JPH08124561A - Method for producing electrode plate for non-aqueous electrolyte secondary battery and active material coating solution used in the method - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to easily obtain a coating film having a thin film thickness and uniform over the entire surface, thereby making it possible to mass-produce nonaqueous electrolyte secondary battery electrode plates more easily. To do. [Structure] A powdery active material, a powdery conductive material, and a binder are mixed in a predetermined solvent to prepare a slurry-form active material coating solution, which is applied to the surface of a current collector, and then the solvent is applied. Non-aqueous electrolyte solution 2 that removes and forms a coating film on the collector
A method of manufacturing an electrode plate for a secondary battery, comprising a binder that is insoluble in a non-aqueous electrolyte solution and soluble in the solvent as the binder.

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 an electrode plate for a non-aqueous electrolyte secondary battery, which comprises forming a coating film of an active material on a metal foil current collector, and particularly to a thin film and The present invention relates to a method for producing an electrode plate for a non-aqueous electrolyte secondary battery, which can easily obtain a uniform coating film over the entire surface, and an active material coating solution used in the method.

[0002]

2. Description of the Related Art In recent years, electronic devices and communication devices have been rapidly reduced in size and weight. Secondary batteries used as power sources for driving these devices are also strongly required to have high energy density and high voltage. A non-aqueous electrolyte secondary battery represented by a lithium-ion secondary battery has been proposed instead of an alkaline storage battery. Here, regarding the electrode plate that greatly affects the performance of the secondary battery, it is proposed to increase the area of the thin film in order to extend the charge / discharge cycle life and increase the energy density. For example, Japanese Patent Laid-Open No. 63-1045
No. 6, JP-A-3-285262, etc. describe positive electrode active material powders such as metal oxides, sulfides, and halides.
A positive electrode obtained by adding a solution of a conductive agent and a binder (binder) dissolved in an appropriate wetting agent (solvent) to prepare a paste-like active material coating solution, and coating the solution on a metal foil current collector. A board is disclosed. As the binder, for example, a fluororesin such as polyvinylidene fluoride or a silicone = acrylic copolymer is used. The binder contained in the active material coating solution has been required to be electrochemically stable with respect to the nonaqueous electrolytic solution and not to be eluted into the nonaqueous electrolytic solution.

Since it is particularly important to increase the area of the thin film in order to increase the energy density of the battery,
It was necessary to easily obtain a coating film having a small thickness and uniform over the entire surface (so-called coating performance). Therefore, when actually manufacturing the electrode plate, the coating performance of the active material coating liquid is adjusted by heating the active material coating liquid (paste) to a viscosity at which it can be molded.

[0004]

However, conventionally,
When preparing a coated electrode plate, it is not taken into consideration whether the binder in the active material coating solution is soluble in the solvent (dispersion medium). Therefore, the coating performance of the active material coating solution is relatively low. Since it had to be applied until now, it was not possible to easily obtain a thin coating film and a uniform coating film over the entire surface, which was a hindrance to mass production of electrode plates. Was there.

[0005]

The present invention has been made in view of the above problems, and it is easy to obtain a coating film having a thin film thickness and uniform over the entire surface, thereby facilitating mass production. In order to carry out, a powdery active material, a powdery conductive material and a binder to prepare a slurry active material coating liquid mixed with a predetermined solvent, the coating liquid is applied to the surface of the current collector,
A method of manufacturing an electrode plate for a non-aqueous electrolyte secondary battery, in which a solvent is then removed to form a coating film on a current collector, wherein the binder is insoluble in the non-aqueous electrolyte solution and not in the solvent. The present invention provides a method for manufacturing an electrode plate for a non-aqueous electrolyte secondary battery, which is characterized by using a soluble binder.

Further, the present invention is a slurry-like non-aqueous electrolyte prepared by mixing a powdery active material, a powdery conductive material and a binder in a predetermined solvent, and coating the active material for producing an electrode plate for a secondary battery. In the liquid, the binder is insoluble in the non-aqueous electrolyte and soluble in the solvent, to provide an active material coating liquid.

[0007]

According to the present invention, the use of a binder that is insoluble in the non-aqueous electrolytic solution and soluble in the solvent as the binder improves the coating performance. It is possible to easily obtain a uniform coating film over the entire area.

