JP2001338641A - Manufacturing method for secondary battery and roll press device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the productivity in the manufacture of secondary battery by wiping out continuously the electrode agent adhered to the rolling roll in the crimping process of the film shape metal foil and the electrode agent by roll press. SOLUTION: The manufacturing method comprises an application process 11 in which an electrode agent is applied on the film shape metal foil for forming a film electrode and a roll press process 14 in which the film electrode is passed between the rolling rollers and the electrode agent is crimped on the film shaped metal foil, while at the same time the electrode agent adhered to the rollers is continuously wiped out. In this rolling press process 14, the electrode agent adhered to the rolling roller surface is continuously wiped out by the rolling brush (nylon brush) which rolls in contact with the rolling roller (elastic roller).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a secondary battery in which a film electrode of the secondary battery is formed by a roll press process, and a roll press apparatus.

[0002]

2. Description of the Related Art Batteries are roughly classified into primary batteries and secondary batteries. When a primary battery is discharged, its life is extended. However, a secondary battery must be recharged and reused many times. Can be.

There are several types of such secondary batteries. For example, there are a lead storage battery, a nickel cadmium (nickel) battery, a nickel hydrogen battery, and a lithium ion battery. Among them, the lithium ion battery has a high capacity density per volume, and can generate a voltage approximately three times as high as that of the nickel cadmium battery. Further, lithium in the battery exists in an ionic state, which has high safety. For this reason, demand as an energy source for electronic devices has been greatly increased in recent years.

In a lithium ion battery, a film-shaped positive electrode and a film-shaped negative electrode having a predetermined width are wound in close contact with a separator interposed therebetween. In these electrodes, for example, a positive electrode in which a lithium composite oxide is applied to both surfaces of an aluminum foil having a thickness of several tens of μm and a negative electrode in which carbon is applied to both surfaces of a copper foil are used.

In the manufacturing process of such an electrode, a film-shaped metal foil wound in a wide roll form is prepared, and while the film-shaped metal foil is pulled out from the roll, an electrode agent is applied, dried and cooled, and then again. Take up in a roll.

Thereafter, the rolls coated with the electrode material are sequentially introduced into a roll press device while being pulled out, and the film-shaped metal foil and the electrode material are pressed against each other by a roll press treatment to increase the density of the electrode material. After the pressure bonding, the film-shaped electrode is wound again into a roll, and the film-shaped electrode is cut into a predetermined width by a cutting device.

[0007]

However, there are the following problems in manufacturing such a secondary battery.
That is, when the film-shaped metal foil and the electrode material are pressed by a roll press device, the roll-press is performed through the film-shaped metal foil coated with the electrode material between the rotating rolls, and one of the rotating rolls (elastic roll) is used. The electrode agent adheres to the surface, and if it exceeds a certain limit, the electrode agent applied to the film metal foil sent next will be peeled off due to the effect of the attached electrode agent, causing a production loss There is a problem. For this reason, if the electrode agent adheres to the surface of the rotating roll to some extent, it is necessary to manually wipe off the attached electrode agent, and during that time, the roll press process cannot be performed, thereby lowering productivity.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve such problems. That is, the method for producing a secondary battery of the present invention comprises the steps of applying an electrode agent to a film-shaped metal foil to form a film electrode, and passing the film electrode between rotating rolls to convert the electrode agent to a film-shaped metal foil. And a step of continuously wiping off the electrode agent adhered to the roll.

Further, the roll press device of the present invention comprises a rotating roll for applying pressure to a film electrode having a film-shaped metal foil coated with an electrode agent and pressing the electrode material to the film-shaped metal foil; Wiping means for wiping the electrode agent adhered to the surface of the rotary roll in contact with the rotating roll.

In the present invention, the electrode material applied to the film-shaped metal foil is pressed by a roll press, and the film-shaped metal foil is passed between the rotating rolls to perform the pressure-bonding process. Since the electrode material thus obtained is continuously wiped, the electrode material does not remain on the roll surface in the roll pressing step, and the work of wiping the electrode material separately from the roll press can be eliminated.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram illustrating a method for manufacturing a secondary battery according to the present embodiment, and FIG. 2 is a perspective view illustrating an internal structure of a secondary battery to be manufactured.

First, the structure of a secondary battery to be manufactured in this embodiment will be described. The secondary battery shown in FIG. 2 mainly includes a lithium ion secondary battery. This lithium ion secondary battery has a sheet shape and a positive electrode lead 1.
a and a negative electrode 2 also formed in a sheet shape and having a negative electrode lead 2a are wound around a separator 3 such as a 25 μm-thick microporous polypropylene film to form a spiral laminated electrode body. The laminated electrode body is formed inside the battery can 5 via the insulator 4.

A safety valve 6 for bleeding gas is formed on the upper portion of the battery can 5, and a gasket 7 for preventing gas leakage is held on the upper portion of the safety valve 6, and a positive electrode lid 8 is fixed by laser welding or the like. An organic electrolytic solution in which LiPF ₆ is dissolved as a mixed solvent at a ratio of 1 mol / l or the like is injected into a battery can 5 containing such a laminated electrode body to form a lithium ion secondary battery.

