JP2019057383A - Manufacturing method of electrode sheet - Google Patents

Abstract

To provide a manufacturing method of an electrode sheet capable of removing at least a portion of a protrusion in a film-like electrode mixture after a deposition step and before a drying step.SOLUTION: A manufacturing method of an electrode sheet includes, before a deposition step (S2) and after a drying step (S4), a removal step (S3) for bringing a surface of a film-like electrode mixture 8 of a collector foil 9 with film-like electrode mixture which includes the film-like electrode mixture 8 on a surface of the collector foil 7, into contact with a surface 41 of a removal roll 40 while conveying the collector foil 9 with film-like electrode mixture, and transferring at least a portion of a protrusion 8d which protrudes outside of a width direction WD, while being positioned in both ends of the film-like electrode mixture 8 in the width direction WD in the film-like electrode mixture 8 of the collector foil 9 with film-like electrode mixture onto the surface 41 of the removal roll 40, thereby removing at least a portion of the protrusion 8d in the film-like electrode mixture 8.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a method for producing an electrode sheet constituting a battery. In detail, it is related with the method of manufacturing the electrode sheet which has an electrode compound-material layer on the surface of current collection foil.

  Conventionally, an electrode sheet having an electrode mixture layer on the surface of a current collector foil is known as an electrode sheet (positive electrode sheet or negative electrode sheet). As a method for manufacturing such an electrode sheet, for example, methods disclosed in Patent Documents 1 and 2 are known. Specifically, first, an electrode mixture composed of a plurality of wet granules obtained by mixing and granulating an electrode active material, a binder, and a solvent is prepared. Next, in the film forming step, the electrode mixture is compressed into a film shape by passing the electrode mixture through a gap between the first roll and the second roll that rotate opposite to each other. Adhere to the surface of the second roll. Furthermore, the current collector foil conveyed by the third roll rotating opposite to the second roll is passed through the gap between the second roll and the third roll, so that the film attached to the surface of the second roll. The electrode mixture is brought into contact with the surface of the current collector foil while being pressed, and transferred onto the surface of the current collector foil. Thereafter, in the drying step, the electrode mixture layer is formed on the surface of the current collector foil by drying the film electrode mixture which is the transferred film electrode mixture.

JP 2013-052353 A JP, 2006-207340, A

  By the way, in the film-like electrode mixture transferred onto the surface of the current collector foil as described above, protrusions that protrude outward in the width direction are formed at both ends in the width direction of the film-like electrode mixture. In some cases, both end portions in the width direction are uneven. In addition, the protrusions of the film electrode mixture are often not in close contact with the surface of the current collector foil, and are easily peeled off from the surface of the current collector foil. For this reason, after the film-forming process (after transferring the film electrode mixture onto the surface of the current collector foil), a part of the protruding portion of the film electrode mixture is peeled off from the surface of the current collector foil. was there. In particular, when the solvent is removed from the membranous electrode mixture by performing the drying step, the protruding portion is easily peeled off from the surface of the current collector foil. For this reason, after the film forming step and before the drying step, at least a part of the protruding portion of the film electrode mixture (the binding force to the surface of the current collector foil is weak, particularly from the surface of the current collector foil) It has been demanded to remove a portion that is easily peeled off.

  The present invention has been made in view of the current situation, and is an electrode sheet that can remove at least a part of the protruding portion of the membrane electrode mixture after the film forming step and before the drying step. An object is to provide a manufacturing method.

  One aspect of the present invention is an electrode sheet manufacturing method for manufacturing an electrode sheet having an electrode mixture layer on the surface of a current collector foil, wherein an electrode active material, a binder, and a solvent are mixed and granulated. By passing the electrode mixture composed of a plurality of wet granulated materials through the gap between the first roll and the second roll rotating oppositely, the electrode mixture is compressed into a film, The electrode mixture is adhered to the surface of the second roll, and the current collector foil conveyed by the third roll rotating opposite the second roll is the second roll and the third roll. The surface of the current collector foil is brought into contact with the surface of the current collector foil while the film-like electrode mixture adhering to the surface of the second roll is pressed against the surface of the current collector foil. Transferred onto the surface of the current collector foil with the film-like electrode mixture A film forming step for producing a current collector foil with a film electrode mixture having a film electrode mixture, and drying the film electrode mixture of the current collector foil with a film electrode mixture; And a drying step of forming the electrode mixture layer on the surface of the electric foil. In the method for producing an electrode sheet, after the film formation step and before the drying step, the collection with the membrane electrode mixture While carrying the electric foil, the surface of the film-like electrode mixture of the current-collecting foil with the film-like electrode mixture is brought into contact with the surface of the removal roll, and the film-like shape of the current-collecting foil with the film-like electrode mixture By transferring at least a part of the protruding portion located at both ends in the width direction of the film-like electrode mixture of the electrode mixture to the outside in the width direction, to the surface of the removal roll, An electrode sheet comprising a removal step of removing at least a part of the protruding portion of the membrane electrode mixture It is a production method.