As described above, when the binder selected has a predetermined relationship (with respect to solubility) with the solvent and the non-aqueous electrolyte, it does not elute into the non-aqueous electrolyte and also electrochemically. Since a stable coating film can be formed, it is possible to sufficiently use a synthetic resin other than the thermosetting resin as the binder.

Specifically, such coating performance can be obtained by selecting a binder, a solvent and a non-aqueous electrolytic solution having the following relative solubility parameters.

That is, a solvent having a solubility parameter difference of 4 or more between the non-aqueous electrolytic solution and the solvent is used as the solvent, and the solubility parameter difference between the solvent and the binder is used as the binder. It is to use a binder having a difference of 2 or less. Further, preferably, a solvent having a solubility parameter difference of 6 or more between the non-aqueous electrolytic solution and the solvent is used as the solvent, and the solubility parameter between the solvent and the binder is used as the binder. The use of a binder having a difference of 1 or less.

If the difference in solubility parameter between the non-aqueous electrolyte solution and the binder is 4 or less, the non-aqueous electrolyte solution may be dissolved in the electrolyte solution and may not be usable for a long time.

On the other hand, when the difference in solubility parameter between the binder and the solvent is 2 or more, the binder is dissolved in the solvent to some extent by heating and stirring, but an ink (varnish) containing a binder with a high concentration is formed. Difficult, that is, the solid content is reduced. When the solid content is low, when applying with a blade coater or the like, unless the gap between the current collector and the blade is increased, it is difficult to obtain the final film thickness of the target. For example, in the case of an active material-containing coating liquid with a solid content of 50%, If the coating film thickness is 200 μm before drying, a coating film of about 100 μm is formed after drying.

Further, when the binder (binder) is difficult to dissolve in the solvent (for example, if only 10% of the binder is soluble in the solvent), the solid content is further reduced, and a 100 μm coating film is obtained when dried. Then, about 5 times 5
The blade coater must be set and coated with a gap of 00 μm. In this case, since the amount of solvent is large, the only way to dry is to raise the drying temperature, lengthen the drying unit, or reduce the drying speed to slowly dry. When the drying temperature rises, there is a risk that voids are likely to occur on the coating surface due to rapid drying. In addition, lengthening the drying unit is not preferable because it requires equipment costs. Furthermore, it is not preferable to perform the drying time slowly because the number of processed sheets and the amount of processing per unit time are reduced. From the above, if the solubility parameters of the solvent and the binder are too far apart (2 or more), application of the active material mixture having a high solid content cannot be obtained, and various problems occur, which is not preferable.

In the present invention, the non-aqueous electrolyte secondary battery is represented by a lithium secondary battery. That is, examples of the positive electrode active material include lithium oxides such as LiCoO ₂ and LiMn ₂ O ₄ , TiS ₂ , MnO ₂ , MoO ₃ , and V.
Among chalcogen compounds such as ₂ O _{5 and the} like, one kind or a plurality of kinds are used in combination, and as a negative electrode active material, lithium, a lithium alloy, or a carbonaceous material such as graphite, carbon black or acetylene black is preferably used. Particularly, by using LiCoO ₂ as the positive electrode active material and the carbonaceous material as the negative electrode active material, a high discharge voltage of about 4 V can be obtained.

The electrode plate in the present invention is kneaded or dispersed with the above-mentioned powdery active material using a binder (binder) and a suitable dispersion medium to prepare an active material coating liquid, which is made of aluminum, It is obtained by coating a metal foil current collector such as copper or stainless steel. It is preferable to mix graphite, carbon black, acetylene black, metal powder and the like as a conductive agent with the active material coating liquid.

As the binder, for example, thermoplastic resin, that is, polyester resin, polyamide resin, polyacrylic acid ester resin, polycarbonate resin, polyurethane resin, cellulose resin, polyolefin resin,
It can be arbitrarily selected from polyvinyl resin, fluorine resin, polyimide resin and the like.

On the other hand, as the electrolytic solution used to form the secondary battery, a non-aqueous electrolytic solution prepared by dissolving a solute lithium salt in an organic solvent is used.

