JP2014191942A - Binder for electrode of lithium secondary battery, and lithium secondary battery using electrode manufactured using the binder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a binder which improves adhesiveness to a collector, prevents occurrence of exfoliation during pressing, has high flexibility and is improved in a binding property and electrolyte resistance, and a lithium secondary battery improved in charging/discharging properties employing an electrode manufactured using the binder.SOLUTION: A binder for an electrode of a lithium secondary battery contains a polyurethane water dispersion formed from: polyisocyanate (component A); a chemical compound including two or more active hydrogen groups (component B); a chemical compound including one or more active hydrogen groups and hydrophilic groups (component C); and a chain extension agent (component D). The binder for the electrode of the lithium secondary battery is characterized in that the (component D) contains an alkoxy silane derivative.

Description

  The present invention relates to a binder for an electrode of a lithium secondary battery, and a lithium secondary battery using an electrode manufactured using the binder.

  Recently, portable electronic devices such as mobile phones, notebook computers, personal digital assistants (PDAs), video cameras, digital cameras, etc. have been widely used, and as these electronic devices are increasingly required to be smaller and lighter, drive power supplies There is an increasing demand for a battery that is smaller, lighter, thinner, and has a higher capacity, and research on this issue is actively underway. Lithium secondary batteries have high voltage and good energy density, and have been widely used as power sources for portable electronic devices. However, as the display industry has been reduced in size and weight, there is a need for a battery that is further reduced in size and weight, resulting in higher driving voltage, longer life, and longer life than conventional lithium secondary batteries. Improved battery characteristics such as high energy density are required. Recently, development of medium- or large-sized lithium secondary batteries for in-vehicle use, industrial use, etc. has been promoted, and there is an expectation for the development of high capacity and high output. Therefore, efforts to improve the performance of various components of the lithium battery are continued in order to satisfy such requirements.

  The characteristics of the battery are greatly influenced by the electrode, electrolyte and other battery materials used. In particular, in the case of electrodes, the characteristics are determined by the electrode active material, the current collector, and the binder that provides an adhesive force between them. Is determined. For example, the amount and type of active material used can determine the amount of lithium ions that can bind to the active material, the higher the amount of active material and the higher the specific capacity active material, the higher the capacity. A battery can be obtained. In addition, when the binder has an excellent adhesive force between the active materials and between the active material and the current collector, electrons and lithium ions move smoothly in the electrode, and the internal resistance of the electrode is reduced. Therefore, highly efficient charging / discharging becomes possible. In the case of a high-capacity battery, a composite electrode such as carbon and graphite, carbon and silicon is required as an anode active material, so that the volume expansion and contraction of the active material greatly occurs during charging and discharging. The above-mentioned binder has excellent elasticity in addition to excellent adhesive force, and must maintain the original adhesive force and restoring force despite the electrode volume repeatedly expanding and contracting considerably. As a binder for obtaining such an electrode, one obtained by dissolving a fluororesin such as polytetrafluoroethylene or polyvinylidene fluoride in an organic solvent is known. However, since the fluororesin is not sufficiently high in adhesion to the metal constituting the current collector and is not sufficiently high in flexibility, it can be obtained particularly when a wound battery is manufactured. There is a problem that a crack occurs in the obtained electrode layer, or peeling between the obtained electrode layer and the current collector occurs. In order to maintain sufficient adhesive strength, the amount of input must be large, so there is a limit to downsizing, and there is a disadvantage that manufacturing is complicated because it is used in combination with an organic solvent. .

  On the other hand, a binder made of styrene-butadiene latex (SBR) is known as a binder capable of forming an electrode layer having high adhesion to the metal constituting the current collector and high flexibility. (Patent Documents 1, 2, and 3). Although this is excellent in elastic characteristics, the adhesive strength is weak, and the structure of the electrode cannot be maintained as charging and discharging are repeated, so that the battery life is not sufficient. In recent years, due to the demand for higher battery capacity, there is a tendency to reduce the content of the binder component as a material constituting the electrode layer, and the electrode layer is subjected to press working in the electrode manufacturing process. Yes. However, in an electrode layer having a low binder component content, the electrode layer is easily peeled off from the current collector during pressing. Therefore, not only does the electrode material contaminate the press machine, but it has been pointed out that the electrode is incorporated in the battery in a state where a part of the electrode layer is peeled off, and the reliability of the battery performance is lowered. Such a problem becomes prominent when a polymer having a low glass transition temperature and a high tackiness is used as a binder component. Therefore, it is suppressed by using a latex having a high glass transition temperature, for example, room temperature or higher. can do. However, when a binder having a high glass transition temperature of the polymer is used, the obtained electrode layer has a problem that it is low in flexibility and easily cracks. The charge / discharge cycle characteristics cannot be obtained.

Japanese Patent Laid-Open No. 5-21068 Japanese Patent Laid-Open No. 11-7948 Japanese Patent Laid-Open No. 2001-210318

  The present invention has been made on the basis of the circumstances as described above, and its purpose is to have high adhesion to the current collector, no peeling during press working, high flexibility, An object of the present invention is to provide a lithium secondary battery excellent in charge and discharge characteristics using a binder excellent in adhesion and electrolyte resistance and an electrode manufactured using the binder.

In order to achieve the above object, the present invention comprises (A component) polyisocyanate, (B component) a compound having two or more active hydrogen groups, (C component) one or more active hydrogen groups and a hydrophilic group. A binder for an electrode of a lithium secondary battery comprising a polyurethane water dispersion consisting of a compound having the formula (D) and a chain extender, wherein the (D) contains an alkoxysilane derivative. A feature of the binder for an electrode of a lithium secondary battery is a first gist.
The (Component B) preferably contains a carbonate polyol, a polyester polyol having an aromatic ring, and / or a polyether polyol having an aromatic ring.
The component (A) preferably contains an alicyclic and / or aromatic isocyanate.
The second gist of the present invention is a lithium secondary battery using an electrode using the binder for an electrode of the lithium secondary battery.
That is, the present inventors obtain a binder that has high adhesion to the current collector, does not cause peeling during press processing, has high flexibility, and has excellent binding properties and electrolyte resistance. In order to achieve this, we have conducted extensive research. (A component) polyisocyanate, (B component) a compound having two or more active hydrogen groups, (C component) a compound having one or more active hydrogen groups and a hydrophilic group, and (D component) A binder for an electrode of a lithium secondary battery containing a polyurethane water dispersion comprising a chain extender, wherein the component (D) is a binder for an electrode using a polyurethane water dispersion containing an alkoxysilane derivative. The inventors have found that the intended purpose can be achieved by the adhesive, and have reached the present invention.

  The binder for the electrode of the lithium secondary battery of the present invention has high adhesion to the current collector, does not cause peeling at the time of pressing, has high flexibility, and has binding properties and electrolyte resistance. It is excellent and a lithium secondary battery excellent in charge / discharge characteristics can be obtained by using an electrode using the binder.

Next, embodiments of the present invention will be described in detail.
The binder for an electrode of the lithium secondary battery of the present invention includes (A component) polyisocyanate, (B component) a compound having two or more active hydrogen groups, (C component) one or more active hydrogen groups and a hydrophilic group. A polyurethane water dispersion comprising a compound having a functional group and a (D component) chain extender, wherein the (D component) contains a polyurethane water dispersion containing an alkoxysilane derivative.

  The polyisocyanate of (Component A) is not particularly limited, and polyisocyanates generally used in the art can be used. Specific examples include aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, and araliphatic polyisocyanates. Aliphatic polyisocyanates include tetramethylene diisocyanate, dodecamethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2-methylpentane-1 , 5-diisocyanate, 3-methylpentane-1,5-diisocyanate and the like. Examples of the alicyclic polyisocyanate include isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, 1,4-cyclohexane diisocyanate, methylcyclohexylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, and the like. Can be mentioned. Aromatic polyisocyanates include tolylene diisocyanate, 2,2′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate (MDI), 4,4′-dibenzyl diisocyanate, 1,5 -A naphthylene diisocyanate, a xylylene diisocyanate, a 1, 3- phenylene diisocyanate, a 1, 4- phenylene diisocyanate etc. can be mentioned. Examples of the araliphatic polyisocyanate include dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, α, α, α, α-tetramethylxylylene diisocyanate, and the like. Moreover, modified bodies, such as a dimer, a trimer of these organic polyisocyanate, and a buret-ized isocyanate, can be mentioned. These may be used alone or in combination of two or more. Of the polyisocyanates, alicyclic and / or aromatic isocyanates are preferred from the viewpoint of binding properties and resistance to electrolytic solution. Specifically, 4,4′-dicyclohexylmethane diisocyanate, isophorone diisocyanate, 1, 3-bis (isocyanatomethyl) cyclohexane is preferred.

