JPH10106546A - Manufacture of electrode for battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the manufacture of a battery having a high capacity, high output characteristic, excellent cycle characteristic and high safety at a low cost by coating an electrode board with the film forming solution, and thereafter, making the coating solution contact the lean solvent of the film forming material so as to manufacture an electrode for the battery. SOLUTION: At the time of manufacturing an electrode, the film forming material at several wt.%-20wt.% is dissolved in the rich solvent, and an electrode board is dipped with the solvent so as to form a coating film. The electrode board formed with the coating film is dipped with the lean solvent such as water, methanol, ethanol acetone, hexane, and the rich solvent in the coating film provided on the electrode board is replaced with the lean solvent, and the film forming material is deposited so as to form the coating film 3, which is provided on the electrode board, into a fine porous film. Thereafter, the film is heated for drying.

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 for a battery, and more particularly, to a method for producing a high-capacity battery by using a microporous membrane-coated electrode to increase the capacity by increasing the filling amount and improving the ion-permeability during high-power discharge. The present invention relates to a battery capable of improving the capacity, further reducing the cost by simplifying the manufacturing process, and further excellent in safety.

[0002]

2. Description of the Related Art In recent years, with the spread of portable devices such as video cameras and notebook personal computers, demand for small and high capacity secondary batteries has been increasing. Most of the currently used secondary batteries are nickel-cadmium batteries or nickel-hydrogen batteries using an alkaline electrolyte, but the battery voltage is as low as about 1.2 V, and it is difficult to improve the energy density. Therefore, non-aqueous electrolyte secondary batteries such as lithium secondary batteries using lithium metal for the negative electrode and lithium ion secondary batteries have been developed. In these batteries, a porous separator is inserted between the positive and negative electrodes to prevent conduction between the positive and negative electrodes.

Specifically, in a lithium ion secondary battery, since a non-aqueous (organic) solvent is used as an electrolyte, a polyolefin synthetic resin having low reactivity with an organic solvent and being inexpensive is preferably used. ing. All such separators are inserted between the positive and negative electrodes when the electrodes are wound as independent films separate from the electrodes.

Regarding formation of a membrane having a separator function on an electrode, there is an example of a polymer electrolyte (Battery Handbook: Yoshiharu Matsuda, Zenichiro Takehara, Ed., Maruzen, [1990]
). However, these separators are clearly different from the microporous membranes according to the invention, because they are themselves (solid) electrolytes. That is, since the polymer solid electrolyte described above is manufactured in a state having ion conductivity from the beginning, it is necessary to work under a non-aqueous atmosphere such as in argon from the time of manufacturing the electrode, and its handling requires care. . In addition, the ionic conductivity of polyethylene oxide (PEO) -lithium salt, which has been studied most often at present, is at most 10 ^-5 S · cm ^-1 which is about 1/100 of that of electrolyte solution. It was insufficient in terms of capacity for high-power discharge, which is expected to increase in demand, such as electric vehicles.

There is also a type of polymer electrolyte in which a porous polymer matrix is impregnated with a low-molecular salt and a polar high-boiling solvent. For example, propylene carbonate (PC) and lithium perchlorate (LiClO) are added to polyvinylidene fluoride (PVDF).
₄ ) is a mixed and dispersed system (M. Watanabe et. Al.,
Makromol.Chem., Rapid Commun. 2, 741-744 (198
1)). The manufacturing method of this electrolyte, PVDF and LiClO ₄ in PC,
It is dispersed at 120 ° C. to the molecular level, molded on a metal substrate, and then made porous by evaporating a part of the PC under reduced pressure at 120 ° C. For this reason, as in the case of the above-mentioned polymer electrolyte, since it already has ionic conductivity at the stage before being loaded into the battery can, it must be operated in a non-aqueous atmosphere such as in argon from the time of electrode preparation,
The handling requires care. Further, it is necessary to perform the treatment under reduced pressure, and there is a problem that the cost is increased in terms of the manufacturing process when continuous treatment is considered. Further, a battery using the polymer solid electrolyte is inferior in coulomb efficiency and cycle characteristics as compared with a battery using a conventional electrolytic solution and a separator, due to the basic performance of the polymer solid electrolyte. It is pointed out that the electrode is insufficient and that the adhesion between the electrode and the solid polymer electrolyte is insufficient.

Japanese Patent Application Laid-Open No. Hei 6-290771 discloses a method of coating an electrode with an ion-permeable membrane, and discloses a method of mixing a solvent, spinning, and removing the solvent to make the electrode porous. Although there is a description, when the solvent is simply removed in this manner, a structure in which ions are easily diffused is not obtained, and the structure is insufficient particularly in that the capacity at the time of high-power discharge is small.

