JP2003157835A - Press device for manufacturing electrode for battery and manufacturing method of electrode for battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a press device for manufacturing an electrode for a battery capable of pressing a sheet-like electrode with high load and to provide a manufacturing method of the electrode for a battery using the press device. SOLUTION: This press device for manufacturing the electrode for a battery is provided with: a pressing unit 3 having a pair of pressing rolls 11 and 12 facing to each other by catching, from both surface sides, the sheet-like electrode having an electrode active material layer C formed on at least one surface of a band-like electrode collector B and carried along a certain path; and cutting units 2 located in the upstream side of the pressing unit 3 of the sheet-like electrode carrying path for cutting electrode collector both-side ear end parts El and Er where the electrode collector B surface is exposed on the surface with the layer C formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressing device for producing an electrode for a battery, and more specifically, it is for pressing a sheet-shaped electrode having an electrode active material layer on at least one surface of a strip-shaped electrode current collector with a high load. The present invention relates to a pressing device for manufacturing a battery electrode. The present invention also relates to a method for manufacturing a battery electrode.

[0002]

2. Description of the Related Art As electronic devices such as various OA devices, VTR cameras, and mobile phones have become smaller and lighter in recent years, smaller size and lighter weight and higher performance of secondary batteries used as driving power sources for these electronic devices are required. ing. In order to meet such a demand, development of a lithium ion secondary battery as a non-aqueous electrolyte battery having a high discharge potential and a high discharge capacity has been rapidly promoted and put into practical use.

For each of the positive electrode and the negative electrode of a non-aqueous electrolyte battery, generally, an electrode coating material (mixture) is prepared by mixing an electrode active material with a binder, and the electrode coating material is applied onto one surface of the electrode current collector. , Drying, and then applying an electrode coating material on the other surface of the electrode current collector, and drying to form a sheet-shaped electrode having an electrode active material layer on both surfaces of the electrode current collector, and then a sheet-shaped electrode It is manufactured by pressing an electrode and cutting it into a predetermined size. In some cases, the electrode active material layer is formed only on one surface of the electrode current collector.

In forming the sheet-like electrode, electrode active material layers are formed by coating at regular intervals in the lengthwise direction of the strip-shaped electrode current collector surface, while between adjacent electrode active material layers, In order to weld the electrode lead wire, it is necessary to secure an exposed portion of the electrode current collector surface without applying the electrode paint. Usually, the electrode paint is not applied to both ends of the electrode current collector, and the exposed portion of the electrode current collector surface remains. In this manner, the sheet-shaped electrode has, on each surface thereof, a coating section in which the electrode active material layer is formed by coating at regular intervals in the length direction, and a non-coating section between adjacent electrode active material layers. The electrode active material layer is not formed by coating on both ends of the ear, and the electrode current collector surface is exposed.

As a conventional apparatus for pressure-processing a sheet-shaped electrode, for example, JP-A-10-64521 discloses an electrode active material layer formed on a strip-shaped electrode current collector at a predetermined pitch in the lengthwise direction thereof. And a pair of pressure rolls that face each other with a sheet-like electrode conveyed along a fixed path from both sides, and two pairs of bearings that support the roll shaft ends of each roll in pairs. A roller press comprising a unit and a pair of spacers respectively interposed between two units at the same end of the bearing unit so as to form a thickness adjusting gap between the outer peripheral surfaces of both rolls. A device is disclosed.

[0006]

In the above-mentioned conventional device, since the thickness adjusting gap is formed to prevent the electrode current collector from being stretched or cut, even if the sheet-like electrode is to be pressed with a high load. If the sheet electrode is pressed and compressed until the adjustment gap becomes equal to the thickness of the sheet electrode, the sheet electrode cannot be further loaded. Therefore, in the above-mentioned conventional device, the sheet electrode cannot be pressed with a high load, and in order to compress the sheet electrode to a target thickness and increase the density of the electrode active material, it is necessary to repeat the pressing step several times. was there.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a pressing device for manufacturing an electrode for a battery, which is capable of pressing a sheet electrode with a high load. Another object of the present invention is to provide a method for manufacturing a battery electrode, particularly a non-aqueous electrolyte battery electrode, using the battery electrode manufacturing press device.