  The component (B) is a compound having two or more hydroxyl groups, amino groups or mercapto groups at the molecular end or in the molecule, specifically, known polyethers, polyesters, polyether esters, polycarbonates, polythioethers, Polyacetal, polyolefin, polysiloxane, fluorine-based, vegetable oil-based and the like can be used. More specifically, ethylene glycol, propylene glycol, propanediol, butanediol, pentanediol, 3-methyl-1,5-pentanediol, hexanediol, neopetyl glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene Glycol, dipropylene glycol, tripropylene glycol, 1,4-cyclohexanedimethanol, bisphenol A, bisphenol F, bisphenol S, hydrogenated bisphenol A, dibromobisphenol A, 1,4-cyclohexanedimethanol, dihydroxyethyl terephthalate, hydroquinone dihydroxy Polyhydric alcohols such as ethyl ether, trimethylolpropane, glycerin, pentaerythritol, and their oxy Alkylene derivatives or their polyhydric alcohols and oxyalkylene derivatives and polycarboxylic acids, polyhydric carboxylic acid anhydrides, or ester compounds from polycarboxylic esters, polycarbonate polyols, polycaprolactone polyols, polyester polyols, polythioethers Polyol compounds such as polyols, polyacetal polyols, polytetramethylene glycols, polybutadiene polyols, castor oil polyols, soybean oil polyols, fluorine polyols, silicone polyols, and modified products thereof may be mentioned. Examples of the alkylene oxide include ethylene oxide, propylene oxide, and butylene oxide. These compounds having a group having two or more active hydrogen groups may be used alone or in combination of two or more.

  The compound is preferably a compound having two or more hydroxyl groups at the molecular terminals. Examples of the compound include ethylene glycol, propylene glycol, propanediol, butanediol, pentanediol, 3-methyl-1,5-pentanediol, hexanediol, neopetyl glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, Dipropylene glycol, tripropylene glycol, 1,4-cyclohexanedimethanol, bisphenol A, bisphenol F, bisphenol S, hydrogenated bisphenol A, dibromobisphenol A, 1,4-cyclohexanedimethanol, dihydroxyethyl terephthalate, hydroquinone dihydroxyethyl ether , And their oxyalkylene derivative polycarbonate polyol, polycaprolactone poly All, polyester polyol, polythioether polyol, polyacetal polyol, polytetramethylene glycol, polybutadiene polyol, and the alkylene oxides of the above-mentioned alkylene derivatives include ethylene oxide, propylene oxide, butylene oxide and the like. Can be mentioned. Among these, the (component B) preferably contains a polycarbonate polyol, a polyester polyol having an aromatic ring, and / or a polyether polyol having an aromatic ring.

  The polycarbonate polyol is not particularly limited, and a polycarbonate polyol generally used in the technical field can be used. Specifically, carbonate polyol of 1,6-hexanediol, carbonate polyol of 1,4-butanediol and 1,6-hexanediol, carbonate of 1,5-pentanediol and 1,6-hexanediol, 3- Carbonate polyols of methyl-1,5-pentanediol and 1,6-hexanediol, carbonates of 1,9-nonanediol and 2-methyl-1,8-octanediol, 1,4-cyclohexanedimethanol and 1,6 -Hexanediol carbonate, 1,4-cyclohexanedimethanol carbonate, and these are PCDL T-6001, T-6002, T-5651, T-5651, T-5650J, T manufactured by Asahi Kasei Chemicals Corporation. -4671, T-4672, Kuraray ( ) Kuraray polyol C-590, C-1050, C-1050R, C-1090, C-2050, C-2050R, C-2070, C-2070R, C-2090, C-2090R, C-3090, C -3090R, C-4090, C-4090R, C-5090, C-5090R, C-1065N, C-2065N, C-1015N, C-2015N and Ube Industries ETERNACOLL UH-50, UH-100 , UH-200, UH-300, UM-90 (3/1), UM-90 (1/1), UM-90 (1/3), UC-100, and the like.

  The polyester polyol having an aromatic ring can be generally obtained by condensation reaction of a dibasic acid and a dihydric alcohol. Specific examples of the dibasic acid include, but are not limited to, aromatic dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid. . Specific examples of the dihydric alcohol include, but are not limited to, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3 -Aliphatic glycols such as methyl-1,5-pentanediol, alicyclic glycols such as cyclohexanediol, and aromatic glycols such as alkylene oxide adducts of bisphenol A.

  Specific examples of the polyether polyol having an aromatic ring include alkylene oxide adducts of bisphenol A (ethylene oxide adducts, propylene oxide adducts) and the like.

  In addition, the (component B) may be added with a single-chain low molecular weight diol such as ethylene glycol, 1,4-butanediol, or 1,4-cyclohexanedimethanol in order to localize the urethane bond in the polyurethane. Good.

  The polycarbonate polyol, the polyester polyol having an aromatic ring, and / or the polyether polyol having an aromatic ring preferably have a number average molecular weight of 300 to 3,000. When the number average molecular weight is less than 300, the binding property decreases, and when the number average molecular weight exceeds 3000, the electrolytic solution resistance tends to decrease.

  Moreover, in order to introduce | transduce a branched structure into a molecule | numerator as said (B component), the oxyalkylene derivative of a polyhydric alcohol and / or a polyhydric alcohol can be used. Specific examples of the compound include polyhydric alcohols such as trimethylolpropane, glycerin, and pentaerythritol, oxyalkylene derivatives thereof, polyhydric alcohols and oxyalkylene derivatives and polycarboxylic acids, polyhydric carboxylic acid anhydrides, or Mention may be made of ester compounds from polyvalent carboxylic acid esters. As described above, a branched structure is introduced into the polyurethane, and localization of the urethane bond is preferable because an effect of improving the electrolytic solution resistance of the electrode using the binder containing the urethane water dispersion can be obtained. The number average molecular weight of the compound is not particularly limited, but is preferably 50 or more and 5000 or less. The content in the polyurethane contained in the polyurethane water dispersion of the (B component) is not particularly limited, but is preferably 30 to 75% by weight in the polyurethane from the viewpoint of compatibility between binding properties and electrolytic solution resistance.

(C component) of the present invention is a compound having one or more hydrophilic groups and one or more active hydrogen groups.
Examples of the hydrophilic group include an anionic hydrophilic group, a cationic hydrophilic group, and a nonionic hydrophilic group. Specifically, as the anionic hydrophilic group, a carboxyl group and a salt thereof, a sulfonic acid group and a salt thereof are cationic. Examples of the hydrophilic hydrophilic group include tertiary ammonium salts and quaternary ammonium salts, and the nonionic hydrophilic group includes a group consisting of ethylene oxide repeating units, a group consisting of ethylene oxide repeating units and other alkylene oxide repeating units, etc. Is mentioned.

  Examples of the compound containing one or more active hydrogen groups and a carboxyl group include 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolvaleric acid, dioxymaleic acid, 2, In addition to carboxylic acid-containing compounds such as 6-dioxybenzoic acid and 3,4-diaminobenzoic acid, derivatives thereof, and salts thereof, polyester polyols obtained using these are included. Further examples include amino acids such as alanine, aminobutyric acid, aminocaproic acid, glycine, glutamic acid, aspartic acid, and histidine, and carboxylic acids such as succinic acid, adipic acid, maleic anhydride, phthalic acid, and trimellitic anhydride.

  Examples of the compound having one or more active hydrogen groups and sulfonic acid groups and salts thereof include, for example, 2-oxyethanesulfonic acid, phenolsulfonic acid, sulfobenzoic acid, sulfosuccinic acid, 5-sulfoisophthalic acid, sulfanilic acid, 1 , 3-phenylenediamine-4,6-disulfonic acid, sulfonic acid-containing compounds such as 2,4-diaminotoluene-5-sulfonic acid and their derivatives, and polyester polyols, polyamide polyols obtained by copolymerizing these, Examples thereof include polyamide polyester polyol. By neutralizing these carboxyl groups or sulfonic acid groups into salts, the finally obtained polyurethane can be made water-dispersible. Examples of the neutralizing agent in this case include non-volatile bases such as sodium hydroxide and potassium hydroxide, tertiary amines such as trimethylamine, triethylamine, dimethylethanolamine, methyldiethanolamine and triethanolamine, and volatile properties such as ammonia. Examples include bases. Neutralization can be performed before, during or after the urethanization reaction.

  Examples of the compound containing one or more active hydrogen groups and a tertiary ammonium salt include alkanolamines such as methylaminoethanol and methyldiethanolamine. By neutralizing these with organic carboxylic acids such as formic acid and acetic acid and inorganic acids such as hydrochloric acid and sulfuric acid to form salts, the polyurethane can be made water-dispersible. Neutralization can be performed before, during or after the urethanization reaction. Of these, those obtained by neutralizing methyldiethanolamine with an organic carboxylic acid are preferred from the viewpoint of ease of emulsification.

  A compound having one or more active hydrogen groups and a quaternary ammonium salt is obtained by reacting alkanolamines such as methylaminoethanol and methyldiethanolamine with dialkyl sulfates such as methyl chloride and methyl bromide, and dimethyl sulfate. It is a graded compound. Among these compounds, methyldiethanolamine is quaternized with dimethylsulfate from the viewpoint of ease of emulsification.

