JP2016110707A - Coating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To coat a surface of an electrode foil of a secondary battery and a surface of a mixture layer with a resin simultaneously and uniformly.SOLUTION: A die coater 10 comprises a die head 11 including: a lip tip 13 which discharges a resin 20 onto a positive electrode foil 34 where a cathode mixture layer 35 is formed, so as to form an insulation layer that is continued from a surface of the cathode mixture layer 35 to the positive electrode foil 34; and a step 14 which is provided in the lip tip 13 and has a height that corresponds to the thickness of the cathode mixture layer 35 in a discharge direction of the resin 20. The lip tip 13 is disposed so as to face the positive electrode foil 34 and the step 14 is disposed so as to face the cathode mixture layer 35, such that a coating gap between the cathode mixture layer 35 and the step 14 and a coating gap between the electrode foil 34 and the lip tip 13 can be made substantially equal.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a coating apparatus, and more particularly to a coating apparatus for forming an insulating layer on an electrode of a secondary battery.

  Patent Document 1 discloses a nonaqueous electrolyte secondary battery in which a positive electrode and a negative electrode each having a positive electrode mixture layer and a negative electrode mixture layer formed on an electrode foil are laminated and wound via a separator. In order to prevent an internal short circuit, the positive electrode mixture layer is not formed on the positive electrode foil, and the positive electrode mixture uncoated portion is insulated from the portion facing the negative electrode mixture layer via the separator. A layer is formed.

  In Patent Document 1, the insulating layer is formed by applying a resin to be an insulating layer on the electrode foil with a die coater. After forming the insulating layer, the positive electrode mixture slurry is applied onto the electrode foil by a die coater to form the positive electrode mixture layer.

  Patent Document 1 discloses a hot melt method in which a resin serving as an insulating layer is applied using a heating die slot so as to cover an end portion of a positive electrode mixture layer formed on an electrode foil in advance. ing. A part of the insulating layer is formed so as to overlap the positive electrode mixture layer.

  Patent Document 2 discloses a die coater that applies a positive electrode mixture slurry and a negative electrode mixture slurry of a secondary battery onto an electrode foil. The tip of the die head has a tapered shape.

JP 2004-259625 A JP 2014-147857 A

  After forming the positive electrode mixture layer on the electrode foil, the inventor uses a die coater simultaneously on the electrode foil and the positive electrode mixture layer so that a part of the insulating layer overlaps the positive electrode mixture layer. It has been found that the following problems occur when coating is applied.

  The distance (coating gap) between the positive electrode mixture layer and the die head tip is greatly different from the distance between the electrode foil and the die head tip. When the resin discharge amount is controlled in accordance with the coating gap between the positive electrode mixture layer and the tip of the die head, it is difficult to uniformly coat the resin on the electrode foil. On the other hand, if the amount of resin discharged is controlled in accordance with the coating gap between the electrode foil and the tip of the die head, excess resin will flow into the portion of the positive electrode mixture layer that does not need to be coated. there is a possibility.

  The present invention has been made against the background of the above problems, and an object of the present invention is to provide a coating apparatus capable of simultaneously and uniformly coating a resin on an electrode foil and a mixture layer. Is to provide.

  The coating apparatus according to the embodiment includes a lip tip portion that discharges resin so as to form a continuous insulating layer from the mixture layer to the electrode foil on the electrode foil on which the mixture layer is formed. And a die head having a step portion provided at the tip of the lip and having a height corresponding to the thickness of the mixture layer in the resin discharge direction.

  By arranging the lip tip part to face the electrode foil and the step part to face the mixture layer, the coating gap between the mixture layer and the step part, and the coating gap between the electrode foil and the lip tip part, Can be made substantially equal.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the coating apparatus which can apply | coat resin uniformly on electrode foil and a mixture layer simultaneously.

