JP5181632B2 - Battery electrode binder composition, battery electrode binder composition manufacturing method, battery electrode paste, battery electrode, and battery electrode manufacturing method - Google Patents

Description

  The present invention relates to a battery electrode binder composition suitably used as a battery electrode binder, a method for producing the same, a battery electrode paste using the battery electrode binder composition, a battery electrode, and a method for producing the battery electrode.

  In recent years, secondary batteries such as nickel metal hydride secondary batteries and lithium ion secondary batteries have been widely used as power sources for electronic devices such as mobile phones and laptop computers.

  The secondary battery includes a positive electrode and a negative electrode. These electrodes are, for example, a paste obtained by dispersing and mixing a binder, an organic solvent such as N-methylpyrrolidone (NMP) as a dispersion medium, and an active material. This paste can be obtained by applying and drying on a current collector.

  Specific examples of the binder include a modified polymer in which a functional group such as a carboxyl group is introduced into a hydrogenated diene polymer (for example, see Patent Document 1), a fluorine-containing polymer, a carboxyl group, and the like. An aqueous dispersion of a composite polymer obtained by combining an acrylic polymer having a functional group (for example, see Patent Document 2) has been reported.

Japanese Patent Laid-Open No. 10-17714 Japanese Patent No. 3601250

  However, the electrode formed using the modified polymer described in Patent Document 1 still has room for improvement in the adhesion between the electrode layer and the current collector, and the mobility of lithium ions has not been sufficient.

  The electrode paste prepared using the aqueous dispersion of the composite polymer described in Patent Document 2 may tend to form a precipitate when left for a long period of time, and the adhesiveness to the current collector is still improved. In addition, the mobility of lithium ions was not sufficient.

  Therefore, the battery (secondary battery) manufactured using the modified polymer described in Patent Document 1 and the aqueous dispersion of the composite polymer described in Patent Document 2 is repeatedly charged and discharged (cycle characteristics). There was a problem that the capacity was greatly reduced and the internal resistance (Ω) was also greatly increased.

  Therefore, along with the development of electronic devices such as mobile phones and notebook computers, the electrodes of batteries (secondary batteries) with excellent capacity characteristics (%) and internal resistance (Ω) and excellent cycle characteristics are formed appropriately. Development of a battery electrode binder composition, a method for producing the same, a battery electrode paste using the battery electrode binder composition, a battery electrode, and a method for producing the battery electrode has been demanded.

  The present invention has been made in order to solve the above-described problems of the prior art, and improves the adhesion with the current collector and the mobility of lithium ions, and the electrode layer has a good balance between them. Battery electrode binder composition that is a material for battery electrode paste that maintains properties such as the uniformity of the solution after standing, a method for producing the same, and this battery electrode binder composition A battery electrode paste is provided. In addition, a battery electrode that can be formed using this battery electrode paste and can form a battery (secondary battery) having a good capacity retention rate (%) and internal resistance (Ω), and a method for manufacturing the same are provided. To do.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the specific polymer ((A) polymer) and at least one anionic functional group and cationic functional group in the molecule thereof, respectively. When the battery electrode binder composition containing the compound ((B) compound) is used, the (A) compound improves the adhesion with the current collector, and the (B) compound is a lithium ion near the battery electrode surface. In order to improve mobility, the present inventors have found that the above problems can be solved, and have completed the present invention.

  Specifically, the present invention provides the following battery electrode binder composition, battery electrode binder composition manufacturing method, battery electrode paste, battery electrode, and battery electrode manufacturing method.

[1] and a polymer having (A) an anionic functional group, (B) in its molecule, contains a compound having at least one anionic functional group and a cationic functional group, respectively, wherein the (B ) The usage-amount of a compound is a binder composition for battery electrodes which is 1-7 mass parts with respect to 100 mass parts of said (A) polymers .

[2] The battery electrode binder composition according to [1], wherein the anionic functional group of the polymer (A) is a sulfonic acid group.

[3] The binder composition for battery electrodes according to [1] or [2], further comprising (D) a polymer containing fluorine atoms.

[4] The binder composition for battery electrodes according to [3], wherein the (A) polymer and the (D) polymer form a composite polymer.

[5] The complex polymer is obtained by polymerizing a monomer having an anionic functional group for constituting the polymer (A) using the polymer (D) as a seed. The binder composition for battery electrodes according to [4].

[6] The anionic functional group of the compound (B) is at least one selected from the group consisting of a carboxyl group, a sulfonic acid group, an imido acid group, and a group represented by the formula: BO ₂ H ₂ . Any one of [1] to [5], wherein the cationic functional group of the compound (B) is at least one selected from the group consisting of an amino group, an imino group, an imidazolium group, and a pyridinium group. The binder composition for battery electrodes described in 1.

[7] The compound (B) is (B-1) a compound having at least one amino group and sulfonic acid group in the molecule, or (B-2) an amino group and carboxyl in the molecule. The binder composition for battery electrodes according to any one of [1] to [6], wherein the binder composition is a compound having at least one group.

[8] The binder composition for battery electrodes according to any one of [1] to [7], further comprising (C) an organic solvent.

[9] A step of obtaining a dispersion in which a polymer having an anionic functional group is dispersed, and a compound having at least one anionic functional group and a cationic functional group in the molecule of the obtained dispersion. To obtain a first mixed liquid, to mix the first mixed liquid and an organic solvent to obtain a second mixed liquid, to remove water from the second mixed liquid, and to A method for producing a binder composition for battery electrodes, comprising: obtaining a binder composition for electrodes.

[10] The method for producing a battery electrode binder composition according to [9], wherein the dispersion is obtained by polymerizing a monomer having an anionic functional group in an aqueous solution.

[11] In the step of obtaining the dispersion, a polymer having an anionic functional group is polymerized in an aqueous solution using a polymer containing a fluorine atom as a seed, and the polymer containing the fluorine atom and an anionic functional The method for producing a binder composition for a battery electrode according to [9], which is a step of obtaining a dispersion in which a polymer in which a polymer having a group is dispersed is dispersed.
[12] A battery electrode binder composition produced by the method for producing a battery electrode binder composition according to any one of [9] to [11].

[ 13 ] A battery electrode paste comprising the battery electrode binder composition according to any one of [1] to [8] and an active material.

[ 14 ] A battery electrode comprising: a current collector; and an electrode layer formed by applying the battery electrode paste according to [ 13 ] on the surface of the current collector and drying.

[ 15 ] A method for producing a battery electrode, wherein the battery electrode paste according to [ 13 ] is applied on the surface of a current collector and then dried at a temperature of 80 ° C. or more to form an electrode layer.

The binder composition for battery electrodes of the present invention comprises (A) a polymer having an anionic functional group, and (B) a compound having at least one anionic functional group and a cationic functional group in the molecule thereof. , And the amount of the compound (B) used is 1 to 7 parts by mass with respect to 100 parts by mass of the polymer (A) , and therefore the adhesion to the current collector and the mobility of lithium ions In addition to being able to form an electrode layer with a good balance between these, it is possible to produce a battery electrode paste material that maintains properties such as the uniformity of the solution after standing. It is.

  The method for producing a binder composition for a battery electrode according to the present invention includes a step of obtaining a dispersion in which a polymer having an anionic functional group is dispersed, and the obtained dispersion has an anionic functional group and a cation in the molecule. Adding a compound each having at least one functional group to obtain a first mixture, mixing the first mixture and an organic solvent to obtain a second mixture, and The step of removing water from the second mixed solution to obtain a battery electrode binder composition has the effect that the battery electrode binder composition of the present invention can be produced satisfactorily.

  Since the battery electrode paste of the present invention contains the battery electrode binder composition of the present invention, the electrode layer improves the adhesion to the current collector and the mobility of lithium ions and has a good balance between these. In addition to being able to form, it is possible to maintain properties such as uniformity of the solution after standing.