As described above, when the conventional separator is used, the price of the separator is high, the manufacturing process is complicated, and the yield decreases due to conduction between the positive electrode and the negative electrode due to the occurrence of winding deviation during electrode fabrication. There was a problem that the cost was increased. Further, in terms of battery performance, there have been problems such as a decrease in capacity due to a large distance between the electrodes and a decrease in capacity during high-output discharge due to resistance to ion permeability. Furthermore, there was a problem in safety at the time of a destructive test such as a nail penetration test.

SUMMARY OF THE INVENTION The present invention aims to solve the above-mentioned problems by increasing the capacity by increasing the filling amount, improving the capacity at the time of high-power discharge by improving the ion permeability, and reducing the cost by simplifying the manufacturing process. It is an object of the present invention to provide a battery that can be realized and has excellent safety.

[0009]

SUMMARY OF THE INVENTION The present invention has the following arrangement to solve the above-mentioned problems.

[0010] "A method for producing a battery electrode, which comprises applying a film-forming solution onto an electrode substrate and then contacting the coating solution with a poor solvent for the film-forming material."

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The electrode of the present invention can be used as an active electrode of various batteries, and there is no particular limitation on what kind of battery such as a primary battery or a secondary battery is used. That is, conventionally, cellulose paper, nonwoven fabric, or the like has been used as a separator in a dry battery, and these can be replaced with these. In addition, a nickel-cadmium battery, a nickel-hydrogen battery, a lithium battery, a lithium-ion battery, and the like use a microporous film of polyvinyl chloride or a polyolefin-based (polypropylene, polyethylene, etc.) synthetic resin. Is also possible. Battery types are square, cylindrical, card,
There is no particular limitation such as a coin type.

The electrode active material used for the electrode according to the present invention is not particularly limited, but particularly when used as a negative electrode, a carbon body is often suitably used.
The carbon body used in the present invention is not particularly limited, and generally used is one obtained by firing an organic substance, graphite, or the like. As the form of the carbon body, a powdered or fibrous carbon body is preferably used. Examples of the powdered carbon body include spherical graphite such as natural graphite, artificial graphite, fluid coke, and Gilsonite coke, mesocarbon microbeads, polyacrylonitrile (PAN), polyvinyl alcohol, lignin, polyvinyl chloride, polyamide, polyimide, Examples include a fired resin such as a phenol resin, furfuryl alcohol, or a copolymer thereof, a pitch of coal or petroleum, and a fired cellulose. Examples of the fibrous carbon body include a PAN-based carbon fiber obtained from PAN or a copolymer thereof, a pitch-based carbon fiber obtained from a pitch such as coal or petroleum, a cellulosic carbon fiber obtained from cellulose, and a gas of a low molecular weight organic substance. And carbon fibers obtained by sintering the above-mentioned polyvinyl alcohol, lignin, polyvinyl chloride, polyamide, polyimide, phenol resin, furfuryl alcohol, and the like. .

[0013] Among them, a carbon body satisfying the characteristics is appropriately selected according to the characteristics of the electrode and the battery in which the carbon body is used. In the case where the carbon material is used for a negative electrode of a secondary battery using a non-aqueous electrolyte containing an alkali metal salt, a PAN-based carbon material, a pitch-based carbon material, and a vapor-grown carbon material are preferable. In particular, a PAN-based carbon body is preferably used in that the doping of an alkali metal ion, particularly, a lithium ion is good. The particle size of the powdered carbon body is
Preferably 0.1 to 100 μm is used, and more preferably 1 to 50 μm. The diameter of the carbon fiber should be determined so that each form can be easily adopted, but preferably 1 to 1000 μm is used, and more preferably 1 to 1000 μm.
It is 20 μm, particularly preferably 3 to 15 μm. It is also preferable to use several types of carbon fibers having different particle sizes. The average length of carbon fiber is 1m
m or less, more preferably 50 μm or less, and still more preferably 8 to 30 μm. Further, as a lower limit, a ratio of a fiber length to a fiber diameter (aspect ratio) is preferably 1 or more. If the thickness exceeds 1 mm, the coating property tends to be poor when a slurry is formed to form a sheet-like electrode, and when the electrode is used, a short circuit between the positive and negative electrodes may easily occur. If the aspect ratio is less than 1, the powder will be cleaved in the fiber direction during powdering to expose an active carbon surface, and the cycle characteristics will tend to be poor. The average length of the fiber is, for example, 20
It is determined by measuring the length of at least one carbon body in the fiber direction. In order to cut or pulverize the carbon fiber to 1 mm or less, various pulverizers can be used.

