least one selected from the group consisting of cyclic carbonates and linear carbonates. In this case, the total proportion of cyclic carbonates and linear carbonates in the non-aqueous solvent is preferably 50% by mass or more and 100% by mass or less, more preferably 60% by mass or more and 100% by mass or less, and even more preferably 80% by mass or more and 100% by mass or less, based on the total amount of the non-aqueous solvent. 【0146】 The non-aqueous solvent content is preferably 99% by mass or less, more preferably 97% by mass or less, and more preferably 90% by mass or less, relative to the total amount of the non-aqueous electrolyte. The non-aqueous solvent content is preferably 60% by mass or more, more preferably 70% by mass or more, relative to the total amount of the non-aqueous electrolyte. 【0147】 The intrinsic viscosity of the non-aqueous solvent is preferably 10.0 mPa·s or less at 25°C, from the viewpoint of further improving the dissociation of the electrolyte and the mobility of ions. 【0148】(3.1.4.3) The electrolyte additive non-aqueous solvent may contain an electrolyte additive. This makes it difficult for side reactions, which are not the original battery reaction, to proceed during the charge-discharge cycle of the lithium secondary battery. The battery reaction is a reaction in which lithium ions enter and leave (intercalate) the positive electrode and the negative electrode. Side reactions include the reductive decomposition reaction of the non-aqueous electrolyte by the negative electrode, the oxidative decomposition reaction of the non-aqueous electrolyte by the positive electrode, and the elution of metal elements in the positive electrode active material. There are no particular restrictions on the electrolyte additive, and any known additive can be used as desired. For example, the additive described in Japanese Patent Application Publication No. 2019-153443 can be used. 【0149】 (3.1.5) Example of a lithium secondary battery Figure 1 is a schematic cross-sectional view showing a stacked lithium secondary battery, which is an example of a lithium secondary battery of the present disclosure. 【0150】 As shown in Figure 1, the lithium secondary battery 1 is a stacked battery. More specifically, in the lithium secondary battery 1, the battery element 10 is enclosed inside the outer casing 30. The outer casing 30 is made of laminate film. The battery element 10 is fitted with a positive electrode lead 21 and a negative electrode lead 22. The positive electrode lead 21 and the negative electrode lead 22 are led out in opposite directions from the inside to the outside of the outer casing 30. 【0151】 As shown in Figure 1, the battery element 10 is made up of a stack of a positive electrode 11, a separator 13, and a negative electrode 12. The positive electrode 11 is formed by forming a positive electrode composite layer 11B on both main surfaces of the positive electrode current collector 11A. The negative electrode 12 is formed by forming a negative electrode composite layer 12B on both main surfaces of the negative electrode current collector 12A. The positive electrode composite layer 11B formed on one main surface of the positive electrode current collector 11A of the positive electrode 11 and the negative electrode composite layer 12B formed on one main surface of the negative electrode current collector 12A of the negative electrode 12 adjacent to the positive electrode 11 face each other via the separator 13. At least one of the positive electrode composite layer 11B and the negative electrode composite layer 12B contains a dried product of the lithium secondary battery composition of this disclosure. 【0152】A non-aqueous electrolyte is injected into the exterior casing 30 of the lithium secondary battery 1. The non-aqueous electrolyte of this disclosure permeates the positive electrode composite layer 11B, the separator 13, and the negative electrode composite layer 12B. In the lithium secondary battery 1, a single cell layer 14 is formed by adjacent positive electrode composite layers 11B, separator 13, and negative electrode composite layer 12B. The positive electrode and negative electrode may be formed with each composite layer located on one side of each current collector. 【0153】 Although lithium secondary battery 1 is a stacked lithium secondary battery, the lithium secondary battery of this disclosure is not limited to this, and may be, for example, a wound lithium secondary battery. A wound lithium secondary battery is formed by stacking a positive electrode, a separator, a negative electrode, and a separator in that order and winding them in layers. Wound lithium secondary batteries include cylindrical lithium secondary batteries and prismatic lithium secondary batteries. 