JP2019145371A - Press device and manufacturing method of electrode - Google Patents

Abstract

To provide a press device of an electrode having excellent productivity, and a manufacturing method of the electrode having excellent productivity.SOLUTION: The present invention provides a role press device that presses an electrode in which an active material layer is provided in band metal foil, comprises: a role that is arranged at a position in contact with a surface of the active material layer and is rotated during conveying the electrode; a cleaning part that is arranged at the position in contact with the surface of the role, is arranged on a role rotational direction downstream side from the position where the role is in contact with the surface of the active material layer, and cleans the surface of the role with a cleaning liquid in which water is a solvent; a dew point adjustment mechanism performing a due point adjustment of a dew point environment adjustment area including at least one part of an electrode conveying direction upstream side from the point where the role is in contact with the surface of the active material layer; and a separation that is arranged on a conveying direction downstream from the dew point environment adjustment area, and separates the dew point environment adjustment area from the cleaning part, and a manufacturing method of the electrode using the same.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a press apparatus excellent in productivity and an electrode manufacturing method excellent in productivity.

  An electrode of a non-aqueous secondary battery such as a lithium ion secondary battery usually has a structure having an active material layer containing an active material and a binder on one side or both sides of a current collector made of a metal foil or the like. It is used. Such an electrode is, for example, an active material-containing composition (a paint for forming an active material layer) containing an active material, a binder, a solvent, and the like on the surface of the current collector drawn from a roll around which the current collector is wound. ) Is applied and dried to form an active material layer, and then a pressing process is performed to adjust the density of the active material layer. In the pressing step, pressure is applied to the active material layer by a roll called a press roll. At that time, a part of the active material layer may be peeled off from the roll and may adhere to the roll and become dirty. If the pressing process is continued with the dirt adhered, the dirt may further increase due to the dirt, a press failure may occur in the electrode, and the battery characteristics may be adversely affected.

  Therefore, Patent Document 1 discloses a technique in which a nonwoven fabric is attached and the roll is cleaned in order to remove foreign matters attached to the roll surface.

  In Patent Document 2, it is disclosed that the dew point environment during pressing of the negative electrode for a nonaqueous electrolyte secondary battery is −10 ° C. or less, and the binder contained in the active material mixture is less likely to adhere to the press roll surface. Has been.

JP, 2015-76230, A JP 2008-204836 A

  By the way, in the method of Patent Document 2, it becomes difficult to get dirt on the press roll in the pressing process, but it is difficult to completely prevent the dirt from being put on the dirt. Is required. Also, if the pressing process is performed without making it difficult to get dirt, the dirt adheres to the rolls, which takes time for cleaning.

  Therefore, by transporting the electrode under the dew point environment adjustment before the pressing process, the adhesion of dirt to the press roll is reduced during the pressing process, and if the cleaning process is performed to clean the press roll after the pressing process, high productivity is achieved. It can be said that it is a method. However, in the case of an aqueous electrode such as a negative electrode of a lithium ion secondary battery, the cleaning process wipes the cleaning liquid using water as a solvent, so that the moisture affects the dew point environment and maintains a specific dew point environment. It becomes difficult.

  This invention is made | formed in view of the said situation, The objective is to provide the manufacturing method of the press apparatus excellent in productivity, and the electrode excellent in productivity.

  The press device of the present invention that has achieved the above object is a roll press device for pressing an electrode in which an active material layer is provided on a strip-shaped metal foil, and is disposed at a position in contact with the surface of the active material layer. A roll that rotates during conveyance of the electrode, and a roll that contacts the surface of the roll, a cleaning unit for cleaning the surface of the roll with water, and the roll contacts the surface of the active material layer. A dew point adjustment mechanism that adjusts the dew point in the dew point environment adjustment area that includes at least a part of the upstream side of the electrode transport direction from the position to be moved, and the dew point environment adjustment area at a positive pressure compared to the downstream side of the dew point environment adjustment area. And a pressure adjusting mechanism.

  Moreover, the manufacturing method of the electrode of this invention manufactures an electrode using the said roll press apparatus.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the press apparatus excellent in productivity and the electrode excellent in productivity can be provided.

It is a figure which represents typically the press apparatus of this invention.