[0008]

According to the present invention, a sheet-like electrode having an electrode active material layer formed on at least one side of a strip-shaped electrode current collector and conveyed along a certain path is sandwiched from both sides. A pressure unit having a pair of pressure rolls facing each other, and an electrode current collector surface in which the electrode current collector surface is exposed on the surface on which the electrode active material layer is formed, upstream of the pressure unit in the sheet-shaped electrode transport path. A pressing device for producing an electrode for a battery, comprising: a cutting unit that cuts off both ends of the body.

In the battery electrode manufacturing press device according to the present invention, the cutting unit is provided on the upstream side of the pressing unit in the sheet electrode conveying path. The ends are cut off. When the conveyed sheet-shaped electrode is pressurized with a high load, the electrode current collector mainly extends in the sheet-shaped electrode conveyance direction. At this time, if the sheet-shaped electrode is pressed without cutting off the both side edge portions, the region where the electrode active material layer is formed on the current collector surface and the both side edge portions where the electrode active material layer is not formed are formed. There is a difference in the degree of stretching between and. That is, the degree of stretching at the both end portions is smaller than the degree of stretching in the region where the electrode active material layer is formed. Therefore, the flatness of the sheet-like electrode after pressure processing may be impaired, which may cause wrinkles and breakage. In the battery electrode manufacturing press device of the present invention, as described above, since the both side edge portions are cut off before the sheet electrode is pressed, the sheet electrode can be formed without causing wrinkles or breakage. It can be pressurized with a high load.

In the pressure unit, a pair of bearing units supporting both ends of the roll shaft of one pressure roll and a pair of bearing units supporting both ends of the roll shaft of the other pressure roll. It is also preferable that shock absorbing spacers are respectively interposed between and.

It is also preferable that the pressure unit includes a backup roll supporting one pressure roll and a backup roll supporting the other pressure roll.

In the pressure unit, a pair of bearing units supporting both ends of the roll shaft of one pressure roll and both ends of the roll shaft of a backup roll supporting the one pressure roll are supported. A shock absorbing spacer is interposed between the pair of bearing units that are in contact with each other, and a pair of bearing units that respectively support both ends of the roll shaft of the other pressure roll, and the other of the pair of bearing units. It is also preferable that the shock absorbing spacers are respectively interposed between the backup roll supporting the pressure roll and the pair of bearing units supporting both ends of the roll shaft.

Further, according to the present invention, an electrode mixture coating material containing an electrode active material and a binder is applied to at least one surface of a strip-shaped electrode current collector, and an electrode active material layer is provided on the at least one surface of the electrode current collector. Further, a sheet-like electrode in which the electrode mixture paint is not applied to both ends of the electrode current collector and the surface of the electrode current collector is exposed is formed, and the both ends of the edge of the electrode current collector are exposed. It is a method for manufacturing a battery electrode, which comprises cutting so as not to leave the sheet electrode, and then pressing the sheet electrode.

At the time of manufacturing the battery electrode, the electrode mixture coating material was applied to at least one surface of the electrode current collector with a constant gap in the length direction of the electrode current collector to form the electrode active material layer. In some cases, a sheet-shaped electrode is formed in which the coating section and the non-coating section where the electrode current collector surface is exposed are alternately arranged in the length direction of the electrode current collector.

In the present invention, it is also preferable to apply a high pressure of 500 kg / cm or more. By pressing the sheet-like electrode with such a high load, the electrode active material layer can be compressed to the target thickness with a small number of pressurizations, and the density of the active material per electrode volume can be increased.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a pressing device for producing a battery electrode according to the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing an example of an embodiment of a pressing device for producing a battery electrode according to the present invention. In FIG. 1, a sheet-like electrode having an electrode active material layer (C) formed on at least one surface of a strip-shaped electrode current collector (B) is indicated by an arrow.
Transported in the direction of (A). In the following description, the left and right sides of the sheet-shaped electrode transport path when viewed from the upstream side to the downstream side are referred to as left and right. The press device shown in FIG.
The feeding unit (1), the cutting unit (2), the pressure unit (3), and a winding unit (not shown) are provided in this order from the upstream side of the sheet-shaped electrode transport path.

In order to facilitate the following description, the sheet-like electrode fed from the feeding unit (1) will be described with reference to FIG. FIG. 2 is a plan view showing an example of a sheet-like electrode for producing a battery electrode in the present invention.