The organic solvent includes cyclic esters, chain esters, cyclic ethers, chain ethers, etc. For example, the cyclic esters include propylene carbonate, butylene carbonate, γ-butyrolactone and vinylene carbonate. 2-methyl-γ-butyrolactone, acetyl-γ-butyrolactone, γ-valerolactone, etc., and chain esters include dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dipropyl carbonate, methyl ethyl carbonate, methyl ethyl. Carbonate, methyl butyl carbonate, methyl propyl carbonate, ethyl butyl carbonate, ethyl propyl carbonate, butyl propyl carbonate, alkyl propionate, dialkyl malonate And alkyl acetate, etc., and cyclic ethers include tetrahydrofuran, alkyltetrahydrofuran, dialkylalkyltetrahydrofuran, alkoxytetrahydrofuran, dialkoxytetrahydrofuran, 1,3-dioxolane, alkyl-3-dioxolane, 1,4-dioxolane. , And as chain ethers,
1,2-dimethoxyethane, 1,2-diethoxyethane, diethyl ether, ethylene glycol dialkyl ether, diethylene glycol dialkyl ether,
Examples include triethylene glycol dialkyl ether and tetraethylene glycol dialkyl ether.

Since the above-mentioned electrolytic solution requires the movement of lithium ions, a solvent having a large polarity is generally used. The solubility parameter of the electrolytic solution described in the Polymer Handbook is, for example, diethyl carbonate 18.
0, propylene carbonate is 13.3, ethylene carbonate is 14.7, caprolactone is 10.1, and tetrahydrofuran is 9.1.

The solubility parameters of various solvents are, for example, 7.3 for n-hexane and 8.
8, toluene 8.9, ethyl acetate 9.1, benzene 9.2, styrene 9.3, methyl ethyl ketone 9.3, chloroform 9.3, acetone 9.9, acetonitrile 11.9. , Methanol is 14.5 and water is 23.4.

As a polymer which is insoluble in the electrolytic solution and soluble in the solvent, when a polymer having a value which is greatly different from the parameter of the electrolytic solution and has a value close to the solubility parameter of the coating solvent is selected, the polymer is selected as the coating solvent. Soluble,
Insoluble in electrolyte.

The solubility parameters of some of the polymers listed in the Polymer Handbook are listed below. For example, polybutadiene has a solubility parameter of 7.2-8.
4, polyethylene 7.7, polyisobutene 7.1
8.6 for polystyrene and 12. for polyacrylonitrile.
35, polymethacrysanmethyl ester was 9.1, polyisoprene (1,4-cis form) was 7.4, polyisoprene (natural rubber) was 7.9, and polyvinyl alcohol was 12.6. Further, the copolymer is, for example,
Poly (butadiene-acrylonitrile) (copolymerization ratio of 80/20) is 9.0, poly (butadiene-acrylonitrile) (70/30) is 9.8 to 9.9, poly (butadiene-styrene) (94/4) ) Is 8.0 to 8.1, poly (butadiene-styrene) (90/10) is 8.4, poly (butadiene-styrene) (70/30) is 8.5,
Polystyrene is 8.5 to 10.3, polymethyl acrylate is 9.5 to 12.8, and polyvinyl acetate is 8.
It is 8-10.2.

In view of the solubility parameters of the electrolyte, the dispersion solvent and the polymer, it is considered that the increase of the acrylonitrile component in the copolymer poly (butadiene-acrylonitrile) causes the increase of the solubility parameter (polyacrylonitrile (Solubility parameter is 12.4), it may dissolve in electrolyte solution. Also, in poly (butadiene-styrene), increasing the styrene content also increases the solubility parameter. From this, it is preferable to select a polymer having as few polar groups as possible or a polymer soluble in a solvent having an extremely large solubility parameter (23.4) such as water.

Here, when the polymer and the coating solvent satisfying the above conditions are selected, the following combinations are obtained. For example, poly (butadiene) and toluene, polyethylene and toluene, poly (butadiene-styrene) (90
/ 10) and toluene, poly (butadiene-styrene) 9
4/4) and toluene, poly (butadiene-styrene)
Examples thereof include (70/30) and toluene. However, it is not limited to toluene alone, and it is sufficient that the polymer is dissolved and the polymer is not dissolved in the electrolyte solvent. Further, although polyvinyl alcohol depends on its saponification degree, those soluble in water can be used because they do not dissolve in the electrolyte.

