JP6068973B2 - Electrode binder composition - Google Patents

Description

  The present invention relates to an electrode binder composition, an electrode slurry using the binder composition, an electrode using the same, a secondary battery, and an electric double layer capacitor.

In recent years, in electronic devices, secondary batteries such as lithium ion secondary batteries, nickel hydride secondary batteries, nickel cadmium secondary batteries and capacitors such as electric double layer capacitors that can be repeatedly used by charging have been used. .
These secondary batteries and capacitors are generally composed of an electrolytic solution containing an electrode, a separator, and an electrolyte. The electrode is made by coating and drying an electrode slurry, in which an electrode active material is dispersed in a solvent in which a resin binder (binder) is dissolved or swollen, on a metal plate for an electrode current collector to form a current collector. It is manufactured by.

  Conventionally, polyvinylidene fluoride (hereinafter referred to as PVDF) has been industrially used as a resin binder for lithium ion secondary battery electrodes, but it has low surface energy and adhesion to current collector metal plates and active materials. There was a problem of insufficient.

  Therefore, SBR and an acrylic copolymer binder have been proposed instead of PVDF. Since these binders exist as gel-like particles of several hundreds of nanometers by emulsion polymerization, there is an advantage that the adhesion area to the active material is increased and the adhesion between the electrode and the active material can be improved.

  In emulsion polymerization, the emulsion stability decreases during the polymerization, and coarse aggregates may be generated during the polymerization process. This may be exposed on the electrode surface and adversely affect the current collector smoothness after binder coating.

  Therefore, Patent Document 1 reports a binder composition for an electrode in which the concentration of coarse particles and / or aggregates having a sphere volume equivalent diameter of 3 μm or more is 2000 ppm or less by filtration. However, this method may cause clogging during filtration, which may make filtration work difficult.

  Patent Document 2 discloses a binder composition comprising a polymer having a gel content of 50% or more and a cellulose compound, and Patent Document 3 includes a gel content obtained by emulsion polymerization using sodium alkyldiphenyl ether disulfonate as an emulsifier. A binder composition comprising at least% polymer and an ethylene-vinyl alcohol copolymer has been proposed. However, in any of these methods, the binder medium is a liquid organic material having a boiling point of 80 ° C. or higher at 760 mmHg. As a result, although the smoothness of the current collector can be obtained, the drying process becomes complicated because an organic solvent having a high boiling point is used, and further, if the solvent vapor generated during drying is released to the atmosphere as it is, there is an environmental problem. Therefore, there is a problem that a recovery facility is required.

JP 2011-76917 A JP-A-10-270046 JP 2001-283855 A

The present invention provides a binder composition for an electrode excellent in storage stability of slurry, defoaming property at the time of slurry preparation, and smoothness of a coating film, and an electrode slurry using the same in view of the above problems and actual conditions. For the purpose. Furthermore, it aims at providing the secondary battery and electric double layer capacitor which were manufactured using this electrode slurry, and were excellent in the discharge rate characteristic and cycle characteristic which were manufactured using this battery. .

（２）（ｂ）（メタ）アクリロイル基を有するスルホン酸誘導体が、（メタ）アクリロイルオキシポリオキシプロピレンスルホン酸ナトリウムであり、（ｃ）エチレン性不飽和カルボン酸が、メタクリル酸である、（１）に記載の電極用バインダー組成物。
（３）（ａ１）化１で表わされる構造単位が、アクリル酸２−エチルヘキシル、およびメタクリル酸メチルである、（１）または（２）に記載の電極用バインダー組成物。

（４）（ａ）エチレン性不飽和カルボン酸エステルが、（ａ１）７７〜９２質量部、（ａ２）３〜８質量部、（ａ３）１〜５質量部である、（１）〜（３）の何れか一つに記載の電極用バインダー組成物。
（５）（ｃ）エチレン性不飽和カルボン酸が、（ａ）エチレン性不飽和カルボン酸エステル、（ｂ）（メタ）アクリロイル基を有するスルホン酸誘導体、および（ｃ）エチレン性不飽和カルボン酸の総和１００質量部中、０．１〜１質量部である、（１）〜（４）の何れか一つに記載の電極用バインダー組成物。
（６）（１）〜（５）のいずれか一つに記載の電極用バインダー組成物に、正極活物質、導電助剤を含有してなる電極用スラリー。
（７）（１）〜（５）のいずれか一つに記載の電極用バインダー組成物に、負極活物質、導電助剤を含有してなる電極用スラリー。
（８）正極活物質が、ＬｉＦｅＰＯ_４、ＬｉＭｎＰＯ_４、ＬｉＭｎ_ＸＦｅ_{（１−Ｘ）}ＰＯ_４（但し、０＜Ｘ＜１）、ＬｉＣｏＰＯ_４又はＬｉ_３Ｖ_２（ＰＯ_４）_３、ＬｉＮｉＰＯ_４からなる群から選択される少なくとも１種のリチウム含有リン酸塩である、（６）に記載の電極用スラリー。
（９）正極活物質が、ＬｉＣｏＯ_２、ＬｉＭｎ_２Ｏ_４、ＬｉＮｉＯ_２、Ｌｉ(Ｍｎ_ＸＮｉ_ＹＣｏ_Ｚ)Ｏ_２又はＬｉ(Ａｌ_ＸＮｉ_ＹＣｏ_Ｚ)Ｏ_２からなる群から選択される少なくとも１種類のリチウム塩である、（６）に記載の電極用スラリー。但し、Ｌｉ(Ｍｎ_ＸＮｉ_ＹＣｏ_Ｚ)Ｏ_２中又はＬｉ(Ａｌ_ＸＮｉ_ＹＣｏ_Ｚ)Ｏ_２中のＸ、Ｙ及びＺは、Ｘ＋Ｙ＋Ｚ＝１と
いう関係を満たしかつ０＜Ｘ＜１、０＜Ｙ＜１、０＜Ｚ＜１という関係を満たす。
（１０）負極活物質が、炭素質材料である、（７）に記載の電極用スラリー。
（１１）負極活物質がＬｉ_４Ｔｉ_５Ｏ_１２、金属スズを内包したスズ酸化物または金属シリコンを内包したシリコン酸化物からなる群から選択される少なくとも１種類である（７）に記載の電極用スラリー。
（１２）導電助剤が、（i）繊維状炭素、（ii）カーボンブラック、（iii）繊維状炭素とカーボンブラックが相互に連結した炭素複合体から選択される少なくとも１種である、（６）〜（１１）のいずれか一つに記載の電極用スラリー。
（１３）（i）繊維状炭素が、平均繊維径が５〜５０ｎｍであり、かつ比表面積が５０〜４００ｍ^２／ｇである、（１２）に記載の電極用スラリー。
（１４）（ii）カーボンブラックが、平均粒径１０〜１００ｎｍの一次粒子が鎖状に結合してなるアセチレンブラックである、（１２）又は（１３）に記載の電極用スラリー。
（１５）（６）〜（１４）のいずれか一つに記載の電極用スラリーを用いて製造される電極。
（１６）（１５）に記載の電極を用いて製造される二次電池。
（１７）（１５）に記載の電極を用いて製造される電気二重層キャパシタ。 That is, this invention which solves the said subject is comprised from the following.
(1) (a) an ethylenically unsaturated carboxylic acid ester, (b) (meth) and a sulfonic acid derivative having an acryloyl group, co obtained by copolymerizing a (c) an ethylenically unsaturated carboxylic acid weight A binder composition for an electrode in which a coalescence is dispersed in water , comprising: (a) an ethylenically unsaturated carboxylic acid ester, (b) a sulfonic acid derivative having a (meth) acryloyl group, and (c) an ethylenically unsaturated carboxylic acid In 100 parts by mass of the total acid, (b) the sulfonic acid derivative having a (meth) acryloyl group is 1 to 8 parts by mass, (c) the ethylenically unsaturated carboxylic acid is 0.1 to 2 parts by mass, (A) The binder composition for electrodes whose ethylenically unsaturated carboxylic acid ester consists of the following (a1)-(a3).
(A1) In the structural unit represented by Chemical Formula 1, a monomer in which R ₂ is an alkyl group having 1 to 20 carbon atoms.
(A2) In the structural unit represented by Chemical Formula 2, a monomer in which R ₃ is a methylene chain having 1 to 7 carbon atoms.
(A3) selected from allyl methacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, tetramethylene glycol dimethacrylate, and 1,3-butylene glycol dimethacrylate,
One or more polyfunctional monomers.