The operation of the lithium ion secondary battery having such a configuration will be briefly described. At the time of charging, lithium is dissolved as lithium ions from the positive electrode active material of the positive electrode 1 into the electrolyte of the separator 3, and the negative electrode of the negative electrode 2 is charged. The lithium ions that have entered the active material and discharged into the negative electrode active material of the negative electrode 2 at the time of discharge are released into the solution and returned to the positive electrode active material of the positive electrode 1 to perform a charge / discharge operation.

Incidentally, a sheet-like positive electrode 1 and a negative electrode 2
Is formed by winding a film-shaped metal foil having a length of approximately 500 m to 1500 m into a roll shape and putting the film-shaped metal foil into a manufacturing process of a lithium ion secondary battery to be sequentially formed. That is, an electrode material corresponding to each of the positive electrode 1 and the negative electrode 2 is applied to this film-shaped metal foil, and the sheet-like positive electrode 1 and the negative electrode 2 are formed through respective processes such as a roll press process and a cutting process.

Next, a manufacturing method of the present embodiment for such a lithium ion secondary battery will be described. As shown in FIG. 1, first, a delivery unit 10 for delivering an aluminum foil (positive electrode material) wound in a wide roll shape or an aluminum foil coated with an electrode agent on one side is used as a starting point. A mixture of 0.5 mol and 1 mol of cobalt carbonate, and calcined for a predetermined time to obtain LiCoO ₂ (lithium composite oxide) in a slurry state are supplied to the coating step 11 as a positive electrode battery agent.

In the coating step 11, such a positive electrode material is applied to both surfaces or one surface of the positive electrode material except for the positive electrode lead 1a (see FIG. 2, the same applies hereinafter).

The positive electrode material coated with the electrode material has a temperature of 10
The film-shaped metal foil coated with the positive electrode agent that has been dried in the drying step 12 at 0 ° C. to 130 ° C. and has passed through the drying step 12 is cooled to room temperature by being cooled in a cooling step 13 or natural cooling by the outside air while being wound into a roll. Is done.

Next, the roll-shaped film-shaped metal foil coated with the electrode agent is subjected to a roll pressing step 1 for compression molding.
4 and supplied between the steel roll and the elastic roll whose temperature is maintained at 50 to 190 ° C. On this occasion,
The pressure applied to the film-like metal foil is a linear pressure of 200 to 1000
kg / cm, and the feed speed is about 10 to 80 m / min.

In this embodiment, the roll pressing step 1
In 4, the electrode material is pressed against the film-shaped metal foil while the film-shaped metal foil is fed between the steel roll and the elastic roll, and the electrode material (transferred from the film-shaped metal foil) adhered to the elastic roll by this pressing. Are continuously wiped off.

For example, using a nylon brush which rotates so as to be in contact with the surface of the elastic roll, the electrode agent adhered to the surface of the elastic roll is peeled off by the nylon brush. This makes it possible to immediately remove the electrode material that has adhered to the surface of the elastic roll while performing pressure bonding, and to prevent trouble caused by the attached electrode material, that is, unnecessary electrode material applied to the film metal foil that is sequentially sent. Can be prevented from being peeled off.

Next, the film-shaped metal foil on which the electrode agent has been pressed is wound again in a roll shape, and the next cutting step 15 is performed.
Sent to In the cutting step 15, the film-shaped metal foil is cut into a predetermined width dimension of a cell to be a battery to obtain a positive electrode 1.

The winding speed in the positive electrode manufacturing process is generally 15 to 100 m / min, and the tension is controlled to approximately 30 kg / 600 mm width.

Similarly, petroleum pitch is used as a starting material, and a coke material powder obtained by calcining the same is used as a slurry to obtain a negative electrode. While controlling this electrode agent at a temperature of 20 to 35 ° C. and a viscosity of 3 to 20 Pa · S,
It is supplied to the coating step 11.

In a coating step 11, the negative electrode material, which is a copper foil, is coated with leaving the negative electrode lead 2a, and in a drying step 12, the solvent is dried.

In this roll pressing step 14, the electrode agent (transferred from the film-like metal foil) adhered to the elastic roll is continuously wiped off together with the pressing of the electrode agent.

Thereafter, in a cutting step 15, the battery cell is cut into a predetermined width dimension to obtain the negative electrode 2. Then, the positive electrode 1, the negative electrode 2
Both are dried through a vacuum drying process 16 and assembled into a secondary battery structure by a cell assembly process (not shown). Thus, a lithium ion secondary battery is completed.

Next, a roll press apparatus according to the present embodiment will be described with reference to the schematic diagram of FIG. This roll press device is used in the roll press step 14 (see FIG. 1) of the above-described method for manufacturing a secondary battery.

This roll press device includes a steel roll R1, an elastic roll R2 (for example, using a thermosetting resin on the surface), a steel roll R3, and a nylon brush NB. In this configuration, the steel rolls R1 and R3 come into contact with the elastic roll R2 and rotate. Further, the nylon brush NB rotates in a state of contacting the surface of the elastic roll R2.