The thermal properties of the binder also limit the choice of polymer. That is, the softening point of the thermoplastic resin is not preferable in the manufacturing process because the heat treatment temperature must be high if it is too high, and if it is too low, it becomes a softened state even at room temperature and peels or particles due to the flow of the coating film. Both of them are not preferable because they may come off. The preferred softening point is, for example, 30 ° C to 200 ° C, more preferably 50 ° C.
~ 170 ° C. Further, in order to maintain the particle shape after the active material coating film is formed by softening and melting of the particulate binder and prevent coating of the active material and conductive material particles, the elastic modulus of the thermoplastic resin during softening is high to some extent. It is necessary.

The active material coating liquid is prepared by mixing a composition in which a particulate binder, a powdery active material, water, a dispersant consisting of an organic solvent of toluene, and a conductive material, if necessary, with a homogenizer, which has been publicly known. A ball mill, a sand mill, a roll mill or the like may be used for mixing and dispersion.

The active material coating solution thus prepared is applied to a metal foil current collector and gravure coat, gravure reverse coat, roll coat, Meyer bar coat, blade coat, knife coat, air knife coat, comma coat, slot. Using a coating method such as die coating, slide die coating, or dip coating, the dry thickness is 10 to 2
The coating is performed in the range of 0 μm, preferably 50 to 150 μm.

After coating the metal foil current collector with the active material coating liquid,
After removing the dispersion medium or at the same time, heat treatment with a dryer, an electric furnace, or the like, or irradiation with electrolytic radiation by an ultraviolet lamp, an electron beam irradiation device, a γ-ray irradiation device, or the like, the particulate binder and the active material of the present invention Also, the active material coating film can be obtained by expressing the adhesive force with the surface of the conductive material particles.

Further, in order to improve the homogeneity of the coating film, it is also preferable to obtain the electrode plate of the present invention by performing a press treatment using a metal roll, a heating roll, a sheet press machine or the like. Press conditions are about 500 kgf / c
If it is less than m ^2, it is difficult to obtain the uniformity of the coating film.
If it is 500 kgf / cm ² or more, the electrode plate itself including the current collector substrate will be damaged. More preferable pressing conditions are about 30
It is from 00 to 5000 kgf / cm ² .

Before moving to a battery assembling process using this electrode plate, in order to remove water in the electrode plate active material coating film,
Further, it is preferable to perform heat treatment, reduced pressure treatment and the like.

LiCl is used as the lithium salt of the solute.
_{O 4, LiBF 4, LiPF 6} , LiAsF 6, LiC
1, inorganic lithium salts such as LiBr, and LiB (C ₆ H
₅ ) ₄ T, LiN (SO ₂ CF ₃ ) ₂ , LiC (SO ₂
CF ₃ ) ₃ , LiOSO ₂ CF ₃ , LiOSO ₂ C ₂ F
₅ , LiOSO ₂ C ₃ F ₇ , LiOSO ₂ C ₄ F ₉ , L
iOSO ₂ C ₅ F ₁₁ , LiOSO ₂ C ₆ F ₁₃ , LiOS
There are organic lithium salts such as O ₂ C ₇ F ₁₅ .

[0032]

【Example】

<Example 1> (Positive electrode plate) 90 parts by weight of LiCoO ₂ powder having a particle size of 1 to 100 μm, 5.0 parts by weight of graphite powder as a conductive material, polyvinylidene fluoride resin (Neotron VDF-850) as a binder, 5.0 parts by weight of Daikin Industries, Ltd. and 20 parts by weight of N-methylpyrrolidone were mixed by stirring with a homogenizer at a rotation speed of 8000 rpm for 10 minutes to obtain a slurry-like positive electrode active material mixture.

Next, the positive electrode active material mixture described above is applied to one side of a current collector made of an aluminum foil having a thickness of 20 μm using a comma roll coater, and then it is heated in an oven at 110 ° C. for 2 hours.
It was dried for another minute and further dried in an oven at 120 ° C. for 2 minutes to remove the solvent to obtain a positive electrode plate having a 100 μm-thick active material mixture coating film formed on the current collector.