It is a mimetic diagram showing composition of a die coater provided with a die head which has a level difference part concerning an embodiment. It is II-II sectional drawing of the die head shown in FIG. It is the figure which looked at the die head shown in FIG. 2 from the direction of the white arrow. It is a figure explaining the structure of the secondary battery 30 formed by the die-coater 10 which concerns on embodiment. It is process drawing explaining the manufacturing method of the secondary battery which concerns on embodiment. It is process drawing explaining the manufacturing method of the secondary battery which concerns on embodiment. It is process drawing explaining the manufacturing method of the secondary battery which concerns on embodiment. 3 is a top view showing a state of the positive electrode 31 before the insulating layer 21 is formed. FIG. FIG. 4 is a side view showing a state of the positive electrode 31 before the insulating layer 21 is formed. FIG. 3 is a top view showing a state after formation of an insulating layer 21 of a positive electrode 31. 3 is a side view showing a state after formation of an insulating layer 21 of a positive electrode 31. FIG. It is a figure which shows the structure of a die coater provided with the die head which does not have a level | step-difference part. It is a figure which shows the state of the insulating layer formed using the die head which does not have a level | step-difference part. It is a figure which shows the state of the insulating layer formed using the die head which does not have a level | step-difference part.

  Prior to the description of the embodiments of the present invention, problems of the present invention found by the present inventor will be described. As described above, after forming the mixture layer on the electrode foil, the insulating layer is applied simultaneously on the electrode foil and the mixture layer by a die coater so that a part of the insulating layer overlaps the mixture layer. In this case, it is difficult to apply the resin uniformly. This is because the distance between the positive electrode mixture layer and the tip of the die head is greatly different from the distance between the electrode foil and the tip of the die head.

  FIG. 8 is a diagram illustrating a configuration of a die coater including a die head that does not have a stepped portion. The example shown in FIG. 8 is a slit-type die coater, and a resin 5 serving as an insulating layer 6 is discharged from the lip tip 2 of the die head 1. As shown in FIG. 8, the lip tip 2 of the die head 1 is linear.

  Thus, when using the die head 1 which does not have a level | step-difference part, when it is going to apply | coat resin 5 simultaneously on the electrode foil 3 and the mixture layer 4, the lip front-end | tip part 2 will hit the mixture layer 4, and a lip front-end | tip There is a possibility that the mixture layer 4 may be scraped off at the portion 2.

  For this reason, as shown in FIG. 8, the lip tip 2 is separated from the mixture layer 4 by a predetermined distance so that the lip tip 2 of the die head 1 does not hit the mixture layer 4. Only the resin 5 is applied to form the insulating layer 6.

  9A and 9B are views showing a state of the insulating layer 6 formed using the die head 1 having no stepped portion. FIG. 9A is a top view of the positive electrode having the electrode foil 3 and the mixture layer 4. FIG. 9B is a side view of the positive electrode. As shown in FIGS. 9A and 9B, a gap is left between the insulating layer 6 and the end portion of the mixture layer 4. For this reason, there exists a problem that the function of the insulating layer which prevents the internal short circuit of a secondary battery is impaired.

  In the embodiment of the present invention, a continuous insulating layer is formed simultaneously from above the mixture layer to the electrode foil by using a die head having a step portion corresponding to the thickness of the mixture layer at the tip of the lip.

  Hereinafter, embodiments will be described with reference to the drawings. In the following drawings, components having the same action are denoted by the same reference numerals. In addition, the dimensional relationship in each figure does not reflect the actual dimensional relationship.

  Other than the configurations specifically mentioned in this specification as the configuration of the secondary battery (for example, the configuration of the positive electrode active material, the negative electrode active material, the separator, the electrolyte, and the manufacturing method thereof) It can be grasped as a design matter of a person skilled in the art based on the prior art in the field.

  First, the configuration of the secondary battery 30 will be described with reference to FIG. FIG. 4 is an exploded view schematically showing the configuration of the secondary battery 30. The secondary battery 30 illustrated in FIG. 4 is a lithium ion secondary battery. The secondary battery 30 includes a positive electrode 31, a negative electrode 32, and a separator 33.

  The positive electrode 31 and the negative electrode 32 are laminated via a separator 33 to constitute an electrode body. The positive electrode 31 includes a positive electrode foil 34, a positive electrode mixture layer 35, and an insulating layer 21. As the positive electrode foil 34, for example, an elongated sheet-shaped aluminum current collector is used. On both surfaces of the positive electrode foil 34, a film-like positive electrode mixture layer 35 is provided. Similar to a typical lithium ion secondary battery, the positive electrode mixture layer 35 includes a predetermined positive electrode active material.

  The negative electrode 32 includes a negative electrode foil 36 and a negative electrode mixture layer 37. As the negative electrode foil 36, for example, an elongated sheet-like copper current collector is used. A coating-like negative electrode mixture layer 37 is provided on both surfaces of the negative electrode foil 36. Similar to a typical lithium ion secondary battery, the negative electrode mixture layer 37 includes a predetermined negative electrode active material.