【0154】 As shown in Figure 1, in the lithium secondary battery 1, the direction in which the positive electrode lead and the negative electrode lead protrude from the inside to the outside of the outer casing 30 is opposite to the outer casing 30, but the disclosure is not limited thereto. For example, the way in which the positive electrode lead and the negative electrode lead protrude from the inside to the outside of the outer casing 30 is the same direction with respect to the outer casing 30. 【0155】 Figure 2 is a schematic cross-sectional view showing a coin-type lithium secondary battery, which is another example of a lithium secondary battery of the present disclosure. 【0156】 In the coin-type lithium secondary battery shown in Figure 2, a disc-shaped negative electrode 42, a separator 45 injected with a non-aqueous electrolyte, a disc-shaped positive electrode 41, and, if necessary, spacer plates 47 and 48 made of stainless steel or aluminum are stacked in this order and housed between the positive electrode can 43 (hereinafter also referred to as the "battery can") and the sealing plate 44 (hereinafter also referred to as the "battery can lid"). The positive electrode can 43 and the sealing plate 44 are crimped and sealed via a gasket 46. 【0157】(4) Blocked isocyanates The blocked isocyanates of the present disclosure are obtained by blocking the isocyanate group of a polyisocyanate compound with a blocking agent, wherein the blocking agent comprises at least two compounds having a five-membered ring or a six-membered ring nitrogen-containing heterocyclic structure. 【0158】 Because the blocked isocyanate of this disclosure has the above-described structure, when the blocked isocyanate of this disclosure is used in the electrode composite layer of a lithium secondary battery, the blocked isocyanate of this disclosure can suppress a decrease in battery capacity even after repeated charging and discharging, and can also suppress an increase in battery resistance at room temperature and low temperature. 【0159】 Examples of the blocked isocyanates in this disclosure are the same as those exemplified as blocked isocyanates that may be included in compositions for lithium secondary batteries. 【0160】 (5) Method for manufacturing electrodes for lithium secondary batteries The method for manufacturing electrodes for lithium secondary batteries according to the present disclosure comprises: preparing a composition for lithium secondary batteries containing a blocked isocyanate (hereinafter also referred to as the "composition preparation step"); mixing the composition for lithium secondary batteries with an active material to prepare a mixture (hereinafter also referred to as the "mixture preparation step"); and applying the mixture to a current collector and drying it to produce electrodes for lithium secondary batteries (hereinafter also referred to as the "electrode preparation step"). The blocked isocyanate is obtained by blocking the isocyanate groups of a polyisocyanate compound with a blocking agent. The blocking agent comprises a guanidino group-containing compound and at least one compound having a five-membered or six-membered ring nitrogen-containing heterocyclic structure. The composition preparation step, the mixture preparation step and the electrode preparation step are carried out in this order. 【0161】 (5.1) Composition preparation process In the composition preparation process, a composition for lithium secondary batteries containing blocked isocyanate is prepared. 【0162】The method for preparing a lithium secondary battery composition containing a blocked isocyanate (hereinafter also referred to as the "composition preparation method") is not particularly limited and includes methods such as preparing a polyisocyanate compound and a blocking agent, and reacting the polyisocyanate compound with the blocking agent. 【0163】 The method for preparing the polyisocyanate compound and the blocking agent is not particularly limited and any known method is acceptable. The polyisocyanate compound may be modified with the hydrophilic compound containing an active hydrogen group as described above. The method for modifying the polyisocyanate compound may be any known method. 