  In the electrode sheet manufacturing method described above, in the film forming step, the electrode mixture composed of a plurality of wet granulation bodies obtained by mixing and granulating the electrode active material, the binder, and the solvent is rotated oppositely. By passing through the gap between one roll and the second roll, the electrode mixture is compressed into a film, and the electrode mixture formed in a film is attached to the surface of the second roll and is opposed to the second roll. The film-like electrode mixture adhering to the surface of the second roll is collected by passing the current collecting foil conveyed by the third roll rotating in the gap between the second roll and the third roll. The surface of the foil is brought into contact with pressure and transferred onto the surface of the current collector foil. Thus, a current collector foil with a film electrode mixture having a film electrode mixture which is a film electrode mixture on the surface of the current collector foil is produced.

  In the film-shaped electrode mixture (film-shaped electrode mixture of the current-collecting foil with the film-shaped electrode mixture) thus transferred onto the surface of the current-collecting foil, at both ends in the width direction of the film-shaped electrode mixture In some cases, protrusions that protrude outward in the width direction are formed, and both end portions in the width direction become uneven. In addition, the protrusions of the film electrode mixture are often not in close contact with the surface of the current collector foil, and are easily peeled off from the surface of the current collector foil.

  On the other hand, in the above-described electrode sheet manufacturing method, after the film forming step and before the drying step, for the current collector foil with the film electrode mixture, at least a part of the protruding portion of the film electrode mixture ( Specifically, in the membrane electrode composite material, the portion that is weaker in binding force to the surface of the current collector foil and easier to peel off from the surface of the current collector foil) than the site located inside the protrusion in the width direction is removed. A removing step is provided.

  Specifically, in the removing step, the film-shaped electrode mixture being conveyed while conveying the current-collecting foil with the film-shaped electrode mixture having the film-shaped electrode mixture on the surface of the current collecting foil in the conveying direction. The film electrode composite material of the current collector foil with the film electrode composite is brought into contact with the surface of the removal roll by bringing the surface of the film electrode composite with the current collector foil into contact with the surface of the removal roll. At least a part of the protrusions that are located at both ends of the protrusion and protrude outward in the width direction are transferred to the surface of the removal roll. Thereby, after the film forming step and before the drying step, at least a part of the protruding portion that protrudes outward in the width direction of the film electrode mixture located on the surface of the current collecting foil is removed from the current collecting foil. It can be removed from the surface.

  In addition, in a protrusion part, since the site | part located in the front end side (outside about the width direction of a membranous electrode compound material) has low adhesiveness with the surface of current collection foil (namely, binding force is weak), a removal process Then, the site | part of the front end side (outside about the width direction of a membranous electrode compound material) among protrusions can be removed especially. Thereby, the protrusion dimension to the width direction of a protrusion part can be made small (the unevenness | corrugation of the width direction can be made small) after a film-forming process and before a drying process.

  The wet granulated body refers to a substance (granular body) in which the solvent is held (absorbed) by the electrode active material particles and the binder, and these are aggregated (bonded).

It is a side view schematic diagram of the electrode sheet manufacturing device concerning an embodiment. It is a perspective schematic diagram of the electrode sheet manufacturing device. It is a top view of current collection foil with a film-like electrode compound material. It is the B section enlarged view of FIG. It is a flowchart which shows the flow of the manufacturing method of the electrode sheet concerning embodiment. It is sectional drawing of the electrode sheet (negative electrode sheet) concerning embodiment. It is a figure which compares the protrusion dimension (average value) of the protrusion part of a membranous electrode compound material. It is a figure which compares the peeling amount (sliding amount) of a film-like electrode compound material.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described in detail with reference to the drawings. In the present embodiment, the present invention is applied to the manufacture of a negative electrode sheet (electrode sheet) of a lithium ion secondary battery. In this embodiment, as a material of the negative electrode mixture (electrode mixture) for forming the negative electrode active material layer (electrode mixture layer) of the negative electrode sheet, a negative electrode active material (electrode active material), a binder, Solvent is used.

  In this embodiment, a powdery carbon material (for example, graphite) is used as the negative electrode active material. Moreover, water is used as a solvent. Moreover, CMC (carboxymethylcellulose) is used as a binder.

  In the present embodiment, first, in the electrode mixture preparation step, the above-mentioned materials are granulated while kneading to produce a large number of wet granulation bodies 16, and a negative electrode mixture composed of a large number of wet granulation bodies 16. 6 is produced. Next, in the film forming step, the negative electrode mixture 6 is attached (applied) in the form of a film on the surface of the current collector foil 7, thereby forming the film negative electrode mixture 8 (film electrode mixture). .

  After that, in the removing step, the film-like negative electrode mixture 8 is located at both end portions (first width direction end portion 8b or second width direction end portion 8c) of the film-like negative electrode mixture 8 in the width direction WD. At least a part of the protruding portion 8d protruding outside the first width direction WD1 or the second width direction WD2 is removed. Next, in the drying step, the film-like negative electrode mixture 8 (film of the negative electrode mixture 6) on the surface of the current collector foil 7 is dried to form the negative electrode mixture layer 18 on the surface of the current collector foil 7. . Thereby, the negative electrode sheet 19 having the negative electrode mixture layer 18 on the surface of the current collector foil 7 is manufactured.