  As the separator 33, a microporous polypropylene film or the like can be used. A separator 33 is disposed between the positive electrode 31 and the negative electrode 32, and the positive electrode 31 and the negative electrode 32 are wound in a state of being insulated from each other, and then leads are connected to predetermined portions of the positive electrode 31 and the negative electrode 32, respectively. A lithium ion secondary battery is formed by being housed in a shaped exterior.

  In the present embodiment, the insulating layer 21 is formed so as not to cause a short circuit between the positive electrode 31 and the negative electrode 32 when the above-described wound electrode body is manufactured. The insulating layer 21 is formed on the positive electrode foil 34 of the positive electrode 31 in an unformed portion where the positive electrode mixture layer 35 is not formed and facing the negative electrode mixture layer 37 via the separator 33. Has been. As the insulating layer 21, for example, a UV curable resin having a solid content of 100% can be used.

  A part of the insulating layer 21 is formed so as to overlap the positive electrode mixture layer 35. That is, the insulating layer 21 is continuously formed from the positive electrode mixture layer 35 to the positive electrode foil 34. The thickness of the insulating layer 21 is thinner than the thickness of the positive electrode mixture layer 35. For example, the insulating layer 21 has a thickness of 10 μm, and the positive electrode mixture layer 35 has a thickness of 30 μm.

  In the embodiment, the insulating layer 21 is continuously formed on the positive electrode mixture layer 35 and the positive electrode electrode foil 34 continuously from the positive electrode mixture layer 35 to the positive electrode electrode foil 34. The insulating layer 21 is formed using a coating apparatus described below so that no gap is generated between the insulating layer 21 and the end portion of the positive electrode mixture layer 35.

  FIG. 1 is a schematic diagram illustrating a configuration of a die coater 10 that is an example of a coating apparatus according to an embodiment. As shown in FIG. 1, the die coater 10 has a die head 11 and a backup roll 12. Although not shown here, the die coater 10 includes a tank for storing the resin 20, a pump for sending the resin in the tank to the die head 11, and the like.

  The die head 11 has a lip tip 13, a step 14, and a manifold 15. 2 is a cross-sectional view of the die head shown in FIG. 1 taken along the line II-II. As shown in FIG. 2, the die head 11 includes a lip upper part 16 and a lip lower part 17. A manifold 15 is formed in the lip lower portion 17. By combining the lip upper portion 16 and the lip lower portion 17 so as to face each other, a slit 18 is formed between the lower surface of the lip upper portion 16 and the upper surface of the lip lower portion 17.

  The manifold 15 distributes the resin 20 introduced inside in the width direction. The resin 20 uniformly distributed in the width direction by the manifold 15 passes through the slit 18 and is continuously and uniformly discharged from the discharge portion 19. FIG. 3 is a view of the die head shown in FIG. 2 as viewed from the direction of the white arrow. As shown in FIG. 3, the discharge portion 19 has a rectangular shape with a predetermined width corresponding to the width of the insulating layer 21 to be formed.

  The backup roll 12 is disposed to face the lip tip 13 of the die head 11. The backup roll 12 supports the positive electrode foil 34 on which the positive electrode mixture layer 35 is formed. The backup roll 12 is rotatably provided. As the backup roll 12 rotates, the positive electrode foil 34 on which the positive electrode mixture layer 35 is formed runs continuously. The resin 20 is applied onto the positive electrode 31 by extruding the resin 20 from the discharge unit 19 onto the traveling positive electrode 31.

  As shown in FIG. 1, a step 14 is formed at the lip tip 13. The step portion 14 is formed corresponding to the thickness of the positive electrode mixture layer 35. The step portion 14 has a predetermined height corresponding to the thickness of the positive electrode mixture layer 35 in the discharge direction of the resin 20 at the lip tip portion 13.

  The die head 11 is horizontally disposed so that the direction of the slit 18 faces the substantial center of the backup roll 12 that conveys the positive electrode 31. Further, the die head 11 is arranged so that the portion where the step portion 14 of the lip tip portion 13 is not formed faces the positive electrode foil 34 so that the step portion 14 of the lip tip portion 13 faces the positive electrode mixture layer 35. Be placed.

  Thereby, the coating gap of the positive mix layer 35 and the level | step-difference part 14 and the coating gap of the positive electrode electrode foil 34 and the lip front-end | tip part 13 can be made substantially equal. The coating gap can be appropriately changed according to the desired film thickness of the insulating layer 21.

