JPH11329417A - Electrode plate for non-aqueous electrolyte secondary battery and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a manufacturing method of an electrode plate for a non- aqueous electrolyte secondary battery, on which patterning of an active material layer can be given with high precision and effectively. SOLUTION: This method comprises a thermocompression bonding process in which a thermoplastic resin sheet 4 is selectively thermocompression-bonded on a prescribed region of an active material layer 2 formed on the surface of a collector 1, and of an exfoliation process in which patterning of the active material layer 2 is given by stripping the thermocompression-bonded thermoplastic sheet 4. In the thermocompression bonding process, a hot plate 20 is pressed on the prescribed region from the thermoplastic resin sheet 4 side through a heat resistant sheet 5 which can be exfoliated from the thermoplastic resin sheet 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrode plate for a non-aqueous electrolyte secondary battery represented by, for example, a lithium secondary battery and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, the size and weight of electronic devices and communication devices have been rapidly reduced. Is coming. For such a request,
Instead of conventional alkaline storage batteries, with high energy density,
A non-aqueous electrolyte secondary battery represented by a lithium ion secondary battery capable of obtaining a high voltage has been proposed.

As for an electrode plate which greatly affects the performance of a secondary battery, it has been proposed to extend the charge / discharge cycle life and increase the area of the thin film in order to increase the energy density. For example, JP-A-63-104
No. 56 and Japanese Unexamined Patent Publication (Kokai) No. 3-285262 disclose a conductive agent and a binder to a positive electrode active material powder such as a metal oxide, a sulfide or a halide, and a suitable wetting agent (solvent). A positive electrode plate is disclosed in which a paste-like active material coating solution prepared by dispersing and dissolving the active material layer on a current collector made of a metal foil to form an active material layer is disclosed.

In this case, as a binder, for example, a fluorine-based resin such as polyvinylidene fluoride or silicone resin is used.
An acrylic copolymer is used. The negative electrode plate was prepared by adding a paste obtained by dissolving a binder in a suitable wetting agent (solvent) to a negative electrode active material such as carbon to prepare a paste-like active material coating solution. It is obtained by coating the current collector. After that, a pressing process is usually performed to increase the density of the active material layer and improve the adhesion of the coating film to the current collector.

When the electrode plate is formed by the above-mentioned coating, the binder used for preparing the active material coating liquid is electrochemically stable with respect to the non-aqueous electrolyte. It is necessary that the solvent does not elute into the electrolytic solution and that it is soluble in some solvent because of coating. The active material layer obtained by applying the above active material coating liquid is required to have sufficient flexibility so that peeling, falling off, and cracking do not occur during the battery assembling process and during charging and discharging.

[0006]

Normally, it is necessary to provide a terminal portion for extracting current from the electrode plate. Also,
Due to the design of the battery, there is a region where the active material is not preferable on the current collector. For this reason, the electrode plate is not formed on the entire surface of the current collector, but is patterned into a predetermined shape according to the design of the battery. In order to perform such patterning, at present, when the electrode coating liquid is applied onto the current collector, the coated portion and the non-coated portion are formed by mechanical control of the coater head and directly patterned. How and
There is a method in which the electrode plate formed on the entire surface is patterned later by peeling the dried coating film by mechanical means.

[0007] However, in the former method, high-speed patterning is difficult due to mechanical accuracy, and the coating film thickness varies. In addition, since the pressing process is performed on the electrode in the state where the uncoated portion is already formed, it is difficult to perform a uniform and high-speed pressing process, and furthermore, when the patterns of the front and back electrode plates do not match. Pressing is difficult.

Further, the latter method has disadvantages in that it takes a long time to peel off, the patterning accuracy is not high, or the edge portion of the pattern is easily broken at the time of peeling, so-called powder drop occurs.

A first object of the present invention is to provide a method of manufacturing an electrode plate for a non-aqueous electrolyte secondary battery, which can pattern an active material layer with high accuracy and efficiency.
A second object of the present invention is to obtain a high-quality electrode plate for a non-aqueous electrolyte secondary battery.

[0010]

According to the first aspect of the present invention, a thermoplastic resin sheet (4) is provided on a predetermined region (2a) of an active material layer (2) formed on the surface of a current collector (1). ), And a peeling step of removing a predetermined area (2a) of the active material layer (2) by peeling off the thermoplastic resin sheet (4) that has been thermocompressed. In the pressure bonding step, the hot plate (20) is pressed from the side of the heat-resistant sheet (5) to the predetermined area (2a) via the heat-resistant sheet (5) that can be separated from the thermoplastic resin sheet (4). .

