JPH08190912A - Manufacture of negative mix of nonaqueous secondary battery - Google Patents

Abstract

PURPOSE: To enhance long storage capability without drop in viscosity of a negative mix by adding a negative active material, a conductor, and a binder to a solvent under existing of a surfactant, and kneading to disperse them. CONSTITUTION: Carboxymethylcellulose and a compound represented by a specific formula as a surfactant are put in water in a dispersion tank 4 to prepare a solution of viscosity increasing agent. Polyvinylidene fluoride, acetylene black, graphite and SiSnO3 are put in the solution of viscosity increasing agent, and a stirring blade 3 and an anchor blade of a stirrer 1 are rotated to disperse them while viscosity is controlled to prepare a negative mix. The negative mix is applied to a copper foil, then dried to prepare a negative electrode. A aggregate such as a binder aggregate and a carbon aggregate in the negative mix is remarkably decreased, reaggregation of the dispersed materials is rarely produced. A secondary battery using this negative mix has long charge/discharge life.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a negative electrode mixture for non-aqueous secondary batteries.

[0002]

2. Description of the Related Art Lead batteries have been used as secondary batteries,
Alkaline storage batteries such as nickel-cadmium batteries are known. Recently, non-aqueous secondary batteries (particularly lithium secondary batteries) have been attracting attention as secondary batteries having higher energy density and higher energy efficiency.

In non-aqueous secondary batteries, lithium metal and lithium alloy are typical as the negative electrode active material. In this case, since lithium metal is mainly used for the negative electrode, it is not necessary to manufacture the negative electrode mixture, but it is necessary to manufacture the positive electrode mixture. The positive electrode mixture is usually prepared by adding a positive electrode active material such as manganese dioxide powder and a conductive agent such as acetylene black powder and graphite powder to a thickener aqueous solution such as polyvinyl alcohol (PVA) and mixing the mixture into a kneader. It is manufactured by adding a binder such as polytetrafluoroethylene dispersion to the resulting kneaded product, kneading again, and degassing in vacuum. As another method, in JP-A-63-236258, an active material, a conductive agent and a binder are added to a thickener solution containing a surfactant and an antifoaming agent and then kneaded. A method of manufacturing a positive electrode mixture is disclosed. Further, in JP-A-1-32067, a positive electrode active material, a conductive agent and a thickener are dry-mixed in advance, and then a diluent and a binder are added to the mixture separately or together and kneaded. A method for producing a positive electrode mixture is disclosed.

In a non-aqueous secondary battery using lithium metal or a lithium alloy as a negative electrode active material, lithium metal grows in a dendritic form during charge / discharge, an internal short circuit occurs, or the activity of the dendritic metal itself is high. There is a risk of ignition. On the other hand, in recent years, metal compounds and carbonaceous materials capable of occluding / releasing lithium have been put into practical use while avoiding such dangers. The negative electrode mixture of the non-aqueous secondary battery when using a metal compound or a carbonaceous material as the negative electrode active material can be obtained by dispersing the negative electrode active material and the like in the binder as described above. For example, a negative electrode sheet is prepared by using a negative electrode active material, scaly graphite (conductive agent), a mixture of polyvinylidene fluoride as a binder and a solvent mixed and dispersed (eg, JP-A-2-265167).
Issue).

[0005]

According to the study of the present inventors, a mixture for a negative electrode of a non-aqueous secondary battery obtained by adding a negative electrode active material, a conductive agent and a binder to a solvent and kneading and dispersing the mixture. , For example, when it was applied to a separator and the surface of the negative electrode sheet obtained by pressing with a roller, coarse aggregates remained, or it was revealed that there were coating film defects due to the loss of aggregates. . It was also clarified that this is due to aggregates of the conductive agent and the binder existing in the negative electrode mixture. According to the study by the present inventor,
It has been clarified that when the negative electrode active material, the conductive agent and the binder are added to a solvent and kneaded and dispersed, the above-mentioned agglomerates are generated because the viscosity tends to decrease. That is, since it is impossible to perform sufficient kneading and dispersion in a state where the viscosity is reduced,
This is because the dispersed state is hardly improved after the viscosity is reduced. It has been found that by using the surfactant of the present invention, a good dispersion state can be obtained in a relatively short time without lowering the viscosity. An object of the present invention is to provide a method for producing a negative electrode mixture for a non-aqueous secondary battery in which a negative electrode active material, a conductive agent, and a binder are uniformly dispersed, have high viscosity, and have almost no aggregates. It is in.

[0006]

Means for Solving the Problems The above-mentioned object is to add a negative electrode active material, a conductive agent and a binder to a solvent in the presence of a surfactant, and knead and disperse the non-aqueous secondary agent. This can be achieved by the method for producing the mixture for battery negative electrode.