【0164】 (5.1.1) If the first or second blocking agent contains only the first blocking agent, the polyisocyanate compound is reacted with the first blocking agent. As a result, the isocyanate group reacts with the first blocking agent to produce the first latent isocyanate. 【0165】 If the blocking agent contains only the second blocking agent, the polyisocyanate compound is reacted with the second blocking agent. As a result, the isocyanate group reacts with the second blocking agent to produce the second latent isocyanate. 【0166】 The equivalent ratio (active group / isocyanate group) of the active group in the first or second blocking agent that can react with the isocyanate group in the polyisocyanate compound to the isocyanate group may be 1.0 or more, 1.5 or less, 1.2 or less, or 1.1 or less. 【0167】 The reaction between the polyisocyanate compound and the first or second blocking agent is carried out, for example, in an inert gas atmosphere. Examples of inert gases include nitrogen gas and argon gas. 【0168】 The reaction temperature may be 0°C or higher, 20°C or higher, 80°C or lower, or 60°C or lower. The reaction pressure may be atmospheric pressure. The reaction time may be 0.5 hours or more, 1.0 hour or more, 24 hours or less, or 12 hours or less. 【0169】 (5.1.2) When the blocking agent contains the first and second blocking agents, the polyisocyanate compound is reacted with the first and second blocking agents. As a result, some of the isocyanate groups react with the first blocking agent to produce the first latent isocyanate, and some of the isocyanate groups react with the second blocking agent to produce the second latent isocyanate. The blocked isocyanate has both the first latent isocyanate group and the second latent isocyanate group in one molecule. 【0170】 The reaction order between the polyisocyanate compound and the first and second blocking agents is not particularly limited, and the first and second blocking agents may be reacted simultaneously or sequentially. Examples of reaction orders include reacting the polyisocyanate compound with the first blocking agent in a proportion that leaves free isocyanate groups, and then reacting the blocked isocyanate having the free isocyanate groups with the second blocking agent; or reacting the polyisocyanate compound with the second blocking agent in a proportion that leaves free isocyanate groups, and then reacting the blocked isocyanate having the free isocyanate groups with the first blocking agent. 【0171】 The equivalent ratio of the active group in the second blocking agent that can react with the isocyanate group to the isocyanate group of the polyisocyanate compound (active group / isocyanate group) may be 0.1 or more, greater than 0.2, 0.3 or more, 0.75 or more, less than 0.99, 0.98 or less, or 0.94 or less. 【0172】 The equivalent ratio of the active group in the first blocking agent that can react with the isocyanate group to the free isocyanate group in the blocked isocyanate (active group / isocyanate group) may be 0.01 or more, 0.05 or more, 1.3 or less, 1.2 or less, or 1.1 or less. 【0173】The reaction conditions for the polyisocyanate compound with the first blocking agent and the second blocking agent are the same as the reaction conditions for the polyisocyanate compound with the first blocking agent or the second blocking agent described above. 【0174】 The completion of the reaction can be determined, for example, by using infrared spectroscopy to confirm the disappearance or decrease of the isocyanate group. 【0175】 Each of the above reactions may be carried out without a solvent, for example, in the presence of an organic solvent. When each of the above reactions is carried out in the presence of an organic solvent, the lithium secondary battery composition containing the blocked isocyanate may contain the organic solvent. 【0176】 Examples of organic solvents include ketones, nitriles, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, glycol ether esters, ethers, halogenated aliphatic hydrocarbons, and polar aprotons. The organic solvent may be used individually or in combination of two or more. 【0177】 (5.1.3) In the neutralized blocked isocyanate, at least a portion of the first blocking agent that blocks the isocyanate group may be neutralized with an acid. 【0178】 Examples of acids and neutralization methods include those similar to those exemplified as possible acids and neutralization methods that may be included in polyisocyanate compounds. When at least a portion of the first blocking agent is neutralized by an acid, the lithium secondary battery composition containing the blocking isocyanate may be an aqueous dispersion of the blocking isocyanate as described above. 