  Since the battery electrode of the present invention includes the electrode layer formed by the battery electrode paste of the present invention, a battery (secondary battery) having good capacity retention rate (%) and internal resistance (Ω) is provided. There is an effect that it is possible.

  Since the battery electrode manufacturing method of the present invention is such that the electrode layer is formed by applying the battery electrode paste of the present invention on the surface of the current collector and then drying it at a temperature of 80 ° C. or higher. The battery electrode can be manufactured satisfactorily.

  Hereinafter, the best mode for carrying out the present invention will be described, but the present invention is not limited to the following embodiment. That is, it is understood that modifications and improvements as appropriate to the following embodiments are also within the scope of the present invention based on ordinary knowledge of those skilled in the art without departing from the spirit of the present invention. Should be.

[1] Battery electrode binder composition:
One embodiment of the binder composition for a battery electrode according to the present invention includes (A) a polymer having an anionic functional group (hereinafter sometimes simply referred to as “(A) polymer”), and (B) its molecule. A compound having at least one anionic functional group and a cationic functional group (hereinafter sometimes simply referred to as “(B) compound”), and the amount of the (B) compound used is (A) It is a thing of 1-7 mass parts with respect to 100 mass parts of polymers .

  The battery electrode binder composition of the present embodiment contains (A) the polymer and (B) compound, thereby improving the adhesion to the current collector and the mobility of lithium ions. In addition to being able to form a well-balanced electrode layer, it can be suitably used as a battery electrode paste material that maintains properties such as the uniformity of the solution after standing. And the battery (secondary battery) provided with the battery electrode formed with the paste for battery electrodes containing the binder composition for battery electrodes of this embodiment has a favorable capacity retention rate (%) and internal resistance (Ω). There is an advantage of being.

[1-1] (A) Polymer:
The polymer (A) having an anionic functional group contained in the battery electrode binder composition of the present embodiment has an anionic functional group. Since the polymer (A) is well dispersed in the battery electrode binder composition of the present embodiment, an electrode layer was formed from the battery electrode paste containing the battery electrode binder composition of the present embodiment. In this case, (A) the polymer having an anionic functional group is well dispersed in the electrode layer. By the way, when (A) polymer is not disperse | distributing favorable in an electrode layer, the part which is not fully adhere | attached with respect to a current collection material will arise, and a nonuniformity will arise in an adhesion part. For this reason, it has been difficult to obtain an electrode layer having sufficient adhesion to the current collector. Therefore, when the (A) polymer is well dispersed in the electrode layer, an electrode layer having good adhesion to the current collector can be obtained. A secondary battery having good adhesion between the current collector and the electrode layer can prevent the electrode layer from being peeled off, thereby preventing deterioration in cycle characteristics caused by the electrode layer peeling off. , Has excellent cycle characteristics.

  (A) As an anionic functional group in a polymer, a carboxyl group, a sulfonic acid group, etc. can be mentioned, for example. Among these, a sulfonic acid group is preferable from the viewpoint that the stationary stability of the battery electrode paste can be improved satisfactorily.

  (A) The polymer is produced, for example, by polymerizing a monomer having an anionic functional group such as a carboxyl group or a sulfonic acid group (hereinafter sometimes referred to as “(a-1) monomer”). can do.

  Examples of the monomer having a carboxyl group include unsaturated monocarboxylic acids such as acrylic acid, (meth) acrylic acid, and crotonic acid; unsaturated polycarboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, and mesaconic acid. Examples thereof include carboxylic acids.

  Examples of the monomer having a sulfonic acid group include styrene sulfonic acid, methallyloxybenzene sulfonic acid, allyloxybenzene sulfonic acid, allyl sulfonic acid, vinyl sulfonic acid, methallyl sulfonic acid, 4-sulfobutyl methacrylate, and Examples include isoprenesulfonic acid and salts thereof. Among these, 2-acrylamido-2-methylpropanesulfonic acid, styrene acid, allyloxybenzenesulfonic acid, and salts thereof are preferable. In addition, the monomer which has these sulfonic acid groups can be used individually by 1 type or in combination of 2 or more types.

  (A) The polymer can be produced using (a-2) other monomers in addition to (a-1) monomers. (A-2) Other monomers include, for example, (meth) acrylic acid alkyl esters; aromatic vinyl compounds such as styrene, α-methylstyrene and divinylbenzene; vinyl esters such as vinyl acetate and vinyl propionate Vinyl halide compounds such as vinyl fluoride, tetrafluoroethylene, vinyl chloride, vinylidene chloride; conjugated dienes such as butadiene, isoprene, chloroprene, ethylene, and the like.

  Examples of the (meth) acrylic acid alkyl ester include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, and (meth) acrylic acid n. -Butyl, i-butyl (meth) acrylate, n-amyl (meth) acrylate, i-amyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth ) N-octyl acrylate, n-nonyl (meth) acrylate, n-decyl (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, Pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meta Mention may be made of acrylate, and the like.

  (A-1) The proportion of the structural unit derived from the monomer is preferably 0.1 to 25% by mass, more preferably 0.1 to 20% by mass, and 0.1 to 18% by mass. % Is particularly preferred. When the proportion of the structural unit derived from the monomer having an anionic functional group is less than 0.1% by mass, the chemical stability of the particulate (A) polymer is insufficient during polymerization in an aqueous system, There is a possibility that it is difficult to obtain a good aqueous dispersion. On the other hand, when it exceeds 25% by mass, the viscosity of the polymer (A) may be excessively high in the polymerization in the aqueous system, and the particulate (A) polymer aggregates together to form a good aqueous dispersion. May be difficult to obtain.

  In particular, when the polymer (A) is a polymer containing a sulfonic acid group among anionic functional groups, the proportion of the structural unit derived from the monomer having a sulfonic acid group is 0.1 to 20 mass. %, More preferably 0.1 to 18% by mass, and particularly preferably 0.1 to 15% by mass. When the ratio is less than 0.1% by mass, the chemical stability of the particulate (A) polymer is insufficient during polymerization in an aqueous system, and it may be difficult to obtain a good aqueous dispersion. On the other hand, if it exceeds 20% by mass, the viscosity of the (A) polymer may become too high during polymerization in the aqueous system, and the particulate (A) polymer will coalesce and coalesce, resulting in a good aqueous dispersion. May be difficult to obtain.

  (A-2) The proportion of structural units derived from other monomers is preferably 0 to 40% by mass, more preferably 0 to 30% by mass, and 0 to 20% by mass. Is particularly preferred. When the ratio is more than 40% by mass, the compatibility between the polymer (A) and the polymer containing fluorine atoms described below is insufficient, and (A) the polymer and the polymer containing fluorine atoms When the composite polymer is formed, there is a possibility that a layer separation phenomenon is likely to occur in the composite polymer.

  (A) The polymer is preferably obtained by polymerizing a monomer having an anionic functional group in an aqueous solution. As the monomer having an anionic functional group, a monomer having an anionic functional group similar to the anionic functional group in the polymer (A) can be suitably used. The polymerization can be performed by a known method.

  The binder composition for battery electrodes of this embodiment preferably further contains a polymer containing a fluorine atom (hereinafter sometimes referred to as “(D) polymer”) in addition to the polymer (A). . (D) By further containing the polymer, the potential resistance at the time of charge / discharge is improved, so that the electrolysis of the binder is suppressed, and as a result, the cycle characteristics are improved.

  Moreover, when the battery electrode binder composition of the present embodiment contains (D) a polymer, a composite polymer (hereinafter referred to as "polymer (A)" and (D) polymer) is formed. It is particularly preferred to contain (sometimes simply referred to as “complexed polymer”). By containing (A) polymer and (D) polymer in a composite state, phase separation of (D) polymer and (A) polymer is suppressed, and slurry stability and dispersibility are improved. As a result, there is an advantage that adhesion to the current collector is improved.