The preferred embodiments of the production method of the present invention are as follows. 1) The production method described above, wherein the surfactant is a nonionic surfactant. 2) The surfactant has the following general formula (I): R- (S-A) _n ... (I) [wherein R represents a hydrophobic group or a group of a hydrophobic polymer,
n represents 1 or 2, and A is the following (1) to
(3):

[0008]

Embedded image

(Wherein R ¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, R ² represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ³ represents a hydrogen atom or a methyl group. R ⁴ represents a hydrogen atom, a methyl group, —CH ₂ COOM ¹ (provided that M ¹ represents a hydrogen atom, —NH ₄ or an alkali metal) or a cyano group, and X represents a hydrogen atom, —COOM ¹ (provided that M ¹ is as defined above or -CONH ₂ and Y is -COOM ¹ (where M ¹ is as defined above) and -SO ₃ M ¹ (where M ¹ is as defined above). , -OSO ₃ M ¹ (where M ¹ is as defined above), -CH
₂ SO ₃ M ¹ (where M ¹ has the same meaning as above), -CONHC (CH ₃ ).
₂ CH ₂ SO ₃ M ¹ (where M ¹ is as defined above) or -CO
NHCH ₂ CH ₂ CH ₂ N ⁺ (CH ₃ ) ₃ Cl ⁻ . ) Represents at least one selected from the group consisting of repeating units represented by ] The manufacturing method of the mixture for non-aqueous secondary battery negative electrodes of Claim 1 which is a compound represented by these.

3) The solvent contains 100% of the above surfactant.
The above-mentioned manufacturing method, which contains 0.01 to 0.1 part by weight with respect to parts by weight. 4) The above production method, wherein the solvent is water. 5) The above production method, wherein the solvent further contains a thickening agent such as carboxymethyl cellulose. 6) The negative electrode active material has the following general formula (II): MB _m (II) [where M is Si, Ge, Sn, Pb, Bi, Sb, P, B, Al and As.
Represents at least one selected from the group consisting of
The above-mentioned production method, which is a compound represented by at least one selected from the group consisting of O, S, Se and Te, and m is in the range of 1 to 10. 7) The above production method, wherein the binder is a fluororesin such as polyvinylidene fluoride. 8) The above production method, wherein the conductive binder is natural graphite (scaly graphite, flake graphite, earthy graphite, etc.), artificial graphite, carbon black and / or acetylene black. 9) Addition of the negative electrode active material, the conductive agent and the binder to the solvent in the presence of the surfactant adds the negative electrode active material, the conductive agent and the binder to the solvent containing the surfactant. The manufacturing method described above.

The manufacturing method of the present invention comprises a negative electrode mixture used for forming a negative electrode containing a negative electrode active material of a non-aqueous secondary battery comprising a positive electrode active material, a negative electrode active material and a non-aqueous electrolyte containing a lithium salt. It is a manufacturing method of an agent. An example of the manufacturing method of the present invention will be described with reference to FIG. In the dispersion tank 4,
A solvent containing a surfactant is charged, a negative electrode active material, a conductive agent and a binder are further charged, and then the stirring blade 3 for dispersion and the anchor blade 2 of the stirrer 1 are rotated to perform kneading dispersion. Generally, stirring is performed for 20 minutes to 2 hours. The obtained dispersion liquid (negative electrode mixture) is taken out by opening the valve 5.
The dispersion is generally 100-1000 mPa · S (25
C).

As the surfactant used in the present invention, any surfactant such as nonionic, anionic or cationic can be used. In the present invention, nonionic surfactants are preferred. Alternatively, the surfactant is
The compound of the following general formula (I) is preferred. R- (SA) _n ... (I) [wherein R represents a hydrophobic group or a group of a hydrophobic polymer,
n represents 1 or 2 (preferably 1), and A is the following (1) to (3):

[0013]

Embedded image

(Wherein R ¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, R ² represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ³ represents a hydrogen atom or a methyl group. R ⁴ represents a hydrogen atom, a methyl group, —CH ₂ COOM ¹ (provided that M ¹ represents a hydrogen atom, —NH ₄ or an alkali metal) or a cyano group, and X represents a hydrogen atom, —COOM ¹ (provided that M ¹ is as defined above or -CONH ₂ and Y is -COOM ¹ (where M ¹ is as defined above) and -SO ₃ M ¹ (where M ¹ is as defined above). , -OSO ₃ M ¹ (where M ¹ is as defined above), -CH
₂ SO ₃ M ¹ (where M ¹ has the same meaning as above), -CONHC (CH ₃ ).
₂ CH ₂ SO ₃ M ¹ (where M ¹ is as defined above) or -CO
NHCH ₂ CH ₂ CH ₂ N ⁺ (CH ₃ ) ₃ Cl ⁻ . ) Represents at least one selected from the group consisting of repeating units represented by ]