【0179】(5.1.4) Other Methods for Preparing Compositions When the blocking agent includes a first blocking agent and a second blocking agent, in addition to the above methods, the first method, the second method, and the third method are also mentioned. In the first method, a polyisocyanate compound is reacted with one of the first and second blocking agents in a proportion that leaves free isocyanate groups, and then the blocked isocyanate having the free isocyanate groups is reacted with the other of the first and second blocking agents. In the second method, a polyisocyanate compound is reacted with the first and second blocking agents simultaneously. In the third method, a polyisocyanate compound blocked by the first blocking agent alone and a polyisocyanate compound blocked by the second blocking agent alone are prepared separately and then mixed. In this case, the composition contains a mixture of blocked isocyanates having a first latent isocyanate group but no second latent isocyanate group, and blocked isocyanates having a second latent isocyanate group but no first latent isocyanate group. 【0180】 (5.2) Mixture preparation step In the mixture preparation step, the lithium secondary battery composition and the active material are mixed to prepare a mixture. 【0181】 Examples of active materials include those similar to those exemplified as active materials that may be included in the lithium secondary battery composition. The method of mixing the lithium secondary battery composition and the active material is not particularly limited and may be a known method. If necessary, at least one of a binder, a conductive additive, and an additive may be added to the mixture. Examples of binders, conductive additives, and additives include those similar to those exemplified as binders, conductive additives, and additives that may be included in the lithium secondary battery composition. 【0182】 (5.3) Electrode Manufacturing Process In the electrode manufacturing process, the mixture is applied to a current collector and dried to manufacture an electrode for a lithium secondary battery. This provides an electrode for a lithium secondary battery. The electrode for a lithium secondary battery comprises a current collector and a dried product of the lithium secondary battery composition (i.e., an electrode composite layer) disposed on at least one surface of the current collector. 【0183】 Examples of current collectors include those similar to those exemplified as current collectors that can be used in the electrodes of this disclosure (i.e., positive electrode current collector and negative electrode current collector). The method of applying the mixture is not particularly limited and any known method is acceptable. The method of drying the mixture is not particularly limited and includes heating the mixture applied to the current collector. 【0184】 The heating temperature for heating the mixture applied to the current collector is preferably 30°C to 200°C, more preferably 50°C to 180°C, and even more preferably 80°C to 150°C. If the heating temperature is between 80°C and 150°C, the blocking agent can be dissociated. 【0185】 The following examples of synthesis will further illustrate this disclosure, but this disclosure is not limited to them. Specific numerical values ​​such as blending ratios (concentrations), physical properties, and parameters used in the following description may be replaced with the corresponding upper limits (numbers defined as "less than or equal to" or "less than") or lower limits (numbers defined as "greater than or equal to" or "greater than or equal to" or "greater than or equal to") of the blending ratios (concentrations), physical properties, and parameters described in the "Modes for Carrying Out the Invention" above. Unless otherwise specified, "parts" and "%" refer to mass. 【0186】 [1] Preparation of Blocked Isocyanates [1.1] Synthesis Example 1 At room temperature (25°C), 200 parts by mass of an isocyanurate derivative of xylylene diisocyanate (XDI) (polyisocyanate compound, trade name: Takenate® D-131N, solid content: 75% by mass, isocyanate group content: 13.7%, manufactured by Mitsui Chemicals, Inc.) and ethyl acetate (solvent) were charged into a 2 L reactor equipped with a stirrer, thermometer, condenser and nitrogen gas inlet tube. 