  The press device of the present invention is a roll press device for pressing an electrode provided on a strip-shaped metal foil. The schematic diagram of an example of a structure of the roll press apparatus of this invention is shown in FIG. A roll press apparatus 1 shown in FIG. 1 includes rolls 2A and 2B for pressing an electrode 10 provided with an active material layer 12 on a strip-shaped metal foil 11, and a cleaning unit 4A for cleaning the roll surface with a cleaning liquid using water as a solvent. 4B, the dew point adjustment mechanism 3 for adjusting the dew point of the dew point environment adjustment area 30, and the dew point environment adjustment area 30 on the downstream side in the electrode transport direction, the dew point environment adjustment area 30, the cleaning units 4A and 4B, And a pressure adjusting mechanism 5 for making the positive pressure from the dew point environment adjusting area to the downstream side in the electrode transport direction.

  Thereby, a press roll apparatus with high productivity can be provided. That is, by setting the dew point environment adjustment area to a positive pressure as compared with the downstream side in the electrode conveyance direction, air containing water derived from a cleaning liquid whose solvent is water used in the cleaning unit is prevented from flowing into the dew point environment adjustment area. This makes it easy to maintain the dew point environment in the dew point environment adjustment area. Therefore, the dew point adjustment, the pressing process, and the cleaning process can be performed continuously and simultaneously without stopping the roll press apparatus in the cleaning process.

  The electrode to be pressed in the roll press apparatus of the present invention includes a water-soluble polymer having a viscosity adjusting function represented by CMC, and a binder that binds the flexibility and active material particles of the electrode represented by SBR. The effect of the present invention can be obtained as long as the electrode has an emulsion (an aqueous dispersion of polymer particles) as a composition. Specifically, there are a positive electrode and a negative electrode of an alkaline electrolyte battery (such as a nickel metal hydride battery or a nickel-cadmium battery), a negative electrode of a lithium ion secondary battery, or the like, and each electrode can have a known material and configuration. .

  Taking the negative electrode of a lithium ion secondary battery as an example, the negative electrode active material includes graphite, pyrolytic carbons, cokes, glassy carbons, fired bodies of organic polymer compounds, MCMB, carbon fibers, activated carbon, etc. One or two or more of carbon materials; metals that can be alloyed with lithium (Si, Sn, etc.), and materials containing these metals (eg, alloys); can be used. As the binder, styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), or the like is preferably used. The strip-shaped metal foil as the negative electrode current collector can be a copper or copper alloy foil.

  For the negative electrode of a lithium ion secondary battery, a negative electrode active material and a binder are dispersed in water to prepare an active material-containing composition, which is applied onto a negative electrode current collector and dried to produce a negative electrode before pressing. . The application means for applying the active material-containing composition onto the negative electrode current collector is not particularly limited, and known application methods (methods using gravure coating, die coating, dam coater, etc.) used in conventional manufacturing, etc. The same method can be adopted.

  More specifically, the roll press apparatus of the present invention will be described with reference to FIG. The rolls 2 </ b> A and 2 </ b> B rotate in the RA and RB directions while being conveyed in the conveying direction TD of the electrode 10, respectively, and apply pressure in the PA and PB directions while being in contact with the surface of the active material layer 12 (pressing process). There is a dew point environment adjustment area 30 (a portion surrounded by a broken line in FIG. 1) on the upstream side in the electrode conveyance direction at a position where the rolls 2A and 2B are in contact with the active material layer 12. In the dew point adjustment area 30, dew point adjustment is performed by the dew point adjustment mechanism 3. In FIG. 1, the dew point environment adjustment area 30 includes a position where the rolls 2 </ b> A and 2 </ b> B are in contact with the active material layer 12, but this is not always necessary, and the dew point environment adjustment area 30 has a part on the upstream side in the electrode transport direction TD. If included, the effect of preventing the adhesion of dirt to the rolls 2A and 2B can be obtained. The dew point adjustment mechanism 3 that adjusts the dew point in the dew point environment adjustment area 30 can use a mechanism such as sending cold air to the dew point environment adjustment area, but is not limited thereto.

  When pressing the negative electrode of a lithium ion secondary battery, it is preferable to adjust the dew point of the dew point environment adjustment area 30 to −10 ° C. or lower. Within this range, it is possible to suitably prevent dirt from adhering to the roll.

  The rolls 2A and 2B are arranged so as to sandwich the belt-like electrode 10 and rotate as shown in FIG. 1 with respect to the electrode transport direction TD. The electrodes pressed on the rotating rolls 2A and 2B are continuously conveyed.

