JP6210001B2 - Roll press machine - Google Patents

Description

  The present invention relates to a roll press apparatus that presses an active material layer formed on a strip-shaped metal foil.

  When manufacturing the electrode used for a secondary battery etc., an electrode paste is apply | coated to a strip | belt-shaped metal foil, an active material layer is formed, and each electrode is stamped out from the strip | belt-shaped metal foil in which the active material layer was formed. At this time, after forming the active material layer on the strip-shaped metal foil, the active material layer is pressed by a roll press device in order to increase the density of the active material layer. In a roll press apparatus, a strip-shaped metal foil on which an active material layer is formed is sandwiched between a pair of press rolls, and the active material layer is pressed with these press rolls (see, for example, Patent Document 1).

JP 2013-223871 A

  However, the following problems exist in the prior art. That is, when an active material layer having convex foreign substances attached to the surface is pressed with a press roll, a large load is locally applied to the press roll, resulting in indentations on the press roll. At this time, if the active material layer is pressed by the indented portion of the press roll, the film thickness of the active material layer becomes non-uniform, and consequently the film thickness of the electrode becomes non-uniform. In addition, if there is an indentation in the press roll, the replacement cost of the press roll increases, so that the repair cost increases.

  The objective of this invention is providing the roll press apparatus which can prevent that an indentation arises in a press roll.

  The present invention relates to a foreign matter detection means for detecting whether or not foreign matter is present in an active material layer and a foreign matter detection means in a roll press apparatus that presses an active material layer formed on a strip-shaped metal foil with a plurality of press rolls. And a control means for controlling to release the press pressure of the press roll when it is detected that a foreign substance is present in the active material layer.

  As described above, in the roll press apparatus of the present invention, it is detected whether or not foreign matter is present in the active material layer formed on the strip-shaped metal foil, and it is detected that foreign matter is present in the active material layer. In some cases, the foreign matter present in the active material layer is prevented from being pressed by the press roll by controlling the press pressure of the press roll to be released. Thereby, since a big load is not applied locally to a press roll, it is prevented that an indentation arises in a press roll.

  According to the present invention, it is possible to prevent indentation from occurring on the press roll. This makes it possible to improve the uniformity of the electrode film thickness. Moreover, since the frequency of replacement of the press rolls is reduced, it is possible to reduce repair costs.

It is a block diagram which shows one Embodiment of the roll press apparatus which concerns on this invention. It is a flowchart which shows the detail of the control processing procedure by the controller shown in FIG. It is a block diagram which shows the state which open | released the press pressure of a pair of press roll shown in FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a roll press apparatus according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a configuration diagram showing an embodiment of a roll press apparatus according to the present invention. The roll press apparatus 1 of this embodiment is used in the press process which is one process for manufacturing the electrode of a secondary battery. The secondary battery is a nonaqueous electrolyte secondary battery such as a lithium ion secondary battery.

  The electrode of the secondary battery is composed of a metal foil and active material layers formed on both the front and back surfaces of the metal foil. The active material layer is formed by applying electrode paste to both the front and back surfaces of the metal foil. The electrode is also provided with a tab to which no electrode paste is applied.

  The metal foil of the positive electrode is, for example, an aluminum foil, and the metal foil of the negative electrode is, for example, a copper foil. The electrode paste contains an active material, a binder, a solvent, and the like. As the positive electrode active material, for example, composite oxide, metallic lithium, and sulfur are used. The composite oxide includes at least one of manganese, nickel, cobalt, and aluminum and lithium. Examples of the active material for the negative electrode include carbon such as graphite, highly oriented graphite, mesocarbon microbeads, hard carbon, and soft carbon, alkali metals such as lithium and sodium, metal compounds, and SiOx (0.5 ≦ x ≦ 1. 5) and other metal oxides and boron-added carbon are used. As the solvent, for example, organic solvents such as NMP (N-methylpyrrolidone), methanol, methyl isobutyl ketone, and water are used. Further, the electrode paste may contain a conductive aid such as carbon black, graphite, acetylene black, and ketjen black, and a thickener such as carboxymethyl cellulose (CMC).

  In addition, an application | coating process and a drying process are performed as a pre-process of a press process. The coating process is a process of coating an electrode paste for forming an active material layer on both surfaces of a strip-shaped metal foil. In the coating step, the electrode paste is intermittently applied to both surfaces of the strip-shaped metal foil at a predetermined interval corresponding to the position of the electrode. As the coating method, for example, a die method is adopted. The drying step is performed immediately after the coating step, and is a step of removing the solvent in the electrode paste by heating and drying the electrode paste applied intermittently on both surfaces of the strip-shaped metal foil. As a result, a band-like electrode is obtained in which active material layers are formed at predetermined intervals on both sides of the band-like metal foil. The strip electrode is wound around a winding roll.