The positive electrode plate thus obtained was aged in a vacuum oven at 80 ° C. for 48 hours to remove water. (Negative electrode plate) Next, 80 parts by weight of graphite powder (LFG, manufactured by Lonza Japan Co., Ltd.), polybutadiene rubber (manufactured by Nippon Zeon Co., Ltd., Nipol BR-1220).
20 parts by weight of L) and 225 parts by weight of toluene as a dispersion solvent were mixed and dispersed at 8,000 rotations using a homogenizer. The obtained negative electrode coating liquid was applied to a rolled copper foil using a comma roll coater and dried in the same manner as the positive electrode plate. The film thickness of the obtained negative electrode plate was 100 μm. (Battery assembly) Using the positive electrode and the negative electrode obtained above,
First, the electrode is wound spirally through a separator made of a polyolefin-based (polypropylene, polyethylene, or copolymer thereof) porous film having a three-dimensional pore structure (sponge-like structure) wider than the positive and negative electrode plates. Made up the body. Next, this electrode body was inserted into a bottomed cylindrical stainless steel container which also serves as a negative electrode terminal, and an AA size battery having a rated capacity of 500 mAh was assembled. EC to this battery
Volume ratio of (ethylene carbonate): PC (propylene carbonate): DME (dimethoxyethane) 1: 1:
In a mixed solvent prepared so that the total amount becomes 1 liter in 2,
A solution in which 1 mol of LiPF ₆ was dissolved as a supporting salt was used as an electrolytic solution and injected.

To measure the battery characteristics, a charge / discharge measuring device was used for each 20 cells at a temperature of 25 ° C., with a maximum charging current of 0.2 CmA and a battery voltage of 4.1 V from the charging direction. Charge, discharge for 10 minutes, then discharge at the same current until 2.75V, and after 10 minutes, charge and discharge are repeated 100 cycles under the same conditions. The measurement was performed (see the table below for the measurement results).

After the measurement, the battery was disassembled and the negative electrode plate was confirmed. As a result, there was no evidence that the active material coating film was dissolved in the electrolytic solution, and the amount of polymer eluted in the electrolytic solution was confirmed for confirmation. Was measured by gas chromatography, the polymer was not detected at all.

Example 2 A positive electrode plate was made of the same material and method as in Example 1.

The negative electrode plate was made of 80 parts by weight of graphite powder (SFG-6 manufactured by Lonza Japan Co., Ltd.) and poly (styrene-
Butadiene rubber) (TR-20, manufactured by Japan Synthetic Rubber Co., Ltd.)
No. 00) was mixed with 20 parts by weight of toluene as a dispersion solvent at a mixing ratio of 212 parts by weight to obtain a slurry-like negative electrode active material mixture by the same method as in Example 1, and then this mixture was mixed with Example 1. In the same manner, a current collector (Fukuda Metal Foil Industry Co., Ltd., electrolytic copper foil 18 μm) was applied and dried to obtain a negative electrode plate having an active material mixture coating film formed thereon. The film thickness after drying was 80 μm.

Using the same method and materials as in Example 1, the battery was assembled and the charge / discharge characteristics (see the table below for the measurement results) were examined. Then, in the same manner as in Example 1,
The polymer dissolved in the electrolyte was measured and was not detected.

Example 3 The positive electrode plate was made of the same material and method as in Example 1.

The negative electrode plate was 80 parts by weight of graphite powder (SFG-6 manufactured by Lonza Japan Co., Ltd.), 20 parts by weight of polyvinyl alcohol (KH-17 manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), and 200 parts by weight of pure water as a dispersion solvent. The mixture was mixed at a mixing ratio of 1 to obtain a slurry negative electrode active material mixture in the same manner as in Example 1, and then a current collector (manufactured by Fukuda Metal Foil Industry Co., Ltd., electrolysis) in the same manner as in Example 1. A copper foil (18 μm) was applied and dried to obtain a negative electrode plate. The film thickness was 100 μm.