  The compound having one or more active hydrogen groups and a nonionic hydrophilic group is not particularly limited, but is preferably a compound containing at least 30% by weight of ethylene oxide repeating units and having a number average molecular weight of 300 to 20,000. Nonionic group content such as oxyethylene glycol or polyoxyethylene-polyoxypropylene copolymer glycol, polyoxyethylene-polyoxybutylene copolymer glycol, polyoxyethylene-polyoxyalkylene copolymer glycol or monoalkyl ether thereof The polyester polyether polyol obtained by copolymerizing a compound or these is mentioned.

  As the component (C), the above compounds may be used alone or in combination. In the case of an anionic hydrophilic group-containing compound, the content of (C component) is preferably 5 to 50 mgKOH / g, and more preferably 5 to 45 mgKOH / g, indicating the anionic hydrophilic group content. Is more preferable. When the acid value is less than 5 mgKOH / g, there is a problem that dispersibility in water becomes difficult. Moreover, when an acid value exceeds 50 mgKOH / g, there exists a problem that electrolyte solution resistance falls. The acid value was determined from the mg number of KOH required to neutralize free carboxyl groups contained in 1 g of the solid content of the polyurethane water dispersion in accordance with JIS K0070-1992. When using a nonionic group containing compound, it is 1-30 weight part, It is preferable to use especially 5-20 weight part. Among these, (C component) is preferably a compound containing one or more active hydrogen groups and a carboxyl group in the molecule from the viewpoint of adhesion to the current collector.

  The alkoxysilane derivative (component D) is preferably a silane coupling agent. As the silane coupling agent in the present invention, a silane coupling agent generally used in the technical field to which the present invention belongs can be used, and although not particularly limited, specifically, 3-aminopropyltrimethoxy Silane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane, N-2 (aminoethyl) 3 -Aminopropyltrimethoxysilane, N-2 (aminoethyl) 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyl Trimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercap Trimethoxysilane can be exemplified 3-isocyanate propyl triethoxysilane. Among these, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane is preferable from the viewpoint of stability of the polyurethane water dispersion and resistance to electrolytic solution. These silane coupling agents can be used in combination of two or more.

  In addition, as the component (D), a chain extender generally used in the technical field can be used in combination with an alkoxysilane derivative. Although not particularly limited, specifically, diamine or polyamine can be used. Examples of the diamine include ethylene diamine, trimethylene diamine, piperazine, and isophorone diamine, and examples of the polyamine include diethylene triamine, dipropylene triamine, and triethylene tetramine.

  The method for producing the polyurethane water dispersion of the present invention is not particularly limited. In general, (B component) a compound having two or more active hydrogen groups (C component) one or more hydrophilic groups and A stoichiometric excess of (component A) polyisocyanate (equivalent of isocyanate group and reactive functional group) from the sum of active hydrogen groups contained in one or more active hydrogen group-containing compounds and (component D) chain extender After the synthesis of an isocyanate-terminated urethane prepolymer by reacting the ratio 1: 0.85 to 1.1) without a solvent or in an organic solvent having no active hydrogen group, An anionic hydrophilic group and a cationic hydrophilic group are neutralized or quaternized, and then dispersed and emulsified in water. Thereafter, an equivalent (D component) chain extender (equivalent ratio of isocyanate group to amino group in the chain extender 1: 0.5 to 0.9) less than the remaining isocyanate group was added to add isocyanate in the emulsion micelle. A urea bond is formed by interfacial polymerization reaction between a cinto group and a (D component) chain extender. Thereby, the high molecular weight in the emulsified micelle or the crosslinking density is improved, and a polyurethane water dispersion exhibiting excellent electrolytic solution resistance is obtained. Then, the polyurethane water dispersion can be obtained by removing the solvent used as needed.

  The organic solvent having no active hydrogen group is not particularly limited, and specific examples include dioxane, methyl ethyl ketone, dimethylformamide, tetrahydrofuran, N-methyl-2-pyrrolidone, toluene, propylene glycol monomethyl ether acetate and the like. These hydrophilic organic solvents used in the reaction are preferably finally removed.

  The number average molecular weight of the polyurethane in the polyurethane water dispersion in the present invention is preferably as large as possible by introducing a branched structure or an internal cross-linked structure, and is preferably 50,000 or more. This is because when the molecular weight is increased to make it insoluble in a solvent, a coating film excellent in electrolytic solution resistance can be obtained.

The polyurethane resin of the polyurethane resin aqueous dispersion used in the present invention preferably has a crosslinking density of 0.01 to 0.50 per 1000 atomic weight of the polyurethane resin. The crosslinking density here is a numerical value obtained by calculation based on the following equation (1). That is, the polyisocyanate (A) having a molecular weight MW _A1 and the functional group number F _A1 is WA ₁ g, the polyisocyanate (A) having a molecular weight MW _A2 and the functional group number F _A2 is WA ₂ g, the molecular weight MW _AJ and the functional group number F _AJ polyisocyanate (a) and W _{Aj g} (j is an integer of 1 or more) of a molecular weight MW _B1, the active hydrogen group-containing compound functional groups F _B1 and (B) and W _B1 g, molecular weight MW _B2 and functionality F _B2 active hydrogen group-containing compound of the (B) and W _B2 g, the active hydrogen group-containing compound having a molecular weight MW _Bk and functional groups F _Bk (B) and W _Bk g (k is an integer of 1 or more), the molecular weight MW _C1 A compound (C) having one or more active hydrogen groups having a functional group number F _C1 and a hydrophilic group W _C1 g, a compound having one or more active hydrogen groups and a hydrophilic group having a molecular weight MW _Cm and a functional group number F _Cm the (C) and _{W Cm} g (m is an integer of 1 or more), the molecular weight MW _D1, a functionality _{F D1} of chain extender and (D) W _D1 g, min The amount MW _Dn, chain length agent functionality F _Dn (D) a W _Dn g (n is an integer of 1 or more) and per 1000 molecular weight of the resin solids contained in the aqueous polyurethane dispersion obtained by reacting the The crosslinking density can be calculated by the following formula.

  When the crosslink density is less than 0.01, the electrolytic solution resistance and the heat resistance tend to be inferior, and when it exceeds 0.50, the flexibility of the urethane resin is lowered and the binding property is also lowered.

  In the polyurethane water dispersion of the present invention, the urethane bond amount in the urethane resin is preferably 150 to 2000 g / eq, and more preferably 200 to 1000 g / eq. If the urethane bond amount is less than 150 g / eq, the polyurethane bond amount is too large, so the flexibility of the polyurethane resin is lowered and the binding property is inferior. If it exceeds 2000 g / eq, the electrolytic solution resistance and heat resistance are inferior.

  In the polyurethane water dispersion of the present invention, the urea bond amount in the urethane resin is preferably 300 to 20000 g / eq, and more preferably 400 to 10000 g / eq. When the amount of urea bonds is less than 300 g / eq, the amount of urea bonds is too large, so the flexibility of the polyurethane resin is lowered and the binding property is inferior, and when it exceeds 20000 g / eq, workability during synthesis may be deteriorated. , And the electrolyte solution resistance and heat resistance are inferior.

  The average particle size of the polyurethane water dispersion used in the present invention is preferably in the range of 0.005 to 0.5 μm from the viewpoint of the amount added, coating properties, and binding properties.

  The lithium secondary battery of the present invention includes a positive electrode and a negative electrode, a separator provided between the positive electrode and the negative electrode and isolating both, and a non-aqueous electrolysis in which a lithium salt is dissolved as a supporting electrolyte in a solvent for conducting lithium ions It is comprised with the electrolyte layer containing a liquid, a polymer, or a polymer gel electrolyte.

  The positive electrode and the negative electrode used in the lithium secondary battery of the present invention include an electrode active material, a conductive agent, a current collector of the electrode active material, and a binder that binds the electrode active material and the conductive agent to the current collector. Composed.

  The lithium secondary battery of this invention is comprised from the electrode manufactured using the binder containing the said polyurethane water dispersion.

  In the lithium secondary battery of the present invention, the binder for the electrode not using the polyurethane water dispersion may be polyvinylidene fluoride (PVDF), PVDF and hexafluoropropylene (HFP), or perfluoromethyl vinyl ether (PFMV). And PVDF copolymer resins such as copolymers with tetrafluoroethylene (TFE), fluorine resins such as polytetrafluoroethylene (PTFE) and fluorine rubber, styrene-butadiene rubber (SBR), ethylene-propylene rubber ( EPDM) polymers such as styrene-acrylonitrile copolymers can be used, but are not limited thereto.

The positive electrode active material used for the positive electrode of the lithium secondary battery of the present invention is not particularly limited as long as it can insert and desorb lithium ions. Examples include metal oxides such as CuO, Cu ₂ O, MnO ₂ , MoO ₃ , V ₂ O ₅ , CrO ₃ , MoO ₃ , Fe ₂ O ₃ , Ni ₂ O ₃ , CoO ₃ , LixCoO ₂ , LixNiO _2. , LixMn ₂ O ₄ , LiFePO ₄ and other complex oxides of lithium and transition metals, metal chalcogenides such as TiS ₂ , MoS ₂ and NASe ₃ , conductive polymers such as polyacene, polyparaphenylene, polypyrrole and polyaniline Compounds and the like.