  (D) Although it will not specifically limit if a polymer contains a fluorine in the molecular structure, (d-1) vinylidene fluoride and (d-2) hexafluoropropylene are included ((alpha)). Those obtained by polymerizing monomer components can be preferably used. That is, the (D) polymer is preferably a polymer containing (d-1) a structural unit derived from vinylidene fluoride and (d-2) a structural unit derived from hexafluoropropylene. By using the (D) polymer having such a configuration, the compatibility with the (A) polymer is improved, and the deterioration with time of the compound compound of the (A) polymer and the (D) polymer is suppressed. There is an advantage that can be.

  The (α) monomer component can contain (d-3) other unsaturated monomers in addition to (d-1) vinylidene fluoride and (d-2) hexafluoropropylene. (D-3) Other unsaturated monomers include (a-2) (meth) acrylic acid alkyl esters, aromatic vinyl compounds, vinyl esters, halogenated compounds exemplified as other monomers described above. Preferred examples include vinyl compounds, conjugated dienes, ethylene, and the like. In addition, these (d-3) other unsaturated monomers can be used individually by 1 type or in combination of 2 or more types.

  (D-1) The proportion of structural units derived from vinylidene fluoride is preferably 50 to 80% by mass, more preferably 55 to 80% by mass, and further preferably 60 to 80% by mass. preferable. When the above ratio is less than 50% by mass, when the composite polymer is formed by the (D) polymer and the (A) polymer, these compatibility is poor and the resulting composite polymer is separated into layers. There is a risk that the phenomenon is likely to occur. On the other hand, when the content exceeds 80% by mass, the (D) polymer and the (A) are formed when the (D) polymer is used as a seed to form a composite polymer of the (D) polymer and the (A) polymer. Since the compatibility with the polymer is insufficient, seed polymerization is difficult to occur, and there is a possibility that a layer separation phenomenon is likely to occur in the obtained composite polymer.

  (D-2) The proportion of structural units derived from propylene hexafluoride is preferably 20 to 50% by mass, more preferably 20 to 45% by mass, and 20 to 40% by mass. Particularly preferred. When the ratio is outside the range of 20 to 50% by mass, when (D) polymer is used as a seed to form a composite polymer of (D) polymer and (A) polymer, Since the compatibility between the polymer and the (A) polymer is insufficient, seed polymerization is difficult to occur, and there is a possibility that a layer separation phenomenon is likely to occur in the resulting composite polymer.

  (D-3) The proportion of structural units derived from other unsaturated monomers is preferably 0 to 30% by mass, more preferably 0 to 25% by mass, and 0 to 20% by mass. It is particularly preferred. When the above ratio is more than 30% by mass, when the composite polymer is formed by the (D) polymer and the (A) polymer, their compatibility is poor and the resulting composite polymer is separated into layers. There is a risk that the phenomenon is likely to occur.

  (D) As a manufacturing method of a polymer, first, a mixed gas composed of (d-1) vinylidene fluoride and (d-2) hexafluoropropylene is obtained, and a polymerization initiator is added to the obtained mixed gas. (D) A latex containing a polymer (hereinafter sometimes referred to as “(D) polymer latex”) by polymerization reaction under conditions of a reaction temperature of 60 ° C. and a pressure of 1.96 MPa in the reaction system. Examples thereof include a method of drying the obtained (D) polymer latex.

  Furthermore, as a manufacturing method of the composite polymer which (A) polymer and (D) polymer combined, the well-known emulsion polymerization method can be mentioned, for example. As a method for producing a composite polymer by the emulsion polymerization method, first, (D) a polymer latex is obtained in the same manner as in the above-mentioned (D) polymer production method, and the obtained (D) polymer latex is obtained. , (A-1) monomer and, if necessary, (a-2) other monomer are added, and (D) polymer in (D) polymer latex is used as a seed, (a -1) A composite polymer in which (A) polymer and (D) polymer are combined by emulsion polymerization of the monomer and, if necessary, (a-2) other monomer An example of the method is a method of obtaining a dispersion (hereinafter, sometimes referred to as a “complexed polymer dispersion”) containing the polymer, and then drying the obtained composite polymer dispersion.

  The ratio of (A) polymer to 100 parts by mass of (A) polymer and (D) polymer is preferably 3 to 60 parts by mass, and more preferably 10 to 50 parts by mass. (A) When the ratio of a polymer is less than 3 mass parts, properties, such as chemical resistance of an electrode layer (battery electrode), may fall. On the other hand, if it exceeds 60 parts by mass, the binder performance of the composite polymer may be lowered, and the capacity and cycle characteristics may be lowered during high-speed discharge.

  The composite polymer is preferably dissolved or dispersed in the organic solvent (C) described later. (C) When the composite polymer is dispersed in an organic solvent, the number average particle size of the composite polymer is preferably 0.02 to 2 μm, and preferably 0.05 to 1.8 μm. Further preferred is 0.1 to 1.5 μm. In the present specification, the “number average particle diameter” is a value measured by a dynamic light scattering method.

[1-2] (B) Compound:
The binder composition for battery electrodes of this embodiment contains (B) a compound having at least one anionic functional group and cationic functional group in its molecule. The (B) compound exists as an amphoteric ion in the electrode layer, and the (B) compound improves the diffusion rate of lithium ions and promotes the desolvation of lithium ions, so that the lithium on the electrode layer Improve the reaction rate of ion insertion and desorption reactions. Therefore, the mobility of lithium ions can be improved. When the electrode layer is formed using the battery electrode binder composition with improved lithium ion mobility as described above, the battery electrode including this electrode layer has low resistance, and therefore has low power loss and good cycle characteristics. Can be obtained.

  When the electrode layer is formed, the binder composition for a battery electrode of the present embodiment improves the adhesion by (A) the polymer, and (B) improves the mobility of lithium ions in the vicinity of the electrode layer by the compound. Has the effect of Here, the improvement in adhesion and the improvement in the mobility of lithium ions are in a trade-off relationship. For example, when trying to improve the adhesion, the surface of the electrode layer is covered with the finely dispersed (A) polymer, and the distance between the particles of the (A) polymer approaches, so that the electrolyte solution penetrates. It becomes difficult to improve the movement of lithium ions. Therefore, it is important to make these compatible. The binder composition for battery electrodes of the present invention can improve adhesion and lithium ion mobility, and can form an electrode layer in which these are compatible.

The anionic functional group of the (B) compound is preferably at least one selected from the group consisting of a carboxyl group, a sulfonic acid group, an imido acid group, and a group represented by the formula: BO ₂ H ₂ . In the case of these groups, the dissociation of the functional group easily proceeds in the electrolytic solution, so that there is an advantage that the battery resistance is further reduced. The number of anionic functional groups in the compound (B) is not particularly limited, but is preferably the same as the number of cationic functional groups. In addition, when the compound (B) has a plurality of anionic functional groups in the molecule, the types of the functional groups may be the same or different.

  The cationic functional group of the compound (B) is preferably at least one selected from the group consisting of an amino group, an imino group, an imidazolium group, and a pyridinium group. In the case of these groups, the dissociation of the functional group easily proceeds in the electrolytic solution, so that the battery resistance is further reduced. The number of anionic functional groups in the compound (B) is not particularly limited, but is preferably the same as the number of cationic functional groups. In addition, when the compound (B) has a plurality of cationic functional groups in the molecule, the types of the functional groups may be the same or different.

  The compound (B) is a combination of the anionic functional group and the cationic functional group (B-1) a compound having at least one amino group and sulfonic acid group in the molecule, and (B- 2) A compound having at least one amino group and carboxyl group in its molecule can be cited as a preferred example. When the compound (B-1) or the compound (B-2) is used, these compounds have an advantage that the compound (B) is difficult to precipitate because the solubility in an aqueous solution is good.