  In the subsequent pressing step, the unwinding roll and the take-up roll are operated so that the strip-shaped electrode is fed out from the unwinding roll, and the strip-shaped electrode and the unwinding roll at a predetermined transport speed in a state where a predetermined tension is applied. It is transported between winding rolls. When conveyance of the strip electrode is started, the roll press apparatus 1 of the present embodiment is operated.

  In FIG. 1, the roll press apparatus 1 includes a pair of upper and lower press rolls 3 </ b> A and 3 </ b> B arranged so as to sandwich the strip-like electrode 2. The strip electrode 2 is composed of a strip-shaped metal foil 4 and an active material layer 5 formed on the front and back surfaces of the metal foil 4 with predetermined intervals. The press rolls 3A and 3B sandwich the active material layer 5 and press it with a predetermined pressure (pressing pressure).

  Further, the roll press apparatus 1 includes a moving drive unit 6 that moves one press roll 3B up and down so that the press rolls 3A and 3B come close to or away from each other, and a rotational drive that rotates the press rolls 3A and 3B in opposite directions. Part (not shown). For example, a hydraulic cylinder is used as the movement drive unit 6.

  Furthermore, the roll press apparatus 1 includes optical sensors 7A and 7B arranged so as to sandwich the belt-like electrode 2 on the upstream side of conveyance from the press rolls 3A and 3B, and a controller 8 connected to these optical sensors 7A and 7B. It has.

  The optical sensor 7A irradiates the active material layer 5 formed on the surface of the metal foil 4 with light, and receives the reflected light from the active material layer 5, whereby the foreign material P convex to the active material layer 5 is received. (See FIG. 3) is detected, and the detection result is output to the controller 8 as an electric signal (detection signal). The optical sensor 7B irradiates the active material layer 5 formed on the back surface of the metal foil 4 with light, and receives the reflected light from the active material layer 5, whereby the foreign material P convex to the active material layer 5 is received. Is detected, and the detection result is output to the controller 8 as an electrical signal (detection signal). The optical sensors 7A and 7B are foreign matter detection means for detecting whether or not the foreign matter P is present in the active material layer 5. When the optical sensors 7A and 7B detect the presence of the foreign matter P in the active material layer 5, the optical sensors 7A and 7B output an ON signal as an electrical signal.

  The controller 8 controls the movement drive unit 6 based on the detection signals of the optical sensors 7A and 7B. The details of the control processing procedure by the controller 8 are shown in FIG. Note that this process is performed during the transport of the strip electrode 2.

  In FIG. 2, first, detection signals of the optical sensors 7A and 7B are acquired (step S101). Then, it is determined whether or not the foreign matter P is attached to the active material layer 5 formed on the metal foil 4 by determining whether the detection signal of any of the optical sensors 7A and 7B is an ON signal (procedure) S102).

  When the detection signals of the optical sensors 7A and 7B are both OFF signals, that is, when the foreign material P is not attached to the active material layer 5, the press rolls 3A and 3B are brought close to each other and the press pressure of the press rolls 3A and 3B is set. The movement drive unit 6 is controlled so that (press load) is applied to the active material layer 5 (step S103). Thereby, as shown in FIG. 1, the active material layer 5 formed on both surfaces of the strip-shaped metal foil 4 is pressed by the press rolls 3A and 3B with a predetermined pressing pressure. Accordingly, the density of the active material layer 5 is increased.

  On the other hand, when the detection signals of the optical sensors 7A and 7B are ON signals, that is, when the foreign matter P adheres to the active material layer 5, the press rolls 3A and 3B are separated from each other and the press roll 3A for the active material layer 5 is separated. , 3B is controlled so as to release the press pressure of 3B (step S104). At this time, the press pressure of the press rolls 3A and 3B is released while keeping the transport speed of the strip electrode 2 constant. The release of the press pressure here means to make the press pressure zero. Thereby, as shown in FIG. 3, the active material layer 5 to which the foreign matter P adheres is conveyed as it is without being pressed by the press rolls 3A and 3B.

  In the above, the controller 8 and the movement drive unit 6 are configured so that when the foreign material detecting means (optical sensors 7A and 7B) detects the presence of the foreign material in the active material layer 5, the press pressures of the press rolls 3A and 3B are detected. The control means which controls to release is constituted.