  Here, the manufacturing method of the electrode sheet (negative electrode sheet 19) concerning this embodiment is demonstrated in detail. FIG. 1 is a schematic side view of an electrode sheet manufacturing apparatus 10 according to an embodiment. FIG. 2 is a schematic perspective view of the electrode sheet manufacturing apparatus 10. FIG. 3 is a plan view of a current collector foil 9 with a film-like negative electrode mixture (current collector foil with a film-like electrode mixture). However, FIG. 3 shows a plan view of the current collector foil 9 with the film-like negative electrode mixture after the film forming step and before the removing step. FIG. 4 is an enlarged view of the B part in FIG. 3 and shows the protruding dimension H of the protruding part 8 d of the film-like negative electrode mixture 8. FIG. 5 is a flowchart showing a flow of a manufacturing method of the electrode sheet (negative electrode sheet 19) according to the embodiment.

  The electrode sheet manufacturing apparatus 10 used in this embodiment includes a roll film forming apparatus 20, a removing apparatus 30, a drying apparatus (not shown), and a winding apparatus (not shown) (see FIGS. 1 and 2). . 1 and 2, the illustration of the drying device and the winding device is omitted, but the drying device is more than the removing device 30 in the conveyance direction CD of the current collector foil 9 with the film-like negative electrode mixture. It is arranged downstream. Furthermore, the winding device is a device that is disposed on the most downstream side in the conveyance direction CD of the current collector foil 9 with the film-like negative electrode mixture (negative electrode sheet 19) and winds up the manufactured negative electrode sheet 19.

  As shown in FIG. 5, first, in step S1 (electrode mixture preparation process), a negative electrode active material (carbon material), a binder (CMC), and a solvent (water) are mixed and granulated to obtain a large number of particles. While producing the wet granulated body 16, the negative electrode mixture 6 composed of a large number of wet granulated bodies 16 is produced. In the present embodiment, the negative electrode active material, the binder and the solvent are mixed (dispersed) in a known agitation granulator (not shown) by introducing the negative electrode active material, the binder and the solvent and stirring them. While granulating, a large number of wet granules 16 are formed. As a result, the negative electrode mixture 6 composed of a large number of wet granules 16 is obtained.

  The wet granulated body 16 is a substance (granular body) in which water as a solvent is held (absorbed) by a plurality of negative electrode active material particles and a binding material, and these are aggregated (bound). . The negative electrode mixture 6 is an aggregate of such wet granulated bodies 16. In the present embodiment, the negative electrode active material, the binder, and the solvent are mixed so that the solid content of the negative electrode mixture 6 (wet granulated body 16) is 70 wt% or more (for example, 78 wt%). Yes.

  Next, it progresses to step S2 (film-forming process), the negative electrode compound material 6 produced at step S1 (electrode compound material production process) is made into a film shape, and the negative electrode mixture material 6 made into a film shape is the surface of the current collector foil 7 Adhere on. In the present embodiment, step S2 (film forming process) is performed using the roll film forming apparatus 20 shown in FIGS.

  As shown in FIGS. 1 and 2, the roll film forming apparatus 20 has three rolls of a first roll 1, a second roll 2, and a third roll 3. The 1st roll 1 and the 2nd roll 2 are arrange | positioned along with the horizontal direction (left-right direction in FIG. 1). On the other hand, the second roll 2 and the third roll 3 are arranged side by side in the vertical direction (vertical direction in FIG. 1). Moreover, the 1st roll 1 and the 2nd roll 2 are facing (opposite) with a slight space | interval. Similarly, the second roll 2 and the third roll 3 are also facing (opposed) with a slight gap therebetween. Furthermore, on the upper side of the facing portion between the first roll 1 and the second roll 2, the partition plates 4 and 5 are arranged apart from each other in the roll width direction (axial direction, the direction perpendicular to the paper surface in FIG. 1). ing.

  Further, the rotation directions of these three rolls 1 to 3 are set so that the rotation directions of two adjacent (facing) rolls are opposite to each other as shown by arrows in FIGS. These two rolls are set to rotate in the forward direction. And in the facing location of the 1st roll 1 and the 2nd roll 2, it sets so that the surface of these rolls may move downward by rotation. Moreover, in the facing location of the 2nd roll 2 and the 3rd roll 3, it sets so that the surface of these rolls may move rightward by rotation. Regarding the rotation speed, the moving speed of the surface of the roll due to the rotation is set to be the slowest in the first roll 1, the fastest in the third roll 3, and intermediate between them in the second roll 2.

  In such a roll film forming apparatus 20, step S <b> 1 (electrode mixture manufacturing step) is performed in the accommodation space between the partition plates 4 and 5 located on the facing portion of the first roll 1 and the second roll 2. The negative electrode composite material 6 produced in (1) is charged. A current collector foil 7 is stretched over the third roll 3.