According to a second aspect of the present invention, in the method for producing an electrode plate for a non-aqueous electrolyte secondary battery according to the first aspect, the active material layer (2) includes a coating containing an active material and a binder. The liquid is applied to the current collector (1) and dried to form a film on the surface of the current collector (1).

A third aspect of the present invention is characterized by being manufactured by the method according to the first or second aspect.

Although reference numerals in the accompanying drawings are added in parentheses to facilitate understanding of the present invention, the present invention is not limited to the illustrated embodiment.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing an electrode plate for a non-aqueous electrolyte secondary battery according to the present invention will be described below with reference to FIGS.

FIG. 1A is a plan view showing an example of an electrode plate manufactured by using the manufacturing method of the present invention, and FIG.
It is an expanded sectional view in the BB line of (a). FIG.
As shown in FIG. 1A and FIG. 1B, the electrode plate 100 includes a current collector 1 and an active material layer 2 formed on the current collector 1, and a cut formed on the active material layer 2. The current collector 1 is exposed through the notch 2a.

The electrode plate 100A shown in FIG. 2 is manufactured by cutting the electrode plate 100 shown in FIG. As shown in FIG. 2, the current can be drawn from the current collector 1 by bringing the terminal 3 into contact with the current collector 1 exposed through the notch 2a. Thus, the notch 2 of the active material layer 2
a is needed to draw current from current collector 1;
When manufacturing the electrode plate 100, the notch 2a needs to be formed by any method. In addition, the horizontal line of FIG. 1 drawn on the electrode plate 100 indicates a cutting position when the electrode plate 100A is created.

Next, the manufacturing method of the present invention will be described with reference to the manufacturing of the electrode plate 100 shown in FIG. 1 as an example. First, FIG.
A current collector 1 having a rectangular shape as shown in FIG. 1 is prepared, and an active material coating liquid is applied to one surface thereof and dried to form an active material layer 2. Note that the manufacturing method of the present invention can also be applied to a case where active material layers are formed on both surfaces.

As the current collector 1 as a base, a metal foil is usually used. For example, an aluminum foil or the like is used as a positive electrode plate, and a copper foil or the like is used as a negative electrode plate. The thickness of these metal foils is preferably about 5 to 50 μm.

An active material coating solution containing at least an active material and a binder is applied to one or both surfaces of the current collector 1, and a coating film is applied and dried to form an active material layer 2. Prior to this, a coupling agent layer may be formed on the surface of the current collector 1 in order to improve the adhesion between the current collector 1 and the active material layer 2. As the coupling agent, for example, silane-based,
Titanate-based or aluminum-based coupling agents can be used, and those having excellent adhesion between the metal foil current collector 1 and the active material layer 2 are selected and used.

The active material includes a positive electrode active material and a negative electrode active material. Examples of the positive electrode active material include LiCoO ₂ and LiN.
lithium oxide of iO _2, LiMn ₂ O ₄ or LiNixMyO ₂ (where M = Co, Al; x, y is any number satisfying x + y = 1), or TiS ₂ , MnO ₂ , M
Chalcogen compounds such as oO ₃ or V ₂ O ₅ can be exemplified. These positive electrode active materials may be used alone or in combination of two or more. As the negative electrode active material, for example, a lithium-containing metal such as lithium metal or a lithium alloy, or a carbonaceous material such as graphite, carbon black or acetylene black is preferably used. In particular, LiCoO ₂ or LiMn ₂
By using O ₄ as a positive electrode active material and using a carbonaceous material as a negative electrode active material, a lithium secondary battery having a high discharge voltage of about 4 volts can be obtained. The positive electrode active material and the negative electrode active material are preferably powders having a particle size in the range of 1 to 100 μm in order to uniformly disperse these active materials in the active material layer.

The binder is electrochemically stable with respect to the non-aqueous electrolyte, does not elute in the electrolyte, and can be applied thinly on the current collector made of metal foil. Need to be soluble in some solvent.

Examples of the binder include a thermoplastic resin,
More specifically, a polyester resin, a polyamide resin, a polyacrylate resin, a polycarbonate resin, a polyurethane resin, a cellulose resin, a polyolefin resin, a polyvinyl resin, a fluorine resin, a polyimide resin, or the like can be used. At this time, an acrylate monomer or oligomer having a reactive functional group introduced therein can be mixed into the binder. Further, an acrylate oligomer alone or a mixed system of an oligomer and a monomer can be used.

However, particularly preferred binders are polyvinylidene fluoride, polystyrene-butadiene copolymer and hydrogenated polystyrene-butadiene copolymer.