[0014] In addition to the carbon body, for example,
Compounds such as metal oxide and polyacene shown in 235293 are also preferably used as the negative electrode active material. In the electrode according to the present invention, a metal such as copper or stainless steel can be used as a current collector to enhance the current collecting effect. As the metal current collector, foil, fiber,
Although not particularly limited to a mesh shape, for example, when a foil-shaped metal current collector is used, a sheet-shaped electrode is produced by applying a slurry on a metal foil. In order to further enhance the current collecting effect, it is preferable to add carbon black such as acetylene black or Ketjen black as a conductive agent to the sheet electrode. further,
It is also preferable to add conductive powder such as carbon powder and metal powder for the purpose of improving conductivity.

When the electrode of the present invention is used for a negative electrode, the positive electrode active material used for the positive electrode includes artificial or natural graphite powder, inorganic compounds such as carbon fluoride and metal oxide, and organic polymer compounds. Used. When an inorganic compound such as a metal oxide is used as a positive electrode, a charge / discharge reaction occurs using doping and undoping of a cation. In the case of an organic polymer compound, a charge / discharge reaction occurs by doping and undoping of an anion. As described above, various charge / discharge reaction modes are adopted depending on the substance, and these are appropriately selected according to the required positive electrode characteristics of the battery. Specifically, inorganic compounds such as transition metal oxides and transition metal chalcogens containing alkali metals, conjugated polymers such as polyacetylene, polyparaphenylene, polyphenylenevinylene, polyaniline, polypyrrole, and polythiophene, and crosslinked polymers having disulfide bonds And positive electrode active materials used in ordinary secondary batteries such as thionyl chloride. Among these, in the case of a secondary battery using a non-aqueous electrolyte containing a lithium salt, cobalt, manganese, nickel, molybdenum, vanadium,
Transition metal oxides such as chromium, iron, copper, and titanium, and transition metal chalcogens are preferably used. In particular, Li _x Co
O ₂ (0 <x ≦ 1.0), Li _x NiO ₂ (0 <x ≦
1.0), or a lithium composite oxide in which part of these metal elements is replaced with an alkaline earth metal element and / or a transition metal element, or Li _x MnO ₂ (0 <x ≦ 1.
0), Li _x Mn ₂ O ₄ (0 <x ≦ 1.3) and the like are preferably used. In these positive electrodes, as described above, aluminum, nickel,
A metal such as stainless steel or titanium can be used as the current collector. As described above, it is also preferable to add carbon black such as acetylene black and Ketjen black as a conductive agent, and further to add conductive powder such as carbon powder and metal powder for the purpose of improving conductivity.

The method of producing these positive and negative electrodes is not particularly limited, but a paste obtained by kneading a binder, an active material, and a conductive agent with an organic solvent or water on the above-mentioned current collector is applied. It is dried, pressed and formed into a sheet. The solvent and the solid content concentration used for the pasting are not particularly limited, but are appropriately determined in consideration of the resin used, the coating method, the drying conditions, and the like. Also, in the paste, a surfactant for improving applicability, an antifoaming agent, a dispersant,
Various additives such as an ultraviolet absorber and a stabilizer for improving storage stability can be added.

As the film-forming material of the electrode of the present invention, almost any material commonly used as a separator can be used. In addition, materials that were difficult to become independent membranes,
In the present invention, it can be used as a separator in the form of a coating film. Specific separator materials include:
As the thermoplastic resin, polypropylene (PP), polyethylene (PE), ethylene vinylene acetate (EV)
A), N-substituted maleimide resin, poly 4-methylpentene
-Polyolefins such as 1, polytetrafluoroethylene (PTFE), polystyrene, polyvinylcarbazole, polyvinylidene fluoride (PVDF), PVDF
And propylene hexafluoride copolymer, polyvinyl chloride (P
VC), lignin, celluloses such as carboxycellulose (CMC), water-soluble polymers such as polyvinyl alcohol (PVA), amides such as polyimide and polyamide, imides, polyacrylonitrile (PAN), poly Acrylics such as acrylates and their copolymers, polycaprolactam, polyethylene terephthalate, esters such as polybutylebutylene terephthalate, other polysulfone, polyester sulfone, polycarbonate, polyarylate, modified polyphenylene oxide, polyether ether ketone, Silicon resin, polyacetal, or the like is used. As the thermosetting resin, phenoxy resin,
Epoxy resin or the like is used. Further, a mixture of a thermoplastic resin and a thermosetting resin, two or more thermoplastic resins,
Also, two or more kinds of thermosetting resins are used. The thickness of the separator is set at 20 to reduce the internal resistance of the battery.
0 μm or less, more preferably 5 μm or less.
0 μm or less, particularly preferably 25 μm or less.

In the present invention, a film containing a good solvent is directly coated on an electrode substrate, and then the film is contacted with a poor solvent to replace the good solvent and the poor solvent, thereby depositing a film-forming material. The coating film on the electrode substrate is made microporous. here,
The electrode substrate means a generally used electrode provided with at least an electrode active material on the current collector.