Among these, a composite oxide of lithium and one or more selected from transition metals such as cobalt, nickel, and manganese, which is generally called a high voltage system, is preferable in terms of lithium ion release properties and high voltage. . Specific examples of the composite oxide of cobalt, nickel, manganese and lithium include LiCoO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , LiNixCo (1-x) O ₂ , LiMnaNibCoc (a + b + c = 1) and the like. It is done.

In addition, these lithium composite oxides doped with a small amount of elements such as fluorine, boron, aluminum, chromium, zirconium, molybdenum, iron, etc., or the surface of lithium composite oxide particles are made of carbon, MgO, Al ₂ O ₃ , those treated with SiO ₂ or the like can also be used. Two or more kinds of the positive electrode active materials can be used in combination.

As the negative electrode active material used for the negative electrode of the present invention, any known active material can be used without particular limitation as long as it can insert / extract metallic lithium or lithium ions. For example, carbon materials such as natural graphite, artificial graphite, non-graphitizable carbon, and graphitizable carbon can be used. In addition, metallic materials such as metallic lithium, alloys, tin compounds, lithium transition metal nitrides, crystalline metal oxides, amorphous metal oxides, silicon compounds, conductive polymers, etc. can be used. , Li ₄ Ti ₅ O ₁₂ , NiSi ₅ C _{6 and the} like.

  A conductive agent is used for the positive electrode and the negative electrode of the lithium secondary battery of the present invention. Any electrically conductive material that does not adversely affect battery performance can be used as the conductive agent. Usually, carbon black such as acetylene black and kettin black is used. A conductive material such as silver, gold, etc.) powder, metal fiber, or conductive ceramic material may be used. These can be included as a mixture of two or more. The addition amount is preferably 0.1 to 30% by weight, particularly preferably 0.2 to 20% by weight, based on the amount of the active material.

  As the current collector for the electrode active material of the lithium secondary battery of the present invention, any electronic conductor can be used as long as it does not adversely affect the constructed battery. For example, as a positive electrode current collector, aluminum, titanium, stainless steel, nickel, calcined carbon, conductive polymer, conductive glass, etc., in addition to aluminum for the purpose of improving adhesiveness, conductivity, and oxidation resistance. A material obtained by treating the surface of copper or copper with carbon, nickel, titanium, silver or the like can be used. In addition to negative electrode current collectors, copper, stainless steel, nickel, aluminum, titanium, calcined carbon, conductive polymer, conductive glass, Al-CD alloy, etc., adhesion, conductivity, oxidation resistance For the purpose of improving the properties, it is possible to use a surface of copper or the like treated with carbon, nickel, titanium, silver or the like. The surface of these current collector materials can be oxidized. Moreover, about the shape, molded bodies, such as a film form, a sheet form, a net form, the punched or expanded thing, a lath body, a porous body, and a foam other than foil shape, are also used. The thickness is not particularly limited, but a thickness of 1 to 100 μm is usually used.

  The electrode of the lithium secondary battery of the present invention is a slurry obtained by mixing an electrode active material, a conductive agent, a current collector of the electrode active material, and a binder that binds the electrode active material and the conductive agent to the current collector. It can be produced by preparing an electrode material and applying it to an aluminum foil or copper foil as a current collector and volatilizing the dispersion medium.

  In the electrode material of the present invention, a thickener such as a water-soluble polymer can be used as a slurry viscosity adjusting agent. Specifically, celluloses such as carboxymethylcellulose, methylcellulose, ethylcellulose, hydroxymethylcellulose, hydroxypropylmethylcellulose, hydroxyethylmethylcellulose; polycarboxylic acid compounds such as polyacrylic acid and sodium polyacrylate; vinylpyrrolidone structures such as polyvinylpyrrolidone 1 type or 2 or more types selected from polyacrylamide, polyethylene oxide, polyvinyl alcohol, sodium alginate, xanthan gum, carrageenan, guar gum, agar, starch and the like can be used, and among them, carboxymethyl cellulose salt is preferable.

  The method and order of mixing the electrode materials are not particularly limited. For example, the active material and the conductive agent can be mixed and used in advance. For mixing in this case, a mortar, a mill mixer, a planetary ball mill is used. Alternatively, a ball mill such as a shaker type ball mill, a mechano-fusion, or the like can be used.

  As the separator used in the lithium secondary battery of the present invention, a separator used in a normal lithium secondary battery can be used without particular limitation, and examples thereof include porous materials made of polyethylene, polypropylene, polyolefin, polytetrafluoroethylene, and the like. Resin, ceramic, non-woven fabric and the like.

  The electrolytic solution used in the lithium secondary battery of the present invention may be an electrolytic solution used in a normal lithium secondary battery, and common ones such as an organic electrolytic solution and an ionic liquid can be used.

Examples of the electrolyte salt used in the lithium secondary battery of the present invention include LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCl, LiAr, LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiI, LiAlCl ₄ , NaClO ₄ , NaAF ₄ , NaI, and the like. In particular, inorganic lithium salts such as LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiN (SO ₂ CxF2x + 1) An organic lithium salt represented by (SO ₂ CyF2y + 1) can be given. Here, x and y represent 0 or an integer of 1 to 4, and x + y is 2 to 8. Specifically, as the organic lithium salt, LiN (SO ₂ F) ₂ , LiN (SO ₂ CF ₃ ) (SO ₂ C ₂ F ₅ ), LiN (SO ₂ CF ₃ ) (SO ₂ C ₃ F ₇ ) LiN (SO ₂ CF ₃ ) (SO ₂ C ₄ F ₉ ), LiN (SO ₂ C ₂ F ₅ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) (SO ₂ C ₃ F ₇ ), LiN (SO ₂ C ₂ F ₅ ) (SO ₂ C ₄ F ₉ ) and the like. Among them, it is preferable to use LiPF ₆ , LiAF ₄ , LiN (CF ₃ SO ₂ ) ₂ , LiN (SO ₂ F) ₂ , LiN (SO ₂ C ₂ F ₅ ) _2, etc. because of excellent electrical characteristics. The above electrolyte salt may be used alone or in combination of two or more. Such a lithium salt is usually contained in the electrolytic solution at a concentration of 0.1 to 2.0 mol / liter, preferably 0.3 to 1.5 mol / liter.

  The organic solvent for dissolving the electrolyte salt of the lithium secondary battery of the present invention is not particularly limited as long as it is an organic solvent used for a non-aqueous electrolyte solution of a normal lithium secondary battery. For example, a carbonate compound, a lactone compound, Examples include ether compounds, sulfolane compounds, dioxolane compounds, ketone compounds, nitrile compounds, and halogenated hydrocarbon compounds. Specifically, 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, vinylene carbonate, lactones such as γ-butyl lactone, Ethers such as dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,4-dioxane, sulfolanes such as sulfolane and 3-methylsulfolane, dioxolanes such as 1,3-dioxolane, 4-methyl-2- Ketones such as pentanone, nitriles such as acetonitrile, pyropionitrile, valeronitrile, benzonitrile, 1,2-di Halogenated hydrocarbons such as Roroetan, other methyl formate, dimethyl formamide, diethyl formamide, dimethyl sulfoxide, imidazolium salts, and ionic liquids such as such as quaternary ammonium salts. Furthermore, a mixture thereof may be used.

  Among these organic solvents, it is particularly preferable to contain one or more types of non-aqueous solvents selected from the group consisting of carbonates because they are excellent in electrolyte solubility, dielectric constant and viscosity.

  In the lithium secondary battery of the present invention, when used as a polymer electrolyte or a polymer gel electrolyte, the polymer compounds such as ether, ester, siloxane, acrylonitrile, vinylidene fluoride, hexafluoropropylene, acrylate, methacrylate, styrene, vinyl acetate , Polymers such as vinyl chloride and oxetane, polymers having a copolymer structure thereof, or cross-linked products thereof, and the like may be one kind or two or more kinds. The polymer structure is not particularly limited, but a polymer having an ether structure such as polyethylene oxide is particularly preferable.

  In the lithium secondary battery of the present invention, a liquid battery is an electrolyte solution, a gel battery is a precursor solution in which a polymer is dissolved in an electrolyte solution, and a solid electrolyte battery is a polymer before crosslinking in which an electrolyte salt is dissolved in a battery container. Accommodate.

  The lithium secondary battery according to the present invention can be formed into a cylindrical shape, a coin shape, a square shape, or any other shape, and the basic configuration of the battery is the same regardless of the shape, and the design is changed according to the purpose. Can be implemented. For example, in a cylindrical type, a wound body in which a negative electrode formed by applying a negative electrode active material to a negative electrode current collector and a positive electrode formed by applying a positive electrode active material to a positive electrode current collector are wound through a separator. It is housed in a battery can, sealed with a non-aqueous electrolyte injected, and insulating plates placed on top and bottom. When applied to a coin-type lithium secondary battery, a disc-shaped negative electrode, a separator, a disc-shaped positive electrode, and a stainless steel plate are stacked and stored in a coin-type battery can, and a non-aqueous electrolyte is injected. Sealed.