  The compound (B-1) preferably has at least one amino group and sulfonic acid group and has a linear or branched alkylene group having 1 to 25 carbon atoms that may be substituted. . Examples of (B-1) compounds include taurine and 3-aminopropanesulfonic acid. Among these, (C) Taurine is preferable because of its good solubility in organic solvents.

  (B-2) Examples of the compound include compounds having a linear alkylene group having 1 to 25 carbon atoms that may be substituted, such as glycine, aminobutyric acid, aminobenzoic acid; alanine, valine, leucine, isoleucine, Compounds having two amino groups in a molecule such as serine, threonine, cysteine, cystine, methionine, phenylalanine, tyrosine, histidine, tryptophan, asparagine, glutamine, lysine, arginine, creatine; in molecules such as aspartic acid and glutamic acid A compound having two carboxyl groups; and the like. Among these, (C) Glycine is preferable because of its good solubility in organic solvents.

  (B) In addition to the compound (B-1) and the compound (B-2), the compound (B-3) is a compound having at least one imino group and a carboxyl group in its molecule, and (B-4) ) Preferred examples include compounds having at least one imidazolium group and carboxyl group in the molecule.

  Examples of (B-3) compounds include histidine, tryptophan, proline, hydroxyproline and the like. (B-4) As a compound, histidine etc. can be mentioned, for example.

  In addition, (B) compound can also be used individually or in mixture of 2 or more types. Further, a compound obtained by forming an amide bond between two or more kinds of (B) compounds, for example, a compound obtained by forming an amide bond between the (B-1) compound and the (B-2) compound, Also good.

  The amount of the (B) compound used is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and 1-2 parts by mass with respect to 100 parts by mass of the (A) polymer. Is particularly preferred. When the amount of the (B) compound used exceeds 5 parts by mass, the (B) compound may not be dissolved in the (C) organic solvent, and may be separated and precipitated.

[1-3] (C) Organic solvent:
It is preferable that the binder composition for battery electrodes of this embodiment contains (C) an organic solvent. (C) The organic solvent preferably has a boiling point at 1 atm of 100 ° C. or higher, more preferably 115 ° C. or higher, and particularly preferably 130 ° C. or higher. When the (C) organic solvent having a boiling point of less than 100 ° C. at 1 atm is used, the adhesion of the formed electrode layer to the metal foil (current collector) may be reduced. In addition, although the upper limit of the boiling point of (C) organic solvent is not particularly limited, it may be substantially 300 ° C. or lower.

  Examples of the organic solvent (C) include toluene, N-methylpyrrolidone (NMP), methyl isobutyl ketone (MIBK), cyclohexanone, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), and the like. Among these, NMP, DMSO, and DMF are preferable.

  (C) The amount of the organic solvent used is preferably 400 to 10000 parts by mass, more preferably 600 to 3000 parts by mass, and 900 to 2000 parts by mass with respect to 100 parts by mass of the polymer (A). It is particularly preferred that (C) When the usage-amount of an organic solvent is less than 400 mass parts, there exists a possibility that the viscosity of a mixed solution may raise remarkably and may gelatinize. On the other hand, if it exceeds 10000 parts by mass, the solubility of the compound (B) in the organic solvent (C) may deteriorate, and the compound (B) may be precipitated.

  The binder composition for battery electrodes of the present embodiment preferably does not contain moisture, but when moisture is contained, the ratio is 2.0% by mass with respect to the total amount of the binder composition for battery electrodes. Or less, more preferably 1.5% by mass or less, and particularly preferably 1.0% by mass or less. If the moisture content is more than 2.0% by mass, the active material may be adversely affected and the battery capacity may be reduced.

[2] Method for producing battery electrode binder composition:
The binder composition for battery electrodes of the present invention is preferably obtained by the method for producing a binder composition for battery electrodes of the present invention, and an embodiment of the method for producing the binder composition for battery electrodes of the present invention is as follows. , A step of obtaining a dispersion in which a polymer having an anionic functional group is dispersed, and a compound having at least one anionic functional group and a cationic functional group in the molecule ((B ) Adding a compound) to obtain a first mixture, mixing the first mixture and an organic solvent to obtain a second mixture, removing water from the second mixture Obtaining a binder composition for battery electrodes. According to such a production method, when the organic solvent and the compound (B) are mixed, the compound (B) becomes difficult to precipitate, and therefore, the battery electrode binder composition of the present invention that exhibits further good effects is obtained. Can do. If the compound (B) is added as it is to a solution obtained by dissolving the composite polymer in an organic solvent, the compound (B) is precipitated because the compound (B) is not dissolved in the organic solvent. There is.

  In the method for producing the binder composition for battery electrodes according to this embodiment, first, a dispersion in which a polymer having an anionic functional group is dispersed is obtained. The dispersion is preferably obtained by polymerizing a monomer having an anionic functional group in an aqueous solution.

  The monomer having an anionic functional group is the same as the monomer having the anionic functional group ((a-1) monomer) contained in the battery electrode binder composition of the present invention. Can be used. The method for polymerizing the monomer having an anionic functional group is not particularly limited, and a known polymerization method can be used, but an emulsion polymerization method is preferably used.

  Further, in the method for producing the battery electrode binder composition of the present embodiment, the step of obtaining the dispersion comprises polymerizing a monomer having an anionic functional group in an aqueous solution using a polymer containing a fluorine atom as a seed. Thus, it is preferable to obtain a dispersion in which a polymer in which a polymer containing a fluorine atom and a polymer having an anionic functional group are combined is dispersed. When such a dispersion is obtained, the stability and dispersibility of the slurry are improved by this dispersion, and as a result, the adhesion to the current collector is further improved. The polymer containing a fluorine atom can use the thing similar to the polymer ((D) polymer) containing the fluorine atom contained in the binder composition for battery electrodes of this invention similarly. Moreover, a conventionally well-known method can be used for the polymerization method, and it is preferable to use an emulsion polymerization method.

  Next, the method for producing the battery electrode binder composition of the present embodiment includes (B) a compound having at least one anionic functional group and a cationic functional group in the molecule of the obtained dispersion. In addition, a first mixture is obtained.

  (B) The compound having at least one anionic functional group and cationic functional group in its molecule is used in the method for producing the battery electrode binder composition of the present embodiment. The battery electrode binder composition of the present invention The thing similar to the (B) compound contained in can be used similarly. (B) It is preferable that the pH of the dispersion at the time of adding a compound is 6-8. In addition, since it is preferable that all the (B) compounds in a dispersion are melt | dissolving, it is preferable to use the aqueous solution of the (B) compound previously dissolved in water.

  Next, the manufacturing method of the binder composition for battery electrodes of this embodiment mixes a 1st liquid mixture and (C) organic solvent, and obtains a 2nd liquid mixture.

  (C) As the organic solvent, the same organic solvent as (C) the organic solvent contained in the binder composition for battery electrodes of the present invention can be used in the same manner.

  Next, in the method for producing the battery electrode binder composition of the present embodiment, water is removed from the second mixed solution to obtain the battery electrode binder composition.

  The method for removing water from the second mixed solution is not particularly limited, and examples thereof include a distillation method, an ultrafiltration method, a fractional filtration method, and a dispersion medium phase conversion method.

[3] Battery electrode paste:
One embodiment of the battery electrode paste of the present invention contains the battery electrode binder composition of the present invention and an active material. Since the battery electrode paste of this embodiment contains the binder composition for battery electrodes, it can maintain a suitable viscosity even when left (stored) for a long period of time. Less likely to cause changes such as sedimentation. Therefore, the battery electrode paste of the present invention is excellent in paste stability. In addition, since the battery electrode paste of the present embodiment contains the binder composition for battery electrodes, the adhesion with the current collector and the mobility of lithium ions are improved, and the balance between these is good. An electrode layer can be formed. And an electrode battery (secondary battery) provided with such an electrode layer has the advantage that a capacity | capacitance maintenance factor (%) and internal resistance ((ohm)) are favorable.