As the hydrophobic group of R in the above general formula (I),
Mention may be made of aliphatic hydrocarbon groups (eg alkyl, alkenyl and alkynyl), aromatic hydrocarbon groups (eg phenyl and naphthyl), alicyclic hydrocarbon groups and these groups having a substituent. As the substituent, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an alicyclic hydrocarbon group, a heterocyclic group, a halogen atom, a hydroxyl group, a cyano group, a nitro group, N-
Examples thereof include a substituted sulfamoyl group, a carbamoyl group, an acylamino group, an alkylsulfonylamino group, an alkoxy group, an aryloxy group, an aralkyl group and an acyl group. The above R is preferably an alkyl group, and particularly preferably an alkyl group having no substituent and an alkyl group substituted with a phenyl group. The number of carbon atoms in the alkyl group is 3
~ 70 is general, 4 ~ 50 is preferred, especially 8 ~ 24
Is preferred. Further, R is an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an alicyclic hydrocarbon group, and these groups having a substituent, and in the case of a hydrophobic polymer group, dispersion stability of the obtained dispersion liquid is obtained. This is preferable because it improves the property.

Examples of the hydrophobic polymer of the hydrophobic polymer group include polystyrene, copolymers containing styrene, polymethacrylic acid esters (eg, polymethylmethacrylate),
Copolymers containing methacrylic acid esters, polyacrylic acid esters, copolymers containing acrylic acid esters, water-insoluble polymers such as polybutene, polyvinyl acetate, polyvinyl chloride, and polyvinyl versatate, including vinyl versatate Examples thereof include water-insoluble copolymers, water-insoluble polyoxyalkylenes such as polyoxypropylene and polyoxytetramethylene, water-insoluble polyamides and water-insoluble polyesters. Among these, polystyrene, a copolymer containing styrene, a polymethacrylic acid ester, a copolymer containing a methacrylic acid ester, a polyacrylic acid ester, a copolymer containing an acrylic acid ester, and polyvinyl chloride are preferable. The polymerization degree of these polymers is preferably 2 to 500, more preferably 2 to 200, and particularly preferably 2 to 100.

The following are preferred examples of the hydrophobic group represented by R in the general formula (I).

[0018]

[Chemical 4]

[0019]

Embedded image

[0020]

[Chemical 6]

[0021]

[Chemical 7]

[0022]

Embedded image

[0023]

[Chemical 9]

[0024]

[Chemical 10]

[0025]

[Chemical 11]

[0026]

[Chemical 12]

A in the general formula (I) is a polymer represented by any of the above (1) to (3).
The repeating unit (1) constituting the polymer A includes a vinyl alcohol unit (that is, a unit corresponding to one vinyl alcohol monomer formed when vinyl alcohol becomes a polymer), α-methyl vinyl alcohol unit and α. Mention may be made of propyl vinyl alcohol units. Vinyl alcohol units are preferred. As the repeating unit (2) constituting the polymer A, a vinyl acetate unit,
Mention may be made of vinyl formate units, vinyl propionate units and their α-substituted units. Vinyl acetate units are preferred. As the repeating unit (3) constituting the polymer A, an acrylic acid unit, a methacrylic acid unit, a crotonic acid unit, a maleic acid unit, an itaconic acid unit, a vinylsulfonic acid unit, a vinylsulfuric acid unit, an acrylicsulfonic acid unit,
Methacrylsulfonic acid unit, 2-acrylamido-3-
Monomers capable of dissociating ions such as methylpropanesulfonic acid (the above acids may be ammonium salts, metal salts such as Na and K) units, acrylamidopropyltrimethylammonium chloride units and methacrylamideamidopropyltrimethylammonium chloride units. Units can be mentioned. Monomer units with carboxylic acids or sulphonic acids are preferred.

Repeating Units (1) to (1) Constituting Polymer A
(3) preferably accounts for 50 to 100 mol% of all units constituting the polymer A, and further 80 to 100 mol%.
Is preferred. When the repeating unit (3) is 1 mol%,
The repeating unit (1) has 50 to 10 of all units constituting the polymer A so that the polymer A has water dispersibility or water solubility.
It is preferably 0 mol%, and more preferably 80 to 100 mol%.

The surfactant represented by the above general formula (1) includes various surfactants having various properties from water solubility to water dispersibility. Therefore, the surfactant of the general formula (1) may contain other monomer units as long as it has water dispersibility or water solubility (preferably within the above range). Other monomer units include ethylene units, propylene units, isobutene units, acrylonitrile units, acrylamide units, methacrylamide units, N-vinylpyrrolidone units, vinyl chloride units and vinyl fluoride units. The polymerization degree of the polymer A is generally in the range of 10 to 3500, preferably in the range of 10 to 2000, and more preferably in the range of 10 to 1.
The range of 000 is preferable, and the range of 10 to 500 is particularly preferable.