(2) (b) (meth) sulfonic acid derivative having an acryloyl group, a (meth) acryloyloxy polyoxypropylene sodium sulfonate, is (c) an ethylenically unsaturated carboxylic acid, methacrylic acid, (1 The binder composition for electrodes as described in ) .
(3) The binder composition for an electrode according to (1) or ( 2) , wherein the structural unit represented by (a1) Chemical formula 1 is 2-ethylhexyl acrylate and methyl methacrylate.

(4) (a) Ethylenically unsaturated carboxylic acid ester is (a1) 77-92 parts by mass, (a2) 3-8 parts by mass, (a3) 1-5 parts by mass, (1)-( 3 The binder composition for electrodes as described in any one of these.
(5) (c) the ethylenically unsaturated carboxylic acid is (a) an ethylenically unsaturated carboxylic acid ester, (b) a sulfonic acid derivative having a (meth) acryloyl group, and (c) an ethylenically unsaturated carboxylic acid The binder composition for electrodes according to any one of (1) to ( 4) , which is 0.1 to 1 part by mass in a total of 100 parts by mass.
(6) A slurry for an electrode comprising a positive electrode active material and a conductive additive in the electrode binder composition according to any one of (1) to ( 5) .
(7) A slurry for an electrode comprising the binder composition for an electrode according to any one of (1) to ( 5) , a negative electrode active material and a conductive additive.
(8) The positive electrode active material is LiFePO ₄ , LiMnPO ₄ , LiMn _X Fe _(1-X) PO ₄ (where 0 <X <1), LiCoPO _4, or Li ₃ V ₂ (PO ₄ ) ₃ , LiNiPO ₄ The electrode slurry according to ( 6) , which is at least one lithium-containing phosphate selected from the group consisting of:
(9) at least a positive electrode active material _is selected from _{LiCoO 2, LiMn 2 O 4,} LiNiO 2, Li (Mn X Ni Y Co Z) O 2 or _{Li (Al X Ni Y Co Z} ) group consisting of _{O 2} The slurry for an electrode according to ( 6) , which is one type of lithium salt. _{However, Li (Mn X Ni Y Co} Z) O 2 in or _{Li (Al X Ni Y Co Z} ) O 2 in the X, Y and Z, X + Y + Z = 1 and satisfies the relationship of 0 <X <1, 0 The relationship of <Y <1, 0 <Z <1 is satisfied.
(10) The electrode slurry according to ( 7) , wherein the negative electrode active material is a carbonaceous material.
(11) The electrode according to the negative electrode active material is Li 4 _Ti 5 _{O 12,} it is at least one selected from the group consisting of silicon oxide containing therein the tin oxide or metal silicon encapsulating the metallic tin (7) Slurry.
(12) conductive additive is at least one selected from (i) fibrous carbon, (ii) carbon black, (iii) a carbon composite fibrous carbon and carbon black are interconnected, (6 ] The slurry for electrodes as described in any one of-( 11) .
(13) The slurry for electrodes according to ( 12) , wherein (i) fibrous carbon has an average fiber diameter of 5 to 50 nm and a specific surface area of 50 to 400 m ² / g.
(14) The slurry for electrodes according to ( 12) or ( 13) , wherein the carbon black is acetylene black formed by binding primary particles having an average particle diameter of 10 to 100 nm in a chain form.
(15) An electrode manufactured using the electrode slurry according to any one of ( 6) to ( 14) .
(16) A secondary battery manufactured using the electrode according to ( 15) .
(17) An electric double layer capacitor produced using the electrode according to ( 15) .

  In the present invention, a specific ethylenically unsaturated carboxylic acid ester, a sulfonic acid derivative having a (meth) acryloyl group, and an ethylenically unsaturated carboxylic acid are copolymerized to store the slurry of the electrode binder composition. It was found that the stability and the defoaming property during slurry preparation were remarkably improved. Moreover, the improvement of defoaming property reduces defects on the surface of the coating film due to air bubbles and improves smoothness. Therefore, an electrode slurry is prepared using the electrode binder composition of the present invention, and a secondary battery and an electric double layer capacitor prepared by using the electrode slurry have electrical characteristics such as discharge rate characteristics and cycle characteristics. Excellent.

<Binder composition>
The electrode binder composition of the present invention (hereinafter sometimes simply referred to as “binder composition”) includes (a) an ethylenically unsaturated carboxylic acid ester, and (b) a sulfonic acid derivative having a (meth) acryloyl group. (C) an ethylenically unsaturated carboxylic acid is copolymerized, and (a) the ethylenically unsaturated carboxylic acid ester is composed of the following (a1) to (a3).
(A1) In the structural unit represented by Chemical Formula 1, a monomer in which R ₂ is an alkyl group having 1 to 20 carbon atoms.
(A2) In the structural unit represented by Chemical Formula 2, a monomer in which R ₃ is a methylene chain having 1 to 7 carbon atoms.
(A3) A polyfunctional monomer containing at least one ethylenically unsaturated group selected from a (meth) acryloyl group and a (meth) allyl group in the molecule.

As the ethylenically unsaturated carboxylic acid ester represented by (a1), the alkyl group has 1 to 20 carbon atoms, and preferably 1 to 10 carbon atoms. The alkyl group can be either a straight chain or branched chain, but is preferably a branched chain.
Specific examples of (a1) include, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, pentyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and pentyl acrylate. , Hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, t-octyl methacrylate, n-dodecyl methacrylate, n-octadecyl methacrylate, nonyl methacrylate, isononyl methacrylate, decyl methacrylate, meta Isodecyl acrylate, stearyl methacrylate, hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, t-octyl acrylate, n-dodecyl acrylate, n-octadecyl acrylate, acrylic Le acid nonyl, isononyl acrylate, decyl acrylate, isodecyl acrylate, and stearyl acrylate and the like. Among these, methyl methacrylate, butyl methacrylate, methyl acrylate, butyl acrylate, 2-ethylhexyl methacrylate and 2-ethylhexyl acrylate are preferable, and a combination of 2-ethylhexyl acrylate and methyl methacrylate is more preferable. 2-ethylhexyl acrylate and methyl methacrylate are particularly preferably 82 to 88 parts by mass of 2-ethylhexyl acrylate and 1 to 7 parts by mass of methyl methacrylate in a total of 100 parts by mass of (a) to (c).
These can be used alone or in combination of two or more.

The addition amount of (a1) is preferably 77 to 92 parts by mass and more preferably 82 to 90 parts by mass in 100 parts by mass of the sum of (a) to (c). When the addition amount is 77 parts by mass or more, the stress relaxation property of the current collector is improved, and the cycle characteristics of the obtained battery are improved. Moreover, the binding property and smoothness of a coating film become favorable because an addition amount shall be 92 mass parts or less.