[0024] The coating liquid contains an appropriately selected active material and a binder in a dispersion medium or solvent comprising an organic solvent such as N-methyl-2-pyrrolidone, toluene, methyl ethyl ketone or a mixture thereof. The binder can be prepared by previously dissolving the binder and, if necessary, mixing and dispersing a mixture obtained by mixing a conductive agent with a disperser such as a homogenizer, a ball mill, a sand mill, a roll mill, or a planetary mixer. In this case, the compounding ratio of the binder and the active material may be determined in consideration of both the performance and the coatability of the electrode plate. For example, in the case of the negative electrode active material, the binder: active material = 1: 9 (Weight ratio). Further, a conductive agent may be mixed into the positive electrode active material as needed. As the conductive agent, for example, a carbonaceous material such as graphite, carbon black or acetylene black is used as necessary.

[0025] The coating solution prepared is a gravure coat, gravure reverse coat, roll coat, Meyer bar coat, blade coat, knife coat, air knife coat, slot die coat, slide die coat, dip coat, die coat, comma roll coat, The active material layer 2 is formed by being applied onto the current collector 1 as a base by a method such as converse coating and screen printing, and then dried.

The active material layer 2 may be formed by repeating coating and drying a plurality of times. As a heat source in the drying step, for example, hot air, infrared light, microwave, high frequency, or a combination thereof is used. In the drying step, a metal roller, a metal sheet, or the like that supports the current collector 1 may be heated, and the coating film may be dried using the heat released. After drying, the active material layer 2 is irradiated with an electron beam or radiation to cause a crosslinking reaction of the binder.
You can also get In this way, the thickness of the active material layer 2 is usually in the range of 10 to 200 μm, preferably 50 to 170 μm. Further, the obtained active material layer 2 is preferably aged in a vacuum oven or the like to remove moisture in the active material layer 2.

Further, the obtained active material layer 2 is formed of a metal roll,
It is also preferable to improve the homogeneity of the active material layer 2 by performing a press treatment using a heating roll or a sheet press. However, press processing may or may not be performed. Press pressure is usually 500-7500kg
f / cm ² , preferably 3000 to 5000 kgf / c
m ² . If the pressing pressure is lower than 500 kgf / cm ^2, it is difficult to obtain uniformity of the active material layer 2, and 7500 kg
If the pressing pressure is higher than f / cm ^2, the electrode plate itself including the current collector 1 may be damaged. In order to improve homogeneity, a single press may be used to achieve a predetermined thickness,
Pressing may be performed several times.

When the pressure of the roll press is controlled by the linear pressure, the pressure is adjusted according to the diameter of the pressure roll, but usually the linear pressure is 0.5 kgf / cm to 1 tf / cm. Pressing may be performed several times in consideration of the thickness of the electrode plate 100 after pressing.

Next, the notch 2a is formed by patterning the active material layer 2. The method of forming the notch 2a will be described later.

The electrode plate 10 manufactured through the above steps
When a secondary battery is manufactured using 0, it is preferable to perform a heat treatment, a decompression treatment, or the like in advance in order to remove moisture in the active material layer before moving to a battery assembly process.

When, for example, a lithium secondary battery is manufactured using the electrode plate 100, a non-aqueous electrolyte obtained by dissolving a lithium salt as a solute in an organic solvent is used. Examples of the lithium salt include LiClO ₄ , LiBF ₄ , L
iPF _6, LiAsF _6, LiCl, inorganic lithium salts such as LiBr, _{or,, LiB (C 6 H 5} ) 4, LiN (SO 2
CF ₃ ) ₂ , LiC (SO ₂ CF ₃ ) ₃ , LiOSO ₂ C
_{F 3, LiOSO 2 C 2 F} 5, LiOSO 2 C 3 F 7, LiO
SO ₂ C ₄ F ₉ , LiOSO ₂ C ₅ F ₁₁ , LiOSO ₂ C ₆ F
₁₃ , organic lithium salts such as LiOSO ₂ C ₇ F _{15 and the} like are used.

Examples of the organic solvent for dissolving the lithium salt include cyclic esters, chain esters, cyclic ethers, and chain ethers. More specifically,
Examples of the cyclic esters include propylene carbonate, butylene carbonate, γ-butyrolactone, vinylene carbonate, 2-methyl-γ-butyrolactone, acetyl-γ-butyrolactone, and γ-valerolactone.

Examples of the chain esters include dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dipropyl carbonate, methyl ethyl carbonate, methyl butyl carbonate, methyl propyl carbonate, ethyl butyl carbonate, ethyl propyl carbonate, butyl propyl carbonate, and alkyl propionate. Examples thereof include esters, dialkyl malonates, and alkyl acetates.

Examples of the cyclic ethers include tetrahydrofuran, alkyltetrahydrofuran, dialkyltetrahydrofuran, alkoxytetrahydrofuran, dialkoxytetrahydrofuran, 1,3-dioxolan, alkyl-1,3-dioxolan, 1,4-dioxolan and the like.

