JP2000113878A - Coating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating device capable of easily varying the coating thickness of an active material and simply stabilizing the coating thickness in a process for coating the paste-like active material for a battery on the surface of an electrode core. SOLUTION: A guide component 3 is provided at the prescribed position near the die slit tip section 2 of a coating die head in slide contact with the surface of a hoop-shaped electrode core being shifted, thus the gap between the die slit tip section 2 and the surface of the electrode core to be coated is invariably kept at the distance suitable for coating stably, this coating device is easily adjusted, and the stable coating thickness of an active material is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for manufacturing electrodes of various batteries such as lithium batteries and nickel-metal hydride batteries, in which a paste-like active material is applied to the surface of an electrode core material. The present invention relates to a coating device used at the time.

[0002]

2. Description of the Related Art An example of a paste-form active material coating apparatus generally used in the process of manufacturing an electrode of a lithium secondary battery or the like will be briefly described. An electrode of a lithium secondary battery is manufactured by applying a paste-like high-viscosity liquid containing an active material as a main component to a uniform thickness on both sides of a hoop-shaped metal foil and drying the same. First, a method of applying and drying a paste-like active material on one surface of a metal foil will be described.

As shown in FIG. 3, in a paste-like active material coating step, which is one of the main steps in the production of a battery electrode, a hoop-shaped metal foil 4 such as aluminum or copper is coated. While keeping a narrow constant gap W with respect to the tip 2 of the die slit, the die slit is moved at a constant speed in the direction indicated by the arrow, and the other paste-like active material is discharged from the paste storage tank at a constant rate. It is continuously supplied to the coating die head 1a using a pump, and a slit-shaped discharge port 2 provided at the tip of the coating die head 1a.
By discharging a predetermined amount of paste stably onto the surface of the metal foil 4 which is to become the electrode core material, an active material layer 16 having a uniform thickness is applied to the surface of the metal foil 4, Subsequently, drying is performed using a drying furnace provided adjacent to the coating apparatus. Then, the coating and drying of the active material are also performed on the back surface of the uncoated metal foil in substantially the same coating process as described above. For reference, the structure of a coating die head 1a described in Japanese Patent Application Laid-Open No. 7-275774 is shown in FIG. 4 as an example of a conventionally used general coating die head. FIG. 4A is a perspective view of the appearance of a conventional coating die head 1a, and FIG. 4B is a cross-sectional view of FIG. 4A cut along line XX.

In FIG. 3, in order to stabilize the coating thickness (weight) t of the paste-like active material to a predetermined value, the temperature and viscosity of the paste and the running speed of the metal foil 4 to be coated are determined. In addition to stabilizing the rotational drive speed of the paste supply constant discharge pump, the gap W between the tip 2 of the coating die slit and the surface of the metal foil 4 to be coated is always kept at a predetermined value. To secure a narrow gap, stabilize the frictional resistance acting on the paste at the coating die slit tip 2 and stabilize the discharge amount of the paste-like active material from the coating die slit 17, a hoop-shaped The metal foil 4 is wound around the cylindrical surface of the backup roll 15, which also has a direction changing function for transferring the metal foil, while applying an appropriate tension to the metal foil 4, thereby stabilizing the position of the metal foil surface, Die slip on this part Distance W that the tip 2 is fixed so as to face in a state of close to, a suitable distance between them to a predetermined coating
And apply.

[0005] The electrode material that has been subjected to the coating and drying steps on both sides of the metal foil is cut into predetermined shapes and dimensions or coated with an active material according to the shape and size of the battery used. For the unnecessary part, the active material applied in the above step is locally peeled off (depending on the recent progress of the coating technique, in some cases, only the part requiring the paste coating is limited). It has also been attempted to selectively apply a paste. FIG. 3 also shows that the active material is being applied intermittently).

The flop-shaped core material coated with the active material is cut into a predetermined electrode plate size, and a cylindrical shape is formed in a state where both positive and negative electrode plates are laminated with a lead wire attached or a separator interposed therebetween. After undergoing a process such as winding, it is incorporated into the battery case.

As described above, in the paste-like active material coating apparatus used in a conventional general electrode manufacturing process for a lithium secondary battery, the hoop-shaped metal foil 4 to be coated is used. Is transported to the die slit tip 2 at a constant speed, and the metal foil 4 to be coated is wound around a cylindrical surface of the backup roll 15 provided in the middle of the transport path under a predetermined tension. Then, the surface of the metal foil is positioned, and the tip 2 of the coating die slit is fixed close to this portion, so that the gap between the tip of the die slit and the surface of the metal foil is adjusted to a gap W suitable for coating. To stabilize the frictional resistance acting on the paste discharged from the tip of the die slit, thereby stabilizing the paste discharge amount to a predetermined set amount, and the paste coating thickness on both surfaces of the metal foil 4. t (coating weight Each is was trying to a predetermined uniform thickness (coat weight).