Next, examples will be described together with comparative examples. However, the present invention is not limited to these examples.
[Synthesis of polyurethane water dispersion]
(Synthesis Example 1)
A four-necked flask equipped with a stirrer, reflux condenser, thermometer, and nitrogen blowing tube was added to Newpole BPE-20NK (manufactured by Sanyo Chemical Co., Ltd., bisphenol A ethylene oxide adduct, average hydroxyl value 360 mgKOH / g, number of active hydrogen groups 2 ) 100 parts by mass, 9.5 parts by mass of trimethylolpropane (number of active hydrogen groups 3), 16.3 parts by mass of dimethylolpropionic acid (number of active hydrogen groups 2), 174.2 parts by mass of dicyclohexylmethane diisocyanate, 200 parts by mass of methyl ethyl ketone In addition, the reaction was carried out at 75 ° C. for 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 4.2% based on the nonvolatile content. The solution was cooled to 45 ° C., 12.3 parts by mass of triethylamine was added to neutralize, 900 parts by mass of water was gradually added, and the mixture was emulsified and dispersed using a homogenizer. Subsequently, 6.1 parts by mass of ethylenediamine (number of active hydrogen groups 2) and N-2- (aminoethyl) -3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Silicone Co., Ltd., product name: KBM-603) 7.4 An aqueous solution obtained by diluting a part by mass with 100 parts by weight of water was added to carry out a chain extension reaction for 1 hour. The solvent was removed under reduced pressure at 50 ° C. to obtain a polyurethane water dispersion A having a nonvolatile content of about 30%.
(Synthesis Example 2)
A four-necked flask equipped with a stirrer, reflux condenser, thermometer, and nitrogen blowing tube was added to Newpole BPE-20NK (manufactured by Sanyo Chemical Co., Ltd., bisphenol A ethylene oxide adduct, average hydroxyl value 360 mgKOH / g, number of active hydrogen groups 2 ) 100 parts by mass, 9.5 parts by mass of trimethylolpropane (number of active hydrogen groups 3), 16.3 parts by mass of dimethylolpropionic acid (number of active hydrogen groups 2), 174.2 parts by mass of dicyclohexylmethane diisocyanate, 200 parts by mass of methyl ethyl ketone In addition, the reaction was carried out at 75 ° C. for 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 4.2% based on the nonvolatile content. The solution was cooled to 45 ° C., 12.3 parts by mass of triethylamine was added to neutralize, 900 parts by mass of water was gradually added, and the mixture was emulsified and dispersed using a homogenizer. Subsequently, 7.0 parts by mass of diethylenetriamine (3 active hydrogen groups) and 14.7 parts by mass of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Silicone Co., Ltd., product name: KBM-903) are diluted with 100 parts by weight of water. The resulting aqueous solution was added to carry out a chain extension reaction for 1 hour. The solvent was removed under reduced pressure at 50 ° C. to obtain a polyurethane water dispersion B having a nonvolatile content of about 30%.
(Synthesis Example 3)
A four-necked flask equipped with a stirrer, reflux condenser, thermometer, and nitrogen blowing tube was added to Newpole BPE-20NK (manufactured by Sanyo Chemical Co., Ltd., bisphenol A ethylene oxide adduct, average hydroxyl value 360 mgKOH / g, number of active hydrogen groups 2 ) 100 parts by mass, 9.5 parts by mass of trimethylolpropane (number of active hydrogen groups 3), 16.3 parts by mass of dimethylolpropionic acid (number of active hydrogen groups 2), 144.2 parts by mass of dicyclohexylmethane diisocyanate, 30.0 diphenylmethane diisocyanate Part by mass and 200 parts by mass of methyl ethyl ketone were added and reacted at 75 ° C. for 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 4.3% based on the nonvolatile content. The solution was cooled to 45 ° C., 12.3 parts by mass of triethylamine was added to neutralize, 900 parts by mass of water was gradually added, and the mixture was emulsified and dispersed using a homogenizer. Subsequently, 7.0 parts by mass of diethylenetriamine (3 active hydrogen groups) and 14.7 parts by mass of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Silicone Co., Ltd., product name: KBM-903) are diluted with 100 parts by weight of water. The resulting aqueous solution was added to carry out a chain extension reaction for 1 hour. The solvent was removed under reduced pressure at 50 ° C. to obtain a polyurethane water dispersion C having a nonvolatile content of about 30%.
(Synthesis Example 4)
Kuraray polyol P-1020 (manufactured by Kuraray Co., Ltd., polyester polyol composed of 3-methyl-1,5-pentanediol and terephthalic acid, average hydroxyl group) 110 mg KOH / g, number of active hydrogen groups 2) 145.2 parts by mass, trimethylolpropane (number of active hydrogen groups 3) 9.5 parts by mass, dimethylolpropionic acid (number of active hydrogen groups 2) 16.3 parts by mass, dicyclohexylmethane diisocyanate 129.0 parts by mass and 200 parts by mass of methyl ethyl ketone were added and reacted at 75 ° C. for 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 3.3% based on the nonvolatile content. The solution was cooled to 45 ° C., 12.3 parts by mass of triethylamine was added to neutralize, 900 parts by mass of water was gradually added, and the mixture was emulsified and dispersed using a homogenizer. Then, 4.2 parts by mass of ethylenediamine (number of active hydrogen groups 2) and N-2- (aminoethyl) -3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Silicone Co., Ltd., product name: KBM-603) 7.4 An aqueous solution obtained by diluting a part by mass with 100 parts by weight of water was added to carry out a chain extension reaction for 1 hour. The solvent was removed under reduced pressure at 50 ° C. to obtain a polyurethane water dispersion D having a nonvolatile content of about 30%.
(Synthesis Example 5)
PCDL T-4671 (manufactured by Asahi Kasei Chemicals Corporation, polycarbonate polyol containing 1,4-butanediol and 1,6-hexanediol as constituents) in a four-necked flask equipped with a stirrer, reflux condenser, thermometer and nitrogen blowing tube Average hydroxyl value 110 mg KOH / g, active hydrogen group number 2) 145.2 parts by mass, trimethylolpropane (active hydrogen group number 3) 9.5 parts by mass, dimethylolpropionic acid (active hydrogen group number 2) 16.3 parts by mass, 129.0 parts by mass of dicyclohexylmethane diisocyanate and 200 parts by mass of methyl ethyl ketone were added and reacted at 75 ° C. for 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 3.3% based on the nonvolatile content. The solution was cooled to 45 ° C., 12.3 parts by mass of triethylamine was added to neutralize, 900 parts by mass of water was gradually added, and the mixture was emulsified and dispersed using a homogenizer. Then, 4.2 parts by mass of ethylenediamine (number of active hydrogen groups 2) and N-2- (aminoethyl) -3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Silicone Co., Ltd., product name: KBM-603) 7.4 An aqueous solution obtained by diluting a part by mass with 100 parts by weight of water was added to carry out a chain extension reaction for 1 hour. The solvent was removed under reduced pressure at 50 ° C. to obtain a polyurethane water dispersion E having a nonvolatile content of about 30%.
(Synthesis Example 6)
PCDL T-4671 (manufactured by Asahi Kasei Chemicals Corporation, polycarbonate polyol containing 1,4-butanediol and 1,6-hexanediol as constituents) in a four-necked flask equipped with a stirrer, reflux condenser, thermometer and nitrogen blowing tube Average hydroxyl value 110 mg KOH / g, active hydrogen group number 2) 145.2 parts by mass, trimethylolpropane (active hydrogen group number 3) 9.5 parts by mass, dimethylolpropionic acid (active hydrogen group number 2) 16.3 parts by mass, 129.0 parts by mass of dicyclohexylmethane diisocyanate and 200 parts by mass of methyl ethyl ketone were added and reacted at 75 ° C. for 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 3.3% based on the nonvolatile content. The solution was cooled to 45 ° C., 12.3 parts by mass of triethylamine was added to neutralize, 900 parts by mass of water was gradually added, and the mixture was emulsified and dispersed using a homogenizer. Subsequently, 4.8 parts by mass of diethylenetriamine (number of active hydrogen groups 3) and N-2- (aminoethyl) -3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Silicone Co., Ltd., product name: KBM-603) 7.4 An aqueous solution obtained by diluting a part by mass with 100 parts by weight of water was added to carry out a chain extension reaction for 1 hour. The solvent was removed under reduced pressure at 50 ° C. to obtain a polyurethane water dispersion F having a nonvolatile content of about 30%.
(Synthesis Example 7)
PCDL T-4671 (manufactured by Asahi Kasei Chemicals Corporation, polycarbonate polyol containing 1,4-butanediol and 1,6-hexanediol as constituents) in a four-necked flask equipped with a stirrer, reflux condenser, thermometer and nitrogen blowing tube Average hydroxyl value 110 mg KOH / g, active hydrogen group number 2) 145.2 parts by mass, trimethylolpropane (active hydrogen group number 3) 9.5 parts by mass, dimethylolpropionic acid (active hydrogen group number 2) 16.3 parts by mass, 129.0 parts by mass of dicyclohexylmethane diisocyanate and 200 parts by mass of methyl ethyl ketone were added and reacted at 75 ° C. for 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 3.3% based on the nonvolatile content. The solution was cooled to 45 ° C., 12.3 parts by mass of triethylamine was added to neutralize, 900 parts by mass of water was gradually added, and the mixture was emulsified and dispersed using a homogenizer. Subsequently, 4.8 parts by mass of diethylenetriamine (3 active hydrogen groups) and 13.0 parts by mass of 3-mercaptopropyltrimethoxysilane (manufactured by Shin-Etsu Silicone Co., Ltd., product name: KBM-803) are diluted with 100 parts by weight of water. The resulting aqueous solution was added to carry out a chain extension reaction for 1 hour. The solvent was removed under reduced pressure at 50 ° C. to obtain a polyurethane water dispersion G having a nonvolatile content of about 30%.
(Synthesis Example 8)
PCDL T-4671 (manufactured by Asahi Kasei Chemicals Corporation, polycarbonate polyol containing 1,4-butanediol and 1,6-hexanediol as constituents) in a four-necked flask equipped with a stirrer, reflux condenser, thermometer and nitrogen blowing tube Average hydroxyl value 110 mg KOH / g, active hydrogen group number 2) 161.7 parts by mass, trimethylolpropane (active hydrogen group number 3) 9.5 parts by mass, dimethylolpropionic acid (active hydrogen group number 2) 16.3 parts by mass, 112.5 parts by mass of isophorone diisocyanate and 200 parts by mass of methyl ethyl ketone were added and reacted at 75 ° C. for 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 3.2% based on the nonvolatile content. The solution was cooled to 45 ° C., 12.3 parts by mass of triethylamine was added to neutralize, 900 parts by mass of water was gradually added, and the mixture was emulsified and dispersed using a homogenizer. Subsequently, 13.7 parts by mass of 4,4′-diamino-diphenylmethane (number of active hydrogen groups 2) and N-2- (aminoethyl) -3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Silicone Co., Ltd., product name: (KBM-603) An aqueous solution obtained by diluting 7.40 parts by mass with 100 parts by weight of water was added, and chain extension reaction was performed for 1 hour. The solvent was removed under reduced pressure at 50 ° C. to obtain a polyurethane water dispersion H having a nonvolatile content of about 30%.