Examples of the chain ether include 1,2-dimethoxyethane, 1,2-diethoxyethane, diethyl ether, ethylene glycol dialkyl ether, diethylene glycol dialkyl ether, triethylene glycol dialkyl ether, and tetraethylene glycol dialkyl ether. Examples can be given.

Next, a step of patterning the active material layer 2 formed on the current collector 1 will be described with reference to FIGS. First, as shown in FIGS. 3 and 4, a pair of unwinding and rewinding rollers is provided above the electrode plate 100 including the current collector 1 and the active material layer 2 (on the side of the active material layer 2). The thermoplastic resin sheet 4 stretched at a constant tension in between, and further above the thermoplastic resin sheet 4,
The heat-resistant sheet 5 stretched with a constant tension is disposed between another pair of rollers prepared separately from the pair of rollers. The support 6 is provided below the electrode plate 100. Next, by pressing the hot plate 20 toward the electrode plate 100, the electrode plate 100 and the thermoplastic resin sheet 4 are interposed between the hot plate 20 and the support 6 as shown in FIG.
And the heat resistant sheet 5 is sandwiched. By such thermocompression bonding, as shown in FIG. 5, only the portion 4A pressed by the hot plate 20 softens or melts the thermoplastic resin sheet 4, so that the thermoplastic resin impregnates the voids of the active material layer 2. .

Next, the hot plate 20 is removed and the electrode plate 100
Is cooled or forcedly cooled to solidify the resin impregnated in the active material layer 2. After the resin is solidified, the thermoplastic resin sheet 4 is removed. As shown in FIG. 6, only the resin-impregnated portion 4A is selectively removed together with the solidified thermoplastic resin sheet 4, and the resin is not impregnated. The active material layer 2 remains as it is in the portion where the heat is applied. On the other hand, since the heat-resistant sheet 5 is sandwiched between the hot plate 20 and the thermoplastic resin sheet 4 during thermocompression bonding, the thermoplastic resin is prevented from adhering to the hot plate 20.

In the manufacturing method of the present invention, the contact surface of the hot plate 20 is formed in advance in a shape corresponding to the electrode pattern, that is, by making the contact surface a pattern for removing the electrode, the desired electrode shape is obtained. I'm trying to get

As the thermoplastic resin used for the thermoplastic resin sheet 4, those generally used as conventional heat seal materials, such as polyolefin resin and EVA, are suitable, and are made of aluminum foil or copper foil. Current collector 1
It is preferable that the adhesive force to the adhesive is not too strong. The softening temperature is preferably 70 to 150 ° C.
The melting point is preferably about 100 to 160 ° C., and the melt flow rate (MFR unit g / 10 min,
(190 ° C to 230 ° C) is preferably about 0.1 to 50. However, the thermoplastic resin usable in the present invention is not limited to this range.

The thickness of the thermoplastic resin sheet 4 is not particularly limited, but is preferably 10 to 200 μm, more preferably 25 to 100 μm. If the thickness of the thermoplastic resin sheet 4 is too small, the active material layer 2 cannot be sufficiently removed.
Cannot be patterned into a sharp shape.

In the present invention, a material that can be peeled off from the thermoplastic resin sheet 4 after thermocompression bonding is used as the heat resistant sheet 5. Then, for example, as shown in FIG. 3, the heat-resistant sheet 5 can be repeatedly used by connecting the heat-resistant sheet 5 in an annular shape and winding it around a roller, and moving the use site. There is no particular limitation on the material of the heat-resistant sheet 5, but it is necessary to use a material that can be peeled off from the thermoplastic resin sheet after thermocompression bonding by the hot plate 20, for example, using polyethylene terephthalate, polyimide, polyphenylene sulfide, or the like. be able to. The thickness of the heat-resistant sheet 5 is 10 to 1 because it can be patterned into a sharp shape.
The thickness is preferably about 00 μm, more preferably about 25 to 50 μm.

As conditions for the thermocompression bonding, the temperature is preferably 100 to 150 ° C., and the pressure is preferably 2 to 10 kgf /
cm ² and the crimping time are preferably 5 seconds or less, but the production method of the present invention is not limited to this range.

In the case where electrodes having a symmetric shape so as to completely face each other with the current collector interposed therebetween are formed on the front and back surfaces of the current collector, a pair of hot plates having a symmetric pressing surface are prepared. Thermocompression bonding may be performed by sandwiching the electrode plate between the hot plates. In this case, a heat-resistant sheet may be disposed between the hot plate and the thermoplastic resin sheet.