Examples of the alkyl group represented by R ² in the repeating unit (2) include alkyl groups having 1 to 10 carbon atoms (eg, methyl, ethyl, propyl, isopropyl and butyl (its isomers)), A methyl group is particularly preferable. Further, the alkyl group may be substituted with a hydroxyl group, an amide group, a carboxyl group, a sulfonic acid group, a sulfinic acid group or a sulfonamide group.

In the repeating unit (3), R ³ is preferably a hydrogen atom, and R ⁴ is preferably a hydrogen atom or --CH ₂ COOM ¹ (provided that M ¹ is preferably a hydrogen atom or Na). X
Is preferably a hydrogen atom or -COOM ¹ (provided that M ¹ is preferably a hydrogen atom or Na), and Y is -COOM ¹ (provided that
M ¹ is preferably a hydrogen atom or Na) or -CONHC (CH
₃ ) ₂ CH ₂ SO ₃ M ¹ (wherein M ¹ is preferably a hydrogen atom or Na) is preferable.

In the surfactant represented by the above general formula (1), the relationship between the molecular weight of the portion represented by R and the molecular weight of the portion represented by A satisfies 0.01≤R / P≤2. It is preferable that 0.01 ≦ R / P ≦ 1 is particularly satisfied. The use of such a surfactant makes a great contribution to reduction of aggregates in the dispersion and improvement of dispersion stability.

Preferred examples of the surfactant represented by the above general formula (1) are shown in Table 1 below.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

[Table 3]

[0037]

[Table 4]

As the solvent for dissolving or dispersing the above-mentioned surfactant, water, dimethylformamide, N-methylpyrrolidone, methanol and the like can be mentioned. Water is preferred. Further, the solvent preferably contains the above surfactant in a proportion of 0.01 to 1 part by weight, particularly preferably 0.01 to 0.1 part by weight, relative to 100 parts by weight of the solvent.

The binder, the negative electrode active material and the conductive agent are dispersed in the solvent containing the above surfactant. As the binder, one kind or a mixture of polysaccharides, thermoplastic resins and polymers having rubber elasticity can be used.
For example, polymers of ethylenically unsaturated monomers, polyesters, polyurethanes, polyethers, polyamides, polyureas, polyurethanes, polysiloxanes, polycarbonates, epoxy resins, phenol resins, celluloses,
Mention may be made of sugars and sugar derivatives. Preferred examples include polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene / hexafluoropropylene copolymer, polyethylene, polypropylene, ethylene / propylene / cyclic diene polymer (EPDM), styrene / butadiene copolymer (SBR), Polymethyl methacrylate, polyvinyl acetate, polyacrylic acid, polyvinyl alcohol, polyvinylpyrrolidone, polymethyl vinyl ether, polyacrylamide, polyhydroxyethyl methacrylate, polyethylene adipate, polyvinyl acetal, polyvinyl butyral (polymers of ethylenically unsaturated monomers) , Hexamethylene diisocyanate / butanediol condensate (above polyurethane), hexamethylene diisocyanate / hexamethylene diamine Polymer (or polyurea), polyethylene oxide, polypropylene oxide (or polyether), polydimethylsiloxane (or polysiloxane), bisphenol A / epichlorohydrin addition polymer (or epoxy resin), phenol / formalin condensate (or phenol resin), Examples thereof include alginic acid, chitin, chitosan, agarose, gelatin (above sugars and saccharide derivatives) and carboxymethyl cellulose, cellulose acetate, hydroxypropyl cellulose (above celluloses). In addition to the above, a copolymer of a monomer constituting the polymer example of the ethylenically unsaturated monomer and another monomer may be used. The binders may be used alone or in combination of two or more. The form of the binder when added to the solvent may be any of powder, solution and dispersion (dispersion, emulsion). The addition amount of the binder is 0.
1 to 20% by weight is preferable, and 0.5 to 10% by weight is particularly preferable. The above polymer can be used by appropriately selecting it as a binder for the positive electrode mixture. As the binder for the negative electrode mixture, it is particularly preferable to use a fluororesin such as polytetrafluoroethylene, polyvinylidene fluoride, or a tetrafluoroethylene / hexafluoropropylene copolymer. When the solvent is water, it is preferable that a water-soluble resin such as carboxymethyl cellulose or polyvinyl alcohol is contained in the solvent as a thickener, and a water-insoluble binder and other materials are dispersed therein.