  The current collector foil 7 is a metal foil (copper foil) and has a thickness of about 10 μm. The current collector foil 7 is conveyed from the lower right side to the upper right side of the third roll 3 through the facing portion (gap) between the second roll 2 and the third roll 3 as the third roll 3 rotates. It has become. Further, in the state where the current collector foil 7 is passed through the facing portion (gap) between the second roll 2 and the third roll 3, a slight gap is further provided between the second roll 2 and the current collector foil 7. Have been there. That is, the gap between the second roll 2 and the third roll 3 (gap in the state where the current collector foil 7 is not present) is slightly wider than the thickness of the current collector foil 7.

  In this step S2 (film formation process), the negative electrode mixture 6 is compressed into a film shape by passing the negative electrode mixture 6 through the gap between the first roll 1 and the second roll 2 that rotate opposite to each other. The shaped negative electrode mixture 6 is adhered to the surface of the second roll 2. At the same time, the surface of the second roll 2 is obtained by passing the current collector foil 7 conveyed by the third roll 3 rotating opposite to the second roll 2 through the gap between the second roll 2 and the third roll 3. The film-like negative electrode mixture 6 adhering to the surface of the current collector foil 7 is brought into contact with the surface of the current collector foil 7 while being pressed and transferred onto the surface of the current collector foil 7.

  More specifically, first, the negative electrode mixture 6 produced in step S1 (electrode mixture production process) is put into the accommodation space between the partition plates 4 and 5 of the roll film forming apparatus 20. The charged negative electrode mixture 6 is supplied into the gap between the facing surfaces of the first roll 1 and the second roll 2 that rotate opposite to each other, and both the rolls 1 are rotated by the rotation of the first roll 1 and the second roll 2. , 2 to form a film (see FIGS. 1 and 2). At this time, since the rotation speed of the second roll 2 is faster than that of the first roll 1, the negative electrode mixture 6 (wet granulated body 16) is carried (attached) on the surface of the second roll 2.

  Then, the film-like negative electrode mixture 6 carried (attached) on the surface of the second roll 2 (referred to as the film-like negative electrode mixture 8) is conveyed along with the rotation of the second roll 2 (FIG. 1). FIG. 2). Then, the surface of the current collector foil 7 and the film-like negative electrode mixture 8 meet at the facing portion of the second roll 2 and the third roll 3, and the current collector foil is between the second roll 2 and the third roll 3. 7 and the film-like negative electrode mixture 8 are sandwiched. Note that the gap size (minimum gap size) between the second roll 2 and the third roll 3 facing each other is smaller than the sum of the thickness of the current collector foil 7 and the thickness of the film-like negative electrode mixture 8.

  Therefore, when the current collector foil 7 and the film-like negative electrode mixture 8 are sandwiched between the second roll 2 and the third roll 3, the film-like negative electrode mixture 8 is collected from the surface of the second roll 2. A pressing load is applied toward the surface of the electric foil 7. Thereby, the film-like negative electrode mixture 8 adhering to the surface of the second roll 2 can be brought into contact with the surface of the current collector foil 7 while being pressed. It is transferred (attached) from the roll 2 onto the surface of the current collector foil 7 rotating together with the third roll 3. Thereby, the current collector foil 9 with the film-like negative electrode mixture in which the film-like negative electrode mixture 8 is formed on the surface of the current collector foil 7 is obtained.

  In the present embodiment, the film-like negative electrode mixture 8 is not formed on the surfaces of both end portions (first end portion 7b and second end portion 7c) of the current collector foil 7 in the width direction WD. (See FIGS. 2 and 3). The first end portion 7b and the second end portion 7c of the current collector foil 7 are used as portions for connection with the electrode terminal member (negative electrode terminal member) of the battery.

  By the way, in the current collector foil 9 with the film-like negative electrode mixture produced as described above, as shown in FIGS. 3 and 4, both end portions (first width) of the film-like negative electrode mixture 8 in the width direction WD. In the direction end portion 8b or the second width direction end portion 8c), there is a protruding portion 8d that protrudes outside the width direction WD (the first width direction WD1 or the second width direction WD2). In some cases, both end portions in the width direction WD are uneven. In addition, the protruding portion 8 d of the film-like negative electrode mixture 8 is often not in close contact with the surface of the current collector foil 7 and is easily peeled off from the surface of the current collector foil 7.

  Specifically, in this embodiment, since the negative electrode mixture 6 made of the wet granulated body 16 is used, the negative electrode mixture 6 is passed through the gap between the first roll 1 and the second roll 2. 6 is made into a film shape while being compressed to produce a film-like negative electrode mixture 8, both end portions in the width direction WD are likely to be uneven, and outside the width direction WD (the first width direction WD 1 or the second width direction WD 2). 8d is easily formed. And the protrusion part 8d located in the both ends of the width direction WD of the film-form negative electrode compound 8 tends to become thinner than the part located in the inner side (center side) of the width direction WD. It was.

  For this reason, sandwiching the current collector foil 7 and the film-like negative electrode mixture 8 between the second roll 2 and the third roll 3, the film-like negative electrode mixture 8 adhering to the surface of the second roll 2, When the film-like negative electrode mixture 8 is transferred onto the surface of the current collector foil 7 by making contact with the surface of the current collector foil 7 while applying pressure, the protrusions 8d positioned at both ends in the width direction WD are Compared with the part located inside (center side) in the width direction WD, the adhesiveness to the surface of the current collector foil 7 tended to be lower. For this reason, the protruding portion 8 d of the film-like negative electrode mixture 8 is easily peeled off from the surface of the current collector foil 7.