After the thermocompression bonding, the thermoplastic resin sheet 4 comes into close contact with the active material layer 2, but when the thermoplastic resin sheet 4 is peeled from this state, most of the active material layer 2 is also removed at the same time. However, the active material layer 2 is not always completely removed up to the contact surface with the current collector 1, and a part of the active material layer 2 may remain as powder. In such a case, the unnecessary active material layer 2 can be completely removed by repeating the steps of thermocompression bonding, cooling and peeling a plurality of times. Further, when the thermocompression bonding is repeated a plurality of times, a new thermoplastic sheet may be used for each thermocompression bonding operation, and in this case, the type of the thermoplastic resin sheet may be changed. .

As described above, in the manufacturing method of the present invention, the active material layer 2 can be patterned into an arbitrary shape by appropriately selecting the shape of the hot plate 20.
By using a heat roll in place of, a strip-shaped pattern along the feeding direction of the electrode plate can be formed.
In this case, the heat-resistant sheet may be sandwiched between the heat roll and the thermoplastic resin sheet, and the heat-resistant sheet may be fed at the same speed as the thermoplastic resin sheet.

At the time of thermocompression bonding, the thermoplastic resin penetrates through the minute gaps in the active material layer 2 toward the interface between the current collector 1 and the active material layer 2. However, if the fluidity is small, it will solidify before reaching the surface of the current collector 1. When the thermoplastic resin sheet 4 is peeled off in such a state, cohesive failure occurs in the middle of the active material layer 2, and only the upper layer of the active material layer 2 is removed and the lower layer remains. Even in this case, the active material layer 2 can be completely removed finally by repeating the thermocompression operation. However, if the thickness of the active material layer 2 that can be removed by one thermocompression operation is large, the number of times of the thermocompression operation is reduced. The manufacturing cost can be reduced.

In general, when the voids in the active material layer 2 are small, the thickness of the active material layer 2 that can be peeled off by a single thermocompression operation is difficult because the molten thermoplastic resin hardly penetrates the active material layer 2. When the film forming strength of the active material layer 2 is strong, many active material layers 2 are easily peeled off at a time. Therefore, the thickness of the active material layer 2 that can be peeled off by one thermocompression bonding operation is as follows. It tends to be larger. For example, when the press treatment is performed on the active material layer 2, the void amount of the active material layer 2 is reduced, but the strength of the film formation of the active material layer 2 is increased. Do not give.

However, if a certain amount or more of press treatment is performed depending on the active material layer 2, the film forming strength of the active material layer 2 is not sufficiently increased although the molten thermoplastic resin does not easily penetrate. In some cases, the thickness that can be removed in a single operation is reduced, and the efficiency is significantly reduced. In such a case, good results can be obtained by infiltrating the active material layer 2 with a wax having a low melt viscosity in advance. That is, in this case, it is considered that the wax easily permeates into the voids of the pressed active material layer 2 and solidifies to give film forming strength to the active material layer 2.

In this case, if the active material layer 2 is impregnated with wax in advance, and then thermocompression bonding is performed, the melting heat is applied in such a manner that the wax existing in the voids of the active material layer 2 is pushed. The thermoplastic resin sheet 4 and the active material layer 2 are peeled off together due to penetration of the thermoplastic resin or adhesion between the wax and the thermoplastic resin.

The method of pre-impregnating the active material layer 2 with the wax includes a method of applying a gravure coating of a molten wax, a method of using a die coater, a method of applying using a rotary screen, and forming a film of the wax having a film forming property. There is a method of infiltrating the active material layer 2 by thermocompression, a method of transferring wax impregnated in a nonwoven fabric, paper, or the like to the active material layer 2 by thermocompression.

Further, as shown in FIG. 7, a thermoplastic resin sheet 41 and a wax layer 42 are previously formed as a thermoplastic resin sheet.
The composite sheet 40 may be used in which the wax of the wax layer 42 is permeated during thermocompression bonding. In this case, as shown in FIG. 8, the wax penetrates to a region 42A deeper than the region 41A to which the thermoplastic resin penetrates, and as shown in FIG. Is removed. Therefore, the active material layer 2 can be efficiently removed with a small number of thermocompression operations.

The wax used in the present invention may be any material that can be easily melted by heating, and low molecular weight polyethylene wax, polypropylene wax, derivatives thereof, and various natural waxes can be used. For accurate patterning of the active material layer 2, it is preferable that the active material layer 2 has low adhesion to the current collector 1 and has a small volume change during solidification.