The electrode active material (negative electrode active material and positive electrode active material) used in the present invention may be any compound which can insert (occlude) and release H ⁺ , Li ⁺ , Na ⁺ and K ⁺ , and transition metal oxidation. Examples thereof include oxides, transition metal chalcogenides, carbonaceous materials, and oxides mainly composed of a metal group IVB or VB of the periodic table. In particular, a lithium-containing transition metal oxide, a transition metal oxide, a carbonaceous material, and an oxide mainly composed of a semimetal of Group IVB or VB of the periodic table can be mentioned (transition metals include Mn, Co, and Ni, V, and Fe are preferable, and Ge, Sn, Pb, Bi, and Si are preferable as the semimetal of Group IVB or VB of the periodic table.

A lithium-containing transition metal as the positive electrode active material
Oxides and transition metal oxides are preferable, and examples thereof include
LiCoO₂, LiNiO₂, LiCo_0.5 Ni_0.5 O
₂, LiMn₂O_Four, LiCoVO_Four, LiNiV
O_Four, LiCo_0.9 Sn_0.1 O₂, LiCo_0.9 Ti_0.1
 O₂ , LiCo_0.9 Al_0.1 O₂ , LiCo_0.9 In
_{0. 1} O₂ , LiCo_0.9 Y_0.1 O₂ , LiCo_0.9 Ce
_0.1 O₂ , Fe₃ O_Four , V₆ O₁₃And V₂ O_Five Give up
be able to. As the negative electrode active material, carbonaceous material and cycle
Compounds mainly composed of IVB or VB group metalloids are preferred.
New As a carbonaceous material, it has an X-ray diffraction spectrum
002 surface spacing is 3.35-3.80Å and the density is
1.1-1.7g / cm³ Materials are preferred, eg black
Lead, petroleum coke, cresol resin fired carbon, furan tree
Fat-fired carbon, polyacrylonitrile fiber-fired carbon, gas phase
Named grown carbon and mesophase pitch calcined carbon
Can be. Mainly composed of IVB or VB group semi-metals
Examples of the compound include SnO, SnO₂ , GeO, GeO
₂ , SnS, Li₂ SnO₃ , SiSnO₃ , SiGe
O₃ , SiPbO₃ , SnSi_0.9 Ge_0.1 O₃ , Sn
Si_0.8 Ge_0.2 O₃ , SnSi_0.5 Ge_0.5 O₃ , S
nSi_0.9 Pb_0.1 O₃ , SnSi_0.8 Pb_0.2 O₃ ,
SnSi_0.5 Pb_0.5 O₃ , SnGe_0.9 Si_0.1 O
₃ , SnGe_0.8 Si_0.2 O₃ , SnPb_0.9 Si_0.1 
O₃ , SnPb_0.8 Si_0.2 O₃ , SnSi_{0. 8} Pb
_0.1 Ge_0.1 O₃ , SnSi_0.8 P_0.2 O_3.1 , SnS
i_0.8 P_0.2 Al_0.2 O_3.4 , SnSi_0.6 P_0.4 O
_3.2 , SnSi_0.6 P_0.4 Al_0.2 O_3.5 , SnSi
_0.8 P_0.4 Sb_0.1 O_3.25, SnSi_0.6 P_0.2 Ge
_0.1 Al_0.1 O_{3. 05}, SnP₂ O₇ , SnP₂ Al_0.2 
O_7.3 And SnSi_0.2 P_0.8 Al_0.2 O_3.7 Give up
be able to.

The negative electrode active material has the following general formula (II): MB _m (II) [where M is Si, Ge, Sn, Pb, Bi, Sb, P, B, Al and As.
Represents at least one selected from the group consisting of
A compound represented by at least one selected from the group consisting of O, S, Se and Te, and m is in the range of 1 to 10] is preferable. Preferable compounds include those exemplified as the compounds mainly containing a semimetal of Group IVB or VB of the above Periodic Table.

In addition to the negative electrode active material and the binder, a conductive agent (a filler or the like) can be added to the negative electrode mixture. The positive electrode mixture can be produced in the same manner, but generally the use of the above surfactant is not always necessary. The conductive agent may be any electron-conductive material that does not cause a chemical change in the constructed battery. Usually, natural graphite (scaly graphite, flake graphite, earthy graphite, etc.), artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers and metals (copper, nickel, aluminum, silver (JP-A-63) No. 148554)))
Powder, metal fiber or polyphenylene derivative
9-20971) and the like, and may be contained as one kind or a mixture thereof. The combined use of graphite and acetylene black is particularly preferred. The amount added is not particularly limited, but is preferably 1 to 50% by weight of the negative electrode mixture, and particularly preferably 2 to 30% by weight. For carbon and graphite, 2 to 15% by weight is particularly preferable. Also, Sn
When the precursor of the electrode active material is made to have electronic conductivity like O ₂ is doped with Sb, the conductive agent can be reduced. In this case, 0 to 10% by weight is preferable.