Using the same method and material as in Example 1, a battery was assembled and the charge / discharge characteristics (see the table below for the measurement results) were examined. Then, in the same manner as in Example 1,
The polymer dissolved in the electrolyte was measured and was not detected.

Comparative Example 1 (Positive electrode plate) 90 parts by weight of LiCoO 2 powder as an active material, 5.0 parts by weight of graphite powder as a conductive material, polyvinylidene fluoride resin (neoflon VDF-) as a binder.
850, manufactured by Daikin Industries, Ltd.) 5.0 parts by weight and N-
20 parts by weight of methylpyrrolidone was stirred and mixed with a homogenizer at a rotation speed of 8000 rpm for 10 minutes to obtain a slurry-like positive electrode active material mixture.

Next, the positive electrode active material mixture described above was applied to one side of a current collector made of an aluminum foil having a thickness of 20 μm using a slot die coater, followed by drying for 2 minutes in an oven at 100 ° C. Was removed to form an active material mixture coating film having a thickness of 80 μm on the current collector.

The obtained electrode plate was aged for 48 hours in a vacuum oven at 80 ° C. to remove water. (Negative electrode plate) As for the negative electrode, 90 parts by weight of graphite powder, 10 parts by weight of poly (acrylonitrile-butadiene rubber) (Nipol 1042 manufactured by Nippon Zeon Co., Ltd.) and 150 parts by weight of ethyl acetate were rotated with a homogenizer at a rotation speed of 8
The mixture was stirred and mixed at 000 rpm for 10 minutes to obtain a slurry-like negative electrode active material mixture.

Next, the above-mentioned negative electrode active material mixture was applied to both sides of each of the current collectors made of copper foil having a thickness of 10 μm using a slot die coater, followed by drying in an oven at 100 ° C. Was removed to obtain an active material mixture coating film having a thickness of 90 μm on the current collector. (Battery assembly) Through a separator made of the same microporous film of polyolefin (polypropylene, polyethylene or copolymers thereof) as in Example 1,
The electrode body was first constructed by spirally winding. Next, this electrode body was inserted into a bottomed cylindrical stainless steel container which also serves as a negative electrode terminal, and an AA size battery having a rated capacity of 500 mAh was assembled. In this battery, EC (ethylene carbonate): PC (propylene carbonate): DME
(Dimethoxyethane) was added as a supporting salt to a mixed solvent prepared in a volume ratio of 1: 1: 2 to a total volume of 1 liter.
A solution obtained by dissolving moles of LiPF ₆ was used as an electrolytic solution and injected.

To measure the battery characteristics, a charge / discharge measuring device was used for each 20 cells at a temperature of 25 ° C., with a maximum charging current of 0.2 CmA and a battery voltage of 4.1 V from the charging direction. Charge, discharge for 10 minutes, then discharge at the same current until 2.75V, and after 10 minutes, charge and discharge are repeated 100 cycles under the same conditions. It was measured.

After the measurement, the negative electrode was dissolved by the electrolytic solution,
The membrane surface was affected.

Comparative Example 2 A positive electrode plate was prepared by using the same method and materials as in Example 1.

The negative electrode plate was composed of 80 parts by weight of graphite powder and polyester resin (manufactured by Toyobo Co., Ltd., Byron 30).
0) 10 parts by weight and 200 parts by weight of methyl ethyl ketone were mixed with a homogenizer at a rotation speed of 8000 rpm for 10 times.
By stirring and mixing for a minute, a negative electrode active material mixture in a slurry form was obtained, and using this mixture, a negative electrode plate was produced in the same manner as in Example 1.

A battery was prepared in the same manner as in Example 1 and the charge / discharge characteristics were measured. However, when the battery was disassembled after the measurement was completed, the electrodes were dissolved by the electrolytic solution.

A battery is constructed by using each of the electrode plates, and the results of evaluating the battery characteristics are shown in the table below.

1 cycle capacity 100 cycle capacity Capacity retention rate (%) Example 1 100 92 92.0 Example 2 96 91 94.8 Example 3 97 90 92.8 Comparative Example 1 83 72 86.7 Comparative Example 2 79 59 74.7 The discharge capacity in the first cycle of Example 1 was set to 100. In the batteries of Example 1, Example 2 and Example 3, the initial capacity at the first cycle was larger than that of Comparative Examples 1 and 2, and the discharge capacity after 100 cycles was relatively high. It showed a large capacity and a high capacity retention rate.