However, as can be understood from a comparison between FIGS. 3A and 3B, when the hoop-shaped metal foil 4 is wound around the cylindrical surface of the backup roll 15, the surface of the metal foil 4 is previously wrapped. FIG. 3 (a) showing the case where the paste-like active material 16 is not applied, and FIG. 3 (a) showing the case where the paste-like active material 16 is already applied to one surface of the metal foil and dried. Comparing FIG. 3 (b), which shows a case where the wire is wound so as to be in contact with the cylindrical surface, the latter is required to keep the distance between the coating die slit tip 2 and the surface of the metal foil to be coated with the paste constant. In the case of (1), it is understood that the coating die head 1a needs to be retracted from the backup roll by a distance corresponding to the active material coating thickness t previously coated. Further, even if only the case where the paste-like active material 16 is already applied to one surface of the metal foil 4 is considered, the thickness t of the already applied paste layer is applied to a completely uniform predetermined thickness. It is not conceivable that the coating is performed on the coating die slit tip 2 and the metal foil 4 under the influence of the existing active material coating thickness t. It can be seen that the gap W between the working surfaces varies slightly. Since the change in the gap W has a delicate effect on the coating thickness t (coating weight) of the active material and is closely related to the variation in battery performance, adjustment of the paste-like active material coating apparatus is frequently performed. In addition, it causes a decrease in productivity and an increase in the number of processing steps.

[0009]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and greatly simplifies the adjustment of a paste-like active material coating apparatus, and at the same time, reduces the thickness of the active material coating. And to provide a coating apparatus which is effective in making the coating uniform.

[0010]

The coating apparatus according to the present invention contacts the surface of the electrode core material where the paste is not applied and slides on the surface of the electrode core material and the tip of the die slit. A guide component for maintaining the gap at a predetermined distance always suitable for paste application during the coating operation is provided close to the tip of the die slit. .

The change in the gap W between the tip of the coating die slit and the surface of the hoop-shaped coated metal foil serving as the electrode core material is one of the main causes of the variation in the paste coating thickness t. In order to reduce the change in the gap W as much as possible, at a predetermined position close to the tip of the coating die slit, the tip consists of a part of a cylindrical surface, and the surface of the metal foil A guide part which is always in contact is provided, and a tip part of the guide part is located at an intermediate position between two direction change rollers for transferring the hoop-shaped metal foil (at least 100 mm away from the direction change roller closer to the guide part). Position), the uncoated portion of the coated metal foil running at a constant speed is brought into contact with the surface of the metal foil so as to be wound at a predetermined angle θ under a predetermined tension. Active material already coated on the back Regardless of whether or not the coating is performed, the gap W between the tip of the coating die slit and the surface of the metal foil to be coated can be set to a constant gap suitable for coating regardless of whether the coating is performed. It becomes possible.

When the winding angle θ is set to a large value and the hoop-shaped metal foil is run with a relatively weak tension applied thereto, the hoop-shaped metal foil surface can be brought into stable contact with the guide component. This is possible, which is preferable for keeping the gap W constant. However, as the winding angle θ increases, the above-described effect is less likely to appear despite the increase in the angle θ,
Further, as θ is increased, unfavorable constraints on the structure of the coating die head and other coating devices are increased.
Preferably, it is set to about 0 degrees. This greatly facilitates the adjustment work of the coating device, increases the actual operation time of the coating device, and leads to an improvement in productivity.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an example of an embodiment in which the present invention is applied to a lithium secondary battery will be described with reference to the drawings.

FIGS. 1 and 2 show an example in which the present invention is applied to an apparatus for applying a paste containing a substance as a main component in a process of manufacturing an electrode for a lithium secondary battery. In addition, as a metal foil which is an object to be coated and is used as an electrode core material, a copper foil or an aluminum foil having a width of about 500 μm and a thickness of about 20 μm is usually used.
While running at m / min, the die slit tip 2
And the gap W between the coating surface and the die slit
/ 200 μm or less, and paste storage tank 1
An intermittent coating in which the coating thickness of the active material is set to 200 μm (thickness after drying and rolling) by turning ON / OFF the on-off valve 11 provided in the middle of the paste supply path from 3 to the die head 1. Do.

Referring to FIGS. 1 and 2, a coating die head 1 is shown.
A guide component 3 of a hoop-shaped metal foil 4 serving as an electrode core material is provided at a predetermined position near the tip 2 of the die slit provided on the right side of the die slit.
And the guide part 3 are composed of separate parts, so that their relative positional relations can be adjusted as required, and each of these parts can also be replaced locally. It has a simple structure.