  That is, since the battery electrode paste of this embodiment contains the binder composition for battery electrodes, the (A) polymer is well dispersed in the electrode layer when the electrode layer is formed. An electrode layer having excellent adhesion to the current collector can be formed. In addition, since the polar (B) compound is dispersed in the electrode layer, the (B) compound improves the diffusion rate of lithium ions and promotes the desolvation of lithium ions. Therefore, the reaction rate of lithium insertion / extraction reaction on the electrode layer formed by the battery electrode paste of the present embodiment is improved, and the mobility of lithium ions is improved.

  When the battery electrode binder composition produced by the method for producing a battery electrode binder composition of the present invention is used as the battery electrode binder composition to be contained in the battery electrode paste of the present embodiment, It is possible to further improve the adhesion and the mobility of lithium ions and to form an electrode layer with a better balance between these.

  Here, conventionally, a slurry containing a graphite sample having an amino acid and an amino acid salt adsorbed on its surface and polyvinylidene fluoride has been reported (for example, JP-A-2002-237304). The electrode layer thus adhered did not have sufficient adhesion to the current collector, and the electrode layer might peel off from the current collector due to repeated charge and discharge. And the secondary battery provided with this electrode layer did not show sufficient cycle characteristics.

When the positive electrode layer is formed using the battery electrode paste of the present embodiment, as the active material, for example, in the case of a nickel-metal hydride battery of an aqueous battery, a hydrogen storage alloy powder is preferably used. it can. Specifically, the hydrogen storage alloy powder is preferably one in which a part of Ni is replaced with an element such as Mn, Al, Co, etc. based on MmNi ₅ . “Mm” represents misch metal which is a mixture of rare earth elements. The active material is preferably a powder having a particle size of 3 to 400 μm, and the active material having such a particle size can be obtained by passing through 100 mesh.

In the case of a nonaqueous battery, for example, MnO ₂ , MoO ₃ , V ₂ O ₅ , V ₆ O ₁₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , TiS ₂ , TiS ₃ , MoS ₃ , FeS ₂ , CuF ₂ , NiF ₂ , composite oxide containing lithium ions (for example, Li _(1-x) CoO ₂ , Li _(1-x) NiO ₂ , Li _x Co _y Sn _z O ₂ , Li _(1-x) Inorganic compounds such as Co _(1-y) Ni _y O ₂ ); fluorinated carbon, graphite, vapor-grown carbon fiber, pulverized vapor-grown carbon fiber, pulverized vapor-grown carbon fiber and vapor-grown carbon fiber PAN-based carbon fiber, PAN-based carbon fiber pulverized product, PAN-based carbon fiber and PAN-based carbon fiber pulverized product, pitch-based carbon fiber, pitch-based carbon fiber pulverized product, pitch-based carbon Fiber and pitch Carbon materials such as a mixture of pulverized carbon fibers; polyacetylene, may be mentioned conductive polymers such as poly -p- phenylene. Among these, from the viewpoint that both the positive electrode and the negative electrode can be assembled in a discharged state, Li _(1-x) CoO ₂ , Li _(1-x) NiO ₂ , Li _x Co _y Sn _z O ₂ , Li _{( 1-x)} Co _(1-y) A composite oxide containing lithium ions such as Ni _y O ₂ is preferred.

  When the negative electrode layer is formed using the battery electrode paste of the present embodiment, examples of the active material include carbon fluoride, graphite, vapor grown carbon fiber, pulverized vapor grown carbon fiber, vapor phase A mixture of pulverized carbon fiber and pulverized carbon fiber, PAN-based carbon fiber, PAN-based carbon fiber pulverized product, PAN-based carbon fiber and PAN-based carbon fiber pulverized product, pitch-based carbon fiber, Carbon materials such as pulverized pitch-based carbon fibers, mixtures of pitch-based carbon fibers and pulverized pitch-based carbon fibers, and graphite materials (for example, natural graphite, artificial graphite, and graphitized mesophase carbon having a high degree of graphitization) Preferred examples include conductive polymers such as polyacetylene and poly-p-phenylene, and amorphous compounds composed of compounds such as tin oxide and fluorine.

  Among these, when a graphite material such as natural graphite, artificial graphite, or graphitized mesophase carbon having a high graphitization degree is used, a battery having good cycle characteristics and a high capacity retention rate (%) can be obtained.

  Further, when a carbon material is used as the active material contained in the electrode layer of the negative electrode, the particle size prevents an increase in internal resistance, prevents a decrease in paste stability, and can be obtained. From the viewpoint of preventing an increase in resistance between particles in the electrode layer of the negative electrode, it is preferably 0.1 to 50 μm, more preferably 1 to 45 μm, and particularly preferably 3 to 40 μm. preferable.

  The battery electrode paste of the present embodiment can be prepared by mixing the battery electrode binder composition of the present invention and an active material together with various additives added as necessary.

  Examples of various additives added as necessary include (C) a viscosity adjusting polymer that can be dissolved in the organic solvent to be used, conductive carbon such as graphite, and conductive materials such as metal powder. it can. Examples of the viscosity adjusting polymer may include ethylene vinyl alcohol, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylamide, polymethyl methacrylate, and polyvinylidene fluoride when NMP is used as the organic solvent (C).

  The battery electrode paste of the present embodiment preferably contains 0.1 to 10 parts by mass of the battery electrode binder composition (solid content) of the present invention with respect to 100 parts by mass of the active material. It is more preferable to contain 0.5-10 mass parts, and it is especially preferable to contain 1-10 mass parts. If the content of the binder composition for battery electrodes is less than 0.1 parts by mass, good adhesion to the metal foil (current collector) may not be obtained. On the other hand, if it exceeds 10 parts by mass, the internal resistance becomes too large and good cycle characteristics may not be obtained. Examples of the method for mixing the battery electrode binder composition and the active material include methods using various kneaders, bead mills, high-pressure homogenizers, and the like.

[4] Battery electrode:
One embodiment of the battery electrode of the present invention comprises an electrode layer formed by applying the battery electrode paste of the present invention on the surface of a current collector and drying it. As described above, the battery electrode of the present embodiment is an electrode layer formed by the battery electrode paste of the present invention, which improves the adhesion with the current collector and the mobility of lithium ions, and has a good balance between these. I have. Therefore, it is possible to provide a battery (secondary battery) having a good capacity retention rate (%) and internal resistance (Ω).

  In the case of an aqueous battery, the current collector provided in the battery electrode of this embodiment includes, for example, Ni mesh, Ni-plated punching metal, expanded metal, wire mesh, foam metal, mesh metal fiber sintered body, and the like. be able to. In the case of a nonaqueous battery, for example, a member such as an aluminum foil or a copper foil can be cited as a suitable example.

[5] Manufacturing method of battery electrode:
In one embodiment of the battery electrode manufacturing method of the present invention, the battery electrode paste of the present invention is applied on the surface of a current collector and then dried at a temperature of 80 ° C. or higher to form an electrode layer. By manufacturing in this way, the adhesion to the current collector and the mobility of lithium ions can be improved, and a battery electrode having an electrode layer with a good balance can be formed. And a battery (secondary battery) provided with the said electrode battery has the advantage that a capacity | capacitance maintenance factor (%) and internal resistance ((omega | ohm)) are favorable. As a method for applying the battery electrode paste on the surface of the current collector, a method using an arbitrary coater head such as a reverse roll method, a comma bar method, a gravure method, or an air knife method can be employed.