  When the resin 20 is discharged from the discharge portion 19 using such a die head 11, the lip tip portion 13 is in the positive electrode mixture even when the insulating layer 21 is thinner than the positive electrode mixture layer 35. Without hitting the layer 35, it becomes possible to apply the resin 20 uniformly on the positive electrode foil 34 and the positive electrode mixture layer 35 that are continuously running. As a result, the positive electrode mixture layer 35 is not scraped by the die head 11.

  Further, the insulating layer 21 continuous from the positive electrode mixture layer 35 to the positive electrode foil 34 can be formed without generating a gap between the positive electrode mixture layer 35 and the insulating layer 21. For this reason, it becomes possible to prevent the internal short circuit of the positive electrode 31 and the negative electrode 32 more reliably.

  Here, with reference to FIG. 5A-5C and FIG. 6A, 6B, 7A, 7B, the manufacturing method of the lithium ion secondary battery which concerns on embodiment is demonstrated. 5A to 5C are process diagrams illustrating a method for manufacturing a secondary battery according to the embodiment. 6A is a top view showing a state of the positive electrode 31 before the insulating layer 21 is formed, and FIG. 6B is a side view thereof. FIG. 7A is a top view showing a state after the insulating layer 21 of the positive electrode 31 is formed, and FIG. 7B is a side view thereof.

  First, as shown in FIG. 5A, the positive electrode mixture layer 35 is formed by intermittently applying and drying a positive electrode active material mixture slurry on both surfaces of a sheet-like positive electrode foil 34. The thickness of the positive electrode mixture layer 35 formed on both surfaces of the positive electrode foil 34 is 30 μm. As a result, as shown in FIGS. 6A and 6B, a portion where the positive electrode mixture layer 35 is formed and an unformed portion where the positive electrode foil 34 is exposed are formed on the positive electrode foil 34.

  After the positive electrode mixture layer 35 is formed on the positive electrode foil 34, as shown in FIG. 5B, the resin 20 (UV curable resin) that becomes the insulating layer 21 is applied using the die coater 10 shown in FIG. The thickness of the resin 20 is 10 μm. As described above, the step portion 14 corresponding to the thickness of the positive electrode mixture layer 35 is formed in the die head 11.

  The die head is arranged such that the portion where the step portion 14 of the lip tip portion 13 is not formed faces the positive electrode foil 34 so that the step portion 14 of the lip tip portion 13 faces the positive electrode mixture layer 35. It becomes possible to prevent 11 from hitting the positive electrode mixture layer 35. Further, the resin 20 can be applied uniformly and continuously from the positive electrode mixture layer 35 to the positive electrode foil 34 without causing a gap between the resin 20 and the end portion of the positive electrode mixture layer 35.

  Thereafter, as shown in FIG. 5C, the resin 20 is irradiated with UV light to form the insulating layer 21. As a result, as shown in FIGS. 7A and 7B, the insulating layer 21 was continuously continuous from the positive electrode mixture layer 35 to the positive electrode foil 34 so as to cover a part of the coated portion of the positive electrode mixture layer 35. The insulating layer 21 can be formed.

  As described above, according to the embodiment, in the portion having a stepped shape such as the end of the positive electrode mixture layer 35 formed on the positive electrode foil 34, It becomes possible to perform uniform coating on any of the agent layers 35 at the same time.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention. Although the lithium ion secondary battery has been described in the embodiment, the present invention is not limited to this. The present invention can be applied to a case where a paint is applied so as to cover a stepped portion such as a mixture layer formed on an electrode foil.

DESCRIPTION OF SYMBOLS 10 Die coater 11 Die head 12 Backup roll 13 Lip tip part 14 Step part 15 Manifold 16 Lip upper part 17 Lip lower part 18 Slit 19 Discharge part 20 Resin 21 Insulating layer 30 Secondary battery 31 Positive electrode 32 Negative electrode 33 Separator 34 Positive electrode foil 35 Positive electrode combination Agent Layer 36 Negative Electrode Foil 37 Negative Electrode Mixture Layer

Claims (1)

On the electrode foil on which the mixture layer is formed, a lip tip that discharges resin so as to form a continuous insulating layer over the electrode foil from the mixture layer;
A stepped portion provided at the lip tip and having a height corresponding to the thickness of the mixture layer in the resin discharge direction;
A die head having
Coating equipment.

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