Hereinafter, a method of directly coating on the electrode substrate will be described in detail with reference to specific examples.

The film-forming material is added to the good solvent in an amount of from several weight% to
Dissolve about 20% by weight. Next, the electrode substrate is immersed in the raw material solution for several seconds to about 10 minutes and pulled up by, for example, a dipping method. If necessary, the excess raw material solution attached to the substrate is removed. Alternatively, the film-forming solution is applied to the electrode substrate using a coating device such as a knife coater to form a coating film. The electrode substrate on which the coating film is formed is immersed in a poor solvent such as water, methanol, ethanol, acetone or hexane (one or a mixture of two or more of them may be used) for several minutes to several tens of minutes. By replacing the good solvent and the poor solvent in the coating film on the substrate and depositing a film-forming material, the coating film is made microporous. Thereafter, drying is performed at a temperature of about several tens to 200 degrees Celsius. If necessary, the cycle characteristics can be improved by press working with a roll press method or the like to increase the binding force between the active materials, between the active material and the conductive agent, and between these electrode materials and the current collector. . By the press working,
Although the pores of the separator membrane may be slightly deformed, a membrane that does not impair the separator performance can be obtained by selecting the pressing conditions (pressure, temperature, etc.), the type and the mixing ratio of the conductive material and the binder, and the like. . This production method is characterized in that it is relatively easy to control the thickness and porosity of the microporous film by appropriately selecting the production conditions.

In the battery using the electrode according to the present invention, the thickness of the separator can be substantially reduced, so that the amount of the active material to be filled can be increased and the battery capacity can be increased. Also,
The microporous membrane directly coated on the electrode is not an independent membrane but integrated with the electrode material, so it can tolerate a certain decrease in membrane strength due to an increase in porosity, and an improvement in capacity during high-power discharge by improving ion permeability Can be achieved. In addition, it is not necessary to use a conventional expensive separator.Furthermore, a reduction in yield due to separator slippage or short circuit is eliminated, and a battery can be manufactured by winding only the positive and negative electrodes, thereby simplifying a manufacturing process. Cost reduction can be realized. It also has the effect of improving safety during safety tests (crush test, nail penetration test). It is speculated that this may have the effect of improving the stability of lithium ions in the negative electrode and suppressing the release of oxygen from the positive electrode when the temperature inside the battery rises due to Joule heat when the positive and negative electrodes are short-circuited. . In addition, it is also preferable to add a heat absorbing material, a flame retardant, an antioxidant, and the like to the porous separator membrane from the viewpoint of further imparting a function. The heat absorbing material is not limited, but preferably has a melting point of about 80 to 200 ° C. and does not dissolve in the electrolytic solution. For example, stearate, palmitate and the like are used. As the salt, for example, zinc, manganese or the like is used. The flame retardant is not limited, but those having a melting point of about 200 ° C. or more and not being dissolved in the electrolytic solution are preferably used. For example, hexabromobenzene is used. Further, as the antioxidant, an antioxidant which suppresses oxidation and does not dissolve in the electrolytic solution, for example, hindered amine or hindered phenol can be preferably used.

In the present invention, the same film-forming material may be used for the positive electrode and the negative electrode, or different film-forming materials may be used.
In addition, it is preferable that the same polymer as the binder of the electrode is used as the film-forming material from the viewpoint of adhesion to the electrode substrate.

The electrolytic solution of the battery using the electrode according to the present invention is not particularly limited, and examples thereof include an acid or alkali aqueous solution and a non-aqueous solvent. Among these, propylene carbonate (PC), ethylene carbonate (EC), γ-
Butyrolactone (BL), N-methylpyrrolidone (NM
P), acetonitrile (AN), N, N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran (THF), 1,3-dioxolan, methyl formate, sulfolane, oxazolidone, thionyl chloride, 1,2-dimethoxyethane (DME) , Dimethyl carbonate (D
MC), diethylene carbonate (DEC), dimethylimidazolidinone, or the like, a derivative thereof, or a mixture of two or more thereof is preferably used. Examples of the electrolyte contained in the electrolytic solution include alkali metal, especially lithium halide, perchlorate, thiocyanate, borofluoride, phosphorus fluoride, arsenic fluoride, aluminum fluoride, trifluoromethyl sulfate, and the like. Is preferably used. Applications of the secondary battery using the electrode according to the present invention include a video camera, a personal computer, a word processor, a boombox, a mobile phone, a handy terminal, a CD player, and an MD player by utilizing the features of light weight, high capacity, and high energy density. It can be widely used for portable small electronic devices such as electric shaving, liquid crystal televisions and toys, and portable small electronic devices such as electric vehicles.