The electrode material is applied to both sides or the surface of the film-shaped metal foil sent to the roll press device. In this state, the steel roll R1 is wound up along the surface from the lower side in the figure and is sent to the space between the elastic roll R2. Incidentally, the feeding speed of this film-shaped metal foil is generally 15
１００100 m / min.

The steel roll R1 has a temperature of 100 to 1
The temperature is kept at 50 ° C., and the film-like metal foil can be heated by being sent along the same.

The film-shaped metal foil is sandwiched between the rotating steel roll R1 and the elastic roll R2, and further sandwiched between the elastic roll R2 and the steel roll R3, and is sequentially fed.

A pressure is applied between each of the steel rolls R1, R3 and the elastic roll R2, and a film-like metal foil is sandwiched and sent between these rolls, so that the pressure is applied to the surface by the pressure. The electrode materials are sequentially pressed.

At the time of this pressure bonding, a part of the electrode agent applied to the film-like metal foil adheres to the surface of the elastic roll R2. When the adhesion of the electrode agent reaches a certain amount, the electrode agent adheres to the electrode agent of the film metal foil to be sent next, and the electrode agent is peeled off from the film metal foil. Therefore, in the roll press device of the present embodiment, the electrode agent attached to the surface of the elastic roll R2 is wiped off by the nylon brush NB that rotates in contact with the surface of the elastic roll R2.

The nylon brush NB is pressed by a predetermined amount t from the position where the tip of the nylon wire comes into contact with the surface of the elastic roll R2. As the predetermined amount t, for example, 0.
About 2 to 0.6 mm is desirable.

The nylon wire diameter of the nylon brush NB is preferably 0.2 to 0.6 mm. That is, 0.2m
It is difficult to remove the electrode material with a material smaller than m.
If it is thicker than mm, the pressing amount is insufficient, and it is not suitable for continuous wiping. Furthermore, nylon wire length is 15mm
The surface length (width) of the nylon brush NB is the same as the electrode material, for example, about 600 mm.

Here, the elastic roll R2 is, for example, 10 to 8
It rotates at 0 rpm, and the nylon brush NB rotates at a higher speed, for example, at 500 to 3000 rpm. In the figure, the elastic roll R2 and the nylon brush NB rotate in opposite directions, but may rotate in the same direction.

By rotating the nylon brush NB at a rotation speed higher than the rotation speed of the elastic roll R2,
The electrode agent attached to the surface of the elastic roll R2 can be reliably wiped.

When the electrode material attached to the surface of the elastic roll R2 is wiped off by the nylon brush NB, the electrode material is removed by the nylon brush NB so that the electrode material does not adhere to the film metal foil below. A suction port V is provided in a direction in which the electrode material is wiped (for example, below the nylon brush NB), and the electrode agent wiped from the nylon brush NB is sucked and removed so as not to be scattered.

With such a roll press device, the electrode agent adhered to the surface of the elastic roll R2 can be continuously wiped while performing the roll press processing of the film-shaped metal foil, and the manual operation is performed separately. It is not necessary to perform the wiping process of the electrode agent.

In the above-described embodiment, the description has been made mainly on a lithium ion secondary battery as an object to be manufactured. However, the present invention is not limited to this. Applicable to molding.

[0042]

As described above, according to the present invention,
In roll pressing of a film-shaped electrode in the production of a secondary battery, the electrode agent attached to the elastic roll can be continuously removed, and the production efficiency can be greatly improved. In addition, it is possible to provide a highly reliable secondary battery without peeling of the electrode agent during roll pressing.

[Brief description of the drawings]

FIG. 1 is a schematic view illustrating a method for manufacturing a secondary battery according to an embodiment.

FIG. 2 is a perspective view illustrating an internal structure of a secondary battery to be manufactured.

FIG. 3 is a schematic diagram illustrating a roll press device according to the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Positive electrode, 1a ... Positive electrode lead, 2 ... Negative electrode, 2a ... Negative electrode lead, 3 ... Separator, 4 ... Insulator, 5 ... Battery can, 6 ... Safety valve, 7 ... Gasket, 8 ... Positive electrode cover, 10 ...
Sending section, 11: coating step, 12: drying step, 13: cooling step, 14: roll pressing step, 15: cutting step, 16
… Vacuum drying process

Claims (5)

[Claims] 1. A step of applying an electrode agent to a film-shaped metal foil to form a film electrode, and pressing the electrode agent onto the film-shaped metal foil by passing the film electrode between rotating rolls; Continuously wiping the electrode material attached to the roll. 2. The method for manufacturing a secondary battery according to claim 1, wherein a rotating brush is brought into contact with the surface of the roll to continuously wipe the electrode agent attached to the roll. 3. A rotating roll for applying pressure to a film electrode in which an electrode agent is applied to a film-shaped metal foil and pressing the electrode agent onto the film-shaped metal foil; A wiping unit for wiping an electrode agent attached to a surface of the rotating roll. 4. The roll press apparatus according to claim 3, wherein said wiping means comprises a rotary brush which rotates while being in contact with the surface of said rotary roll. 5. The roll press device according to claim 4, wherein the rotary brush rotates at a higher rotation speed than the rotary roll.