  As a method for drying the battery electrode paste after being applied on the surface of the current collector, for example, it is allowed to stand and dry naturally, as well as a blower dryer, hot air dryer, infrared heater, or far infrared heating A drying method using a machine or the like can be employed. A drying temperature is 80 degreeC or more, and it is preferable that it is 130-170 degreeC. Thus, by drying at 80 degreeC or more, there exists an advantage that the water | moisture content contained in an electrode layer can be removed favorably and deterioration of an electrode can be prevented. The drying time is preferably 1 to 120 minutes, more preferably 5 to 60 minutes.

  The thickness of the electrode layer is not particularly limited, but is preferably 10 to 300 μm, more preferably 20 to 150 μm, and particularly preferably 30 to 100 μm. If the thickness of the electrode layer is less than 10 μm, the metal of the current collector is exposed, which may cause corrosion or short circuit of the electrode during charge / discharge. On the other hand, if it exceeds 300 μm, the coating layer may crack and peel off.

  In addition, the battery electrode of this invention can be used suitably as an electrode of any battery of a water-system battery and a non-aqueous battery. In particular, when used as a positive electrode for nickel-metal hydride batteries among water-based batteries, it exhibits excellent characteristics (for example, cycle characteristics), and is used as a positive electrode for alkaline secondary batteries, a positive electrode for lithium ion batteries, etc. among non-aqueous batteries. Then, excellent characteristics (for example, cycle characteristics) are exhibited.

When assembling a battery using the battery electrode of the present invention, it is preferable to use an electrolyte obtained by dissolving an electrolyte in a non-aqueous solvent as the non-aqueous electrolyte. The electrolyte is not particularly limited, but in the case of an alkaline secondary battery, for example, LiClO ₄ , LiBF ₄ , LiAsF ₆ , CF ₃ SO ₃ Li, LiPF ₆ , LiI, LiAlCl ₄ , NaClO ₄ , NaBF ₄ , NaI , (N-Bu) ₄ NClO ₄ , (n-Bu) ₄ NBF ₄ , KPF _{6 and the} like.

  Non-aqueous solvents include, for example, ethers, ketones, lactones, nitriles, amines, amides, sulfur compounds, chlorinated hydrocarbons, esters, carbonates, nitro compounds, and phosphate esters. Examples thereof include compounds and sulfolane compounds. Among these, ethers, ketones, nitriles, chlorinated hydrocarbons, carbonates, and sulfolane compounds are preferable.

  Specifically, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, anisole, monoglyme, diglyme, triglyme, acetonitrile, propionitrile, 4-methyl-2-pentanone, butyronitrile, valeronitrile, benzonitrile, 1, 2-dichloroethane, γ-butyrolactone, dimethoxyethane, methyl formate, propylene carbonate, ethylene carbonate, dimethylformamide, dimethyl sulfoxide, dimethylthioformamide, sulfolane, 3-methyl-sulfolane, trimethyl phosphate, or triethyl phosphate, or And a mixed solvent thereof. In addition, it is preferable to use 5N or more potassium hydroxide aqueous solution as electrolyte solution for water based batteries.

  Furthermore, the battery assembled using the battery electrode of this invention can be comprised using components, such as a separator, a terminal, and an insulating board, as needed. The structure of the battery to be assembled is not particularly limited. For example, a positive electrode, a negative electrode, and a paper structure having a separator as a single layer or a multilayer, a positive electrode, a negative electrode, and a cylindrical structure in which a separator is wound in a roll shape. Etc.

  A battery (secondary battery) manufactured using the battery electrode of the present invention can be suitably used for AV equipment, OA equipment, communication equipment, and the like.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. In the examples and comparative examples, “parts” and “%” are based on mass unless otherwise specified.

  The obtained binder composition for an electrode battery was evaluated for various physical properties and various properties by the measurement methods shown below.

[Uniformity]:
The obtained binder composition for an electrode battery was placed in a 100 ml sample bottle and allowed to stand at room temperature for 3 days. The electrode battery binder composition after standing was visually observed, and the binder composition for an electrode battery was observed. The “uniformity” is evaluated according to the following criteria.
○: No separation of precipitates or solution was confirmed, transparent solution Δ: No separation of precipitates or solution was confirmed, but turbidity was confirmed solution ×: Separation of precipitates or solution was confirmed solution

[Preparation of paste for battery electrode]:
A battery electrode paste is prepared by mixing and stirring 100 parts of LiCoO ₂ as an active material, 3 parts of acetylene black, ₂ parts of an electrode battery binder composition (in terms of solid content) and 50 parts of NMP. The battery electrode paste is adjusted so that its viscosity is about 4000 mPa · s. The viscosity of the battery electrode paste is measured with a B-type viscometer (manufactured by Toki Sangyo Co., Ltd.) under conditions of a rotor rotational speed of 30 rpm.

[Preparation of battery electrode]:
The obtained battery electrode paste was applied onto an aluminum foil (current collector) and then dried at 120 ° C. for 20 minutes to obtain a film (electrode layer) having a film thickness of 100 μm and formed from the battery electrode paste. . Thereafter, the electrode layer is compressed so as to have a thickness of 60 μm by a roll press to produce a battery electrode for a positive electrode.

[Production of battery]:
In a two-pole coin cell (trade name “HS Flat Cell”, manufactured by Hosen Co., Ltd.), a product name “Piox Cell A100” manufactured by Pionics, which is punched to a diameter of 16.16 mm, is disposed as a negative electrode. A separator (trade name “Celguard # 2400”, manufactured by Celgard) made of a polypropylene porous film punched to a diameter of 18 mm is disposed on the negative electrode, and then an electrolyte is injected so that air does not enter. After that, a positive electrode punched out to a diameter of 15.95 mm in advance is placed in the bipolar coin cell into which the electrolyte is injected, the outer body of the bipolar coin cell is placed, and the screw is closed to produce a secondary battery. To do. As the electrolytic solution, a solution in which LiPF ₆ is dissolved at a concentration of 1 mol / liter in a solvent of ethylene carbonate / diethyl carbonate = 1/1 (volume / volume) is used.

[Adhesion to metal foil (current collector)]:
First, the battery electrode prepared in “Preparation of Battery Electrode” is cut out as a test piece having a width of 2 cm and a length of 10 cm. After a double-sided tape is attached to the surface of the electrode layer of the test piece, the test piece is attached to an aluminum plate with the double-sided tape. Thereafter, a 18 mm wide tape (trade name “Cello Tape (registered trademark)”, manufactured by Nichiban Co., Ltd.) defined in JIS Z1522, was attached to the surface of the aluminum foil (current collector) of the test piece, and 50 mm / 90 ° in the 90 ° direction. The strength (g / cm) when the tape is peeled off at a rate of minutes is measured 5 times, and the average value is calculated as the peel strength (g / cm). In addition, it can be evaluated that the greater the peel strength value, the better the adhesion between the current collector and the electrode layer, and the more difficult the electrode layer peels from the current collector.

[Capacity maintenance rate (%)]:
For the battery (lithium ion secondary battery) produced in “Battery production”, “charge / discharge” is performed 50 times in an atmosphere of 25 ° C., which is charged to 4 V by a constant current method of 0.2 C and then discharged to 3 V. Repeat (50 cycles). In this charging / discharging, after measuring the discharge capacity (mAh) at 5 cycles, 20 cycles, and 50 cycles, the discharge capacity (mAh / g) per 1 g of the active material is calculated. Using the calculated discharge capacity (mAh / g) per gram of active material, the capacity retention rate (%) at 20 cycles and 50 cycles is calculated from the following formula (1). The capacity maintenance ratio (%) is “D” when it is 59% or less, “C” when it is more than 59% and 74% or less, and “C” when it is more than 74% and 84% or less. "B", more than 84% and less than 100% was evaluated as "A".