  For this reason, after transferring the film-like negative electrode mixture 8 onto the surface of the current collector foil 7 in the film forming step (step S2), at least a part of the protruding portion 8d of the film-like negative electrode mixture 8 (in detail, the film Part of the negative electrode composite material 8 in the width direction WD is weaker than the inner part 8g located on the inner side than the projecting part 8d, and has a weak binding force to the surface of the current collector foil 7, and is easily peeled off from the surface of the current collector foil 7, The same applies hereinafter) may peel off from the surface of the current collector foil 7. In particular, when the solvent is removed from the film-like negative electrode mixture 8 by performing the drying step (step S4) described later, at least a part of the protruding portion 8d is easily peeled off from the surface of the current collector foil 7. For this reason, it has been required to remove at least a part of the protruding portion 8d of the film-like negative electrode mixture 8 after the film forming step (step S2) and before the drying step (step S4). .

  On the other hand, in this embodiment, as shown in FIG. 5, after the film forming step (step S2) and before the drying step (step S4), at least a part of the protruding portion 8d from the film-like negative electrode mixture 8 is obtained. The removal process (step S3) which removes is provided. In the present embodiment, the process of step S3 (removal process) is performed using the removal apparatus 30 shown in FIGS.

  The removing device 30 includes a removing roll 40 and a scraping device 50. Among these, the removal roll 40 is made of metal, and has a cylindrical shape extending in the width direction WD of the current collector foil 9 with the film-like negative electrode mixture (film-like negative electrode mixture 8). The surface 41 (outer peripheral surface) of the removal roll 40 is in a state of being in contact (pressure contact) with the surface of the film-like negative electrode mixture 8 conveyed in the conveyance direction CD. Thereby, the removal roll 40 is conveyed from the film-form negative electrode mixture 8 in the contact part with the film-form negative electrode mixture 8 among the surfaces 41 with the movement to the conveyance direction CD of the film-form negative electrode mixture 8. FIG. It receives a force in the direction CD (from left to right in FIG. 1), and thereby rotates around its own central axis (counterclockwise in FIG. 1).

  Further, the scraping device 50 includes a scraping blade 51 and a collecting and picking-up unit 55. Among these, the scraping blade 51 is fixed in position in such a manner that the front end portion 51 b is in contact with the surface 41 of the removing roll 40. Further, the collecting portion 55 is disposed below the tip end portion 51 b of the scraping blade 51. As will be described later, the collecting portion 55 is a portion of the protruding portion 8d of the film-shaped negative electrode mixture 8 that is transferred to the surface 41 of the removing roll 40 and then scraped off by the scraping blade 51 (referred to as a removing portion 8f). ) Is collected (accepted). Note that a dust collection port of a dust collector (not shown) is disposed inside the collection unit 55. Thereby, the removal part 8f (projection part 8d) collected by the collection part 55 can be collected by the dust collector which is not shown in figure.

  In step S3 (removal process) of the present embodiment, the current collector foil 9 with the film-like negative electrode mixture 8 having the film-like negative electrode mixture 8 on the surface of the current collector foil 7 is conveyed while being conveyed in the conveyance direction CD. The surface of the film-like negative electrode mixture 8 in the current collector foil 9 with the film-like negative electrode mixture is brought into contact with the surface 41 of the removal roll 40. In other words, of the current collector foil 9 with the film-like negative electrode mixture, the current collector foil 9 with the film-like negative electrode mixture in a state where the surface of the film-like negative electrode mixture 8 is in contact with the surface 41 of the removal roll 40. Is conveyed in the conveyance direction CD (see FIGS. 1 and 2).

  Thereby, among the film-like negative electrode mixture 8 of the current collector foil 9 with the film-like negative electrode mixture, both end portions (the first width direction end 8b or the second width direction) of the film-like negative electrode mixture 8 in the width direction WD. At least a portion (removal portion 8f) of the protruding portion 8d located at the end portion 8c and protruding outside the first width direction WD1 or the second width direction WD2 from the surface of the current collector foil 7 It can be transferred to the surface 41 of the removal roll 40 (see FIG. 1).

  As described above, of the film-like negative electrode mixture 8 formed on the surface of the current collector foil 7, the protrusions 8 d located at both ends in the width direction WD are closer to the inner side (center of the width direction WD). Compared to the inner portion 8g located on the side), the surface tends to be peeled off from the surface of the current collector foil 7. Furthermore, in the protruding portion 8d, the closer to the tip side (the apex side, the outer side in the width direction WD of the film-like negative electrode composite 8), the lower the adhesion with the surface of the current collector foil 7 (that is, the binding). The adhesive force is weakened) and tends to be easily peeled off from the surface of the current collector foil 7.