(Synthesis Example 9)
ETERNACOLL UM-90 (1/3) (manufactured by Ube Industries, Ltd., 1,6-hexanediol and 1,4-cyclohexanedimethanol was added to a four-necked flask equipped with a stirrer, reflux condenser, thermometer and nitrogen blowing tube. Polycarbonate polyol as constituent components, average hydroxyl value 125 mgKOH / g, number of active hydrogen groups 2) 141.9 parts by mass, trimethylolpropane (number of active hydrogen groups 3) 9.5 parts by mass, dimethylolpropionic acid (number of active hydrogen groups 2) 16.3 parts by mass, 132.3 parts by mass of dicyclohexylmethane diisocyanate, and 200 parts by mass of methyl ethyl ketone were added and reacted at 75 ° C. for 4 hours, and methyl ethyl ketone of a urethane prepolymer having a free isocyanate group content of 3.3% based on the nonvolatile content. A solution was obtained. The solution was cooled to 45 ° C., 12.3 parts by mass of triethylamine was added to neutralize, 900 parts by mass of water was gradually added, and the mixture was emulsified and dispersed using a homogenizer. Subsequently, 4.2 parts by mass of ethylenediamine (number of active hydrogen groups 2) and N-2- (aminoethyl) -3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Silicone Co., Ltd., product name: KBM-603) 7.4 An aqueous solution obtained by diluting a part by mass with 100 parts by weight of water was added to carry out a chain extension reaction for 1 hour. The solvent was removed under reduced pressure at 50 ° C. to obtain a polyurethane water dispersion I having a nonvolatile content of about 30%.
(Synthesis Example 10)
Kuraray polyol C-1065N (manufactured by Kuraray Co., Ltd., 1,9-nonanediol and 2-methyl-1,8-octanediol) was added to a four-necked flask equipped with a stirrer, reflux condenser, thermometer and nitrogen blowing tube. Polycarbonate polyol, average hydroxyl value 110 mgKOH / g, active hydrogen group number 2) 145.2 parts by mass, trimethylolpropane (active hydrogen group number 3) 9.5 parts by mass, dimethylolpropionic acid (active hydrogen group number 2) 16. 3 parts by mass, 129.0 parts by mass of dicyclohexylmethane diisocyanate and 200 parts by mass of methyl ethyl ketone were added and reacted at 75 ° C. for 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 3.3% based on the nonvolatile content. Obtained. The solution was cooled to 45 ° C., 12.3 parts by mass of triethylamine was added to neutralize, 900 parts by mass of water was gradually added, and the mixture was emulsified and dispersed using a homogenizer. Subsequently, 4.2 parts by mass of ethylenediamine (number of active hydrogen groups 2) and N-2- (aminoethyl) -3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Silicone Co., Ltd., product name: KBM-603) 7.4 An amine aqueous solution diluted with 100 parts by weight of water was added to carry out a chain extension reaction for 1 hour. The solvent was removed under reduced pressure at 50 ° C. to obtain a polyurethane water dispersion J having a nonvolatile content of about 30%.
(Synthesis Example 11)
Kuraray polyol C-1065N (manufactured by Kuraray Co., Ltd., 1,9-nonanediol and 2-methyl-1,8-octanediol) was added to a four-necked flask equipped with a stirrer, reflux condenser, thermometer and nitrogen blowing tube. Polycarbonate polyol, average hydroxyl value 110 mgKOH / g, active hydrogen group number 2) 145.2 parts by mass, trimethylolpropane (active hydrogen group number 3) 9.5 parts by mass, dimethylolpropionic acid (active hydrogen group number 2) 16. 3 parts by mass, 129.0 parts by mass of dicyclohexylmethane diisocyanate and 200 parts by mass of methyl ethyl ketone were added and reacted at 75 ° C. for 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 3.3% based on the nonvolatile content. Obtained. The solution was cooled to 45 ° C., 12.3 parts by mass of triethylamine was added to neutralize, 900 parts by mass of water was gradually added, and the mixture was emulsified and dispersed using a homogenizer. Subsequently, 9.5 parts by mass of diethylenetriamine (number of active hydrogen groups 3) and 15.0 parts by mass of 3-isocyanatopropyltriethoxysilane (manufactured by Shin-Etsu Silicone Co., Ltd., product name: KBE-9007) are diluted with 100 parts by weight of water. The resulting aqueous solution was added to carry out a chain extension reaction for 1 hour. The solvent was removed under reduced pressure at 50 ° C. to obtain a polyurethane water dispersion K having a nonvolatile content of about 30%.
(Synthesis Example 12)
To a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen blowing tube, Kuraray polyol P-1020 (manufactured by Kuraray Co., Ltd., polyester polyol composed of 3-methyl-1,5-pentanediol and terephthalic acid, Average hydroxyl value 110 mgKOH / g, number of active hydrogen groups 2) 147.0 parts by weight, trimethylolpropane (number of active hydrogen groups 3) 9.5 parts by weight, N-methyldiethanolamine (number of active hydrogen groups 2) 14.5 parts by weight, dicyclohexyl 129.0 parts by weight of methane diisocyanate and 200 parts by weight of methyl ethyl ketone were added and reacted at 75 ° C. for 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 3.2% based on the nonvolatile content. Next, this solution was cooled to 45 ° C., quaternized by adding 15.3 parts by weight of dimethyl sulfuric acid, and then emulsified and dispersed using a homogenizer while gradually adding 900 parts by weight of water, and N-2- (Aminoethyl) -3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Silicone Co., Ltd., product name: KBM-603) was added with an aqueous solution obtained by diluting 7.4 parts by mass with 100 parts by weight of water, and chain extension reaction was performed for 1 hour. . The solvent was removed under reduced pressure at 50 ° C. to obtain a polyurethane water dispersion L having a nonvolatile content of about 30%.
(Synthesis Example 13)
In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen blowing tube, PCDL T-4671 (manufactured by Asahi Kasei Chemicals Corporation, 1,4-butanediol and 1,6-hexanediol as constituent components) Polycarbonate polyol, average hydroxyl value 110 mgKOH / g, active hydrogen group number 2) 147.0 parts by weight, trimethylolpropane (active hydrogen group number 3) 9.5 parts by weight, N-methyldiethanolamine (active hydrogen group number 2) 14.5 parts by weight Part, dicyclohexylmethane diisocyanate 129.0 parts by weight, and methyl ethyl ketone 200 parts by weight were reacted at 75 ° C. for 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 3.2% based on the nonvolatile content. It was. Next, the solution was cooled to 45 ° C., quaternized by adding 15.3 parts by weight of dimethyl sulfate, and then emulsified and dispersed using a homogenizer while gradually adding 900 parts by weight of water, and ethylenediamine (active hydrogen Radical number 2) 4.2 parts by mass and N-2- (aminoethyl) -3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Silicone Co., Ltd., product name: KBM-603) 7.4 parts by mass of water 100 parts by weight A chain extension reaction was performed for 1 hour by adding an aqueous solution diluted with 1. The solvent was removed under reduced pressure at 50 ° C. to obtain a polyurethane water dispersion M having a nonvolatile content of about 30%.
(Synthesis Example 14)
PolyTHF1000 (manufactured by BASF, polytetramethylene ether glycol, average hydroxyl value 110 mg KOH / g, number of active hydrogen groups 2) 181.7 parts by mass in a four-necked flask equipped with a stirrer, reflux condenser, thermometer and nitrogen blowing tube, Add 9.5 parts by mass of trimethylolpropane (number of active hydrogen groups 3), 16.3 parts by mass of dimethylolpropionic acid (number of active hydrogen groups 2), 92.5 parts by mass of hexamethylene diisocyanate, 200 parts by mass of methyl ethyl ketone at 75 ° C. The reaction was performed for 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 3.8% based on the nonvolatile content. The solution was cooled to 45 ° C., neutralized by adding 12.3 parts by weight of triethylamine, and then 900 parts by weight of water was gradually added and emulsified and dispersed using a homogenizer. Subsequently, a chain extension reaction was performed with water (2 active hydrogen groups) for 1 hour. The solvent was removed under reduced pressure at 50 ° C. to obtain a polyurethane water dispersion N having a nonvolatile content of about 30%.
(Synthesis Example 15)
Kuraray polyol P-1010 (trade name, manufactured by Kuraray Co., Ltd., polyester polyol consisting of 3-methyl-1,5-pentanediol and adipic acid) was added to a four-necked flask equipped with a stirrer, reflux condenser, thermometer and nitrogen blowing tube. Average hydroxyl value 110 mg KOH / g, active hydrogen group number 2) 181.7 parts by mass, trimethylolpropane (active hydrogen group number 3) 9.5 parts by mass, dimethylolpropionic acid (active hydrogen group number 2) 16.3 parts by mass, 92.5 parts by mass of hexamethylene diisocyanate and 200 parts by mass of methyl ethyl ketone were added and reacted at 75 ° C. for 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 3.8% based on the nonvolatile content. The solution was cooled to 45 ° C., neutralized by adding 12.3 parts by weight of triethylamine, and then 900 parts by weight of water was gradually added and emulsified and dispersed using a homogenizer. Subsequently, an aqueous amine solution in which 7.8 parts by mass of diethylenetriamine (number of active hydrogen groups 3) was diluted with 100 parts by weight of water was added, and a chain extension reaction was performed for 1 hour. The solvent was removed under reduced pressure at 50 ° C. to obtain a polyurethane water dispersion O having a nonvolatile content of about 30%.
(Synthesis Example 16)
Kuraray polyol P-1010 (trade name, manufactured by Kuraray Co., Ltd., polyester polyol consisting of 3-methyl-1,5-pentanediol and adipic acid) was added to a four-necked flask equipped with a stirrer, reflux condenser, thermometer and nitrogen blowing tube. Average hydroxyl value 110 mg KOH / g, active hydrogen group number 2) 212.9 parts by mass, trimethylolpropane (active hydrogen group number 3) 0.3 part by mass, dimethylolpropionic acid (active hydrogen group number 2) 16.3 parts by mass, 70.5 parts by mass of hexamethylene diisocyanate and 200 parts by mass of methyl ethyl ketone were added and reacted at 75 ° C. for 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 2.2% based on the nonvolatile content. The solution was cooled to 45 ° C., neutralized by adding 12.3 parts by weight of triethylamine, and then 900 parts by weight of water was gradually added and emulsified and dispersed using a homogenizer. A chain extension reaction was carried out with water (2 active hydrogen groups) for 1 hour. The solvent was removed under reduced pressure at 50 ° C. to obtain a polyurethane water dispersion P having a nonvolatile content of about 30%.
[Evaluation of polyurethane water dispersion]
The following methods were used for each measurement regarding the obtained polyurethane water dispersion. The results are shown in Table 1.
(Nonvolatile content of polyurethane water dispersion)
It measured according to JIS K 6828.
(Acid value of polyurethane resin, urethane bond amount, urea bond amount)
It calculated from the charged amount at the time of the synthesis | combination of a urethane resin, and the free isocyanate group content with respect to the non volatile matter after reaction.