The wax has a melting point of 20 to 250 ° C.
Preferably, the temperature is about 60 to 150 ° C. If the melting point is too low, it becomes too soft at room temperature, so that it is difficult to handle and the productivity is poor. On the other hand, if the melting point is too high, it is uneconomical in terms of energy and may impair the current collector 1 as a base material when impregnating the active material layer 2. Melt viscosity of wax is 100-50,000c
ps, preferably about 400 to 6,000 cps. If the melt viscosity is too high, it is uneconomical in terms of energy. If the melt viscosity is too low, the wax tends to spread in the horizontal direction when penetrating into the active material layer 2, making accurate patterning difficult.

Examples of the above-mentioned polyethylene or polypropylene which are preferable examples of the wax include a non-oxidizing type low density type, a non-oxidizing type medium density type, a non-oxidizing type high density type,
There are oxidized low density type, oxidized medium density type, oxidized high density type, non-polar type, polar type, powder type and the like, all of which are suitable for the method of the present invention.

As described above, in the above-described embodiment, after the thermoplastic resin sheet 4 is thermocompression-bonded to the active material layer 2, the thermoplastic resin sheet 4 is peeled off to remove a part of the active material layer 2. Therefore, patterning of the active material layer 2 can be performed with high accuracy and efficiency. Therefore, a high-quality electrode can be obtained at low cost.

Further, the heat-resistant sheet 5 is replaced with the thermoplastic sheet 4.
Since the heat-resistant sheet 5 is separated from the thermoplastic resin sheet 4 after thermocompression bonding, the heat-resistant sheet 5 can be used repeatedly, and the manufacturing cost can be reduced.

In this embodiment, since the active material layer 2 is formed by applying and drying a coating liquid, the film thickness of the active material layer 2 can be made uniform. However, the method for forming the active material layer 2 is not limited to a method of applying a coating liquid, and various methods can be used.

-Modification- Prior to forming the active material layer 2, a release layer may be formed in advance on the current collector 1 in a region where the notch 2a is to be formed. As the release agent used for the release layer, a material having a weak adhesive force to the current collector 1 and a stronger adhesive force to the active material layer 2 is selected.

If such a release layer is formed in advance,
When the thermoplastic sheet 4 is peeled off, the peeling layer is easily peeled off together with the active material layer 2, so that the active material layer 2 in the cutout portion 2a can be completely removed by a single thermocompression bonding operation.

[0060]

EXAMPLES Example 1 First, 89 parts by weight of LiCoO ₂ powder having a particle diameter of 1 to 80 μm as the positive electrode active material and having an average particle diameter of 10 μm, 8 parts by weight of graphite powder as a conductive agent, Varnish of polyvinylidene fluoride resin (KF # 1120, 12% N-methyl-2-produced by Kureha Chemical Industry Co., Ltd.) as a binder
(Pyrrolidone solution) at a mixing ratio of 33 parts by weight to prepare a positive electrode coating solution. Specifically, after mixing the above two kinds of powder materials into the varnish, the mixture is stirred for 30 minutes using a planetary mixer (manufactured by Kodaira Seisakusho Co., Ltd.).
A positive electrode coating solution was obtained.

Subsequently, a current collector made of an aluminum foil having a thickness of 20 μm and a width of 320 mm was prepared, and the above-mentioned positive electrode coating solution was applied on the current collector using a die coater. Thereafter, the resultant was moved in a drying oven having a total length of 8 m at a speed of 4 m per minute, and dried to form an active material layer of a positive electrode, thereby obtaining a positive electrode plate. The coating weight of the formed active material layer coating film was 200 g / m ² .

Next, 85 parts by weight of graphite powder as a negative electrode active material, and a varnish of polyvinylidene fluoride resin as a binder (KF # 1120, manufactured by Kureha Chemical Industry Co., Ltd.)
125% by weight of a 12% N-methyl-2-pyrrolidone solution) and 115 parts of N-methyl-2-pyrrolidone as a dispersion medium.
The mixture was mixed at a blending ratio of parts by weight to prepare a negative electrode coating liquid.

Specifically, after mixing the graphite powder into the varnish and the dispersion medium, the mixture was stirred with a planetary mixer (manufactured by Kodaira Seisakusho) for 30 minutes to obtain a negative electrode coating liquid.

Subsequently, a current collector made of a rolled copper foil having a thickness of 14 μm was prepared, and the above-mentioned negative electrode coating solution was applied on the current collector using a die coater. Thereafter, the substrate was moved in a drying oven having a total length of 8 m at a speed of 4 m per minute, and dried to form an active material layer of a negative electrode, thereby obtaining a negative electrode plate. The coating weight of the coating film of the formed active material layer is 110 g /
m ² .