  If the electrode has passed through the dew point environment adjustment area 30, the rolls 2 </ b> A and 2 </ b> B are less likely to get dirty in the pressing process, but even in the case of the dirt, the roll rotation direction is more than the position where the rolls 2 </ b> A and 2 </ Since the cleaning portions 4A and 4B are provided on the downstream side of the RA and RB, the contaminated portion of the rolls 2A and 2B is cleaned, and the contamination is removed when the portion contacts the active material layer next time. It becomes.

  In the cleaning units 4A and 4B, the surfaces of the rolls 2A and 2B are cleaned with a cleaning liquid containing water. The cleaning liquid containing water (cleaning liquid using water as a solvent) is water, a liquid obtained by mixing water and alcohol, an aqueous solution containing a surfactant, or the like. The cleaning units 4A and 4B can be made, for example, by impregnating a nonwoven fabric with a cleaning liquid containing water. The cleaning units 4A and 4B may be connected to a cleaning liquid supply mechanism (not shown) that continuously supplies a cleaning liquid containing water.

  The roll press apparatus of the present invention includes a pressure adjustment mechanism 5. The pressure adjustment mechanism 5 adjusts the dew point environment adjustment area 30 so as to have a positive pressure as compared with the downstream side of the dew point environment adjustment area 30 in the electrode transport direction. The pressure adjusting mechanism 5 is, for example, an air adjusting duct, and there is a means for adjusting the air volume with the air adjusting duct and realizing a positive pressure in the dew point environment adjusting area 30.

  In FIG. 1, the pressure adjustment mechanism 5 is arranged in the dew point environment adjustment area 30 and adjusted so that the area becomes higher than the air pressure, but is not limited thereto. For example, the pressure adjusting mechanism 5 can be arranged by dividing the downstream side of the electrode conveyance direction from the dew point environment adjustment area 30 and the air in the divided area can be adjusted to be lower than the air pressure by pumping or the like. .

  The roll press apparatus of FIG. 1 includes partitions 6A and 6B that partition the dew point environment adjustment area 30 and the cleaning units 4A and 4B downstream of the dew point environment adjustment area 30 in the electrode transport direction TD. Thereby, the influence which the water | moisture content used in cleaning part 4A, 4B has on the dew point environment adjustment area 30 can further be reduced, and the dew point environment maintenance of the dew point environment adjustment area 30 can be made easier.

  The partitions 6A and 6B can take various forms. For example, cloth curtains, partitions, and walls may be constructed. For example, it is possible to use a structure in which a moisture adsorbing material is arranged on the surface of the wall on the cleaning section 4A, 4B side.

  Moreover, if an electrode is manufactured using such a roll press apparatus, it can be set as the manufacturing method with high productivity.

  The present invention is not limited to the above-described embodiment, and can be implemented by appropriately modifying the above-described embodiment without departing from the spirit thereof.

Claims (5)

A roll press apparatus for pressing an electrode provided with an active material layer on a strip-shaped metal foil,
A roll that is disposed at a position in contact with the surface of the active material layer and rotates during the conveyance of the electrode;
A cleaning unit that is disposed at a position in contact with the surface of the roll and on the downstream side in the roll rotation direction with respect to the surface of the active material layer, and cleans the surface of the roll with a cleaning liquid using water as a solvent. When,
A dew point adjusting mechanism for adjusting a dew point in a dew point environment adjusting area including at least a part of the upstream side of the electrode transport direction from the position where the roll contacts the surface of the active material layer;
A pressure adjustment mechanism for setting the dew point environment adjustment area to a positive pressure as compared with the downstream side in the electrode transport direction from the dew point environment adjustment area;
A roll press apparatus comprising:   A roll press apparatus provided with a partition that is disposed downstream of the dew point environment adjustment area in the transport direction and partitions the dew point environment adjustment area and the cleaning unit.   The roll press apparatus according to claim 1 or 2, wherein the dew point environment adjustment area includes a position where the roll contacts the surface of the active material layer.   The roll press apparatus according to claim 1, wherein the electrode is a negative electrode of a lithium ion secondary battery. An electrode manufacturing method comprising:

The manufacturing method which manufactures an electrode using the roll press apparatus of Claim 1 or 2.

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