The ethylenically unsaturated carboxylic acid ester represented by (a2) has 1 to 7 carbon atoms in the methylene chain, and preferably 1 to 3 carbon atoms.
Specific examples of (a2) include, for example, 2-hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, hydroxycyclohexyl methacrylate, 2-hydroxyethyl acrylate, 4-hydroxybutyl methacrylate. Etc. Among these, 2-hydroxyethyl methacrylate and 4-hydroxybutyl acrylate are preferable.
These may be used alone or in combination of two or more.

The added amount of (a2) is preferably 3 to 8 parts by mass, more preferably 4 to 6 parts by mass, in 100 parts by mass of the sum of (a) to (c). By making the addition amount 3 parts by mass or more, the swelling resistance to the electrolytic solution is improved, and the cycle characteristics of the battery are improved. Moreover, the dispersibility of a slurry improves and the smoothness of a coating film becomes favorable because an addition amount shall be 8 mass parts or less.

As a polyfunctional monomer containing at least one kind of ethylenically unsaturated group selected from (meth) acryloyl group and (meth) allyl group represented by (a3) in the molecule, methacryl Examples include allyl acid, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, tetramethylene glycol dimethacrylate, and 1,3-butylene glycol dimethacrylate. Among these, allyl methacrylate and ethylene glycol dimethacrylate and allyl methacrylate are preferable, and ethylene glycol dimethacrylate is particularly preferable.
These can be used alone or in combination of two or more.

  The addition amount of (a3) is preferably 1 to 5 parts by mass, more preferably 1 to 3 parts by mass, out of 100 parts by mass of the sum of (a) to (c). When the addition amount is 1 part by mass or more, the swelling resistance to the electrolytic solution is improved, and the cycle characteristics of the obtained battery are improved. Moreover, by setting it as 5 mass parts or less, the stress relaxation property of a collector can be ensured and the binding property of a coating film becomes favorable.

Specific examples of the sulfonic acid derivative having a (meth) acryloyl group represented by (b) include 2- (methacryloyloxy) ethanesulfonic acid and salts thereof, 1- (methacryloyloxy) -2-methyl-1-propane Sulfonic acid and its salt, 4- [8- (methacryloyloxy) octyloxy] benzenesulfonic acid and its salt, 2-hydroxy-3- (methacryloyloxy) propane-1-sulfonic acid and its salt, methacryloyloxypolyoxypropylene Examples include sulfonic acid and its salts. Examples of the salt include alkali metal salts (sodium, potassium, etc.) and ammonium salts.
Among these, methacryloyloxypolyoxypropylenesulfonic acid and its salt, 2- (methacryloyloxy) ethanesulfonic acid and its salt are preferable, and sodium methacryloyloxypolyoxypropylenesulfonic acid is particularly preferable. In addition, you may use these individually or in combination of 2 or more types.

The added amount of (b) is preferably 1 to 8 parts by mass and more preferably 2 to 4 parts by mass in 100 parts by mass of the sum of (a) to (c). By making the addition amount 1 mass part or more, the vacuum defoaming property can be improved, so that the smoothness of the coating film can be improved. Moreover, by setting it as 8 mass parts or less, the dispersibility of a slurry is ensured and the smoothness of a coating film is securable.

  Specific examples of the ethylenically unsaturated carboxylic acid represented by (c) include unsaturated monocarboxylic acids such as methacrylic acid, acrylic acid, crotonic acid, and 3-butenoic acid, maleic acid, fumaric acid, and itaconic acid. An unsaturated dicarboxylic acid is mentioned. Among these, methacrylic acid and itaconic acid are preferable, and methacrylic acid is particularly preferable. In addition, you may use these individually or in combination of 2 or more types.

The addition amount of (c) is preferably 0.1 to 2 parts by mass, more preferably 0.5 to 1 part by mass, in 100 parts by mass of the sum of (a) to (c). When the addition amount is 0.1 parts by mass or more, the binding property with the active material can be improved. Moreover, the storage stability of a slurry is securable by setting it as 2 mass parts or less.

  In the present invention, monomers other than (a) to (c) can be used in combination as long as the effects of the present invention are not impaired. Specific examples of monomers other than (a) to (c) include styrene, acrylonitrile, butadiene, isoprene, (meth) acrylamide, N-phenol maleimide and the like.

  The method for producing the binder composition of the present invention is not particularly limited, and can be produced by a known method such as an emulsion polymerization method, a suspension polymerization method, or an emulsion dispersion method. Among these, emulsion polymerization is preferable in terms of easy production. In emulsion polymerization, all of the monomer, water, emulsifier, and polymerization initiator may be added all at once, but some of these may be mixed and dispersed in advance and added during the polymerization.

  Examples of the polymerization initiator that can be used for preparing the binder composition include inorganic salts of persulfuric acid such as potassium persulfate, ammonium persulfate, and sodium persulfate, t-butyl hydroperoxide, cumene hydroperoxide, and p-menthane hydroperoxide. And hydroperoxides such as cumene hydroperoxide and diisopropylbenzene hydroperoxide, and peroxyesters such as t-butyl peroxybenzoate and t-butyl peroxydecanoate. Among these, potassium persulfate and ammonium persulfate are preferable because the degree of gelation of the polymer can be easily adjusted. The amount of the polymerization initiator is added at a ratio of 0.01 to 3 parts by mass with respect to 100 parts by mass of all monomers.

  The emulsifier that can be used for preparing the binder composition can obtain a good binder composition even if the sulfonic acid derivative having a (meth) acryloyl group represented by (b) in the present invention is used alone. Other emulsifiers may be used in combination. Other emulsifiers include dodecylbenzene sulfonate, alkyl sulfates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl phenyl ether sulfates, dialkyl sulfosuccinates, polyoxyethylene alkyl ethers, polyoxyethylene alkyl ethers, And oxyethylene alkylphenyl ethers.

  In the preparation of the binder composition, chain transfer agents such as mercaptans and terpenes can be used for the purpose of adjusting the molecular weight. Specific examples of the chain transfer agent include n-octyl mercaptan, t-dodecyl mercaptan, n-dodecyl mercaptan, n-tetradecyl mercaptan, n-octadecyl mercaptan and terpinolene. Among these, n-octyl mercaptan, t-dodecyl mercaptan and n-dodecyl mercaptan are preferably used. In addition, you may use these individually or in combination of 2 or more types.

  An anti-aging agent etc. can be added to a binder composition as needed.

  The binder composition preferably has an average particle size of 100 to 300 nm. By setting the average particle size to 100 nm or more, an increase in the viscosity of the binder composition can be suppressed, and workability during slurry preparation can be improved. Moreover, since the particle | grains of a binder composition become easy to enter the gap | interval of an active material because an average particle diameter shall be 300 nm or less, an adhesion area with an active material can be increased.

  The binder composition preferably has a pH of 5 to 10, more preferably a pH of 6 to 9, in view of the corrosiveness of the current collector metal plate, the dispersion stability of the active material, and the like. The pH can be adjusted by adding a basic aqueous solution in which ammonia, alkali metal hydroxide or the like is dissolved. Examples of the alkali metal hydroxide include sodium hydroxide and potassium hydroxide.

<Slurry for electrodes>
The slurry for electrodes of the present invention can be obtained by mixing the binder composition of the present invention, an active material, and a conductive additive. The electrode slurry of the present invention is preferably used for forming an electrode in a lithium ion secondary battery, a nickel hydride secondary battery, an electric double layer capacitor or the like, and particularly used for forming a lithium ion secondary battery electrode. Is preferred.