[Production of electrodes]
[Preparation of negative electrode]
(Negative electrode 1)
100 g of natural graphite as a negative electrode active material, 0.5 g of carbon black as a conductive agent (Supercal-P, manufactured by Timcal) and carboxymethyl cellulose (CMC) as a thickener (Daiichi Kogyo Seiyaku, product name: Cellogen WS-C) 100 g of a 2 wt% aqueous solution and 6.7 g of a 30 wt% solution of polyurethane water dispersion A as a binder were mixed with a planetary mixer to prepare a negative electrode slurry so that the solid content was 50%. This negative electrode slurry was coated on an electrolytic copper foil having a thickness of 10 μm with a coating machine, dried at 120 ° C., and then subjected to a roll press treatment, to obtain a negative electrode 1 having a negative electrode active material of 7 mg / cm ² .
(Negative electrodes 2-11, negative electrodes 14-17)
The polyurethane water dispersion A was prepared in the same manner as the negative electrode 1 except that the polyurethane water dispersion A described in Table 2 was changed to SBR.
(Negative electrodes 12-13)
100 g of natural graphite as a negative electrode active material, 0.5 g of carbon black as a conductive agent (Super-P, manufactured by Timcal) and hydroxyethyl cellulose (HEC) as a thickener (Daicel Chemical, product name: HEC Daicel SP900) 1 wt% aqueous solution 100 g and 6.7 g of a 30% by weight polyurethane water dispersion listed in Table 2 as a binder were mixed with a planetary mixer to prepare a negative electrode slurry so that the solid content was 50%. This negative electrode slurry was coated on an electrolytic copper foil having a thickness of 10 μm with a coating machine, dried at 120 ° C., and then subjected to a roll press treatment, to obtain a negative electrode having a negative electrode active material of 7 mg / cm ² .
(Negative electrode 18)
As a negative electrode active material, SiO (average particle size 4.5 μm, specific surface area 5.5 m ² / g) 100 g, as a conductive agent 5 g of carbon black (manufactured by Timcal, Super-P) and as a thickener carboxymethyl cellulose (CMC) (Daiichi Kogyo Seiyaku Co., Ltd., product name: Serogen WS-C) 2% by weight aqueous solution 100g, 30% by weight polyurethane aqueous dispersion A solution 6.7g as a binder was mixed with a planetary mixer to a solid content of 50%. A negative electrode slurry was prepared so as to be. The negative electrode slurry perform a coating on an electrolytic copper foil having a thickness of 10μm with a coater, dried at 120 ° C., followed by conducting roll press treatment, to obtain a negative electrode of the negative electrode active material 2.5mg / c m ^2.
(Negative electrode 19)
It was prepared in the same manner as the negative electrode 18 except that the polyurethane water dispersion A was changed to SBR.
(Negative electrode 20)
As a negative electrode active material, Li ₄ Ti ₅ O ₁₂ 100 g, as a conductive agent 5 g of carbon black (manufactured by Timcal, Super-P) and as a thickener carboxymethylcellulose (CMC) (Daiichi Kogyo Seiyaku, product name: Serogen WS— C) 100 g of a 2 wt% aqueous solution and 6.7 g of a 30 wt% solution of polyurethane water dispersion E as a binder were mixed with a planetary mixer to prepare a negative electrode slurry so as to have a solid content of 50%. This negative electrode slurry was coated on an electrolytic copper foil having a thickness of 10 μm with a coating machine, dried at 120 ° C., and then subjected to a roll press treatment to obtain a negative electrode having a negative electrode active material of 9.7 mg / cm ² .
(Negative electrode 21)
It was prepared in the same manner as the negative electrode 20 except that the polyurethane water dispersion A was changed to SBR.
[Preparation of positive electrode]
(Positive electrode 1)
LiNi _1/3 Co _1/3 Mn _1/3 O ₂ 100 g as a positive electrode active material, 7.8 g of carbon black (Super-P, manufactured by Timcal) as a conductive agent, 6 g of polyvinylidene fluoride as a binder, dispersion As a medium, 61.3 g of N-methyl-2-pyrrolidone was mixed with a planetary mixer to prepare a positive electrode slurry so as to have a solid content of 65%. This positive electrode slurry was coated on an aluminum foil having a thickness of 20 μm with a coating machine, dried at 130 ° C., and then subjected to a roll press treatment to obtain a positive electrode having a positive electrode active material of 13.8 mg / cm ² .
(Positive electrode 2-3)
LiNi _1/3 Co _1/3 Mn _1/3 O ₂ 100 g as a positive electrode active material, 7.8 g of carbon black (manufactured by Timcal, Super-P) as a conductive agent, carboxymethyl cellulose (Daiichi Kogyo) as a thickener 100 g of 2 wt% aqueous solution manufactured by Pharmaceutical, product name: Serogen WS-C) and 6.7 g of a 30 wt% solution of polyurethane water dispersion listed in Table 2 as a binder were mixed with a planetary mixer to obtain a solid content of 50%. A positive electrode slurry was prepared as described above. This positive electrode slurry was coated on an aluminum foil having a thickness of 20 μm with a coating machine, dried at 130 ° C., and then subjected to a roll press treatment to obtain a positive electrode having a positive electrode active material of 13.8 mg / cm ² .
(Positive electrode 4)
100 g of LiMn ₂ O _{4 as} a positive electrode active material, ₅ g of carbon black (manufactured by Timcal, Super-P) as a conductive agent, 6 g of polyvinylidene fluoride as a binder, and 59.8 g of N-methyl-2-pyrrolidone as a dispersion medium Were mixed with a planetary mixer to prepare a positive electrode slurry to a solid content of 65%. This positive electrode slurry was coated on an aluminum foil having a thickness of 20 μm with a coating machine, dried at 130 ° C., and then subjected to a roll press treatment to obtain a positive electrode having a positive electrode active material of 22 mg / cm ² .
(Positive electrode 5)
LiMn ₂ O ₄ 100 g as a positive electrode active material, carbon black (manufactured by Timcal, Super-P) as a conductive agent, 5 g, carboxymethyl cellulose (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name: Serogen WS-C) as a thickener A positive electrode slurry was prepared so as to have a solid content of 50% by mixing 100 g of a 100% aqueous solution and 6.7 g of a 30 wt% solution of polyurethane aqueous dispersion J as a binder. This positive electrode slurry was coated on an aluminum foil having a thickness of 20 μm with a coating machine, dried at 130 ° C., and then subjected to a roll press treatment to obtain a positive electrode having a positive electrode active material of 22 mg / cm ² .
(Positive electrode 6)
100 g LiFePO _{4 as a} positive electrode active material, ₅ g carbon black (manufactured by Timcal, Super-P) as a conductive agent, 6 g polyvinylidene fluoride as a binder, and 135.7 g N-methyl-2-pyrrolidone as a dispersion medium A positive electrode slurry was prepared so as to have a solid content of 45% by mixing with a mold mixer. This positive electrode slurry was coated on an aluminum foil having a thickness of 20 μm with a coating machine, dried at 130 ° C., and then subjected to a roll press treatment to obtain a positive electrode having a positive electrode active material of 14.5 mg / cm ² .
(Positive electrode 7)
LiFePO ₄ 100 g as a positive electrode active material, carbon black (manufactured by Timcal, Super-P) as a conductive agent, 5 g, carboxymethyl cellulose (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name: Cellogen WS-C) as a 2 wt% aqueous solution 100 g and 6.7 g of a 30 wt% solution of polyurethane water dispersion C as a binder were mixed with a planetary mixer to prepare a positive electrode slurry so as to have a solid content of 50%. This positive electrode slurry was coated on an aluminum foil having a thickness of 20 μm with a coating machine, dried at 130 ° C., and then subjected to a roll press treatment to obtain a positive electrode having a positive electrode active material of 14.5 mg / cm ² .