The sheet-shaped electrode (M) is formed by forming a large number of rectangular electrode active material layers (C) having a width (Wc) on a strip-shaped electrode current collector (B) having a width (Wb). The active material layers (C) are arranged in a row in the lengthwise direction of the electrode current collector with a gap between adjacent ones at a constant pitch (P). As a result, the electrode active material layer is formed on the strip-shaped electrode current collector (B) in the length direction.
Application sections (S) where (C) is formed and non-application sections (N) where the surface of the electrode current collector (B) is exposed are alternately arranged. Even in the coating section (S), the electrode active material layer (C) is not formed by coating on the left and right ear ends (El) (Er) of the electrode current collector (B). ) The exposed surface remains. A current collector (B) depending on the type of the target battery electrode
The formation pattern of the coating section (S) and the non-coating section (N) may be the same or different on both surfaces. In addition, the active material layer (C) may be formed on only one surface of the current collector (B).

Referring to FIG. 1, a cutting unit (2) is provided downstream of the feeding unit (1) in the sheet-shaped electrode transport path.
Is provided. In FIG. 1, the cutting unit (2)
Is shown conceptually. The cutting unit (2)
For example, a known cutting means such as a rotary blade of a shear method or a gang method or a laser can be used.

The cutting unit (2) cuts the left and right ear ends (El) (Er) of the electrode current collector (B) described in FIG. If dust or the like occurs when cutting off both end edges (El) (Er), in order to avoid damage to the sheet electrode, use a rotating brush,
It is preferable to remove dust and the like with an ultrasonic wave, an air knife, a dust suction device, or the like.

Referring to FIG. 3, the above cutting unit (2)
The sheet-shaped electrode after cutting off both end edges (El) (Er) will be described. FIG. 3 is a plan view showing an example of a sheet-shaped electrode in which both ends of the current collector are cut off. In FIG. 3, the width (W1) of the current collector (B) after the removal of both end portions is equal to the width of the electrode active material layer (C) in this figure. In the present invention, the both end edges (El) (Er) are cut off so as not to leave the exposed portions of the electrode current collector (B) surface on the left and right of the electrode active material layer (C). That is, the width (W1) and (Wb) described in FIG.
The cutting is performed so that the relationship with (Wc) is (W1) ≦ (Wc) <(Wb). Similar to that described in FIG. 2, in the length direction,
The coating sections (S) in which the electrode active material layer (C) is formed and the non-coating sections (N) in which the surface of the electrode current collector (B) is exposed are alternately arranged.

Referring to FIG. 1, a pressurizing unit (3) is provided downstream of the cutting unit (2) in the sheet electrode transport path. In the example of FIG. 1, a four-high rolling mill is provided as the pressure unit (3). In FIG. 1, a pressing unit (3) includes a horizontal upper roll (11) and a lower roll (11) extending in the left-right direction, which are arranged so as to face each other with a sheet-like electrode conveyed along a fixed path therebetween. 12)
These upper and lower rolls (11) and (12) have the width (W
Has a wider length than 1).

An upper rotary shaft (13) is provided on the upper roll (11) so that both left and right ends of the upper roll shaft (13) protrude left and right from the end surface of the upper roll (11). Similarly, the lower roll (12) is also provided with lower rotation shafts (14) so that the left and right ends of the lower rotation shaft (14) respectively project from the end surface of the lower roll (12) to the left and right. Upper rotation axis (1
The left and right ends of (3) are a pair of left and right upper bearing units (1
It is supported by 5). The left and right ends of the lower rotary shaft (14) are supported by a pair of left and right lower bearing units (16).

As the pressure roll, a known mechanism for controlling the lateral thickness distribution of the sheet electrode, for example, roll bending, roll reverse bending, crown roll, variable crown roll, roll cloth, etc. is used in combination. In some cases. As a material for both rolls (11) and (12), a metal such as steel or a hard synthetic resin is generally used. Both rolls (11) and (12) may be made of the same material or a combination of different materials. In use, the surface temperature of both rolls (11), (12) is generally from room temperature to 20
It is kept constant in the range of 0 ° C.

In the example of FIG. 1, a pair of left and right impact absorbing spacers (17) are interposed between the left and right pair of upper and lower bearing units (15) and (16) on the same left and right sides. . The shock absorbing spacer (17) is composed of pressure rolls (11), (1
2) With no load applied to both pressure rolls (11), (12)
Both pressure rolls (11), (12) with nothing sandwiched between them
It is advisable to interpose the gap between them to be 0.01 to 1 mm. In this state, 500 to 20000 kg on the pressure roll
When a load of / cm is applied, both pressure rolls (11) and (12) contact each other without a gap. The sheet electrode can be pressed with a high load, and the vibrations of both rolls (11) and (12) are alleviated.
Therefore, the coating section (S) and the non-coating section described in FIG.
Even when pressing the sheet electrode (M1) having (N) and (N), both rolls (11), (12 ), The wrinkles do not occur on the electrode current collector (B) in the non-application section (N).