(Positive electrode active material)
As the positive electrode active material of the lithium ion secondary battery, LiFePO ₄ , LiMnPO ₄ , LiMn _X Fe _(1-X) PO ₄ (where 0 <X <1), LiCoPO ₄ or Li ₃ V ₂ (PO ₄ ) ₃ And lithium-containing phosphates such as LiNiPO ₄ . Of the lithium-containing phosphates, LiFePO ₄ is particularly suitable for the binder composition of the present technology.

Further, the lithium ion secondary battery as the positive electrode active _{material, LiCoO 2, LiMn 2 O 4} , LiNiO 2, Li (Mn X Ni Y Co Z) O 2 or _{Li (Al X Ni Y Co Z} ) O 2 , etc. lithium salt _{(however, Li (Mn X Ni Y Co} Z) O 2 in or _{Li (Al X Ni Y Co Z} ) O 2 in the X, Y and Z, X + Y + Z = 1 and satisfies the relationship of 0 <X < 1 and 0 <Y <1, and 0 <Z <1). Among these, LiCoO ₂ and LiMn ₂ O ₄ are suitable for the binder composition of the present technology.

  Moreover, as a positive electrode active material other than for lithium ion secondary batteries, as a general formula, AaMmZzOoNnFf (A is an alkali metal element; M is a transition metal element (Fe, Mn, V, Ti, Mo, W, Zn) or its Composite; Z is a non-metallic element (P, S, Se, As, Si, Ge, B); O is an oxygen element; N is a nitrogen element; F is a fluorine element; a, m, z, n, f ≧ 0 A compound represented by o> 0), nickel hydroxide, activated carbon and the like.

(Negative electrode active material)
A carbonaceous material can be used as the negative electrode active material of the lithium ion secondary battery. Specific examples thereof include carbon-based compounds such as graphite, polyacene, and polyacetylene, and aromatic hydrocarbon compounds including an acene structure such as pyrene and perylene. Of these, graphite is preferred.

As a negative electrode active material for lithium ion secondary batteries other than carbonaceous materials, the negative electrode active material included lithium titanate represented by Li ₄ Ti ₅ O ₁₂ , tin oxide including metal tin, or metal silicon. Examples thereof include silicon oxide. Among these, lithium titanate and silicon oxide containing metal silicon are preferable.

  As the negative electrode active material other than the lithium ion secondary battery, for example, a hydrogen storage alloy can be used as the negative electrode active material of the nickel hydrogen secondary battery. Moreover, activated carbon etc. are mentioned as a negative electrode active material of an electric double layer capacitor.

  It is preferable that the quantity of the binder composition in the slurry for electrodes of this invention shall be 0.1-10 mass parts with respect to 100 mass parts of active materials. When the amount of the binder composition is 0.1 parts by mass or more, the active material is easily dispersed uniformly in the slurry, and the strength of the dried film after coating is easily obtained. Moreover, since internal resistance can be suppressed as the quantity of a binder composition is 10 mass parts or less, the battery excellent in the rate characteristic can be obtained.

(Conductive aid)
A conductive additive can also be added to the slurry for electrodes of the present invention.

  Examples of the conductive assistant include carbon black such as acetylene black, ketjen black (registered trademark), channel black, furnace black, and thermal black, carbon nanotube, fibrous carbon, graphite powder, and various graphites. These may be used alone or in combination of two or more. Among these, fibrous carbon and carbon black are preferable.

5-50 nm is preferable and, as for the average fiber diameter of fibrous carbon, More preferably, it is 10-30 nm. The specific surface area of the fibrous carbon is preferably 50 to 400 m ² / g, more preferably 100 to 300 m ² / g. When the average fiber diameter of the fibrous carbon is 5 to 50 nm and the specific surface area is 50 to 400 m ² / g, a higher effect as a conductive additive can be obtained.

  Among carbon blacks, acetylene black in which primary particles having an average particle diameter of 10 to 100 nm are bonded in a chain form is more preferable from the viewpoint of the effect as a conductive additive.

(Carbon composite)
The electrode slurry of the present invention may contain a carbon composite in which a plurality of conductive assistants and active materials are linked in order to improve the conductivity imparting ability and conductivity of the conductive assistant and the active material. For example, in the case of a slurry for a lithium ion secondary battery electrode, a carbon composite in which fibrous carbon and carbon black are linked, and a lithium-containing phosphate such as carbon-coated LiFePO ₄ are used as fibrous carbon and carbon black. Examples include composites that are combined and integrated. A carbon composite in which fibrous carbon and carbon black are linked can be obtained, for example, by firing a mixture of fibrous carbon and carbon black. Moreover, what baked the mixture of this carbon composite and active materials, such as lithium containing phosphate, can also be made into a carbon composite.

(Additive)
You may add a viscosity modifier to the slurry for electrodes of this invention as needed.

  As a viscosity modifier, water-soluble polymers, such as polyvinyl alcohol, carboxymethylcellulose, methylcellulose, polymethacrylic acid, its salt, etc. are mentioned.

  The electrode slurry is subjected to vacuum defoaming at a stage before coating in order to ensure smoothness without causing defects in the coating film. If the defoaming property is poor, the slurry expands in the container at the time of vacuum defoaming and the liquid level rises, so that the vacuum defoaming cannot be performed. Moreover, since defoaming becomes insufficient, a defect is generated in the coating film, which causes the smoothness to be impaired.

<Electrode>
The electrode can be obtained by laminating a current collector obtained by applying the electrode slurry of the present invention on a metal plate and drying it. In addition, a positive electrode is manufactured with the slurry for electrodes containing a positive electrode active material, and a negative electrode is manufactured with the slurry for electrodes containing a negative electrode active material. The electrode of the present invention is preferably used for the production of a lithium ion secondary battery, a nickel hydrogen secondary battery and an electric double layer capacitor, and particularly preferably used for the production of a lithium ion secondary battery.

(Metal plate for current collector)
Usually, aluminum is preferably used as the metal plate of the positive electrode current collector. Moreover, as a metal plate of the negative electrode current collector, copper is usually preferably used. The shape of the metal plate is not particularly limited, but a foil shape is preferable. The thickness of the metal plate is preferably 5 to 30 μm from the viewpoint of facilitating workability.

(Method for manufacturing electrode)
As a method for applying the electrode slurry, a general method can be used. Examples thereof include a reverse roll method, a direct roll method, a blade method, a knife method, an extrusion method, a curtain method, a gravure method, a bar method, a dip method, and a squeeze method. Of these, blade method (comma roll or die cut), knife method and extrusion method are preferable. Under the present circumstances, the surface state of a favorable coating layer can be obtained by selecting a coating method according to the solution physical property and drying property of a binder. The application may be performed on one side or both sides, and in the case of both sides, each side may be sequentially or simultaneously. The application may be continuous, intermittent, or striped. The application thickness, length, and width of the electrode slurry may be appropriately determined according to the size of the battery. For example, the application thickness of the slurry for electrodes, that is, the thickness of the current collector can be in the range of 10 μm to 500 μm.

  As a method for drying the electrode slurry, a generally adopted method can be used. In particular, it is preferable to use hot air, vacuum, infrared rays, far-infrared rays, electron beams and low-temperature air alone or in combination. In the present invention, by using an electrode slurry prepared using water as a medium, drying can be performed at a temperature of about 50 to 130 ° C., and energy for drying can be reduced.

  The electrode can be pressed as needed. As the pressing method, a generally adopted method can be used, and a die pressing method and a calendar pressing method (cold or hot roll) are particularly preferable. The press pressure in the calendar press method is not particularly limited, but is preferably 0.2 to 3 ton / cm.