[Electrode evaluation]
The obtained electrode was evaluated for the following items. The evaluation results are shown in Table 3 below.
(Evaluation of binding properties)
After the coated surface of the electrode obtained above was bent 180 degrees outward and returned, the extent of falling off of the active material on the coated surface (the ratio of the area of the dropped portion to the whole) was visually judged.
Evaluation criteria:
5 points: 0% dropout 4 points: 25% dropout 3 points: 50% dropout 2 points: 75% dropout 1 point: 100% dropout (electrolytic solution resistance evaluation)
The electrode obtained above was EC (ethylene carbonate) / PC (propylene carbonate) / DMC (dimethyl carbonate) / EMC (ethyl methyl carbonate) / DEC (diethyl carbonate) = 1/1/1/1/1 (vol). The appearance of the coating film after being immersed in the mixed solvent at 60 ° C. for 7 days was visually judged.
Evaluation criteria ○: No change in the coating film △: Several points of swelling occur in the coating film ×: The coating film peels off.

[Production of lithium secondary battery]
The positive electrode and negative electrode obtained above are combined as shown in Table 4 below, and a polyolefin (PE / PP) separator is sandwiched between the electrodes as a separator, and a positive electrode terminal and a negative electrode terminal are ultrasonically welded to each positive and negative electrode. did. This laminate was put in an aluminum laminate packaging material, and heat sealed, leaving an opening for injection. The positive electrode area of 18cm ^2, to prepare a liquid injection before batteries with anode area 19.8cm ^2. Next, an electrolytic solution in which LiPF ₆ (1.0 mol / L) was dissolved in a solvent in which ethylene carbonate and diethyl carbonate (30/70 vol ratio) were mixed was poured, the opening was heat sealed, and an evaluation battery was prepared. Obtained.

[Evaluation of battery performance]
About the produced lithium secondary battery, the performance test in 20 degreeC was done. The test method is as follows. The test results are shown in Table 5.
(Cell impedance)
For the cell impedance, an impedance analyzer (manufactured by ZAHNER) was used to measure the resistance value at a frequency of 1 kHz.
(Charge / discharge cycle characteristics)
The charge / discharge cycle characteristics were measured under the following conditions.
When LiNi _1/3 Co _1/3 Mn _1/3 O ₂ or LiMn ₂ O ₄ is used as the positive electrode active material and natural graphite is used as the negative electrode active material, CC (constant current) up to 4.2 V at a current density equivalent to 1C. ) Charging, followed by switching to CV (constant voltage) charging at 4.2V, charging for 1.5 hours, and then performing a CC discharge to 2.7V at a current density equivalent to 1C for 300 cycles at 20 ° C. The 1C discharge capacity ratio after 300 cycles to the initial 1C discharge capacity at this time was defined as the 1C charge / discharge cycle retention rate.
When LiFePO ₄ is used as the positive electrode active material and natural graphite is used as the negative electrode active material, CC (constant current) charging is performed up to 4.0 V at a current density equivalent to 1 C, followed by CV (constant voltage) charging at 4.0 V. After charging for 1.5 hours, a cycle of CC discharge to 2.0 V at a current density equivalent to 1 C is performed 300 cycles at 20 ° C., and the 1 C discharge capacity ratio after 300 cycles to the initial 1 C discharge capacity at this time is 1 C The charge / discharge cycle retention rate was used.
When LiNi _1/3 Co _1/3 Mn _1/3 O ₂ is used as the positive electrode active material and Li ₄ Ti ₅ O ₁₂ is used as the negative electrode active material, CC (constant current) up to 2.9 V at a current density equivalent to 1C. Charge, then switch to CV (constant voltage) charge at 2.9V, charge for 1.5 hours, and then perform a cycle of CC discharge to 1.0V at a current density equivalent to 1C, 300 cycles at 20 ° C The 1C discharge capacity ratio after 300 cycles with respect to the initial 1C discharge capacity was defined as the 1C charge / discharge cycle retention rate.
When LiNi _1/3 Co _1/3 Mn _1/3 O ₂ is used as the positive electrode active material and SiO is used as the negative electrode active material, CC (constant current) charging is performed up to 4.2 V at a current density equivalent to 1 C, and then After switching to CV (constant voltage) charging at 4.2V and charging for 1.5 hours, 50 cycles of CC discharge to 2.7V at a current density equivalent to 1C were performed at 20 ° C, and the initial 1C discharge at this time The 1C discharge capacity ratio after 50 cycles with respect to the capacity was defined as the 1C charge / discharge cycle retention rate.

From Table 5, the case where the polyurethane water dispersion of the present invention is used is superior to the case where the conventionally used styrene butadiene rubber or polyvinylidene fluoride is used. It can be seen that the capacity retention after the characteristics is kept high.

The binder of this invention can be utilized as a binder of the electrode for lithium secondary batteries, and the electrode manufactured from it is used for manufacture of various lithium secondary batteries. The obtained lithium secondary battery is a medium- or large-sized lithium battery mounted on various portable devices such as mobile phones, notebook computers, personal digital assistants (PDAs), video cameras, and digital cameras, as well as electric bicycles and electric vehicles. Can be used for secondary batteries.

Claims (4)

(Component A) polyisocyanate, (Component B) a compound having two or more active hydrogen groups, (Component C) a compound having one or more active hydrogen groups and a hydrophilic group, and (Component D) a chain extender, A binder for an electrode of a lithium secondary battery comprising an aqueous polyurethane dispersion comprising: a binder for an electrode of a lithium secondary battery, wherein the (D component) contains an alkoxysilane derivative .   The binder for an electrode of a lithium secondary battery according to claim 1, wherein the (component B) contains a carbonate polyol, a polyester polyol having an aromatic ring, and / or a polyether polyol having an aromatic ring. . The binder for an electrode of a lithium secondary battery according to any one of claims 1 to 2, wherein the (component A) contains an alicyclic and / or aromatic isocyanate. The lithium secondary battery using the electrode using the binder for electrodes of the lithium secondary battery described in any one of Claims 1 thru | or 3.