  For this reason, when the surface of the film-like negative electrode mixture 8 formed on the surface of the current collector foil 7 is brought into contact (pressure contact) with the surface 41 of the removal roll 40, the width direction WD of the film-like negative electrode mixture 8 is obtained. At least a part of the projecting portion 8d located at both ends (particularly, a portion located on the distal end side of the projecting portion 8d) is transferred to the surface 41 of the removal roll 40. Thereby, from the current collector foil 9 with the film-shaped negative electrode mixture, at least a part of the protrusions 8d located at both ends in the width direction WD of the film-shaped negative electrode mixture 8 (particularly, on the tip side of the protrusions 8d). (Positioned portion) is selectively removed as the removing portion 8f, and the protruding dimension H of the protruding portion 8d in the width direction WD is reduced (the unevenness in the width direction WD of the film-like negative electrode mixture 8 is reduced). be able to.

  Further, the removal portion 8 f (the portion constituting the protruding portion 8 d) transferred to the surface 41 of the removal roll 40 in the film-like negative electrode mixture 8 is rotated with the rotation of the removal roll 40 and the tip portion of the scraping blade 51. It moves to the position where 51b is arranged. Then, the removing portion 8f adhering to the surface 41 of the removing roll 40 collides with the tip portion 51b of the scraping blade 51 and scrapes downward from the surface 41 of the removing roll 40 by the tip portion 51b of the scraping blade 51. Be dropped.

  The removing unit 8 f scraped off from the surface 41 of the removing roll 40 is collected (received) by the collecting unit 55 positioned below the scraping blade 51. The removing unit 8f collected by the collecting unit 55 is sucked and removed by a dust collector (not shown). Thereby, after the film forming step (step S2) and before the drying step (step S4), both end portions (first width direction end portion 8b or second width) of the film-like negative electrode mixture 8 in the width direction WD. At least a part (removal part 8f) of the protruding part 8d located at the direction end part 8c) and protruding outside the first width direction WD1 or the second width direction WD2 in the width direction WD. Can be removed appropriately from

  Therefore, in the present embodiment, after the film forming step (step S2), the negative electrode mixture 6 that is peeled off from the surface of the current collector foil 7 (not intentionally peeled off from the surface of the current collector foil 7 and removed) The amount of the negative electrode mixture 6) that peels off naturally can be reduced. In particular, in this embodiment, since the removing device 30 is provided immediately after the film forming step (step S2), the film-shaped negative electrode is formed immediately after the film-shaped negative electrode mixture 8 is formed on the surface of the current collector foil 7. At least a part (removal portion 8 f) of the protruding portion 8 d of the composite material 8 can be removed from the surface of the current collector foil 7. For this reason, the amount of the negative electrode mixture 6 that peels off from the surface of the current collector foil 7 can be further reduced.

  Then, as shown in FIG. 5, it progresses to step S4 (drying process), and the current collection foil 9 with a film-form negative electrode mixture is dried (the film-form negative electrode mixture 8 is dried). Specifically, the film-like negative electrode mixture 8 (film) transferred to the surface of the current collector foil 7 by passing the current collector foil 9 with the film-like negative electrode mixture through the inside of a drying device (drying furnace) (not shown). The negative electrode composite material 6) is dried. As a result, the solvent (water) absorbed (retained) in the film-like negative electrode mixture 8 (wet granulated body 16) is removed (evaporated), and the film-like negative electrode mixture 8 becomes the negative electrode mixture layer 18. (Electrode mixture layer). Thereby, the negative electrode sheet 19 (refer FIG. 6) in which the negative mix layer 18 was formed on the surface of the current collection foil 7 is produced.

  The negative electrode mixture layer 18 may be formed only on one side of the current collector foil 7 (that is, a single-side coated negative electrode sheet is manufactured), or may be formed on both sides (that is, double-sided coated negative electrode sheet). May be manufactured). In the case of forming the negative electrode mixture layer 18 on both surfaces of the current collector foil 7, after producing a single-side coated negative electrode sheet in which the negative electrode mixture layer 18 is formed on one side of the current collector foil 7, the single-side coated negative electrode sheet The processing of steps S2, S3, and S4 may be sequentially performed on the surface of the current collector foil 7 on which the negative electrode mixture layer 18 is not formed.

  The produced negative electrode sheet 19 can be used, for example, as a negative electrode sheet of a lithium ion secondary battery. Specifically, for example, the negative electrode sheet 19 is combined with a positive electrode sheet and a separator to form an electrode body. Subsequently, after attaching a terminal member to this electrode body, an electrode body and electrolyte solution are accommodated in a battery case. Thereby, a lithium ion secondary battery is completed.

Example 1
In Example 1, as the removing roll 40, the removing roll 40 whose surface 41 (outer peripheral surface) was covered with a PTFE coating was used. That is, the surface 41 of the removing roll 40 is made of a PTFE coating. By doing in this way, in step S3 (removal process), the removal portion 8f transferred to the surface 41 of the removal roll 40 (the portion constituting the protruding portion 8d of the film-like negative electrode mixture 8) is scraped off. The blade 51 can be easily scraped off.