Examples of the material of the shock absorbing spacer (17) include metals such as iron, copper, aluminum and lead, polyethylene terephthalate, polyester, vinyl chloride, polyethylene, polyimide, Teflon (registered trademark), cellophane, nylon, Resins such as polypropylene, glass fibers, carbon fibers, non-woven fabrics, and the like, and composites of these materials are used.

In the example of FIG. 1, the upper roll (11) is supported by the upper backup roll (21) and the lower roll (12) is supported by the lower backup roll (22). The upper backup roll (21) is provided with upper rotating shafts (23) so that the left and right ends thereof protrude from the end surface of the upper backup roll (21) to the left and right respectively. Similarly, the lower backup roll (22) also has the lower rotary shaft (24) on both left and right ends thereof.
(22) It is provided so as to project to the left and right from the end face. The left and right ends of the upper rotary shaft (23) are supported by a pair of left and right upper bearing units (25). The left and right ends of the lower rotary shaft (24) are supported by a pair of left and right lower bearing units (26).

The backup rolls (21) and (22) are usually
Use a roll having a diameter larger than that of the pressure rolls (11) and (12). As the backup rolls (21) and (22), the left and right lengths are pressure rolls.
In some cases, a plurality of shorter than (11) and (12) may be used.
In the example of FIG. 1, each of the backup rolls (21) and (22) is composed of five rolls. Since each of the loads of the plurality of backup rolls can be controlled, the lateral thickness distribution of the battery electrode can be controlled by adjusting the lateral load balance.
As the material of the backup rolls (21) and (22), as with the material of the pressure rolls (11) and (12), a metal such as steel or a hard synthetic resin is used. Backup Roll (21), (22)
May be made of the same material as or different materials from the pressure rolls (11) and (12) supported by them.

In the example of FIG. 1, a pair of left and right upper shock absorbing spacers (27) are interposed between the left and right upper bearing units (15) and (25) on the same side. There is. Left and right pair of lower bearing units (16), (2
A pair of left and right lower shock absorbing spacers (28) are interposed between those on the same side of 6).

The upper and lower impact absorbing spacers (27) and (28) are the pressure rolls (11) and (12) and the backup roll ( It is advisable to interpose so that the gap between (21) and (22) is both 0.01 to 1 mm. 500 ~ 20 in this state
When a load of 000 kg / cm is applied, the pressure roll (11),
(12) and backup rolls (21), (22) supporting each
And come into contact with each other. The sheet-like electrode can be pressed with a high load, and the vibrations of the pressure rolls (11) and (12) are alleviated. Therefore, even when the sheet electrode (M1) having the coating section (S) and the non-coating section (N) described in FIG. 3 is pressed, the coating section (S) is applied to the non-coating section (N). Since the vibrations of both rolls (11) and (12) due to the impact when the pressure roll is transferred are alleviated, wrinkles do not occur on the electrode current collector (B) in the non-application section (N).

The upper and lower impact absorbing spacers (27), (28) may be made of the same material as the impact absorbing spacer (17). For example, metals such as iron, copper, aluminum and lead, polyethylene terephthalate, polyester, vinyl chloride, polyethylene, polyimide, Teflon, cellophane,
Examples thereof include resins such as nylon and polypropylene, glass fibers, carbon fibers, non-woven fabrics, and the like, and composites of these materials.

As described above, in the example of FIG. 1, the four-high rolling mill is provided as the pressure unit (3). It is also possible to use a two-high rolling mill having no backup rolls (21) and (22) or a multi-high rolling mill having a multi-stage backup roll. Further, in the example of FIG. 1, the shock absorbing spacer (17) is interposed, and the upper and lower shock absorbing spacers (27) and (28) are respectively interposed. Spacer (1
7) and the upper and lower spacers (27) and (28) may be used in combination, and either the spacer (17) and the upper and lower spacers (27) and (28) may be used. In some cases, the shock absorbing spacer (17) and the upper and lower shock absorbing spacers (27) and (28) are not used.