[0024]

EXAMPLES Specific embodiments of the present invention will be described below with reference to examples, but the present invention is not limited thereto.

Example 1 (1) Preparation of Positive Electrode Commercially available lithium carbonate (Li ₂ CO ₃ ) and basic cobalt carbonate (2CoCO ₃ .3Co (OH) ₂ were used in a molar ratio of Li.
/ Co = 1/1, weighed so as to be 1/1, wet-mixed with a zirconia ball mill (using ethanol as a grinding solvent), and then heat-treated at 900 ° C. in the air for 20 hours to synthesize LiCoO ₂ . This was pulverized by the ball mill to obtain a LiCoO ₂ powder as a positive electrode active material.

The cathode active material was 91% by weight, PVDF (KF polymer # 1100 manufactured by Kureha Chemical Co., Ltd.) was 6% by weight,
Acetylene black ("Denka Black", manufactured by Denki Kagaku Co., Ltd.) was weighed at 3% by weight, and the same amount of NMP was added and kneaded to prepare a positive electrode paste. This positive electrode paste was coated on one side of an aluminum foil having a thickness of 16 μm, with an electrode part having a width of 8 cm.
Length 60 cm, weight of cathode active material per unit area is 20
0 g / m ² , dried at 100 ° C. for 15 minutes, coated on the other side, dried at 100 ° C. for 30 minutes, and further dried at 180 ° C. for 15 minutes to form a sheet electrode using LiCoO _2. Was prepared. The sheet electrode is applied with a linear pressure of about 1
After being pressed with a roller press at 00 kg / cm and pressed against an aluminum current collector, it was slit into a width of 54 mm and a length of 465 mm,
A positive electrode having a total thickness of 190 μm was obtained.

(2) Preparation of Negative Electrode 85% by weight of short fibrous carbon fiber ("Treca" milled fiber: MLD-30, manufactured by Toray Industries, Inc.) was used as the negative electrode active material.
10% by weight of DF (described above), acetylene black (described above)
Was weighed in an amount of 5% by weight, about 1.4 times NMP was added thereto, and kneaded to obtain a paste B.

This negative electrode paste was applied to one side of a copper foil having a thickness of 10 μm, and the width of the electrode portion was 8 cm and the length was 60 cm.
After drying at 100 ° C. for 15 minutes, the other surface is slightly reduced in the basis weight (the amount of active material per unit area) and applied.
It was dried at 0 ° C. for 30 minutes and further dried at 200 ° C. for 15 minutes in a nitrogen stream to produce a sheet-like electrode using short fibrous carbon fibers. This sheet-shaped electrode was slit to a width of 65 mm, roller-pressed at a linear pressure of about 100 kg / cm and pressed on a copper foil current collector, and then slit to a width of 56 mm and a length of 500 mm to obtain a 200 μm thick battery electrode. .

(3) Preparation of Raw Material Solution for Microporous Membrane PVDF (KF Polymer # 2300 manufactured by Kureha Chemical Co., Ltd.)
After adding MP and stirring to completely dissolve, vacuum degassing was performed to prepare an NMP solution containing 15% by weight of PVDF.

(4) Preparation of Microporous Membrane The positive electrode prepared in (1) was immersed in the solution prepared in (3), then pulled up by a dipping method, and placed in a methanol solution.
Then, the electrode was dried at 60 ° C. for 20 minutes to produce an electrode. The thickness of the microporous film coated on the electrode material was 15 μm as observed by a scanning electron microscope (SEM).
The microporous film was coated on the negative electrode prepared in (2) in the same manner. The thickness of the obtained microporous membrane was 12 μm. FIG. 1 shows an electrode directly covered with a microporous membrane.

(5) Electrolyte LiPF ₆ was dissolved at a ratio of 1 mol / l in an equal volume mixed solvent of PC and DMC.

(6) Evaluation of Electrode Performance A part of the positive and negative electrodes produced as described above was cut out and subjected to electric evaluation using a three-electrode cell using a metallic lithium foil as a counter electrode and a reference electrode. For the positive electrode, the current density per active material was 4.2 V (vs. Li ⁺ / Li) at a constant current of 130 mA / g.
, And constant-potential charging was performed at 4.2 V, and charging was continued until the total charging time reached 3 hours. After charging, the current density
The battery was discharged at 3.0 mA / g to 3.0 V (vs. Li ⁺ / Li) to determine the initial capacity. Further, the same charge is performed, and after the charge, a charge / discharge cycle of discharging at a constant current to 3.0 V (vs. Li ⁺ / Li) at the same current density as the charge is repeated.
The discharge capacity at the 300th charge / discharge cycle at A / g was compared with the discharge capacity at the first time, and the capacity retention expressed by the following equation was determined.