On the other hand, the batteries of Comparative Example 1 and Comparative Example 2 were compared with the batteries of Example 1, Example 2 and Example 3
The discharge capacity at the cycle was small, and the capacity retention rate after 100 cycles was inferior.

As described above, the batteries produced in Examples 1, 2 and 3 have excellent characteristics such as high capacity and high capacity retention rate, and thus can be sufficiently used as a secondary battery. .

[0056]

As described in detail above, according to the method for producing an electrode plate for a non-aqueous electrolyte secondary battery of the present invention, a powdery active material, a powdery conductive material and a binder are mixed in a predetermined solvent. A non-aqueous electrolyte secondary battery electrode for preparing a slurry-like active material coating solution, applying the coating solution on the surface of a current collector, and then removing the solvent to form a coating film on the current collector In the method for manufacturing a plate, since a binder that is insoluble in the non-aqueous electrolyte and soluble in the solvent is used as the binder, a thin film and a uniform coating film over the entire surface can be obtained. The electrode plate for a non-aqueous electrolyte secondary battery can be easily obtained, and thus can be easily mass-produced.

If the selected binder has a predetermined relationship with the solvent and the non-aqueous electrolytic solution, a coating film which is not eluted into the non-aqueous electrolytic solution and which is electrochemically stable is formed. Therefore, it is possible to sufficiently use a synthetic resin other than the thermosetting resin as the binder.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuichi Miyazaki 1-1-1, Ichigayakaga-cho, Shinjuku-ku, Tokyo Dai Nippon Printing Co., Ltd. (72) Inventor Kazuo Umeda, Ichiya-kaga, Shinjuku-ku, Tokyo 1-1-1, Machi Dai Nippon Printing Co., Ltd. (72) Inventor Kenji Nakano 23-6, Hashidashi, Joban Shimofunao-cho, Iwaki City, Fukushima Prefecture Furukawa Battery, Iwaki Plant (72) Inventor, Manga Toru Hara, Joban Shimo-Funao-cho, Iwaki City, Fukushima Prefecture 23-6 Furukawa Battery Co., Ltd. Iwaki Plant

Claims (6)

[Claims] 1. A powdery active material, a powdery conductive material, and a binder are mixed with a predetermined solvent to prepare a slurry-form active material coating solution, which is applied to the surface of a current collector, and A method for producing an electrode plate for a non-aqueous electrolyte secondary battery, which comprises removing a solvent to form a coating film on a current collector, wherein the binder is insoluble in the non-aqueous electrolyte solution and is not soluble in the solvent. A method for producing an electrode plate for a non-aqueous electrolyte secondary battery, which comprises using a binder that is a melt. 2. A binder having a solubility parameter difference of 4 or more between the non-aqueous electrolyte and the binder is used as the binder, and a solubility parameter difference between the solvent and the binder is used as the solvent. The manufacturing method according to claim 1, wherein a solvent having a difference of 2 or less is used. 3. A binder having a solubility parameter difference of 6 or more between the non-aqueous electrolyte and the binder is used as the binder, and a solubility parameter difference between the solvent and the binder is used as the solvent. The manufacturing method according to claim 1, wherein a solvent having a difference of 1 or less is used. 4. An active material coating solution for producing an electrode plate for a non-aqueous electrolyte secondary battery in the form of a slurry, which is prepared by mixing a powdery active material, a powdery conductive material and a binder in a predetermined solvent. A coating liquid for active material, wherein the binder is insoluble in the non-aqueous electrolyte and soluble in the solvent. 5. The binder is a binder having a solubility parameter difference between the non-aqueous electrolyte solution and the binder of 4 or more, and the solvent has a solubility parameter difference between the solvent and the binder. The active material coating liquid according to claim 4, wherein the solvent has a difference of 2 or less. 6. The binder is a binder having a solubility parameter difference of 6 or more between the non-aqueous electrolyte and the binder, and the solvent has a solubility parameter difference between the solvent and the binder. The active material coating liquid according to claim 4, wherein the solvent has a difference of 1 or less.