Dust or the like may be generated when the sheet electrode is pressed. In this case, pressure rolls (11), (12)
Be careful not to attach dust to the backup rolls (21) and (22), and if dust is attached, immediately use a felt pad, resin knife, metal blade, ultrasonic wave, dust suction device, etc. Should be removed.

With reference to FIG. 4, the effect obtained by cutting off the left and right ear ends (El) (Er) in advance before pressurizing will be described. FIG. 4 is a perspective view of a coating section of the sheet electrode shown in FIG. In the example of FIG. 4, the coating section (S) is formed on both surfaces of the current collector (B) with the same formation pattern.

When the sheet-like electrode to be conveyed is pressurized with a high load, the electrode current collector (B) mainly extends in the conveying direction (A). When the sheet-shaped electrode is pressed with a high load without cutting off the left and right ear ends (El) (Er), the electrode active material layer is applied to the current collector (B) surface.
Compared with the degree of stretching (Xc) in the region where (C) is formed, both edge portions (E) where the electrode active material layer (C) is not formed (E
l) The degree of stretching (Xb) in (Er) is small. These degree of stretching
Due to the difference between (Xc) and (Xb), the flatness of the sheet-like electrode after pressurization may be impaired, which may cause wrinkles and breakage. As described with reference to FIG. 1, the pressing device of the present invention is provided with the both side edge parts upstream of the pressurizing unit (3) in the sheet electrode transport path.
Since the cutting unit (2) for cutting off (El) (Er) is provided, both end edges (El) (E) that cause the difference in the stretching degree are
Preliminarily excise r) and pressurize. Therefore, even if the sheet-like electrode is pressed with a high load, the flatness of the sheet-like electrode is not impaired, and wrinkles and breakage do not occur.

Referring to FIG. 1, the sheet-like electrode is fed from the feeding unit (1) and conveyed in the direction indicated by arrow (A). The electrode active material layer (C) is not formed and the surface of the electrode current collector (B) is exposed. Both ends of the electrode current collector (El) (Er)
Are cut by a cutting unit (2) provided upstream of the pressure unit (3) in the sheet electrode transport direction. After the both edge portions (El) (Er) are cut off, the sheet electrode passes between the upper and lower pressure rolls (11) and (12). Electrode current collector
(B) The active material layer (C) is applied and formed, and the active material layer (C) is pressed when the coating section passes between the upper and lower pressure rolls (11) and (12). Compressed. As described with reference to FIG. 4, since the both edge portions (El) (Er) are cut off in advance before being pressed, the flatness of the sheet electrode is impaired even if the sheet electrode is pressed with a high load. No wrinkles or breaks. Referring to Fig. 3, coating section (S) and non-coating section (N)
Even when a sheet-shaped electrode in which and are alternately arranged in the length direction of the electrode current collector is pressed, the shock absorbing spacer (17)
And / or by using the upper and lower impact absorbing spacers (27), (28), both rolls (11), (12) due to the impact when the pressure roll moves from the coating section (S) to the non-coating section (N) Since the vibration of the electrode is relaxed, wrinkles do not occur in the electrode current collector (B) in the non-application section (N). After applying the pressure, the sheet electrode is wound up by a winding unit (not shown).

The present invention also relates to a method of manufacturing a battery electrode. In the present invention, first, an electrode active material and a binder are mixed with a solvent to prepare a slurry electrode mixture coating material. At this time, a conductive agent or an additive may be added, if necessary.

The electrode active material is not particularly limited as long as it has been conventionally used as an electrode active material, and various materials can be used. As the positive electrode active material,
For example, an oxide or carbon material that can be doped / dedoped with lithium ions can be used. Examples of such an oxide include a composite oxide containing lithium. For example, lithium cobalt oxide Li _x CoO ₂ (0 <x ≦
1.0), lithium manganate Li _{1 + x} Mn _2-x O
₄ (0 ≦ x ≦ 1/3), lithium nickel oxide Li _x Ni
O ₂ (0 <x ≦ 1.0) and the like can be mentioned. The average particle size of these oxide powders is preferably about 1 to 40 μm.

As the negative electrode active material, for example, carbonaceous materials, lithium metal, lithium alloys, oxides such as tin oxide are used. The carbonaceous material is not particularly limited, and for example, amorphous carbon, acetylene black, petroleum coke, coal coke, artificial graphite, natural graphite, graphite-based carbon fiber, non-graphitizable carbon, etc. can be used. . A person skilled in the art can appropriately select from these, depending on the characteristics of the intended battery.