Capacity retention (%) = {(300th discharge capacity) /
(First discharge capacity)} × 100 For the negative electrode, the current density per active material was 300 mA.
/ G at a constant current of 0 V (vs. Li ⁺ / Li)
And the charging was continued until the total charging time became 8 hours. After charging, 1.5% at a current density of 60 mA / g
V (vs. Li ⁺ / Li) was discharged to determine the initial capacity. Further, the same charge was performed with a charge time of 5 hours, and a charge / discharge cycle of discharging a constant current to 1.5 V (vs. Li ⁺ / Li) at a current density of 500 mA / g after charging was repeated 300 times.
The capacity retention was determined in the same manner as for the positive electrode. Table 1 shows the evaluation results of the initial capacity, the capacity at the first charge / discharge cycle, and the capacity retention for each of the positive electrode and the negative electrode.

Comparative Example 1 A positive / negative electrode was prepared in the same manner as in Example 1 except that a microporous membrane was not directly coated on the electrode and a commercially available polyethylene separator (Celgard # 2400 made by Hoechst, thickness 25 μm) was used. Fabricated and evaluated. Table 1 shows the evaluation results of the initial capacity, the capacity at the first charge / discharge cycle, and the capacity retention for each of the positive electrode and the negative electrode.

Example 2 An artificial graphite (KS-25, manufactured by Lonza) was used as the negative electrode active material, and an equal volume of a mixed solvent of PC, EC, and DMC was used as the electrolyte (1:25).
1: 1), except that an electrolyte prepared by dissolving LiPF ₆ at a rate of 1 mol / l was used.
Table 1 shows the evaluation results of the initial capacity, the capacity at the first charge / discharge cycle, and the capacity retention.

Comparative Example 2 A negative electrode was prepared and evaluated in the same manner as in Example 2 except that the microporous membrane was not directly coated on the electrode and the above-mentioned polyethylene separator was used. Table 1 shows the evaluation results of the initial capacity, the capacity at the first charge / discharge cycle, and the capacity retention.

[0037]

[Table 1] Example 3 Using the electrode manufactured in Example 1, a secondary battery was manufactured by the following method. FIG. 2 shows a schematic longitudinal sectional view of the non-aqueous electrolyte secondary battery of the present invention. The battery is obtained by winding the negative electrode 1 and the positive electrode 2 of the present invention obtained above and storing the battery in a battery can 5 with insulators 4 installed above and below.

A battery lid 7 is provided with a sealing gasket 6 on the battery can 5.
And are electrically connected to the negative electrode 1 and the positive electrode 2 via the negative electrode lead 10 and the positive electrode lead 11, respectively, so as to function as a battery.

Such a non-aqueous electrolyte secondary battery was manufactured as follows. A negative electrode lead 10 made of nickel and a positive electrode lead 11 made of aluminum were previously welded to the current collector portions of the negative electrode 1 of the present invention and the positive electrode 2 of the present invention. After uniformly applying and curing a room temperature curing type epoxy resin (electrical insulating property) on the current collector portions of the negative electrode 1 and the positive electrode 2, the negative electrode 1 and the positive electrode 2 are spirally wound while being laminated, and the outer diameter is about 17 mm. Was obtained. Here, as a method for preventing an electrical short circuit between the current collector of the positive electrode 2 and the negative electrode 1, in addition to the above-described coating of the electrically insulating resin, for example, the electrical Any method may be used as long as the object of the short-circuit prevention is achieved.

After the insulating plates 4 are arranged on the upper and lower end surfaces of the spirally wound electrode thus produced, the battery can 5
Then, the positive electrode lead 11 was welded to the battery lid, and the negative electrode lead 10 was welded to the battery can 5. An electrolytic solution was injected into the battery can 5 in a glove box in an argon atmosphere.

The battery lid 5 is fixed by caulking the battery can 5 via the insulating sealing gasket 6 coated on the surface with asphalt, and the airtightness is maintained in the battery.
Four cylindrical nonaqueous electrolyte secondary batteries having a size were assembled.

One of these batteries was charged at a constant current / constant voltage for 3 hours under the conditions of a charge end voltage of 4.2 V and a charge current of 1 A, followed by a discharge end voltage of 3.0 V and a discharge current of 0.1 V.
The initial capacity was determined by discharging at a constant current under the condition of 2A. Then, the average discharge voltage is obtained, and the initial energy (Ah) is multiplied by the average discharge voltage (integral average value: V) to obtain the battery energy (W
h) was determined. The battery energy (Wh) divided by the battery weight (18650 type) is the weight energy density (Wh / kg), and the battery energy (Wh) divided by the battery volume (18650 type) is the volume energy density (Wh / kg). Wh / l). Further, the same charge is performed, and after the charge, the discharge end voltage is 3.0 V and the discharge current is 2.0 A.
The charge / discharge cycle of constant current discharge was repeated 300 times under the conditions described above, and the capacity retention was determined in the same manner as for the electrodes. Table 2 shows the evaluation results of the weight energy density, the volume energy density, the capacity retention, and the high output retention expressed by the following formula.