【0187】 Next, 3,5-dimethylpyrazole (DMP, second blocking agent) was added to the reactor. The amount of DMP added was as shown in Table 1, relative to 100 moles of isocyanate groups in the isocyanurate derivative of XDI. Then, the isocyanurate derivative of XDI and DMP were reacted. 【0188】Next, 1,1,3,3-tetramethylguanidine (TMG, first blocking agent) was added to the reactor. The amount of TMG added was as shown in Table 1, relative to 100 moles of isocyanate groups in the isocyanurate derivative of XDI. The isocyanurate derivative of XDI and TMG were then reacted. This yielded a reaction product of the isocyanurate derivative of XDI, DMP, and TMG. 【0189】 Subsequently, by measuring the FT-IR spectrum, it was confirmed that all isocyanate groups in the reactant were blocked. This yielded a reaction solution containing blocked isocyanates. 【0190】 Next, acetic acid (acid) was added to the reaction mixture and stirred. The ratio of acetic acid added was the number of moles shown in Table 1 per mole of the first blocking agent (TMG) used. At this time, the temperature of the reaction mixture was 28°C. The stirring time was 0.5 hours. 【0191】 As a result, the amino group of the first blocking agent was neutralized by acetic acid, forming an ammonium acetate salt as a cationic group. This yielded a reaction solution containing the blocked isocyanate. 【0192】 Subsequently, 300 parts by mass of water were added to 120 parts by mass of the reaction solution containing the blocked isocyanate. Then, the reaction solution and water were emulsified by stirring with a homomixer. 【0193】 Next, under reduced pressure, ethyl acetate (solvent) was removed from the emulsion by distillation, along with a portion of the water. 【0194】 A blocked isocyanate aqueous dispersion was prepared as described above. The solid content concentration of the blocked isocyanate aqueous dispersion was 20% by mass. 【0195】 [1.2] Synthesis Example 2 An aqueous dispersion of blocked isocyanate was prepared in the same manner as in Synthesis Example 1, except that the polyisocyanate compound was changed. 【0196】 In synthesis example 2, 1,3-H was used as the polyisocyanate compound. ６An isocyanurate derivative of XDI (polyisocyanate compound, trade name: Takenate® D-127N, solid content: 75% by mass, isocyanate group content: 13.5%, manufactured by Mitsui Chemicals, Inc.) was used. 【0197】 [1.3] Synthesis Example 3 At room temperature (25°C), 600 parts by mass of an isocyanurate derivative of xylylene diisocyanate (XDI) (polyisocyanate compound, trade name: Takenate® D-131N, solid content: 75% by mass, isocyanate group content: 13.7%, manufactured by Mitsui Chemicals, Inc.) and ethyl acetate (solvent) were charged into a 2 L reactor equipped with a stirrer, thermometer, condenser and nitrogen gas inlet tube. 【0198】 Next, methoxyPEG1000 (methoxy polyethylene glycol, trade name: methoxyPEG1000) was added to the reactor as a hydrophilic compound. The addition ratio of methoxyPEG1000 was the number of moles shown in Table 1 per 100 moles of isocyanate groups present in the isocyanurate derivative of XDI. Then, the isocyanurate derivative of XDI and methoxyPEG1000 were reacted. 【0199】 Next, DMP (second blocking agent) was added. The amount of DMP added was as shown in Table 2, relative to 100 moles of isocyanate groups in the isocyanurate derivative of XDI. Then, the isocyanurate derivative of XDI and DMP were reacted. 【0200】 Next, imidazole (IMZ, the second blocking agent) was added to the reaction solution. The amount of IMZ added was as shown in Table 1, relative to 100 moles of isocyanate groups in the isocyanurate derivative of XDI. Then, the isocyanurate derivative of XDI and IMZ were reacted. This yielded a reaction product of the isocyanurate derivative of XDI, DMP, and IMZ. 【0201】 Subsequently, by measuring the FT-IR spectrum, it was confirmed that all isocyanate groups in the reactant were blocked. This yielded a reaction solution containing blocked isocyanates. 【0202】Subsequently, 220 parts by mass of water were added to 120 parts by mass of the reaction solution containing the blocked isocyanate. Then, the reaction solution and water were emulsified by stirring with a homomixer. 【0203】 Next, under reduced pressure, ethyl acetate (solvent) was removed from the emulsion by distillation, along with a portion of the water. 【0204】 Based on the above, an aqueous dispersion of blocked isocyanate (polyisocyanate component) was prepared. The solid content concentration of this aqueous dispersion was 30% by mass. 【0205】 [1.4] Synthesis Example 4 An aqueous dispersion of blocked isocyanate was prepared in the same manner as in Synthesis Example 3, except that the polyisocyanate compound was changed. 