As the filler, any fibrous material which does not cause a chemical change in the battery constructed can be used. Generally, olefin polymers such as polypropylene and polyethylene, fibers such as glass and carbon are used. The amount of the filler added is not particularly limited, but is preferably 0 to 30% by weight of the negative electrode mixture.

In the production method of the present invention, the negative electrode active material, the conductive agent and the binder are added to a solvent containing the surfactant and kneaded and dispersed using the disperser shown in FIG. It is done by Examples of the mixing and dispersing machine used for the above mixing and dispersing are a horizontal cylindrical mixer, a V-shaped mixer, a double cone type mixer, a paddle type mixer, a ribbon mixer, a planetary motion type mixer, a screw type mixer, A high speed fluid type mixer, a horizontal single-screw kneader and a horizontal double-screw kneader can be mentioned. Specifically, vertical ribbon mixers, horizontal ribbon mixers, vertical screw mixers, horizontal screw mixers, ball mills, pin mixers, double-arm kneaders, pressure kneaders, sand grinders, universal mixers and ladle machines. Can be mentioned. A ball mill is particularly preferable. These mixing and dispersing machines may be used alone or in combination.

The negative electrode mixture and the positive electrode mixture obtained above are applied to a current collector to form an electrode (sheet), and a battery is prepared using the following electrolyte and separator.

The electrolyte is generally composed of a solvent and a lithium salt (anion and lithium cation) which is soluble in the solvent. As the solvent, propylene carbonate, ethylene carbonate, butylene carbonate,
Dimethyl carbonate, diethyl carbonate, γ-butyrolactone, methyl formate, methyl acetate, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, Ethyl monoglyme, phosphoric acid triester (JP-A-60-23973)
JP-A-61-4170.
JP-A-62-1577.
1, JP-A-62-22372, JP-A-62-62
-108474), sulfolane (JP-A-62-3)
1959), 3-methyl-2-oxazolidinone (JP-A-62-44961), propylene carbonate derivative (JP-A-62-290069, JP-A-6-290069).
2-290071), tetrahydrofuran derivative (JP-A-63-32872), ethyl ether (JP-A-63-62166), 1,3-propanesultone (JP-A-63-102173). Aprotic organic solvents such as, and these are used alone or in combination of two or more. Examples of the cation of a lithium salt that dissolves in these solvents include ClO
_{^{4 -, BF 4 -, PF}} 6 -, CF 3 SO 3 -, CF 3 C
O ₂ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , (CF ₃ SO ₂ ) _{2
^{N -, B 10 Cl 10 2-}} ( JP 57-74974 JP), (1,2-dimethoxyethane) ₂ ClO ₄ ^- (JP 57-74977 JP), lower aliphatic carboxylic acid ion ( JP-A-60-41773), AlCl ₄
^{-, Cl -, Br -,} I - ( JP 60-247265
No.), an anion of a chloroborane compound (JP-A-61)
165957) and tetraphenyl borate ion (JP-A-61-214376).
These 1 type (s) or 2 or more types can be used.
Among them, propylene mosquitoes - BONNET - DOO or ethylene carbonate and 1,2-dimethoxyethane and / or LiCF ₃ SO ₃ in a mixture of diethyl carbonate, Li
An electrolyte containing ClO ₄ , LiBF ₄ and / or LiPF ₆ is preferred.

The amount of these electrolytes to be added to the battery is not particularly limited, but a necessary amount can be used depending on the amount of the positive electrode active material or the negative electrode active material and the size of the battery.

As the separator, an insulating thin film having a large ion permeability and a predetermined mechanical strength is used. A sheet or non-woven fabric made of olefin polymer such as polypropylene or glass fiber or polyethylene is used because of its resistance to organic solvent and hydrophobicity. The pore size of the separator is in the range generally used for batteries. For example, 0.01 to 10 μ
m is used. The thickness of the separator is generally within the range for batteries. For example, 5 to 300 μm is used.

The collector of the electrode active material may be any electron conductor as long as it does not undergo a chemical change in the constructed battery. For example, for the positive electrode, in addition to stainless steel, nickel, aluminum, titanium, calcined carbon, etc. as the material, carbon on the surface of aluminum or stainless steel,
Those treated with nickel, titanium or silver, and the negative electrode are made of stainless steel, nickel, copper, titanium,
In addition to aluminum and calcined carbon, copper, stainless steel whose surface is treated with carbon, nickel, titanium, or silver), an Al-Cd alloy, or the like is used. It is also used to oxidize the surface of these materials. The shape is
In addition to the foil, a film, a sheet, a net, a punched product, a lath body, a porous body, a foamed body, a molded body of a fiber group and the like are used. The thickness is not particularly limited, but is 1 to 5
Those having a diameter of 00 μm are used.