  After the pressing process, an appearance inspection process for inspecting the appearance of the strip electrode 2 is performed. In the appearance inspection process, defective products are detected by image processing using a camera, for example. At this time, a defective product mark is given to the active material layer 5 to which the foreign matter P adheres.

  Thereafter, a punching process is performed. In the punching process, the electrode is formed by punching the metal foil 4 on which the active material layer 5 is formed into a predetermined shape. At this time, the electrode with the defective product mark is discarded as a defective product.

  As described above, in the present embodiment, whether or not the foreign matter P is attached to the active material layer 5 formed on the metal foil 4 is detected by the optical sensors 7A and 7B. Since the press pressure of the press rolls 3A and 3B is released, the foreign matter P adhering to the active material layer 5 is avoided from being pressed by the press rolls 3A and 3B. This prevents a large load from being locally applied to the press rolls 3A and 3B, thereby preventing indentation on the press rolls 3A and 3B. As a result, it is possible to prevent the thickness of the active material layer 5 from becoming non-uniform, and consequently to prevent the electrode from becoming non-uniform. In addition, since it is not necessary to frequently replace the press rolls 3A and 3B, maintenance costs can be reduced.

  The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the press pressure of the press rolls 3A and 3B is released in a state in which the transport speed of the strip electrode 2 is secured at a constant speed, but it takes time for the press pressure of the press rolls 3A and 3B to decrease. In such a case, you may reduce the conveyance speed of the strip | belt-shaped electrode 2 as needed.

  In the above embodiment, whether or not the foreign matter P is attached to the active material layer 5 formed on the metal foil 4 is optically detected by the optical sensors 7A and 7B. The means for detecting whether or not the toner is attached is not limited to the optical sensors 7A and 7B, and for example, a camera, an ultrasonic sensor, an X-ray sensor, or the like may be used.

  Moreover, although the said embodiment is an apparatus which presses the active material layer 5 formed with the predetermined space | interval by intermittently apply | coating an electrode paste to the strip | belt-shaped metal foil 4, this invention is an electrode to the strip | belt-shaped metal foil 4. The present invention is also applicable to an apparatus that presses an active material layer 5 continuously formed by continuously applying a paste.

  Furthermore, although the said embodiment is an apparatus which presses the active material layer 5 formed in the front and back both surfaces of the strip | belt-shaped metal foil 4, this invention is an active material layer formed in only one surface of the strip | belt-shaped metal foil 4. FIG. It is applicable also to the apparatus which presses 5.

  Moreover, although the said embodiment is an apparatus which presses the active material layer 5 formed in the strip | belt-shaped metal foil 4 with a pair (two) press roll 3A, 3B, this invention is a strip | belt-shaped metal foil 4. The present invention can also be applied to an apparatus that presses the active material layer 5 formed in (3) with three or more press rolls.

  Moreover, although the said embodiment is an apparatus used in the process of manufacturing the electrode of secondary batteries, such as a lithium ion secondary battery, this invention is not restricted to a secondary battery in particular, For example, an electric double layer capacitor It can also be applied to a device used in a process of manufacturing an electrode of a power storage device such as a lithium ion capacitor.

  DESCRIPTION OF SYMBOLS 1 ... Roll press apparatus, 3A, 3B ... Press roll, 4 ... Metal foil, 5 ... Active material layer, 6 ... Movement drive part (control means), 7A, 7B ... Optical sensor (foreign substance detection means), 8 ... Controller ( Control means), P ... foreign matter.

Claims (3)

In a roll press device that presses an active material layer formed on a strip-shaped metal foil conveyed in a state where a predetermined tension is applied between an unwinding roll and a winding roll with a plurality of press rolls,
Foreign matter detection means for detecting whether or not convex foreign matter exists in the active material layer during conveyance of the metal foil ,
Control for controlling to release the press pressure of the press roll during the transport of the metal foil when the foreign matter detecting means detects that the convex foreign matter is present in the active material layer and means,
The roll press apparatus according to claim 1, wherein the foreign matter detection means is any one of an optical sensor, a camera, an ultrasonic sensor, and an X-ray sensor .   The roll press apparatus according to claim 1, wherein the foreign matter detecting means detects whether or not the convex foreign matter is present in the active material layer at predetermined intervals for the metal foil being conveyed. . In the metal foil, the active material layer is formed with a predetermined interval,
  The roll press apparatus according to claim 2, wherein the foreign matter detecting means detects whether or not the convex foreign matter exists in the active material layer formed on the metal foil with a predetermined interval.

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