[Internal resistance (Ω)]:
For the battery (lithium ion secondary battery) prepared in [Preparation of Battery], charge / discharge 50 to 3 V after charging to 4 V by a constant current method of 0.2 C in an atmosphere at 25 ° C. Repeated 50 times (after 50 cycles), and then calculate the internal resistance (Ω) when charging to 4.0V. In calculating the internal resistance, a linear relationship {(voltage) = (internal resistance) × (current)} is established among Ohm's law among the voltage, current, and DC resistance.

[Paste stability]:
The obtained battery electrode paste is placed in a 100 ml sample bottle and allowed to stand at room temperature for 2 days, and then 1 ml of the battery electrode paste at a position of 5 mm from the liquid surface of the battery electrode paste is sampled. Thereafter, the difference between the solid content concentration of the battery electrode paste immediately after the preparation and the solid content concentration of the battery electrode paste after standing is calculated to be “change in solid content concentration”. This “solid content concentration change” is evaluated as paste stability. In addition, paste stability is so favorable that the value of solid content concentration change is small.

(Synthesis Example 1)
The interior of an autoclave with an internal volume of about 6 liters equipped with an electromagnetic stirrer was sufficiently purged with nitrogen, then charged with 2.5 liters of deoxygenated pure water and 25 g of ammonium perfluorodecanoate as an emulsifier, and stirred at 350 rpm. The temperature was raised to 60 ° C. After raising the temperature, a mixed gas consisting of 44.2% vinylidene fluoride (hereinafter referred to as “VDF”) and 55.8% propylene hexafluoride (hereinafter referred to as “HFP”) was introduced into the autoclave. It charged until it reached 1.96 MPa. Thereafter, 25 g of Freon 113 (CCl ₂ FCClF ₂ ) solution containing 20% of diisopropyl peroxydicarbonate as a polymerization initiator was injected using nitrogen gas to start the polymerization reaction. During the polymerization reaction, a mixed gas composed of 60.2% VDF and 39.8% HFP was sequentially injected to maintain the pressure in the reaction system at 1.96 MPa. In addition, since the polymerization rate decreases with the progress of the polymerization reaction, 25 hours of Freon 113 solution containing 20% of diisopropyl peroxydicarbonate was injected into the reaction system using nitrogen gas after 3 hours from the start of polymerization. After the press-fitting, the reaction was continued for another 3 hours. After the reaction, the reaction solution was cooled to room temperature. Thereafter, stirring is stopped, the reaction is stopped by releasing unreacted monomers, and latex containing a polymer ((D) polymer) containing fluorine atoms (in Table 1, “(D) polymer” Labeled latex).

  Next, 10 parts of the obtained (D) polymer latex (in terms of solid content) and 200 parts of ion-exchanged water were charged into a separable flask. On the other hand, in a separate container from this separable flask, 90 parts of ion-exchanged water and 1 part of reactive emulsifier (trade name “ADEKA rear soap SR10” manufactured by Asahi Denka Kogyo Co., Ltd.), 20 parts of methyl methacrylate, n-butyl acrylate 67 parts, 10 parts of styrene, 2 parts of sodium styrene sulfonate (trade name “Spinomer NaSS”, manufactured by Tosoh Corporation) as a monomer having a sulfonic acid group, and 1 part of acrylic acid are emulsified with stirring and emulsified. Got. The obtained emulsion was put into a separable flask charged with (D) polymer latex and ion-exchanged water, and mixed to obtain a mixture. The resulting mixture was purged with nitrogen while stirring. Thereafter, the temperature was raised to 50 ° C., 0.6 part of potassium persulfate and 0.2 part of sodium sulfite were added, and the mixture was stirred for 3 hours while maintaining the temperature. After stirring, the temperature was raised to 75 ° C., and stirring was performed for 1 hour while maintaining the temperature. After stirring, the mixture is cooled to 25 ° C., adjusted to pH 7 with a 2% aqueous sodium hydroxide solution, and a composite polymer dispersion (a composite polymer in which (A) polymer and (D) polymer are combined) is prepared. Containing dispersion).

  The number average particle size of the composite polymer in the composite polymer dispersion (shown as “number average particle size” in Table 1) was 0.1 μm. The number average particle size of the composite polymer was measured using a light scattering measurement device “ALV5000” manufactured by ALV, which uses a 22 mW He—Ne laser (λ = 632.8 nm) as a light source. did. Moreover, the ratio of the structural unit derived from the monomer which has a sulfonic acid group in (A) polymer is 2 mass%, and (100) with respect to a total of 100 parts of (A) polymer and (D) polymer ( A) The proportion of the polymer was 90 parts.

  In Table 1, “nBA” means n-butyl acrylate, “MMA” means methyl methacrylate, “ST” means styrene, “AA” means acrylic acid, “IA” Means itaconic acid and “NASS” means sodium styrenesulfonate. Further, “(A) polymer” in Table 1 is the blending amount (part by mass) shown in Table 1, and “nBA”, “MMA”, “ST”, “AA”, “IA”, and “NASS”. ”Indicates that the polymer obtained by using (A) is a polymer.

(Synthesis Examples 2 to 4)
Except that (D) the polymer latex, n-butyl acrylate, methyl methacrylate, styrene, acrylic acid, itaconic acid, and sodium styrene sulfonate obtained in Synthesis Example 1 were used in the amounts shown in Table 1, In the same manner as in Synthesis Example 1, a composite polymer dispersion was obtained. However, since Synthesis Example 3 and Synthesis Example 4 were synthesized without using (D) polymer latex, not (A) polymer was dispersed in the obtained dispersion instead of the composite polymer. .

Example 1
[Preparation of binder composition for electrode battery]:
110 parts of the composite polymer dispersion obtained in Synthesis Example 1 (in terms of solid content) (shown as “dispersion” in Table 2) is added 1 part of taurine as the compound (B), and the first mixed liquid Then, (C) 1300 parts of n-methylpyrrolidone (shown as “NMP” in Table 2) as an organic solvent was added to obtain a second mixed solution. The obtained second mixed liquid was distilled under reduced pressure under the conditions of a pressure of 0.01 MPa and a temperature of 80 ° C. to evaporate the water, thereby obtaining an electrode battery binder composition. Taurine was added as an aqueous solution.

  The electrode battery binder composition of this example has a uniformity evaluation of ○, and the electrode layer produced using the electrode battery binder composition of this example has a peel strength of 50 g / cm. The capacity retention rate of the electrode battery produced using the binder composition for an electrode battery of the example is 86% at 20 cycles, 80% at 50 cycles, and the internal resistance is 51Ω. The paste stability evaluation (change in solid content concentration) of the battery electrode paste formed from the battery binder composition was “<1” (less than 1).

(Examples 2 to 7)
A binder composition for an electrode battery in the same manner as in Example 1, except that the dispersion of Synthesis Example 1 or Synthesis Example 4, the compound (B), and the organic solvent (C) were used in the amounts shown in Table 2. Got. About the obtained binder composition for electrode batteries, it carried out similarly to Example 1, and performed said various evaluation. The measurement results are shown in Table 2.

(Comparative Examples 1 and 2)
A binder composition for an electrode battery in the same manner as in Example 1, except that the dispersion of Synthesis Example 1 or Synthesis Example 2, (B) compound, and (C) organic solvent were used in the amounts shown in Table 3. Got. About the obtained binder composition for electrode batteries, it carried out similarly to Example 1, and performed said various evaluation. The measurement results are shown in Table 3.

(Comparative Example 3)
(B) A binder composition for an electrode battery was obtained in the same manner as in Example 1 except that 1 part of sodium dodecylbenzenesulfonate and 1 part of lauryltrimethylammonium chloride were added in place of the compound taurine. About the obtained binder composition for electrode batteries, it carried out similarly to Example 1, and performed said various evaluation. The measurement results are shown in Table 3. In addition, sodium dodecylbenzenesulfonate and lauryltrimethylammonium chloride were added as respective aqueous solutions.