<Secondary battery and electric double layer capacitor>
The secondary battery and the electric double layer capacitor are obtained using the electrode of the present invention. Examples of the secondary battery include a lithium ion secondary battery and a nickel hydride secondary battery. Among these, the electrode of the present invention is particularly suitable for use in a lithium ion secondary battery. Further, the secondary battery or electric double layer capacitor of the present invention comprises the electrode (positive electrode and negative electrode) of the present invention, a separator, and an electrolyte solution (hereinafter sometimes simply referred to as “electrolyte”). Are preferred. In addition, you may combine the positive electrode or negative electrode of this invention, and the electrode other than this invention.

(separator)
Any separator can be used as long as it has sufficient strength, such as an electrically insulating porous film, a net, and a nonwoven fabric. In particular, it is preferable to use a material that has low resistance to ion migration of the electrolytic solution and excellent in solution holding. The material is not particularly limited, and examples thereof include inorganic fibers such as glass fibers or organic fibers, synthetic resins such as polyethylene, polypropylene, polyester, polytetrafluoroethylene, and polyflon, and layered composites thereof. From the viewpoint of adhesion and safety, polyethylene, polypropylene, or a layered composite film thereof is desirable.

(Electrolytes)
Electrolyte, any known lithium salt can be _{used, LiClO 4, LiBF 4, LiBF} 6, LiPF 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiB 10 Cl 10, LiAlCl 4, LiCl LiBr, LiI, LiB (C ₂ H ₅ ) ₄ , LiCF ₃ SO ₃ , LiCH ₃ SO ₃ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , lithium lower fatty acid carboxylate and the like can be mentioned, but not particularly limited.

(Electrolyte)
As the electrolyte in the case of a lithium ion secondary battery, an electrolyte composed of a non-aqueous organic solvent that dissolves an electrolyte of a lithium salt is suitable. Examples of these organic solvents include carbonates, lactones such as γ-butyrolactone, ethers, sulfoxides such as dimethyl sulfoxide, oxolanes, nitrogen-containing compounds, esters, inorganic acid esters, amides, glymes, One or two or more mixed solvents such as ketones, sulfolanes such as sulfolane, oxazolidinones such as 3-methyl-2-oxazolidinone, and sultone can be used.
Specific examples of carbonates include propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.
Examples of ethers include trimethoxymethane, 1,2-dimethoxyethane, diethyl ether, 2-ethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran and the like.
Examples of oxolanes include 1,3-dioxolane and 4-methyl-1,3-dioxolane.
Nitrogen-containing compounds include acetonitrile, nitromethane, N-methyl-2-pyrrolidone and the like.
Examples of the esters include methyl formate, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, ethyl propionate, and phosphoric acid triester.
Examples of inorganic acid esters include sulfate esters, nitrate esters, and hydrochloric acid esters.
Examples of amides include dimethylformamide and dimethylacetamide.
Examples of the glymes include diglyme, triglyme, and tetraglyme.
Examples of ketones include acetone, diethyl ketone, methyl ethyl ketone, and methyl isobutyl ketone.
Examples of sultone include 1,3-propane sultone, 4-butane sultone, naphtha sultone and the like.

Among the electrolytes of these lithium ion secondary batteries, non-aqueous electrolytes in which LiPF ₆ is dissolved in carbonates are preferred, and the electrolyte concentration varies depending on the electrodes and electrolytes used, but 0.5-3 mol / L is preferred.

  Examples of the electrolytic solution in the case of a nickel metal hydride battery include aqueous solutions of electrolytes such as sodium hydroxide, lithium hydroxide, and potassium hydroxide. The electrolytic solution in the case of the electric double layer capacitor is configured to have a non-aqueous solvent such as an organic solvent containing an electrolyte such as an ammonium salt or a sulfonium salt. As the organic solvent in this case, one kind or two or more kinds of mixed solvents such as carbonates, alcohols, nitriles, amides and ethers can be used.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited to this.

< Reference Example 1 >
(Preparation of binder composition)
In a temperature-adjustable container equipped with a stirrer, (a1) 86.5 parts by mass of 2-ethylhexyl acrylate (hereinafter simply referred to as “part”), methyl methacrylate 5.1 parts, (a2) methacrylic acid 2 -5 parts of hydroxyethyl, 2 parts of ethylene glycol dimethacrylate as (a3), sodium methacryloyloxypolyoxypropylene sulfonate as (b) ("Eleminol (registered trademark) RS-3000" manufactured by Sanyo Chemical Industries Ltd.), and the same hereinafter ) 0.6 parts, 0.8 parts of methacrylic acid as (c) and 100 parts of ion-exchanged water were added, and the inside of the container was replaced with nitrogen. Next, polymerization was started at 80 ° C. with 0.2 part of ammonium persulfate, and when the polymerization rate reached 99%, cooling was performed to obtain a binder composition. A 10% aqueous potassium hydroxide solution was added to the obtained binder composition to adjust the pH to 7. The obtained binder composition had a solid content of 50% by mass and an average particle size of 226 nm.

(Average particle size of binder composition)
The obtained binder composition was diluted with pure water, and the volume average particle size was measured using a laser scattering particle size measuring device (LS-13-320, manufactured by Beckman Coulter, Inc.).

(Preparation of positive electrode material slurry)
The following raw materials were used for the preparation of the positive electrode slurry.
Carboxymethyl cellulose: “D2200” manufactured by Daicel Corporation
Etherification degree 0.8-1.0, 1% solution viscosity 2,000 mPa · s (25 ° C.)
LiFePO ₄ : “P2” manufactured by Clariant Inc., average primary particle diameter 600 nm
LiCoO ₂ : “C-10N” manufactured by Nippon Chemical Industry Co., Ltd., average primary particle size of 12 μm
LiMn ₂ O ₄ : manufactured by Tosoh Corporation, average primary particle size of 10 μm
Acetylene black: “HS-100” manufactured by Denki Kagaku Kogyo Co., Ltd., average primary particle size 35 n
m
-Fibrous carbon: “MDCNF” manufactured by MD Nanotech Co., Ltd., average diameter 15 nm, specific surface area 240 m ³ / g

In planetary mixer, 5 parts of the resulting binder composition solids, carboxymethylcellulose 2 parts, LiFePO ₄ and 84 parts of acetylene black) 7 parts of mixed solid fibrous carbon 2 parts of ion-exchanged water A 42% positive electrode material slurry was prepared. Furthermore, the obtained positive electrode material slurry was vacuum defoamed for 15 minutes under the condition of a gauge pressure of 0 mmHg in a planetary mixer.

(Evaluation of positive electrode material slurry)
[Defoamability during slurry preparation]
100 mL of the adjusted positive electrode material slurry was placed in a graduated cylinder, which was sealed in a desiccator and allowed to stand for 15 minutes under reduced pressure at a gauge pressure of 0 mmHg. During this time, the defoaming property was evaluated from the volume when the liquid level reached the highest point and the volume ratio before the pressure reduction treatment. In the evaluation, the case where the volume ratio was expanded by 3 times or more was “impossible”, the case where it was 2 times or more and less than 3 times was “good”, and the case where it was less than 2 times was “good”.
Volume ratio = v2 / v1
However, v1: Volume before decompression, v2: Volume at the highest liquid level during decompression

[Slurry storage stability]
The prepared positive electrode slurry was allowed to stand at 23 ° C., and the slurry properties were evaluated after 1 week. “No” when gel or agglomerate was generated or sludge was found to be settled, “good” when agglomerate was generated, slurry was settled, no change in viscosity was observed, viscosity change occurred Those that did not cause the formation of aggregates were evaluated as “OK”.