Next, an apparatus as shown in FIG. 3 was used, and a polyethylene sealing material (Mooretec 0238N manufactured by Idemitsu Oil Co., Ltd., thickness 1) was used as a thermoplastic resin sheet.
30 μm), using a polyethylene terephthalate film (thickness: 25 μm) as a heat-resistant sheet, and the above-described positive electrode plate was thermocompression-bonded with a hot plate 20 having a pressing surface of 3 cm × 5 cm through these sheets.
After thermocompression bonding at 170 ° C., 3 kgf / cm ² for 2 seconds, the polyethylene sealing material was peeled off together with the polyethylene terephthalate film, and most of the active material layer was formed according to the shape of the pressing surface of the hot plate 20. It was peeled off at the same time. After the peeling, the powder of the active material layer slightly remained on the current collector surface, but after feeding the polyethylene sealing material until the unused portion was opposed to the hot plate 20, the same crimping operation was performed on the same portion. By repeating the process again, the powder was completely removed, and a good pattern was formed.

Next, when the thermocompression bonding operation was performed on the negative electrode plate in the same manner as in the case of the positive electrode, the active material layer could be completely removed.

In each of the thermocompression bonding operations, the polyethylene terephthalate film was easily peeled off from the polyethylene sealant after thermocompression bonding, and no adhesion of the resin to the polyethylene terephthalate film was observed. For this reason, the same part of the polyethylene terephthalate film could be used repeatedly.

Example 2 First, an active material layer was formed by applying and drying an active material layer to a similar current collector using the same materials and steps as in Example 1. Next, the total thickness of the electrode plate was 6 before pressing.
Pressing was performed until the concentration became 0%, and patterning of the active material layer was performed on the electrode plate after the pressing in the same manner as in Example 1. As a result, as in Example 1, good patterns could be obtained on both the positive electrode plate and the negative electrode plate.

In each of the thermocompression bonding operations, the polyethylene terephthalate film could be easily peeled off from the polyethylene sealant after thermocompression bonding, and no adhesion of the resin to the polyethylene terephthalate film was observed.

Example 3 When a polyimide film (thickness: 50 μm) was used as a heat-resistant sheet instead of the polyethylene terephthalate film used in Example 1, good patterning was possible as in Example 1. .

In each of the thermocompression bonding operations, the polyimide film could be easily peeled off from the polyethylene sealing material after thermocompression bonding, and no resin adhered to the polyimide film.

Example 4 When a polyethylene sealing material (Mirason 206P, 50 μm thick, manufactured by Mitsui Petrochemical Co., Ltd.) was used in place of the polyethylene sealing material used in Example 1, good patterning was obtained in the same manner as in Example 1. Was possible.

In each of the thermocompression bonding operations, the polyethylene terephthalate film could be easily peeled off from the polyethylene sealing material after thermocompression bonding, and no resin adhered to the polyethylene terephthalate film.

Comparative Example 1 A coating liquid was prepared by dispersing a positive electrode material composed of the same powder as in Example 1, and a coating liquid having a thickness of 20 μm was formed using a slot die coater.
The coating liquid was applied to an aluminum foil having a width of 300 mm and a width of 300 mm. During the application, the supply of the coating liquid was controlled in order to perform patterning by creating a coated portion and an uncoated portion while performing continuous feeding. As a result, distortion of the coating film pattern occurred with an increase in the coating speed. In addition, the coating amount was also suppressed for the coating portion to obtain the target coating thickness, but the target coating thickness was too small for coating by the slot die coater, and stable coating could not be performed.

Comparative Example 2 First, a coating solution was applied to the same current collector and dried using the same materials and steps as in Example 1 to form an active material layer. An adhesive tape was applied to the active material layers of the obtained positive electrode plate and negative electrode plate, and an attempt was made to peel off a part of the active material layer by peeling the adhesive tape. However, even if the adhesive tape is peeled, the active material layer cannot be sufficiently removed, and the edge of the formed pattern is not sharp,
At the time of peeling, a part of the active material layer was broken, and so-called powder dropping was observed.

Comparative Example 3 First, a coating solution was applied to the same current collector and dried using the same materials and steps as in Example 1 to form an active material layer. By scraping off a part of the active material layers of the obtained positive electrode plate and negative electrode plate using a spatula, the width 1
An attempt was made to form an uncoated portion over a length of 0 mm and a length of 200 mm. However, the active material layer cannot be sufficiently removed, the edge of the formed pattern is not sharp, and a part of the active material layer is broken at the time of peeling.
A so-called powder drop was observed.

[0077]

According to the first and second aspects of the present invention, the thermoplastic resin sheet is selectively thermocompression-bonded to a predetermined region of the active material layer, and the thermocompression-bonded thermoplastic resin sheet is peeled off. Since the active material layer is patterned, good patterning of the active material layer can be efficiently performed.
Further, at the time of thermocompression bonding, since the hot plate is pressed via a heat-resistant sheet that can be peeled off from the thermoplastic resin sheet, the heat-resistant sheet can be used repeatedly, and thus the manufacturing cost can be reduced.