The binder for the electrode coating material is not particularly limited, and various binders such as crystalline resins and amorphous resins which have been conventionally used can be used. For example, as the binder, polyacrylonitrile (PAN), polyethylene terephthalate, polyvinylidene fluoride (PVDF), polyvinyl fluoride,
A fluorocarbon resin such as fluororubber can be used. The binder is used in an amount of usually 1 to 40 parts by weight, preferably 2 to 25 parts by weight, particularly preferably 5 to 15 parts by weight, based on 100 parts by weight of the electrode active material.

The solvent for the electrode coating material is not particularly limited, and various solvents conventionally used in preparing the electrode coating material can be used. For example, N-methylpyrrolidone (NMP), methyl isobutyl ketone (MIBK), methyl ethyl ketone (ME
K), cyclohexanone, toluene and the like.

The conductive agent can be added, if necessary, for the purpose of supplementing the electronic conductivity of the electrode active material.
The conductive agent is not particularly limited, and various known conductive agents may be used. For example, acetylene black, graphite, gold / silver / copper fine particles and the like can be mentioned.
Further, various known additives such as lithium carbonate, oxalic acid and maleic acid may be added.

Mixing of the electrode active material, the binder, the conductive agent, the solvent and the like can be carried out by a conventional method. For example, by a roll mill method, mixing is performed under dry air or an inert gas atmosphere.

Next, the obtained slurry-like electrode coating material is applied onto a strip-shaped electrode current collector. The application may be performed on both sides of the current collector or only on one side, depending on the purpose of the electrode. When applying the electrode coating material on both sides of the current collector, it may be applied to both sides at the same time and the next drying step may be performed, or it may be applied to one side to perform the drying step, and then to the other side. Then, the drying step may be performed.

In applying the electrode coating material, in order to form the coating section (S) and the non-coating section (N) at a predetermined pitch (P) in the length direction of the current collector, for example, the coating liquid is intermittently supplied to the die nozzle. Method (Japanese Patent Application Laid-Open No. 2000-149929), a method of masking the non-application section (N) in advance (Japanese Patent Application No. 2001-119140 by the present applicant, filed on April 18, 2001), etc. Good to apply. Of course, other various methods may be applied.

The electrode coating material can be applied to the electrode current collector by a known method, for example, extrusion coating, gravure coating, reverse roll coating, dip coating, kiss coating, doctor coating, knife coating, curtain coating, nozzle coating, screen. It can be performed by a coating method such as printing.

In the present invention, a metal foil, a metal sheet, a punching metal, a metal net or the like is used as the electrode current collector, and a metal foil or a punching metal is preferable. The metal material for the electrode current collector is not particularly limited, and various metal materials conventionally used for electrode current collectors can be used. Examples of such a metal material include copper, aluminum, stainless steel, nickel, iron and the like, and copper, aluminum and the like are preferable. The thickness of the electrode current collector is usually 1 to 30 μm, preferably 5 to 20 μm.

Subsequent to the application of the electrode paint, drying is carried out to remove the solvent. Drying can be performed by a conventional method. For example, drying is performed at 30 to 150 ° C. for about 5 to 15 minutes. In this way, referring to FIG. 2, the electrode current collector (B)
The electrode active material layer (C) is formed on one or both sides of the sheet-shaped electrode (M) ) Get In the sheet electrode (M), the both ends of the electrode current collector (B) (E
The electrode active material layer (C) is not formed by coating on l) (Er), and the surface of the electrode current collector (B) is exposed.

After drying, the both end edges (El) (Er) are cut off so that the exposed surface of the current collector (B) is not left, and then the sheet electrode is pressed to activate the electrode. The thickness of the material layer is made thin and uniform, and the density of the active material per electrode volume is increased. At this time, the pressing device of the present invention including a cutting unit and a pressure unit may be used.

The pressurizing pressure is, for example, 5 kg / cm.
Or more, preferably 500 kg / cm or more,
More preferably, it is 1000 kg / cm or more. 10
When pressing with a high load of 00 kg / cm or more, it is preferable to use a multi-high rolling mill such as a 4-high rolling mill in order to suppress the bending of the pressure roll and uniformly press the sheet electrode. The upper limit of the pressurizing pressure is, for example, 20000 kg / cm
It is about 10 kg / cm, and preferably up to about 10,000 kg / cm.

The surface treatment of the sheet electrode may be performed immediately before and / or immediately after the pressure processing. The surface treatment includes, for example, a far-infrared ray, a heating furnace using hot air, an electron beam, an α-ray,
It can be performed using a radiation irradiation device such as β rays, γ rays, X rays, and ultraviolet rays.