【0206】 In synthesis example 4, 1,3-H was used as the polyisocyanate compound. ６ An isocyanurate derivative of XDI (polyisocyanate compound, trade name: Takenate® D-127N, solid content: 75% by mass, isocyanate group content: 13.5%, manufactured by Mitsui Chemicals, Inc.) was used. 【0207】 【0208】 In Table 1, "TMG" represents 1,1,3,3-tetramethylguanidine, "DMP" represents 3,5-dimethylpyrazole, and "IMZ" represents imidazole. 【0209】 [2] Example 1 An aqueous dispersion of graphite, carbon black, sodium carboxymethylcellulose, an aqueous dispersion of styrene-butadiene rubber (SBR), and an aqueous dispersion of the blocked isocyanate obtained in Synthesis Example 1 were mixed to obtain a negative electrode mixture slurry (i.e., a composition for lithium secondary batteries). The amount of graphite as the negative electrode active material was 95.7 parts by mass, the amount of carbon black as a conductive additive was 1 part by mass, the amount of sodium carboxymethylcellulose as a binder was 1.0 part by mass, the amount of SBR as a synthetic rubber was 2.0 parts by mass, and the amount of isocyanate was 0.3 parts by mass. 【0210】[2.1] Battery Construction [2.1.1] Negative Electrode Preparation A copper foil with a thickness of 10 μm was prepared as the negative electrode current collector. The obtained negative electrode slurry was applied onto the copper foil, dried, and then rolled in a press to obtain a sheet-like negative electrode. The drying temperature was 120°C. The negative electrode consists of a negative electrode current collector and a negative electrode mixture layer. 【0211】 [2.1.2] Preparation of the positive electrode LiNi as the positive electrode active material ０．８ Co ０．１ Mn ０．１ O ２ A mixture was obtained by mixing (94% by mass) with carbon black (3% by mass) as a conductive additive and polyvinylidene fluoride (PVdF) (3% by mass) as a binder. The obtained mixture was dispersed in N-methylpyrrolidone solvent to obtain a positive electrode mixture slurry. A 20 μm thick aluminum foil was prepared as the positive electrode current collector. The obtained positive electrode mixture slurry was coated onto the aluminum foil, dried, and then rolled in a press to obtain a sheet-like positive electrode. The positive electrode consists of a positive electrode current collector and a positive electrode mixture layer. 【0212】 [2.1.3] Preparation of Non-Aqueous Electrolyte Ethylene carbonate (hereinafter, "EC"), dimethyl carbonate (hereinafter, "DMC"), and ethyl methyl carbonate (hereinafter, "EMC") were mixed. The volume ratio of EC, DMC, and EMC (EC:DMC:EMC) was 30:35:35. A mixed solvent was obtained as a non-aqueous solvent. LiPF was added to the obtained mixed solvent as an electrolyte. ６ The solution was dissolved so that the final concentration in the non-aqueous electrolyte was 1.0 mol / L, thereby obtaining the non-aqueous electrolyte. 【0213】 [2.1.4] Preparation of the separator A porous polyethylene film was prepared as the separator. 【0214】[2.1.5] Fabrication of Lithium Secondary Battery The negative electrode was punched out in a disc shape with a diameter of 14 mm, the positive electrode in a disc shape with a diameter of 13 mm, and the separator in a disc shape with a diameter of 17 mm. This yielded coin-shaped negative electrode, coin-shaped positive electrode, and coin-shaped separator. The obtained coin-shaped negative electrode, coin-shaped separator, and coin-shaped positive electrode were stacked in this order inside a stainless steel battery case (size: 2032 size). Next, 20 μL of non-aqueous electrolyte was poured into the battery case, and the separator, positive electrode, and negative electrode were impregnated with the non-aqueous electrolyte. Then, an aluminum plate (thickness 1.2 mm, diameter 16 mm) and a spring were placed on the positive electrode, and the battery was sealed by crimping the battery case lid via a polypropylene gasket. As a result, a coin-type lithium secondary battery precursor (i.e., a lithium secondary battery before charging and discharging) having the configuration shown in Figure 2 was obtained. The size of the lithium secondary battery precursor was 20 mm in diameter and 3.2 mm in height. The lithium secondary battery precursor described above was charged at a temperature range of 25°C to 70°C with a cutoff voltage of 1.5V to 3.5V, and then allowed to rest for 5 to 50 hours. The battery precursor was then charged at a cutoff voltage of 3.5V to 4.2V and held for 5 to 50 hours. Next, it was charged to 4.2V at a temperature range of 25 to 70°C, and then discharged to 2.5V to obtain a lithium secondary battery. 