  Thereby, even when the negative electrode sheet 19 is manufactured continuously for a long time, the removal portion 8f transferred to the surface 41 of the removal roll 40 is prevented from remaining and depositing on the surface 41 of the removal roll 40. Can do. Therefore, even when the negative electrode sheet 19 is manufactured continuously for a long time, it is possible to appropriately remove at least a part of the protruding portion 8d of the film-like negative electrode mixture 8 in Step S3 (removal step).

(Example 2)
In Example 2, as the removing roll 40, the removing roll 40 whose surface 41 (outer peripheral surface) had an uneven shape and was covered with a PTFE coating was used. In step S3 (removal step), by using such a removal roll 40, the removal part 8f transferred to the surface 41 of the removal roll 40 (part constituting the protruding part 8d of the film-like negative electrode mixture 8). Can be easily scraped off by the scraping blade 51. In the second embodiment, the surface 41 (outer peripheral surface) of the removal roll 40 is formed into a concavo-convex shape having a large number of small depressions by performing dimple processing.

(Manufacturing method evaluation test)
Tests for evaluating the production methods of Example 1 and Example 2 were performed. Specifically, the negative electrode sheet 19 having a length of 200 m was continuously manufactured by the manufacturing method of each example. As described above, Example 1 and Example 2 are different only in that the process of Step S3 (removal process) is performed using the removal roll 40 having a different form of the surface 41, and the other is the same. The negative electrode sheet 19 is manufactured.

  During the production period of the negative electrode sheet 19 according to each example, the current-collecting foil 9 with the film-like negative electrode mixture (film-like negative electrode mixture 8) is removed immediately after step S3 (removal step) by a known displacement meter. The position in the width direction WD of the first width direction end portion 8b of the film-like negative electrode mixture 8 immediately after passing through the device 30 was measured. And based on this measurement result, the average value of the protrusion dimension H of the protrusion part 8d of the film-like negative electrode mixture 8 immediately after step S3 (removal process) (included in the film-like negative electrode mixture 8 having a length of 200 m). The average value of the protrusion dimension H of the protrusion 8d was determined.

  In addition, the protrusion dimension H of the protrusion part 8d is the distance concerning the width direction WD between the peak and valley which comprise each protrusion part 8d, as shown in FIG. The average value of the protrusion dimension H of the protrusion 8d of the film-like negative electrode mixture 8 immediately after step S3 (removal process) is the protrusion before the drying process (step S4) after the film formation process (step S2). It is an average value of the protrusion dimension H of the part 8d.

  In addition, a negative electrode sheet having a length of 200 m was also continuously produced by the production method of Comparative Example 1. Note that the manufacturing method of Comparative Example 1 is different from the manufacturing methods of Examples 1 and 2 only in that the process of Step S3 (removal step) is not performed, and the others are the same. That is, in Comparative Example 1, a negative electrode having a length of 200 m was used by using an electrode sheet manufacturing apparatus that was different from the electrode sheet manufacturing apparatus 10 used in Examples 1 and 2 only in that it did not have a removal device 30. Sheets were produced continuously.

  Also for the manufacturing method of Comparative Example 1, the average value of the protruding dimension H of the protruding portion 8d of the film-like negative electrode mixture 8 was determined in the same manner as in Examples 1 and 2. In Comparative Example 1 as well, a displacement meter that measures the position in the width direction WD of the first width direction end portion 8b of the film-like negative electrode mixture 8 is the same position as in Examples 1 and 2 in the electrode sheet manufacturing apparatus. And measuring the position in the width direction WD of the first width direction end 8b of the film-like negative electrode mixture 8. However, in Comparative Example 1, since the process of step S3 (removal process) is not performed, the average value of the protrusion dimension H is the value for the protrusion 8d immediately after the process of step S2 (film formation process). However, as in the first and second embodiments, the average value of the protrusion dimension H of the protrusion 8d after the film forming process (step S2) and before the drying process (step S4) is obtained. The average value of the protrusion dimension H concerning Examples 1, 2 and Comparative Example 1 is shown in FIG.

  As shown in FIG. 7, in the manufacturing method of Comparative Example 1, the average value of the protrusion dimension H of the protrusion 8d was 3.0 mm. On the other hand, in the manufacturing methods of Examples 1 and 2, the average value of the protrusion dimension H of the protrusion 8d could be reduced to 1.0 mm or less. In detail, in the manufacturing method of Example 1, the average value of the protrusion dimension H of the protrusion 8d was 1.0 mm. Moreover, in the manufacturing method of Example 2, the average value of the protrusion dimension H of the protrusion 8d was 0.8 mm.

  As described above, in Examples 1 and 2, the reason why the average value of the protrusion dimension H of the protrusion 8d can be reduced after the film formation process (step S2) and before the drying process (step S4). By performing the process of step S3 (removal process) after the film forming process (step S2) and before the drying process (step S4), at least a part of the protruding portion 8d of the film-shaped negative electrode mixture 8 ( This is because the tip portion) could be removed.