The guide part 3 of the present invention has a wide width so as to uniformly contact the entire width of the hoop-shaped metal foil 4 serving as an electrode core material, and its tip portion is formed of a part of a cylindrical surface having a diameter of 16 mm. The one made of cemented carbide material was used after the surface was polished smoothly. However, the diameter is not limited to 16 mm, and it is considered that a function as a guide component is sufficiently exhibited in a range of about 6 to 20 mm. Further, the guide part 3 does not necessarily need to be in uniform contact with the entire width of the hoop-shaped metal foil 4, but may be divided into a plurality of parts to be manufactured and partially contacted. It is also possible to reduce the frictional resistance acting on the running metal foil by making it rotatable with a rotating body.

A coating die head 1 having such a guide part 3 at a position close to the tip 2 of the die slit.
Is disposed at an intermediate position between two directional change rollers 5a and 5b used for transferring a hoop-shaped metal foil such as aluminum or copper which is an object to be coated. / Min, the metal foil 4 is pressed against the uncoated portion of the hoop-shaped metal foil 4, and the coated surface of the metal foil comes into contact with the leading end of the guide component 3 so as to be wound by an angle θ. Changes by the angle θ. In this case, the angle θ is set to about 10 degrees, but the angle θ is set to be larger than 5 degrees and about 30 degrees or less, thereby stabilizing the interval W between the die slit tip 2 and the surface to be coated, that is, It is preferable to stabilize the thickness t of the paste coating layer to a predetermined thickness, and the structure of the coating apparatus is reasonable and almost all parts of the conventional coating apparatus can be used.

The accuracy of the paste coating thickness t (coating weight) depends on the traveling speed of the metal foil 4 and the paste storage tank 1.
Since the influence of the variation in the discharge amount of the paste supply constant-rate discharge pump 12 from 3 to the die slit portion 17 is very large, as a countermeasure against these variations, the rotational speeds of both of these driving motors are stabilized. In addition, the motor was driven using a servo motor whose speed was easily adjusted. Further, with regard to the roller 6 for setting the transfer speed of the hoop-shaped metal foil 4, the roller diameter is set as large as possible to φ500 to influence the running speed of the metal foil 4 due to the local variation of the paste coating thickness t. In order to reduce the influence and to minimize the slip between the cylindrical surface of the transfer speed setting roller 6 and the metal foil, the angle at which the metal foil is wound around the roller is set to be as large as about 170 degrees as much as possible. In addition, the tension setting roller 7 of the metal foil 4 is set to have an angle around which the metal foil is wound around as large as about 90 degrees as much as possible, and further, a large number of small holes are formed in the cylindrical surface of the tension setting roller 7. 19, these holes are connected to a vacuum pump 14 via a rotary coupling (not shown) so that the surface of the metal foil 4 is attracted to the surface of the tension setting roller 7 to prevent slip. I made it.

From the viewpoint of the capacity of the lithium battery, it is advantageous to reduce the thickness of the metal foil 4 to be coated to increase the amount of the active material. In order to reduce scratches and the like caused by slip on the surface of the metal foil and the surface to which the paste is applied, the tension applied to the object to be coated is set as small as possible. However, if it is too small, when the front end of the guide part 3 is brought into contact with the surface of the object to be wound, if the active material has already been applied to the back surface of the metal foil, both surfaces are completely uncoated. The rigidity (hardness) of the core material is greater than that of the metal foil, and it tends to be hard to adhere to the tip of the guide component 3. Therefore, since the allowable range of the tension applied to the metal foil is narrowly limited, a powder clutch (not shown) having a stable transmission torque is incorporated in the shaft of the tension setting roller 7 of the metal foil and applied to the metal foil. Tension 1
It was set to 0 kgf. As described above, when applying the active material using the coating apparatus of the present invention, as long as the guide component 3 and the surface of the object 4 are in contact with each other, the surface of the object Since the gap W between the coating head 1 and the coating head 1 is always stable at a constant value, the adjustment time of the coating apparatus is greatly reduced. As a result, the operation time is improved by nearly 10% compared to the conventional apparatus. The coating thickness of the active material (thickness after rolling) could be kept at 200 μm ± 1%, and the quality was stable.

[0020]

As described above, according to the present invention, a guide component of a hoop-shaped metal foil serving as an electrode core material is provided at a predetermined position close to the tip of a die slit of a coating die head. The surface of the electrode core material to be coated with the paste is wound around the tip of the guide component so that the surface of the electrode core material is in contact with a predetermined angle, thereby forming the tip of the coating die slit. Since the distance between the surfaces to be coated can always be maintained at a constant value suitable for coating, the coating thickness of the paste is easily stabilized, the adjustment of the coating device becomes easy, and the effect of reducing the occurrence of defective products is reduced. There is. In particular, when the active material paste is applied to both sides of the electrode core material, and the active material has already been applied to the back side, it is not possible to adjust the coating apparatus to a predetermined coating thickness. However, in the conventional apparatus, it was very troublesome to be affected by the active material coating thickness in the preceding step, but by using the coating apparatus of the present invention, regardless of the coating thickness in the preceding step. In order to maintain a constant distance between the tip of the coating die slit and the surface of the core material to be coated,
There is no need to adjust the gap between the surface to be coated and the tip of the die slit, and the paste viscous resistance at the die slit outlet is stable, and the discharge rate of the paste pump is also stable. Becomes stable. Therefore, it greatly contributes to the improvement of battery performance, quality and productivity.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a main part of a coating apparatus according to the present invention.