【0215】 [2.2] Evaluation [2.2.1] Measurement of initial discharge capacity The lithium secondary battery described above was charged to 4.2V in a constant temperature bath at 25°C, and then discharged to 2.5V, and the discharge capacity [mAh] (hereinafter also referred to as "initial discharge capacity") was measured. 【0216】 [2.2.2] Measurement of Initial Resistance After measuring the initial discharge capacity, the lithium secondary battery was charged to 3.7V, and then the voltage drop (= voltage before discharge - voltage 10 seconds after discharge) was measured in a constant temperature bath at -20°C for each discharge rate from 0.1C to 1.0C due to CC10s discharge. Here, CC10s discharge means discharge performed at a constant current for 10 seconds. Based on the obtained voltage drop and each current value (i.e., each current value corresponding to the discharge rate from 0.1C to 1.0C), the DC resistance [Ω] as the initial resistance was measured. 【0217】 [2.2.3] High-temperature storage Next, the lithium secondary batteries whose battery volume was measured were CC-CV charged to 4.2V at a charge rate of 0.1C at 25°C, and then stored in a temperature environment of 60°C for 14 days (hereinafter referred to as "high-temperature storage"). 【0218】 [2.2.4] Measurement of Discharge Capacity Retention Rate After High-Temperature Storage and Calculation of Relative Value Next, the discharge capacity of the lithium secondary battery after high-temperature storage was measured in the same manner as the initial discharge capacity. The discharge capacity of the lithium secondary battery after high-temperature storage was also measured in the same manner for Comparative Example 1, described below. The discharge capacity retention rate of Example 1 after high-temperature storage was calculated as a relative value, with the discharge capacity retention rate of Comparative Example 1 after high-temperature storage set to 100 (see the formula below). An acceptable discharge capacity retention rate is 103% or higher. Discharge capacity retention rate of Example 1 after high-temperature storage (relative value) = (Discharge capacity retention rate of Example 1 after high-temperature storage) / (Discharge capacity retention rate of Comparative Example 1 after high-temperature storage) × 100 【0219】 [2.2.5] Measurement of Resistance Increase Rate After High-Temperature Storage and Calculation of Relative Value [2.2.5.1] Measurement of Resistance Increase Rate After High-Temperature Storage (25°C) Next, the resistance value of the lithium secondary battery after high-temperature storage was measured in a constant temperature bath at 25°C. The lithium secondary battery, after high-temperature storage and discharge capacity measurement, was charged until the SOC reached 50%. The DCIR (direct current resistance) [Ω] of the charged lithium secondary battery was measured. The obtained result was defined as the battery resistance (SOC 50%). For Comparative Example 1 described later, the resistance value of the lithium secondary battery after high-temperature storage and discharge capacity measurement was measured using the same method. The resistance increase rate after high-temperature storage (25°C) of Example 1 was calculated as a relative value when the resistance increase rate after high-temperature storage (25°C) of Comparative Example 1 was set to 100 (see the formula below). An acceptable resistance increase rate after high-temperature storage (25°C) is 90% or less. The rate of resistance increase after high-temperature storage in Example 1 (at 25°C) (relative value) = (Rate of resistance increase after high-temperature storage in Example 1 (at 25°C)) / (Rate of resistance increase after high-temperature storage in Comparative Example 1 (at 25°C)) × 100 【0220】[2, 2.5.2] Measurement of Resistance Increase Rate After High-Temperature Storage (-10°C) Next, the resistance value of the lithium secondary battery after high-temperature storage was measured in a constant temperature bath at -10°C. The lithium secondary battery, after the resistance measurement after high-temperature storage (25°C), was charged until the SOC reached 50%. The DCIR (direct current resistance) [Ω] of the charged lithium secondary battery was measured. The obtained result was defined as the battery resistance (SOC 50%). For Comparative Example 1 described later, the resistance value of the lithium secondary battery