(Preparation of positive electrode)
The prepared positive electrode slurry was applied to both sides of an aluminum foil having a thickness of 20 μm by an automatic coating machine so that each side was 140 g / m ² and pre-dried at 60 ° C. and a residence time of 15 minutes. Next, it pressed with the linear pressure of 0.2-3 ton / cm with the roll press machine, and prepared so that the thickness of a positive electrode electrical power collector might be 148 micrometers on both surfaces. Further, the current collector was cut into a width of 54 mm to produce a strip-shaped current collector sheet. After ultrasonically welding a current collector tab made of aluminum to the end of the current collector sheet, in order to completely remove volatile components such as residual solvent and adsorbed moisture, vacuum drying was performed at 120 ° C. for 14 hours to obtain a positive electrode. . About the produced positive electrode, the smoothness of a coating film, binding property, and pencil hardness were evaluated with the following method.

(Evaluation of positive electrode)
[Smoothness of coating film (number of defects)]
The positive electrode surface cut to 54 mm × 100 mm was visually observed, the number of defects was counted, and the smoothness of the coating film was evaluated. The arithmetic average of the number of defects having a diameter of 0.1 mm or more was calculated for the three positive electrode surfaces. Here, the term “defect” refers to an active material, an agglomerate of a conductive additive and a binder composition, and a portion that appears to be non-uniform due to the generation of bubbles. In addition, the diameter of each defect was confirmed by observing a magnification as 100 times using an optical microscope.

[Binding property]
Using the produced positive electrode, according to JIS K 5600-5-6, the binding property of the coating film was evaluated by a cross-cut method test with a grid pattern of 25 squares at a cut interval of 2 mm. Evaluation is performed in 6 stages of 0 to 5, and the smaller the number, the better the binding property of the coating film.

(Preparation of negative electrode material slurry)
The following raw materials were used for the preparation of the negative electrode material slurry.
Carboxymethyl cellulose: “D2200” manufactured by Daicel Corporation
Etherification degree 0.8-1.0, 1% solution viscosity 2,000 mPa · s (25 ° C.)
Graphite: “Carbotron P” manufactured by Kureha Co., Ltd., average particle size 9 μm
Li ₄ Ti ₅ O ₁₂ : manufactured by Altair Nanotechnology, specific surface area 130 m ² / g
・ SiO: “SiO” manufactured by Osaka Titanium Technologies, Ltd.
Acetylene black: “HS-100” manufactured by Denki Kagaku Kogyo Co., Ltd., average primary particle size 35 n
m
-Fibrous carbon: “MDCNF” manufactured by MD Nanotech Co., Ltd., average diameter 15 nm, specific surface area 240 m ³ / g

  In a planetary mixer, 98 parts of graphite as the negative electrode active material, 1 part of the prepared binder composition and 1 part of carboxymethylcellulose are mixed, and an appropriate amount of water is added so that the total solid content is 50% by mass. In addition, kneading was performed to prepare a negative electrode material slurry. Furthermore, the negative electrode material slurry obtained was vacuum defoamed for 15 minutes under the condition of a gauge pressure of 0 mmHg in a planetary mixer.

(Preparation of negative electrode)
The prepared negative electrode material slurry was applied to both sides of a copper foil having a thickness of 10 μm by an automatic coater so that each side was 70 g / m ^2, and preliminarily dried at 60 ° C. and a residence time of 10 minutes. Next, it pressed with the linear pressure of 0.2-3 ton / cm with the roll press machine, and prepared so that the thickness of a negative electrode electrical power collector might be 90 micrometers on both surfaces. Further, the negative electrode current collector was cut into a width of 54 mm to produce a short current collector sheet. After ultrasonically welding a nickel current collector tab to the end of the current collector sheet, the anode was obtained by vacuum drying at 120 ° C. for 14 hours in order to completely remove volatile components such as residual solvent and adsorbed moisture. .

(Production of lithium ion secondary battery)
The obtained positive electrode and negative electrode were combined and wound through a polyethylene microporous membrane separator having a thickness of 25 μm and a width of 60 mm to produce a spiral wound group, which was then inserted into a battery can. Next, after injecting 5 ml of a non-aqueous electrolyte solution (ethylene carbonate / methyl ethyl carbonate = 30/70 (mass ratio) mixed solution) in which LiPF ₆ was dissolved at a concentration of 1 mol / L as an electrolyte, The inlet was caulked and sealed to produce a cylindrical lithium secondary battery (3.4 V-940 mAh) having a diameter of 18 mm and a height of 65 mm. About the produced lithium ion secondary battery, the battery performance was evaluated with the following method.

(Evaluation of lithium ion secondary battery)
The prepared lithium ion secondary battery was charged at a constant current and a constant voltage with a limit of 4.0 V and 0.2 ItA (188 mA) at 25 ° C., and then discharged to 2.0 V at a constant current of 0.2 ItA.

[Discharge rate characteristics (High rate discharge capacity maintenance rate)]
Next, the discharge current was changed to 0.2 ItA and 1 ItA, and the discharge capacity for each discharge current was measured. The recovery charge in each measurement was a constant current constant voltage charge of 4.0 V (1 ItA cut). And the high rate discharge capacity maintenance factor at the time of 1 ItA discharge with respect to the time of 0.2 ItA discharge was calculated.

[Cycle characteristics (cycle capacity retention rate)]
At an environmental temperature of 25 ° C., a constant current and constant voltage charge with a charge voltage of 4.0 V and 1 ItA and a constant current discharge of 1 ItA with a discharge end voltage of 2.0 V were performed. The cycle of charging and discharging was repeated, and the ratio of the discharge capacity at the 500th cycle to the discharge capacity at the first cycle was determined as the cycle capacity maintenance rate.

  The results are shown in Table 1.

<Examples 2 to 7, Reference Example 8 >
It was shown in Reference Example 1 except that the addition amount of (a1) 2-ethylhexyl acrylate and methyl methacrylate and (b) sodium methacryloyloxypolyoxypropylene sulfonate was changed to those shown in Table 1. The binder composition was produced by the method. Furthermore, a positive electrode material slurry, a negative electrode material slurry, a positive electrode, and a negative electrode were prepared in the same manner as in Reference Example 1, and each evaluation was performed. The results are shown in Table 1.

< Reference Example 9 >
(A1) was changed to 2-ethylhexyl acrylate (85.05 parts), methyl methacrylate (4.9 parts), (b) sodium methacryloyloxypolyoxypropylene sulfonate (c) and (c) 0.05 parts methacrylic acid. Except for the above, a binder composition was prepared by the method shown in Reference Example 1 . The average particle size was 174 nm. Furthermore, a positive electrode material slurry, a negative electrode material slurry, a positive electrode, and a negative electrode were prepared in the same manner as in Reference Example 1, and each evaluation was performed. The results are shown in Table 2.

<Examples 10 to 15 and Reference Example 16 >
A binder composition was prepared in the same manner as in Reference Example 9 except that (a1) 2-ethylhexyl acrylate and methyl methacrylate and (c) the amount of methacrylic acid added were changed to those shown in Table 2. Furthermore, a positive electrode material slurry, a negative electrode material slurry, a positive electrode, and a negative electrode were prepared in the same manner as in Reference Example 1, and each evaluation was performed. The results are shown in Table 2.

< Reference Example 17 >
(A1) 6-part 2-ethylhexyl acrylate, 3.7 parts methyl methacrylate, (a2) 10 parts 2-hydroxyethyl methacrylate, (a3) 7 parts ethylene glycol dimethacrylate, (b) A binder composition was prepared by the method shown in Reference Example 1 except that 8 parts of sodium methacryloyloxypolyoxypropylene sulfonate was used and 7 parts of methacrylic acid was used as (c). The average particle size was 155 nm. Furthermore, a positive electrode material slurry, a negative electrode material slurry, a positive electrode, and a negative electrode were prepared in the same manner as in Reference Example 1, and each evaluation was performed. The results are shown in Table 3.