High output retention (%) = {(capacity at 2.0 A discharge) / (battery capacity at 0.2 A discharge) × 100
Each of the pieces was subjected to constant current / constant voltage charging for 3 hours under the conditions of a charging end voltage of 4.2 V and a charging current of 1 A, and then a safety test (crush test, nail penetration test) was performed according to UL standards. The results are also shown in Table 2.

COMPARATIVE EXAMPLE 3 The positive electrode and negative electrode battery electrodes of Example 1 were laminated in the order of positive electrode / separator (separator described in Comparative Example 1) / negative electrode / separator, and spirally wound into an outer shape of 17 mm Was obtained. Hereinafter, Example 1
A cylindrical nonaqueous electrolyte secondary battery was assembled in the same manner as described above. The weight energy density, volume energy,
Table 2 shows the evaluation results of the high output retention, the capacity retention, and the safety test.

Example 4 Using artificial graphite (manufactured by Lonza, KS-25) as the negative electrode active material, and using an equal volume of a mixed solvent of PC, EC, and DMC as the electrolyte (1:25)
1: 1), except that an electrolytic solution prepared by dissolving LiPF ₆ at a rate of 1 mol / L was used.
Table 2 shows the weight energy density, volume energy, high output retention, capacity retention, and evaluation results of the safety test of this battery.

Example 5 Example 1 was repeated except that the microporous membrane was not directly coated on the positive electrode.
Was performed in the same manner as described above. Table 2 shows the weight energy density, volume energy, high output retention, capacity retention, and evaluation results of the safety test of this battery.

Example 6 Example 1 was repeated except that the microporous film was not directly coated on the negative electrode.
Was performed in the same manner as described above. Table 2 shows the weight energy density, volume energy, high output retention, capacity retention, and evaluation results of the safety test of this battery.

Example 7 The same procedure as in Example 1 was performed except that the film-forming material was changed to polyacrylonitrile. The weight energy density, volume energy, high output retention, capacity retention,
Table 2 shows the evaluation results of the safety tests.

Example 8 The same procedure as in Example 1 was carried out except that the film-forming material was changed to polyimide (Ricacoat SN-20, manufactured by Shin Nihon Rika Co., Ltd.). Table 2 shows the weight energy density, volume energy, high output retention, capacity retention, and evaluation results of the safety test of this battery.

Example 9 The same procedure as in Example 1 was carried out except that the film-forming material was changed to aramid. Table 2 shows the weight energy density, volume energy, high output retention, capacity retention, and evaluation results of the safety test of this battery.

Example 10 The same procedure as in Example 1 was carried out except that 50% of PVDF was changed to polymethyl acrylate. Table 2 shows the weight energy density, volume energy, high output retention, capacity retention, and evaluation results of the safety test of this battery.

Example 11 The film-forming material was polysulfone (P-1700 NT-
11, Amoco Chemical Japan Co., Ltd.). Table 2 shows the weight energy density, volume energy, high output retention, capacity retention, and evaluation results of the safety test of this battery.

Example 12 The same procedure as in Example 4 was carried out except that 50% of PVDF was replaced with zinc stearate (reagent grade: manufactured by Wako Pure Chemical Industries, Ltd.). Table 2 shows the weight energy density, volume energy, high output retention, capacity retention, and evaluation results of the safety test of this battery.

Example 13 An experiment was carried out in the same manner as in Example 4 except that 50% of PVDF was replaced with manganese stearate (reagent: manufactured by Wako Pure Chemical Industries, Ltd.). Table 2 shows the weight energy density, volume energy, high output retention, capacity retention, and evaluation results of the safety test of this battery.

Example 14 The same procedure as in Example 4 was performed except that 25% of PVDF was replaced with zinc stearate (described above) and 25% of the PVDF was replaced with manganese stearate (described above). Table 2 shows the weight energy density, volume energy, high output retention, capacity retention, and evaluation results of the safety test of this battery.

Example 15 The same procedure as in Example 4 was carried out except that 10% of PVDF was replaced with hexabromobenzene (reagent: manufactured by Wako Pure Chemical Industries, Ltd.). Table 2 shows the weight energy density, volume energy, high output retention, capacity retention, and evaluation results of the safety test of this battery.