after the resistance measurement after high-temperature storage (25°C) was measured using the same method. The resistance increase rate after high-temperature storage (-10°C) of Example 1 was calculated as a relative value, with the resistance increase rate after high-temperature storage (-10°C) of Comparative Example 1 set to 100 (see formula below). An acceptable resistance increase rate after high-temperature storage (-10°C) is 90% or less. The rate of resistance increase after high-temperature storage in Example 1 (-10°C) (relative value) = (Rate of resistance increase after high-temperature storage in Example 1 (-10°C)) / (Rate of resistance increase after high-temperature storage in Comparative Example 1 (-10°C)) × 100 【0221】 [3] Examples 2 to 8 and Comparative Example 1 The same procedure as in Example 1 was followed except that the blocked isocyanate was changed. The results are shown in Table 2. 【0222】 【0223】 [4] Results The lithium secondary battery compositions of Examples 1 to 8 contained polyisocyanate compounds. As a result, in Examples 1 to 8, the discharge capacity retention rate was 103% or more, the resistance increase rate after high-temperature storage (25°C) was 90% or less, and the resistance increase rate after high-temperature storage (-10°C) was 90% or less. These results show that the lithium secondary battery compositions of Examples 1 to 8 are "lithium secondary battery compositions that can suppress the decrease in battery capacity even when charge and discharge are repeatedly performed, and can also suppress the increase in battery resistance at room temperature and low temperature." 【0224】The disclosure of Japanese Patent Application No. 2024-214669, filed on 9 December 2024, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference.

Claims

1. A composition for lithium secondary batteries comprising a polyisocyanate compound.

2. The lithium secondary battery composition according to claim 1, wherein the polyisocyanate compound comprises at least one of an isocyanurate derivative of 1,3-bis(isocyanatomethyl)cyclohexane and an isocyanurate derivative of xylylene diisocyanate.

3. The lithium secondary battery composition according to claim 1, wherein the polyisocyanate compound is a blocked isocyanate obtained by blocking the isocyanate group of the polyisocyanate compound with a blocking agent, and the blocking agent comprises at least one of a guanidino group-containing compound and a compound having a five-membered or six-membered nitrogen-containing heterocyclic structure.

4. The lithium secondary battery composition according to claim 1, wherein the content of the polyisocyanate compound is 0.1 parts by mass to 3.0 parts by mass per 100 parts by mass of solid content of the lithium secondary battery composition.

5. The lithium secondary battery composition according to claim 1, wherein the content of isocyanate groups (NCO%) in the polyisocyanate compound is 5% by mass to 30% by mass.

6. The lithium secondary battery composition according to claim 1, further comprising an active material.

7. The lithium secondary battery composition according to claim 6, wherein the active material is a carbon material.

8. A lithium secondary battery composition according to any one of claims 1 to 7, used in the electrodes of a lithium secondary battery.

9. An electrode comprising a dried product of the lithium secondary battery composition according to any one of claims 1 to 7.

10. A lithium secondary battery comprising the electrode described in claim 9.

11. A method for producing an electrode for a lithium secondary battery, comprising: preparing a composition for a lithium secondary battery containing a blocked isocyanate; mixing the composition for a lithium secondary battery with an active material to prepare a mixture; and applying the mixture to a current collector and drying it to prepare an electrode for a lithium secondary battery, wherein the blocked isocyanate is formed by blocking the isocyanate group of a polyisocyanate compound with a blocking agent, and the blocking agent comprises at least one of a guanidino group-containing compound and a compound having a five-membered or six-membered nitrogen-containing heterocyclic structure.

12. A blocked isocyanate, wherein the isocyanate group of a polyisocyanate compound is blocked by a blocking agent, and the blocking agent comprises at least two compounds having a five-membered or six-membered nitrogen-containing heterocyclic structure.

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