(Comparative Example 4)
After the inside of the 7-liter separable flask was sufficiently purged with nitrogen, 3 parts of 2- (1-allyl) -4-nonylphenoxypolyethylene glycol sulfate ammonium was charged as an emulsifier and heated to 75 ° C. Next, 67 parts of n-butyl acrylate, 30 parts of styrene, 2 parts of acrylic acid, 1 part of itaconic acid and an appropriate amount of water were added and stirred at 75 ° C. for 30 minutes. Thereafter, 0.5 part of sodium persulfate was added as a polymerization initiator, and polymerization was carried out at 85 to 95 ° C. for 2 hours. The reaction was stopped by cooling to obtain an aqueous dispersion of a functional group-containing polymer (Synthesis Example 3). 900 parts of NMP and 1 part of taurine as a compound (B) were added to 100 parts of the solid content of the obtained aqueous dispersion. Taurine was added as an aqueous solution. Using a rotary evaporator with a water temperature set to 85 ° C., water was distilled off under reduced pressure conditions to obtain a binder composition for an electrode battery. About the obtained binder composition for electrode batteries, it carried out similarly to Example 1, and performed said various evaluation. The measurement results are shown in Table 3.

(Comparative Example 5)
First, 110 parts as a solid content of the composite polymer dispersion obtained in Synthesis Example 1 and 1300 parts of n-methylpyrrolidone as an organic solvent (C) were mixed to obtain a binder composition for an electrode battery.

Next, 1410 parts of the obtained binder composition for an electrode battery, 100 parts of LiCoO ₂ as an active material, and 3 parts of prepared acetylene black prepared in advance were mixed and stirred to prepare a battery electrode paste. The battery electrode paste was adjusted to have a viscosity of about 4000 mPa · s. The viscosity of the battery electrode paste was measured with a B-type viscometer (manufactured by Toki Sangyo Co., Ltd.) at a rotor rotation speed of 30 rpm. The prepared acetylene black was prepared by adding 50 ml of 2% taurine aqueous solution (containing 1 part of taurine in terms of solid content) and 3 parts of acetylene black to a 100 ml beaker, and maintaining a temperature of 80 ° C. And evaporating to dryness with stirring.

  The above various evaluations were carried out in the same manner as in Example 1 for the electrode battery binder composition obtained in this Comparative Example and the produced battery electrode paste. The measurement results are shown in Table 3.

  As is clear from Tables 2 and 3, the battery electrode binder compositions of Examples 1 to 5 and 7 have the same uniformity of the solution after standing as the battery electrode binder compositions of Comparative Examples 1 to 5. Degree or good. The battery electrode pastes obtained from the battery electrode binder compositions of Examples 1 to 6 have the same stability as the battery electrode pastes of Comparative Examples 1, 3, and 5 after standing. The electrode layer formed by the battery electrode paste obtained from the battery electrode binder compositions of Examples 1 to 4 is the same level as the electrode layer formed by the battery electrode paste of Comparative Examples 1 to 3. In addition to having adhesiveness to (current collector), that is, peel strength, a battery electrode provided with an electrode layer formed by the battery electrode paste obtained from the battery electrode binder compositions of Examples 1 to 7 is compared. Provided is a battery (secondary battery) having a better capacity retention ratio (%) and internal resistance (Ω) than the battery electrode provided with the electrode layer formed by the battery electrode paste of Examples 1 to 5. It was confirmed that it is possible. That is, the battery electrode binder compositions of Examples 1 to 7 have improved adhesion to the current collector and lithium ion mobility compared to the battery electrode binder compositions of Comparative Examples 1 to 5, In addition to being able to form an electrode layer having a good balance, it was confirmed that the electrode layer was suitable as a material for battery electrode paste that maintained properties such as the uniformity of the solution after standing.

  The binder composition for battery electrodes of the present invention can improve the adhesion to the current collector and the mobility of lithium ions, and can form an electrode layer having a good balance between them. The battery provided (secondary battery) has a good capacity retention rate (%) and internal resistance (Ω) (ie, low capacity reduction and excellent cycle characteristics), so AV equipment, OA equipment, communication equipment, etc. It can be suitably used as a battery material.

  The manufacturing method of the binder composition for battery electrodes of this invention can manufacture the binder composition for battery electrodes which can be used conveniently as battery materials, such as AV apparatus, OA apparatus, and communication apparatus.

  The battery electrode paste of the present invention can be suitably used as a battery material for AV equipment, OA equipment, communication equipment and the like.

  The battery electrode of the present invention can be suitably used as an electrode for batteries of AV equipment, OA equipment, communication equipment and the like.

  The battery electrode manufacturing method of the present invention can suitably manufacture battery electrodes for AV equipment, OA equipment, communication equipment, and the like.

Claims (15)

(A) a polymer having an anionic functional group;
(B) a compound having at least one anionic functional group and cationic functional group in the molecule;
Contain,
The usage-amount of the said (B) compound is a binder composition for battery electrodes which is 1-7 mass parts with respect to 100 mass parts of said (A) polymers .   The binder composition for battery electrodes according to claim 1, wherein the anionic functional group of the polymer (A) is a sulfonic acid group.   Furthermore, (B) The binder composition for battery electrodes of Claim 1 or 2 containing the polymer containing a fluorine atom.   The battery electrode binder composition according to claim 3, wherein the (A) polymer and the (D) polymer form a composite polymer.   The composite polymer is obtained by polymerizing a monomer having an anionic functional group for constituting the polymer (A) using the polymer (D) as a seed. The binder composition for battery electrodes as described. The anionic functional group of the compound (B) is at least one selected from the group consisting of a carboxyl group, a sulfonic acid group, an imido acid group, and a group represented by the formula: BO ₂ H ₂ ;
The cationic functional group of the (B) compound is at least one selected from the group consisting of an amino group, an imino group, an imidazolium group, and a pyridinium group. The binder composition for battery electrodes.   The compound (B) is (B-1) a compound having at least one amino group and a sulfonic acid group in the molecule, or (B-2) an amino group and a carboxyl group in the molecule, respectively. It is a compound which has at least one, The binder composition for battery electrodes as described in any one of Claims 1-6.   (C) The binder composition for battery electrodes as described in any one of Claims 1-7 which further contains an organic solvent. Obtaining a dispersion in which a polymer having an anionic functional group is dispersed;
Adding a compound having at least one anionic functional group and cationic functional group in the molecule to the obtained dispersion to obtain a first mixed liquid;
Mixing the first mixed liquid and the organic solvent to obtain a second mixed liquid;
Removing the water from the second mixed solution to obtain a binder composition for battery electrodes, and a method for producing a binder composition for battery electrodes.   The method for producing a battery electrode binder composition according to claim 9, wherein the dispersion is obtained by polymerizing a monomer having an anionic functional group in an aqueous solution.   The step of obtaining the dispersion comprises polymerizing a monomer having an anionic functional group in an aqueous solution using a polymer containing a fluorine atom as a seed in an aqueous solution to form the polymer containing the fluorine atom and the anionic functional group. The method for producing a binder composition for a battery electrode according to claim 9, which is a step of obtaining a dispersion in which a polymer in which a polymer having the polymer is dispersed is dispersed. The binder composition for battery electrodes manufactured by the manufacturing method of the binder composition for battery electrodes as described in any one of Claims 9-11. The binder composition for battery electrodes according to any one of claims 1 to 8,
A battery electrode paste containing an active material. Current collector,
A battery electrode comprising: an electrode layer formed by applying the battery electrode paste according to claim 13 on a surface of the current collector and drying the paste. A method for producing a battery electrode, wherein the battery electrode paste according to claim 13 is applied on the surface of a current collector and then dried at a temperature of 80 ° C or higher to form an electrode layer.