FIG. 2 is a partially enlarged view of a main part of a coating apparatus according to the present invention.

FIG. 3A shows a state in which a pasty active material is coated on one surface of an electrode core material using a conventional coating apparatus (the back surface is not coated). Of a paste active material being applied to one surface of the electrode core material using the coating device shown in Fig. (Backside is already coated)

FIG. 4 (a) is an external perspective view of a conventional coating die head. FIG. 4 (b) is a cross-sectional view of the conventional coating die head (X in FIG. 4 (a)).
-X cross section)

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Coating die head (of the present invention) 1a Coating die head (conventional one) 2 Die slit tip 3 Guide part 4 Coating object (hoop-shaped metal foil) 5a Hoop-shaped metal foil direction changing roller 5b Roller for changing the direction of hoop-shaped metal foil 6 Roller for setting the transfer speed of the object to be coated 7 Roller for setting the tension of the object to be coated 8 Coating die head position adjusting stand 9 Coating die head position adjusting screw 10 Die pocket 11 Opening / closing Valve 12 Paste active material fixed quantity discharge pump 13 Paste storage tank 14 Vacuum pump 15 Backup roller 16 Paste active material coating unit 17 Die slit 18 Vacuum hole cover 19 Vacuum hole θ Angle of change in traveling direction of workpiece to be coated by guide parts (Angle of winding around the tip of the guide part) W Clearance between the surface to be coated and the tip of the die slit Material coating thickness

Continuing on the front page (72) Inventor Kenichi Oshima 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Reference) 5H014 AA04 BB08 BB17 HH00 5H029 AJ14 AK00 AL00 CJ22 DJ07 HJ00 HJ04 HJ12

Claims (7)

[Claims] 1. A paste mainly composed of a battery active material is discharged from a coating die head to move at a constant relative speed while maintaining a predetermined gap with respect to a die slit tip of the die head. In a coating apparatus for forming a coating surface of an active material on the surface of the electrode core material, which is the object to be coated, by sliding in contact with the paste uncoated surface of the electrode core material, A guide component for maintaining a gap between the surface of the electrode core material and the tip of the die slit at a predetermined distance always suitable for paste coating during the coating operation,
A coating device, wherein the coating device is provided close to a tip end of the die slit. 2. A gap between the surface of the electrode core material and the tip of the coating die slit is formed by sliding the tip of the guide component in contact with the surface of the uncoated portion of the electrode core material. In a coating device that guides to a suitable predetermined gap,
The main part of the tip of the guide part is formed of a part of a cylindrical surface, and during the coating operation of the paste-like active material, the surface of the electrode core material running at a constant speed with a predetermined tension is applied to the cylindrical surface. 2. The coating device according to claim 1, wherein the coating device is in constant contact along the direction. 3. A tip end portion of a die slit of a coating die head is provided so as to approach and face the surface of the electrode core material so as to perform coating at an intermediate position between two direction change rollers of the electrode core material. The coating device for an active material for a battery according to claim 1 or 2, wherein 4. The method according to claim 1, wherein the direction in which the electrode core travels is changed by an angle of 5 degrees or more before and after the electrode core contacts the guide component. 3. The coating device according to any one of 3. 5. A vacuum device is provided on both or one of the tension setting roller and the transfer speed setting roller in order to prevent the electrode core material to be coated from slipping on the surface of the transfer roller. The coating device according to any one of claims 1 to 4, wherein a number of small holes for vacuum suction connected to the coating device are provided. 6. The guide part provided close to the tip of the coating die slit is formed by a separate part different from the part constituting the coating die head, and the tip of the coating die slit is provided. The coating apparatus according to any one of claims 1 to 5, wherein a relative positional relationship between the coating apparatus and the apparatus is adjustable, and the structure is replaceable as needed. 7. The tension applied to the electrode core material during the coating operation to transfer the electrode core material and to secure a predetermined gap between the tip of the die slit and the surface of the electrode core material is controlled by the electrode core material. 7. The power transmission device according to claim 1, wherein the drive motor transmission shaft is set by a powder clutch incorporated in a drive force transmission system between the drive motor output shaft and the electrode core material tension setting roller. Coating equipment.