The shape of the battery can be any of coins, buttons, sheets, cylinders, corners and the like. When the shape of the battery is a coin or a button, the mixture of the positive electrode active material and the negative electrode active material is used by being compressed into a pellet shape. The thickness and diameter of the pellet are determined by the size of the battery. Further, when the shape of the battery is a sheet, a cylinder, or a corner, the mixture of the positive electrode active material and the negative electrode active material is applied (coated) on the current collector, dried and compressed, and is mainly used. As a coating method, 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. The blade method, knife method and extrusion method are preferred. The coating is preferably carried out at a speed of 0.1 to 100 m / min. At this time, a good surface condition of the coating layer can be obtained by selecting the above-mentioned coating method according to the solution physical properties and drying properties of the mixture. The thickness, length and width of the coating layer are determined by the size of the battery, but the thickness of the coating layer is particularly preferably 1 to 2000 μm in a compressed state after drying.

As a method for drying or dehydrating the pellets or sheets, 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 humidity air alone or in combination. The temperature is preferably in the range of 80 to 350 ° C, particularly 10
The range of 0 to 250 ° C. is preferable. The water content of the whole battery is preferably 2000 ppm or less, and the content of each of the positive electrode mixture, the negative electrode mixture and the electrolyte is preferably 500 ppm or less from the viewpoint of cycleability. As a pellet or sheet pressing method, a generally adopted method can be used, but a die pressing method or a calendar pressing method is particularly preferable. The pressing pressure is not particularly limited, but is 0.2 to 3 t /
cm ² is preferred. The press speed of the calendar press method is preferably 0.1 to 50 m / min. The pressing temperature is preferably room temperature to 200 ° C.

The mixture sheet is rolled or folded and inserted into a can, the can and the sheet are electrically connected, an electrolytic solution is injected, and a sealing plate is used to form a battery can. At this time, the safety valve can be used as a sealing plate. Other than safety valve,
Various conventionally known safety elements may be provided. For example, a fuse, a bimetal, a PTC element or the like is used as the overcurrent prevention element. In addition to the safety valve, a method of making a notch in the battery can, a method of cracking a gasket, or a method of cracking a sealing plate can be used as a measure for increasing the internal pressure of the battery can. Further, the charger may be provided with a circuit incorporating measures against overcharge and overdischarge. For the can and the lead plate, a metal or alloy having electrical conductivity can be used. For example, metals such as iron, nickel, titanium, chromium, molybdenum, copper and aluminum or alloys thereof are used. As a method for welding the cap, the can, the sheet, and the lead plate, a known method (eg, DC or AC electric welding, laser welding, ultrasonic welding) can be used. As the sealing agent for sealing, a conventionally known compound or mixture such as asphalt can be used.

[0054]

EXAMPLES The present invention will be described in more detail with reference to specific examples below, but the present invention is not limited to the examples as long as the gist of the invention is not exceeded.

Example 1 A negative electrode mixture was prepared by using the disperser shown in FIG. In the dispersion tank 4, 1 part by weight of carboxymethyl cellulose and the following compound as a surfactant:

[0056]

[Chemical 13]

50 parts by weight of water containing 0.05% by weight of was added to prepare a thickener solution. To this solution, 2 parts by weight of polyvinylidene fluoride, 1 part by weight of acetylene black, 3 parts by weight of graphite and 43 parts by weight of SiSnO ₃ were added, and a stirring blade 3 (disper blade) for dispersion of the stirrer 1 and an anchor blade 2 were added. Then, they were rotated at 2500 rpm and 60 rpm, respectively, and dispersed for 60 minutes while controlling the viscosity to obtain a negative electrode mixture. The solid content of the obtained negative electrode mixture was 50% by weight,
The apparent viscosity was 300 mPa · S (25 ° C.).

This negative electrode mixture was applied on a copper foil having a thickness of 20 μm using an extrusion type injector, and dried to prepare a negative electrode. When coating with an extrusion type injector, the distance between the tip of the slot nozzle and the copper foil is 0.2 mm, the slot clearance is 0.5 mm,
The width of the inlet side lip surface was 0.1 mm, and the conveying speed was 1 m / min.

[Example 2] In Example 1, the following compounds were used as surfactants:

[0060]

Embedded image

A negative electrode mixture and a negative electrode were produced in the same manner as in Example 1 except that the same amount was used.

Example 3 The following compounds were used as the surfactant in Example 1:

[0063]

[Chemical 15]

The same amount was used, and the stirring blade 3 for dispersion of the stirrer 1 was changed from a disper blade to a homomixer.
A negative electrode mixture and a negative electrode were prepared in the same manner as in Example 1, except that the negative electrode mixture was rotated at 00 rpm.