<Examples 18 to 26>
A binder composition was prepared by the method shown in Reference Example 1 except that the monomers were changed to those shown in Table 3. Furthermore, a positive electrode material slurry, a negative electrode material slurry, a positive electrode, and a negative electrode were prepared in the same manner as in Reference Example 1, and each evaluation was performed. The results are shown in Table 3.

<Example 27>
(A1) 2ethylhexyl acrylate 88.1 parts, methyl methacrylate 5.1 parts, (a2) 2-hydroxyethyl methacrylate 1 part, (a3) ethylene glycol dimethacrylate 2 parts, (b) A binder composition was prepared by the method shown in Reference Example 1 , except that 3 parts of sodium methacryloyloxypolyoxypropylene sulfonate was used and 3 parts of (c) was changed to 0.8 part of methacrylic acid. The average particle size was 155 nm. Furthermore, a positive electrode material slurry, a negative electrode material slurry, a positive electrode, and a negative electrode were prepared in the same manner as in Reference Example 1, and each evaluation was performed. The results are shown in Table 4.

<Examples 28 to 32>
A binder composition was prepared by the method shown in Reference Example 1 except that the monomers were changed to those shown in Table 4. Furthermore, a positive electrode material slurry, a negative electrode material slurry, a positive electrode, and a negative electrode were prepared in the same manner as in Reference Example 1, and each evaluation was performed. The results are shown in Table 4.

<Example 33>
(A1) 85.7 parts 2-ethylhexyl acrylate, 5 parts methyl methacrylate, (a2) 5 parts 2-hydroxyethyl methacrylate, (a3) 0.5 parts ethylene glycol dimethacrylate, (b) A binder composition was prepared by the method shown in Reference Example 1 , except that 3 parts of sodium methacryloyloxypolyoxypropylene sulfonate was used and 3 parts of (c) was changed to 0.8 part of methacrylic acid. The average particle size was 181 nm. Furthermore, a positive electrode material slurry, a negative electrode material slurry, a positive electrode, and a negative electrode were prepared in the same manner as in Reference Example 1, and each evaluation was performed. The results are shown in Table 5.

<Examples 34 to 37>
A binder composition was prepared by the method shown in Reference Example 1 except that the monomers were changed to those shown in Table 5. Furthermore, a positive electrode material slurry, a negative electrode material slurry, a positive electrode, and a negative electrode were prepared in the same manner as in Reference Example 1, and each evaluation was performed. The results are shown in Table 5.

<Example 38>
According to the composition shown in Table 6, a binder composition was prepared in the same manner as in Reference Example 1 except that (a1) methyl methacrylate was not added. The average particle size was 183 nm. Furthermore, a positive electrode material slurry, a negative electrode material slurry, a positive electrode, and a negative electrode were prepared in the same manner as in Reference Example 1, and each evaluation was performed. The results are shown in Table 6.

<Examples 39 to 43>
A binder composition was prepared in the same manner as in Example 38 except that 2-ethylhexyl acrylate and methacrylic acid were changed to those shown in Table 6. Furthermore, a positive electrode material slurry, a negative electrode material slurry, a positive electrode, and a negative electrode were prepared in the same manner as in Reference Example 1, and each evaluation was performed. The results are shown in Table 6.

<Example 44>
(A1) 39.2 parts of 2-ethylhexyl acrylate, 50 parts of 2-ethylhexyl methacrylate, (a2) 5 parts of 2-hydroxyethyl methacrylate, (a3) 2 parts of ethylene glycol dimethacrylate, (b) A binder composition was prepared by the method shown in Reference Example 1 , except that 3 parts of sodium methacryloyloxypolyoxypropylene sulfonate was used and 3 parts of (c) was changed to 0.8 part of methacrylic acid. The average particle size was 192 nm. Furthermore, a positive electrode material slurry, a negative electrode material slurry, a positive electrode, and a negative electrode were prepared in the same manner as in Reference Example 1, and each evaluation was performed. The results are shown in Table 7.

<Examples 45-51>
A binder composition was prepared by the method shown in Reference Example 1 except that the monomers were changed to those shown in Table 7. Furthermore, a positive electrode material slurry, a negative electrode material slurry, a positive electrode, and a negative electrode were prepared in the same manner as in Reference Example 1, and each evaluation was performed. The results are shown in Table 7.

<Comparative Example 1>
In Comparative Example 1, a binder composition was prepared in which the monomer represented by (a2) Chemical Formula 2 was not added. The average particle size was 188 nm. Further, a positive electrode material slurry, a negative electrode material slurry, a positive electrode, and a negative electrode were prepared in the same manner as in Reference Example 1, and each evaluation was performed. However, the smoothness of the coating film was poor, and the high rate discharge capacity maintenance rate and The cycle capacity retention rate was also low. The results are shown in Table 8.

<Comparative example 2>
In Comparative Example 2, a binder composition was prepared in which (a3) a polyfunctional monomer containing two or more ethylenically unsaturated groups in the molecule was not added. Further, a positive electrode material slurry, a negative electrode material slurry, a positive electrode, and a negative electrode were prepared in the same manner as in Reference Example 1 and evaluated, but the high rate discharge capacity retention rate and cycle capacity retention rate were low. . The results are shown in Table 8.

<Comparative Example 3>
In Comparative Example 3, 3 parts of sodium allyl sulfonate was added in place of the sulfonic acid derivative having (b) (meth) acryloyl group to prepare a binder composition. Further, a positive electrode material slurry, a negative electrode material slurry, a positive electrode, and a negative electrode were prepared in the same manner as in Reference Example 1 and evaluated, but the results were inferior in vacuum defoaming property and smoothness of the coating film during slurry adjustment. It became. The results are shown in Table 8.

<Comparative example 4>
In Comparative Example 4, in accordance with the formulation shown in Table 8, polymerization was attempted at 80 ° C. in the same manner as in Reference Example 1 without adding the sulfonic acid derivative having (b) (meth) acryloyl group. Polymerization did not proceed even after the lapse of time, and a binder composition could not be prepared.

<Comparative Example 5>
In Comparative Example 5, a binder composition was prepared without adding (c) ethylenically unsaturated carboxylic acid, but the cycle capacity retention rate was low. The results are shown in Table 8.

<Example 52>
A positive electrode material slurry was prepared in the same manner as in Reference Example 1 except that the binder composition of Example 4 was used and the positive electrode active material was LiCoO ₂ . Further, a negative electrode material slurry, a positive electrode, and a negative electrode were prepared in the same manner as in Reference Example 1, and each evaluation was performed. The results are shown in Table 9.

<Example 53>
A positive electrode material slurry was prepared in the same manner as in Reference Example 1 except that the binder composition of Example 4 was used and the positive electrode active material was LiMn ₂ O ₄ . Further, a negative electrode material slurry, a positive electrode, and a negative electrode were prepared in the same manner as in Reference Example 1, and each evaluation was performed. The results are shown in Table 9.

<Example 54>
A negative electrode material slurry was produced in the same manner as in Reference Example 1 except that the binder composition of Example 4 was used and the negative electrode active material was silicon oxide containing metallic silicon ("SiO" manufactured by Osaka Titanium Technologies). Was prepared. Further, a positive electrode material slurry, a positive electrode, and a negative electrode were prepared in the same manner as in Reference Example 1, and each evaluation was performed. The results are shown in Table 9.

<Example 55>
A negative electrode material slurry was prepared in the same manner as in Reference Example 1 except that the binder composition of Example 4 was used and Li ₄ Ti ₅ O ₁₂ was used as the negative electrode active material. Further, a positive electrode material slurry, a positive electrode, and a negative electrode were prepared in the same manner as in Reference Example 1, and each evaluation was performed. The results are shown in Table 9.