After the pressure processing, the sheet electrode is cut into a predetermined size. The cutting is generally composed of a slit process for making the electrode a predetermined width along the manufacturing flow direction and a cutting process for making the electrode a desired length.

[0054]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. [Example 1: Production of positive electrode] A slurry-like positive electrode coating material having the following composition was prepared.

[0055] (Composition of positive electrode paint) Positive electrode active material: 100 parts by weight of lithium cobalt oxide Conductive agent: acetylene black 6 parts by weight Binder: Fluorine rubber 5 parts by weight Solvent: N-methylpyrrolidone (NMP) 39 parts by weight Solvent: methyl isobutyl ketone (MIBK) 39 parts by weight

First, 5 parts by weight of the binder is added to MIBK20.
A lacquer was prepared by dissolving it in parts by weight. Next, the conductive agent 6
25 parts by weight of the lacquer was added to the parts by weight and kneaded, and then 19 parts by weight of MIBK and 39 parts by weight of NMP were added to the kneaded product and dissolved to prepare a paste. Paste 8 above
100 parts by weight of the positive electrode active material was added to 9 parts by weight and mixed well to obtain a positive electrode coating material.

Next, referring to FIG. 2, the thickness is 20 μm and the width is
(Wb) Electrode current collector made of 400mm aluminum foil
The positive electrode coating material was intermittently applied to one surface of (B) by nozzle coating, and then dried in a drying oven at 80 to 130 ° C. to form an electrode active material layer (C). Coating section (S) current collector length direction length 400 mm, width (Wc) 380 mm, non-coating section (N)
The length of the current collector was 20 mm. After that, the same coating operation is performed on the other surface of the aluminum foil to form the electrode active material layer.
(C) was formed. As a result, a sheet electrode (M) having a total thickness of the electrode current collector (B) and the electrode active material layers (C) on both surfaces of 350 μm was obtained.

Using the pressing apparatus of the present invention equipped with the cutting unit (2) and the pressure unit (3), the sheet-like electrode (M) obtained has both end portions (El) where the aluminum foil surface is exposed. ) (Er) was excised, and then the sheet electrode was pressed. With reference to FIG. 3, the width after excision of both end edges and before pressurization
(W1) was 370 mm. Referring to FIG. 1, diameter 4
20 mm metal pressure rolls (11), (12), 5 each
Individual metal backup rolls with a diameter of 500 mm (2
1) and (22) were used. Bearing unit so that the gap between the unloaded rolls (11) and (12) is 0.46mm with nothing sandwiched between the upper and lower pressure rolls (11) and (12).
Metal shock absorbing spacers (17) and (17) were interposed between (15) and (15) and the bearing units (16) and (16). The vertical shock absorbing spacers (27) (27), (28) (28) were not interposed. A sheet-like electrode with a thickness of 350 μm before pressurization has a target thickness of 230 μm.
A load was applied so that it could be compressed to m to manufacture a battery electrode. The load applied to the pressurizing part at this time is 4600k
When the sheet-shaped electrode was not sandwiched between the upper and lower rolls (11) and (12), both rolls (11) and (12) were in contact with each other without a gap.

[Comparative Example 1] A battery electrode was manufactured in the same manner as in Example 1 except that both ends (El) (Er) were not cut off. When pressurizing, the load applied to the pressurizing part is 4600 kg.
Was / cm.

Example 2 A battery electrode was manufactured in the same manner as in Example 1 except that the shock absorbing spacers (17) and (17) were not interposed. When pressurizing, the load applied to the pressurizing part is 18
It was 00 kg / cm.

[Embodiment 3] The gap between the pressure roll (11) and the backup roll (21) and the pressure roll ( The gap between 12) and the backup roll (22) is both 0.1mm
So that the upper shock absorbing spacers (27) (27) made of metal and the lower shock absorbing spacers (28) (28) made of metal are interposed, a battery electrode is manufactured in the same manner as in Example 1. did. During pressurization, the load applied to the pressurizing part was 3000 kg / cm.

[Embodiment 4] Upper shock absorbing spacers (27) (27)
And except that the lower shock absorbing spacers (28) and (28) are interposed,
A battery electrode was manufactured in the same manner as in Example 1. The shock absorbing spacers (27) and (28) are the shock absorbing spacers used in the third embodiment.
The same material and same size as (27) and (28) were used.
During pressurization, the load applied to the pressurizing part is 7400 kg / c
It was m.