  Furthermore, after the negative electrode sheet 19 having a length of 200 m was continuously manufactured by the manufacturing method of Example 1, the roll film forming apparatus 20 wound the electrode foil manufacturing apparatus 10 in the transport direction CD of the current collector foil 7. The negative electrode mixture 6 (one of the film-like negative electrode mixture 8) peeled off from the surface of the current collector foil 7 within the range up to the removing device (that is, the position downstream of the roll film forming device 20 in the transport direction CD). Part) was collected, and the total weight (the amount of peeling off) was measured. That is, when the negative electrode sheet 19 having a length of 200 m was continuously manufactured by the manufacturing method of Example 1, the total weight of the negative electrode mixture 6 peeled off from the surface of the current collector foil 7 was obtained. Further, for Example 2 and Comparative Example 1, the amount of peeling off was measured in the same manner. These results are shown in FIG.

  Note that the negative electrode mixture 6 peeled off from the surface of the current collector foil 7 does not include the negative electrode mixture 6 (removal portion 8f) removed from the surface of the current collector foil 7 in step S3 (removal step). The negative electrode mixture 6 peeled off from the surface of the current collector foil 7 is the negative electrode composite material 6 that has been naturally peeled off (dropped off) from the surface of the current collector foil 7 during manufacture (during transportation). It is.

  As shown in FIG. 8, in the manufacturing method of Comparative Example 1, the amount of the negative electrode mixture 6 peeled off was 42 g. On the other hand, in the manufacturing methods of Examples 1 and 2, the amount of peeling off of the negative electrode mixture 6 could be reduced to 12 g or less. In detail, in the manufacturing method of Example 1, the amount of peeling of the negative electrode mixture 6 was 12 g. Moreover, in the manufacturing method of Example 2, the amount of peeling of the negative electrode mixture 6 was 8 g.

  As described above, in Examples 1 and 2, the reason that the amount of the negative electrode mixture 6 peeled off from the surface of the current collector foil 7 could be reduced is that the drying process (step S2) is followed by the drying process (step S2). Before step S4), by performing the process of step S3 (removal process), at least a part (tip portion) of the protruding portion 8d that easily peels off from the surface of the current collector foil 7 in the film-like negative electrode composite 8 is removed. This is because it is forcibly removed (before it naturally peels off from the surface of the current collector foil 7).

  From the result of this test, by performing the process of step S3 (removal process) after the film forming process (step S2) and before the drying process (step S4), the protruding portion 8d of the film-like negative electrode mixture 8 is obtained. By removing at least a part of the negative electrode composite material 6 (film-form negative electrode composite material), the projecting dimension of the projecting portion 8d of the film-form negative electrode composite material 8 can be reduced. 8) can be reduced.

In the above, the present invention has been described with reference to the embodiments (Examples 1 and 2). However, the present invention is not limited to the above-described embodiments, and can be appropriately modified and applied without departing from the gist thereof. Needless to say, it can be done.
For example, in the embodiment, a method for producing a negative electrode sheet has been exemplified as a method for producing an electrode sheet according to the present invention. However, you may make it apply this invention to the manufacturing method of a positive electrode sheet.

1 1st roll 2 2nd roll 3 3rd roll 6 Negative electrode mixture (electrode mixture)
7 Current collector foil 8 Film-like negative electrode mixture (film-like electrode mixture)
8d Projection 8f Removal 9 Current collector foil with film-like negative electrode mixture (current collector foil with film-like electrode mixture)
DESCRIPTION OF SYMBOLS 10 Electrode sheet manufacturing apparatus 16 Wet granule 18 Negative electrode compound material layer (electrode compound material layer)
19 Negative electrode sheet (electrode sheet)
20 roll film forming apparatus 30 removing apparatus 40 removing roll 41 surface 50 scraping apparatus 51 scraping blade CD transport direction WD width direction S1 electrode mixture preparation process S2 film forming process S3 removing process S4 drying process

Claims (1)

An electrode sheet manufacturing method for manufacturing an electrode sheet having an electrode mixture layer on the surface of a current collector foil,
By passing an electrode mixture composed of a plurality of wet granulation bodies, which are granulated by mixing an electrode active material, a binder, and a solvent, through a gap between a first roll and a second roll that rotate oppositely, The electrode mixture is formed into a film while being compressed, and the film-formed electrode mixture is attached to the surface of the second roll, and is conveyed by a third roll that rotates opposite to the second roll. By passing the current collector foil through the gap between the second roll and the third roll, the film-like electrode mixture adhering to the surface of the second roll is used as the surface of the current collector foil. A film-like electrode having a film-like electrode mixture that is a film-like electrode mixture on the surface of the current-collecting foil. A film forming process for producing a current collector foil with a mixture;
A drying step of forming the electrode mixture layer on the surface of the current collector foil by drying the film electrode mixture of the current collector foil with the membrane electrode material. In the method
After the film forming step and before the drying step, the surface of the film electrode composite material of the current collector foil with film electrode material mixture is removed while conveying the current collector foil with film electrode material composite In contact with the surface of the roll, out of the film electrode mixture of the current collector foil with the film electrode mixture, located at both ends in the width direction of the film electrode mixture and on the outside in the width direction The manufacturing method of an electrode sheet provided with the removal process which removes at least one part of the said protrusion part among the said film-like electrode compound materials by transferring at least one part of the protrusion part which protrudes to the said surface of the said removal roll.

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