According to the third aspect of the present invention, the thermoplastic resin sheet is selectively thermocompression-bonded to a predetermined region of the active material layer, and the thermocompression-bonded thermoplastic sheet is separated to pattern the active material layer. Accordingly, the shape of the active material layer can be made favorable, and a high-quality electrode plate can be obtained. Further, at the time of thermocompression bonding, since the hot plate is pressed via a heat-resistant sheet that can be peeled off from the thermoplastic resin sheet, the heat-resistant sheet can be used repeatedly, and thus the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a view showing an example of an electrode plate for a non-aqueous secondary battery according to the present invention, wherein FIG. 1 (a) is a plan view and FIG. 1 (b) is FIG.
It is sectional drawing in the BB line of (a).

FIG. 2 is a plan view showing another example of the electrode plate for a non-aqueous secondary battery according to the present invention.

FIG. 3 is a conceptual diagram illustrating a thermocompression bonding step in the method for manufacturing an electrode plate for a non-aqueous secondary battery according to the present invention.

FIG. 4 is a cross-sectional view illustrating a thermocompression bonding step.

FIG. 5 is a cross-sectional view showing a state subsequent to FIG. 4 in the thermocompression bonding step.

FIG. 6 is a cross-sectional view showing a state subsequent to FIG. 5 in the thermocompression bonding step.

FIG. 7 is a cross-sectional view illustrating a thermocompression bonding step using a composite sheet provided with a wax layer.

FIG. 8 is a cross-sectional view showing a state subsequent to FIG. 7 in the thermocompression bonding step.

FIG. 9 is a cross-sectional view showing a state subsequent to FIG. 8 in the thermocompression bonding step.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Current collector 2 Active material layer 2a Notch 4 Thermoplastic sheet 5 Heat resistant sheet 20 Hot plate

[Procedure amendment]

[Submission date] April 16, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0078

[Correction method] Change

[Correction contents]

According to the third aspect of the present invention, the thermoplastic resin sheet is selectively thermocompression-bonded to a predetermined region of the active material layer, and the thermocompression-bonded thermoplastic resin sheet is separated to pattern the active material layer. Therefore, the shape of the active material layer can be made favorable, and a high-quality electrode plate can be obtained. Further, at the time of thermocompression bonding, since the hot plate is pressed via a heat-resistant sheet that can be peeled off from the thermoplastic resin sheet, the heat-resistant sheet can be used repeatedly, and thus the manufacturing cost can be reduced.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a view showing an example of an electrode plate for a non-aqueous electrolyte secondary battery according to the present invention. FIG. 1 (a) is a plan view, and FIG. 1 (b) is a line BB in FIG. 1 (a). FIG.

FIG. 2 is a plan view showing another example of the electrode plate for a non-aqueous electrolyte secondary battery according to the present invention.

FIG. 3 is a conceptual diagram illustrating a thermocompression bonding step in the method for manufacturing an electrode plate for a non-aqueous electrolyte secondary battery according to the present invention.

FIG. 4 is a cross-sectional view illustrating a thermocompression bonding step.

FIG. 5 is a cross-sectional view showing a state subsequent to FIG. 4 in the thermocompression bonding step.

FIG. 6 is a sectional view showing a peeling step .

FIG. 7 is a cross-sectional view illustrating a thermocompression bonding step using a composite sheet provided with a wax layer.

FIG. 8 is a cross-sectional view showing a state subsequent to FIG. 7 in the thermocompression bonding step.

FIG. 9 is a cross-sectional view showing a peeling step .

[Description of Signs] 1 Current collector 2 Active material layer 2a Notch 4 Thermoplastic sheet 5 Heat resistant sheet 20 Heat plate

Claims (3)

[Claims] 1. A thermocompression bonding step of selectively thermocompression bonding a thermoplastic resin sheet to a predetermined region of an active material layer formed on a current collector surface, and peeling off the thermocompression bonded thermoplastic resin sheet. A removing step of removing the predetermined region of the active material layer, wherein in the thermocompression bonding step, from the side of the heat resistant sheet to the predetermined region via a heat resistant sheet peelable from the thermoplastic resin sheet. A method for producing an electrode plate for a non-aqueous electrolyte secondary battery, wherein a hot plate is pressed. 2. The active material layer is formed by applying a coating liquid containing an active material and a binder to the current collector and drying the same to form a film on the surface of the current collector. The method for producing an electrode plate for a non-aqueous electrolyte secondary battery according to claim 1, wherein: 3. An electrode plate for a non-aqueous electrolyte secondary battery, produced by the method according to claim 1.