The states of the battery electrodes manufactured in Examples 1 to 4 and Comparative Example 1 were observed. Examples 1, 3, 4
Then, the flatness of the obtained battery electrode was good, and
The electrode current collector (B) exposed in (N) did not have wrinkles or breaks. In Example 2, wrinkles were generated in the electrode current collector (B) exposed in the non-application section (N), but there was no problem in practicality. On the other hand, in Comparative Example 1, the flatness of the battery electrode was poor and the battery electrode was broken at several locations.

[0064]

According to the present invention, the sheet-like electrode can be pressed with a high load, the flatness of the sheet-like electrode is not impaired even after the pressurization with a high load, and wrinkles and breakage do not occur. . The electrode active material layer can be compressed to a target thickness with a small number of pressurizations, and the density of the active material per electrode volume can be increased.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of an embodiment of a pressing device for producing a battery electrode of the present invention.

FIG. 2 is a plan view showing an example of a sheet-like electrode for producing a battery electrode in the present invention.

FIG. 3 is a plan view showing a sheet-shaped electrode in which both ends of the current collector are cut off.

FIG. 4 is a perspective view of a coating section of the sheet electrode shown in FIG.

[Explanation of symbols]

(1): Feeding unit (2): Cutting unit (3): Pressurizing unit (11): Pressure roll (12): Pressure roll (17): Shock absorbing spacer (21): Backup roll (22): Backup roll (27): Shock absorbing spacer (28): Shock absorbing spacer (B): Electrode current collector (C): Electrode active material layer (M): Sheet electrode (M1): Sheet electrode (El) (Er): Both ends

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5H050 AA19 BA17 CA08 CA09 CB02                       CB07 CB08 CB09 CB12 DA02                       DA03 DA04 GA03 GA04 GA22                       GA29 HA15

Claims (7)

[Claims] 1. A pair of pressure rolls having an electrode active material layer formed on at least one surface of a strip-shaped electrode current collector and facing each other with a sheet-like electrode conveyed along a certain path sandwiched from both sides. The pressing unit and the pressing unit of the sheet-shaped electrode transport path are cut off at both ends of the electrode current collector where the electrode current collector surface is exposed on the surface on which the electrode active material layer is formed. A press device for producing an electrode for a battery, comprising a cutting unit. 2. In the pressure unit, a pair of bearing units supporting both ends of the roll shaft of one pressure roll, and a pair of bearing units supporting both ends of the roll shaft of the other pressure roll. The press device for manufacturing an electrode for a battery according to claim 1, wherein impact absorbing spacers are respectively interposed between the bearing unit and the bearing unit. 3. The battery electrode manufacturing method according to claim 1, wherein the pressure unit includes a backup roll supporting one pressure roll and a backup roll supporting the other pressure roll. Press machine. 4. In the pressure unit, a pair of bearing units supporting both ends of the roll shaft of one pressure roll, and both ends of the roll shaft of a backup roll supporting the one pressure roll. And a pair of bearing units that respectively support both ends of the roll shaft of the other pressure roll, and shock absorbing spacers are respectively interposed between the pair of bearing units that support the other. 4. The battery electrode according to claim 3, wherein a shock absorbing spacer is interposed between each of the pair of bearing units supporting both ends of the roll shaft of the backup roll supporting the pressure roll. Manufacturing press machine. 5. An electrode mixture coating material containing an electrode active material and a binder is applied to at least one surface of a strip-shaped electrode current collector,
Forming a sheet-like electrode having an electrode active material layer on at least one surface of the electrode current collector, and the electrode mixture paint is not applied to both ends of the electrode current collector and the electrode current collector surface is exposed. A method for producing an electrode for a battery, which comprises cutting off the end portions on both sides so as not to leave the exposed electrode collector surface, and then pressing the sheet-like electrode. 6. An electrode mixture coating material is applied to at least one surface of an electrode current collector with a certain gap in the length direction of the electrode current collector, and a coating section in which an electrode active material layer is formed and an electrode current collector. The method for manufacturing a battery electrode according to claim 5, wherein a sheet-like electrode is formed by alternately arranging the non-application section where the surface of the current collector is exposed in the lengthwise direction of the electrode current collector. 7. The method for producing a battery electrode according to claim 5, wherein the pressure is applied at a pressure of 500 kg / cm or more.