<Example 56>
By adding 1.9 parts of fibrous carbon, 7.4 parts of acetylene black, and 83.7 parts of LiFePO ₄ to 1000 parts of ethanol and using a stirring medium made of alumina balls, the mixture is wet-stirred with a vibration mill for 5 hours. The mechanochemical combination of fibrous carbon and acetylene black and mixing with LiFePO ₄ were performed simultaneously. After stirring, the ethanol was removed by filtration, dried at 100 ° C. for 3 hours with a dryer, and further crushed for 8 hours using a rougher. The mixture was filled in a muffle furnace, and a carbon composite made of fibrous carbon, acetylene black, and LiFePO ₄ was fired at 700 ° C. for 1 hour while flowing nitrogen gas. To 93 parts of the obtained carbon composite, 5 parts of the binder composition obtained in Example 4 and 2 parts of carboxymethyl cellulose were mixed to prepare a positive electrode material slurry. Further, a negative electrode material slurry, a positive electrode, and a negative electrode were prepared in the same manner as in Reference Example 1, and each evaluation was performed. The results are shown in Table 9.

<Example 57>
2 parts of fibrous carbon, 3.9 parts of acetylene black, 92.1 parts of silicon oxide containing metal silicon (hereinafter abbreviated as silicon oxide) are added to 1000 parts of ethanol, and a stirring medium made of alumina balls is added. The mixture was mixed with silicon oxide and mechanochemical composite of fibrous carbon and acetylene black by wet stirring with a vibration mill for 5 hours. Further, firing was performed in the same manner as in Example 37 to obtain a carbon composite. 98 parts of the obtained carbon composite is mixed with 1 part of the binder composition obtained in Example 4 and 1 part of carboxymethylcellulose, and an appropriate amount of water is added so that the total solid content is 50% by mass. In addition, kneading was performed to prepare a negative electrode material slurry. Further, a positive electrode material slurry, a positive electrode, and a negative electrode were prepared in the same manner as in Reference Example 1, and each evaluation was performed. The results are shown in Table 9.

In addition, when the negative electrode material slurry and the negative electrode using various active materials were evaluated in the same manner as the positive electrode, the evaluation results were good regardless of the difference in the active materials.

  From the results of Tables 1 to 9, the electrode slurry obtained from the binder composition for lithium ion secondary battery electrodes of the examples of the present invention is excellent in storage stability and defoaming property at the time of slurry preparation. It shows that the smoothness is good and the discharge rate characteristics and cycle characteristics of the lithium ion secondary battery are good.

By utilizing the slurry for electrodes containing the binder composition of the present invention, the defoaming operation at the time of slurry preparation becomes easy, and an electrode excellent in the smoothness of the coating film can be obtained. Thereby, a lithium ion secondary battery, a nickel hydride secondary battery, an electric double layer capacitor, etc. excellent in discharge rate characteristics and cycle characteristics can be obtained.

Claims (17)

A copolymer obtained by copolymerizing (a) an ethylenically unsaturated carboxylic acid ester, (b) a sulfonic acid derivative having a (meth) acryloyl group, and (c) an ethylenically unsaturated carboxylic acid is water. A binder composition for an electrode dispersed in (a) an ethylenically unsaturated carboxylic acid ester, (b) a sulfonic acid derivative having a (meth) acryloyl group, and (c) a sum of ethylenically unsaturated carboxylic acids In 100 parts by mass, (b) the sulfonic acid derivative having a (meth) acryloyl group is 1 to 8 parts by mass, (c) the ethylenically unsaturated carboxylic acid is 0.1 to 2 parts by mass, (a) The binder composition for electrodes in which an ethylenically unsaturated carboxylic acid ester is composed of the following (a1) to (a3).
(A1) In the structural unit represented by Chemical Formula 1, a monomer in which R ₂ is an alkyl group having 1 to 20 carbon atoms.
(A2) In the structural unit represented by Chemical Formula 2, a monomer in which R ₃ is a methylene chain having 1 to 7 carbon atoms.
(A3) selected from allyl methacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, tetramethylene glycol dimethacrylate, and 1,3-butylene glycol dimethacrylate,
One or more polyfunctional monomers.

(B) (meth) sulfonic acid derivative having an acryloyl group, (meth) acryloyloxy polyoxypropylene sodium sulfonate, is (c) an ethylenically unsaturated carboxylic acid, methacrylic acid, according to claim 1 Electrode binder composition. (A1) The binder composition for electrodes according to claim 1 or 2 , wherein the structural unit represented by Chemical Formula 1 is 2-ethylhexyl acrylate and methyl methacrylate.

(A) an ethylenically unsaturated carboxylic acid ester, (a1) 77-92 parts by weight, (a2) 3 to 8 parts by weight, (a3) from 1 to 5 parts by weight, any one of claims 1 to 3 The binder composition for an electrode according to Item. (C) The ethylenically unsaturated carboxylic acid is a total of 100 masses of (a) an ethylenically unsaturated carboxylic acid ester, (b) a sulfonic acid derivative having a (meth) acryloyl group, and (c) an ethylenically unsaturated carboxylic acid. The binder composition for electrodes as described in any one of Claims 1-4 which is 0.1-1 mass part in a part. The electrode slurry formed by containing the positive electrode active material and the conductive support agent in the binder composition for electrodes as described in any one of Claims 1-5 . The slurry for electrodes formed by including the negative electrode active material and the conductive support agent in the binder composition for electrodes as described in any one of Claims 1-5 . The positive electrode active material is selected from the group consisting of LiFePO ₄ , LiMnPO ₄ , LiMn _X Fe _(1-X) PO ₄ (where 0 <X <1), LiCoPO ₄ or Li ₃ V ₂ (PO ₄ ) ₃ , LiNiPO _4. The electrode slurry according to claim 6 , which is at least one lithium-containing phosphate selected. The positive electrode active _material, at least one selected from _{LiCoO 2, LiMn 2 O 4,} LiNiO 2, Li (Mn X Ni Y Co Z) O 2 or _{Li (Al X Ni Y Co Z} ) group consisting of _{O 2} The electrode slurry according to claim 6 , which is a lithium salt. _{However, Li (Mn X Ni Y Co} Z) O 2 in or _{Li (Al X Ni Y Co Z} ) O 2 in the X, Y and Z, X + Y + Z = 1 and satisfies the relationship of 0 <X <1, 0 The relationship of <Y <1, 0 <Z <1 is satisfied. The electrode slurry according to claim 7 , wherein the negative electrode active material is a carbonaceous material. The electrode slurry according to claim 7 , wherein the negative electrode active material is at least one selected from the group consisting of Li ₄ Ti ₅ O ₁₂ , tin oxide containing metal tin, or silicon oxide containing metal silicon. Conductive auxiliary agent is at least one selected from (i) fibrous carbon, (ii) carbon black, (iii) a carbon composite fibrous carbon and carbon black are interconnected, claim 6-11 The slurry for electrodes as described in any one of these. (I) fibrous carbon has an average fiber diameter of 5 to 50 nm, and a specific surface area of 50 to 400 m ² / g, the electrode slurry according to claim 12. 14. The electrode slurry according to claim 12 or 13 , wherein (ii) carbon black is acetylene black formed by binding primary particles having an average particle diameter of 10 to 100 nm in a chain form. Electrode produced by using the electrode slurry according to any of claims 6-14. A secondary battery manufactured using the electrode according to claim 15 . An electric double layer capacitor manufactured using the electrode according to claim 15 .