[Example 4] In Example 1, the following compounds were used as surfactants:

[0066]

Embedded image

The same amount was used, and the stirring blade 3 for dispersion of the stirrer 1 was changed from a disper blade to a homomixer.
A negative electrode mixture and a negative electrode were prepared in the same manner as in Example 1, except that the negative electrode mixture was rotated at 00 rpm.

Comparative Example 1 A negative electrode mixture and a negative electrode were prepared in the same manner as in Example 1, except that the surfactant was not used.

The negative electrodes (sheets) obtained in the above Examples and Comparative Examples were evaluated as follows. 1) The aggregates of binder existing on the surface of 1000 cm ² of the negative electrode sheet were visually counted. The number is shown. 2) The number of acetylene black (carbon) aggregates present on the surface of the negative electrode sheet 1000 cm ² was visually counted. The number is shown. The above results are shown in the table below.

Table ────────────────────────── Binder aggregate Carbon aggregate ──────────── ────────────── Example 1 0 0 Example 2 0 0 Example 3 0 0 Example 4 2 1 ───────────────── ────────── Comparative Example 1 36 7 ──────────────────────────

[0071]

According to the production method using the surfactant of the present invention, aggregates such as binder aggregates and carbon aggregates in the negative electrode mixture can be formed without lowering the viscosity of the negative electrode mixture. It can be drastically reduced. Further, the negative electrode mixture obtained in the present invention hardly causes reaggregation of the dispersion, and is excellent in long-term storage stability. The secondary battery prepared by using the negative electrode mixture obtained according to the present invention has an advantage that it has a long charge / discharge life.

[Brief description of drawings]

FIG. 1 shows a cross-sectional view of an example of a disperser that can be used in the manufacturing method of the present invention.

[Explanation of symbols]

 1 Stirrer 2 Anchor blade 3 Stirring blade 4 Dispersion tank 5 Valve

Claims (8)

[Claims] 1. A method for producing a mixture for a negative electrode of a non-aqueous secondary battery, which comprises adding a negative electrode active material, a conductive agent and a binder to a solvent in the presence of a surfactant, and kneading and dispersing the mixture. . 2. The method for producing a negative electrode mixture for a non-aqueous secondary battery according to claim 1, wherein the surfactant is a nonionic surfactant. 3. The surfactant has the following general formula (I): R- (S-A) _n ... (I) [wherein R represents a hydrophobic group or a group of a hydrophobic polymer,
n represents 1 or 2, and A is the following (1) to
(3): [Chemical formula 1] (However, R ¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R ² is a hydrogen atom or 1 to 6 carbon atoms.
10 represents an alkyl group, R ³ represents a hydrogen atom or a methyl group, R ⁴ represents a hydrogen atom, a methyl group, —CH ₂ COOM ¹
(Wherein M ¹ represents a hydrogen atom, —NH ₄ or an alkali metal) or a cyano group, X represents a hydrogen atom, —COOM ¹
(Wherein M ¹ has the same meaning as above) or -CONH ₂ , Y represents -COOM ¹ (where M ¹ has the same meaning as above),
-SO ₃ M ¹ (where M ¹ is as defined above), -OSO ₃ M
¹ (however, M ¹ has the same meaning as above), -CH ₂ SO ₃ M ¹ (however, M ¹ has the same meaning as above), -CONHC (CH ₃ ) ₂ CH ₂ SO ₃ M ¹
(However, M ¹ has the same meaning as above) or −CONHCH ₂ CH ₂ CH
Represents ₂ N ⁺ (CH ₃ ) ₃ Cl ⁻ . ) Represents at least one selected from the group consisting of repeating units represented by ] The manufacturing method of the mixture for negative electrodes of a nonaqueous secondary battery of Claim 1 which is a compound represented by these. 4. The negative electrode for a non-aqueous secondary battery according to claim 1, wherein the solvent contains a surfactant in a proportion of 0.01 to 0.1 part by weight based on 100 parts by weight of the solvent. Method of manufacturing mixture. 5. The negative electrode active material has the following general formula (II): MB _m ... (II) [wherein M is Si, Ge, Sn, Pb, Bi, Sb, P, B, Al and As
Represents at least one selected from the group consisting of
The compound for a negative electrode of a non-aqueous secondary battery according to claim 1, which is a compound represented by at least one selected from the group consisting of O, S, Se and Te, and m is in the range of 1 to 10. Method of manufacturing agent. 6. The method for producing a mixture for a negative electrode of a non-aqueous secondary battery according to claim 1, wherein the solvent is water. 7. The method for producing a mixture for a negative electrode of a non-aqueous secondary battery according to claim 1, wherein the binder is a fluororesin. 8. The method for producing a negative electrode mixture for a non-aqueous secondary battery according to claim 1, wherein the solvent contains a thickener.