Example 16 The same procedure as in Example 4 was carried out except that 10% of the PVDF was replaced with a hindered amine organic compound (ADK STAB LA-82: manufactured by Asahi Denka Kogyo KK). Table 2 shows the weight energy density, volume energy, high output retention, capacity retention, and evaluation results of the safety test of this battery.

Example 17 The same procedure as in Example 4 was carried out except that the method of applying the film-forming solution to the electrode was changed from the dipping method to the knife-coating method. Table 2 shows the weight energy density, volume energy, high output retention, capacity retention, and evaluation results of the safety test of this battery.

Example 18 The same procedure as in Example 4 was carried out except that the following active material was used as the positive electrode active material. Lithium hydroxide (Li (O
H)), nickel hydroxide (Ni (OH) _2), strontium hydroxide octahydrate _{(Sr (OH) 2 · 8H} 2 O),
Cobalt hydroxide (Co (OH) ₂ ) is converted to Li
_It was weighed so as to be _0.98 Sr _0.002 Ni _0.90 Co _0.10 O ₂ , held at 650 ° C. for 16 hours, and pre-baked. After cooling to room temperature, the mixture was pulverized again in an automatic mortar for 30 minutes to break up aggregation of secondary particles. Then, in the same atmosphere as in the preliminary firing, main firing was performed at 750 ° C. for 8 hours, cooled to room temperature, and then pulverized again with an automatic mortar to obtain a positive electrode active material powder. Table 2 shows the weight energy density, volume energy, high output retention, capacity retention, and evaluation results of the safety test of the battery using the positive electrode active material according to the present invention.

Example 19 The same procedure as in Example 4 was performed except that MLD-30 was heat-treated at 1150 ° C. for 4 hours in a nitrogen atmosphere. Table 2 shows the weight energy density, volume energy, high output retention, capacity retention, and evaluation results of the safety test of this battery.

[0061]

[Table 2]

[0062]

By using the electrode according to the present invention, a battery having high capacity, high output characteristics and good cycle characteristics, low cost and high safety can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of an electrode according to the present invention.

FIG. 2 is a schematic longitudinal sectional view showing an example of the secondary battery of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Negative electrode 2 ... Positive electrode 3 ... Microporous film 4 ... Insulating plate 5 ... Battery can 6 ... Sealing gasket 7 ... Battery cover 8 ... Negative electrode current collector 9・ ・ ・ Positive electrode current collector 10 ・ ・ ・ Negative electrode lead 11 ・ ・ ・ Positive electrode lead

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Naoki Shimoyama 1-1-1, Sonoyama, Otsu, Shiga Prefecture Toray Industries, Inc. Shiga Plant (72) Inventor Yoshio Matsuda 1-1-1, Sonoyama, Otsu, Shiga Prefecture Toray Industries, Inc. Shiga Plant

Claims (16)

[Claims] 1. A method for producing a battery electrode, comprising: applying a film-forming solution on an electrode substrate; and contacting the coating solution with a poor solvent for a film-forming material. 2. The method according to claim 1, wherein said contact means is immersed in said poor solvent. 3. The method according to claim 1, wherein said solution contains at least one selected from a heat absorbing material, a flame retardant material and an antioxidant. 4. The method for producing a battery electrode according to claim 3, wherein said heat absorbing material contains an organic compound containing zinc and / or manganese. 5. The method according to claim 3, wherein the flame retardant contains a bromine-containing organic compound. 6. The method according to claim 3, wherein the antioxidant contains a hindered amine. 7. The method for producing an electrode for a battery according to claim 1, wherein the film-forming solution is a thermoplastic resin solution. 8. The method according to claim 7, wherein said thermoplastic resin contains a fluorine-containing polymer and / or a sulfur-containing polymer. 9. The method for producing an electrode for a battery according to claim 1, wherein the film-forming solution is a thermosetting resin solution. 10. The method for manufacturing a battery electrode according to claim 1, wherein the electrode is formed by pressing an electrode material on a current collector. 11. The method for manufacturing a battery electrode according to claim 10, wherein said electrode material includes an active material, a binder and a conductive material. 12. The method according to claim 11, wherein the active material is a lithium composite oxide. 13. The lithium composite oxide according to claim 13, wherein said lithium composite oxide is Li _x CoO.
₂ (0 <x ≦ 1.0), Li _x NiO ₂ (0 <x ≦ 1.
The method for producing a battery electrode according to claim 12, wherein the method is selected from 0) and those obtained by substituting a part of these metal elements with an alkaline earth metal element and / or a transition metal element. 14. The method for producing a battery electrode according to claim 11, wherein said active material is a carbonaceous material. 15. The method according to claim 14, wherein the carbonaceous material is carbon fiber. 16. The method according to claim 15, wherein said carbon fibers are in the form of short fibers having an average length of 30 μm or less.