Manufacturing device for electrode mixture sheet

Abstract

A manufacturing device 1 for an electrode mixture sheet S comprises a first roll 2 and a second roll 4. The first roll 2 and the second roll 4 place a dry electrode mixture P on a first circumferential surface 2a of the first roll 2 and a second circumferential surface 4a of the second roll 4, supply the dry electrode mixture P to a gap between the two rolls to form an electrode mixture sheet S, and support and convey the electrode mixture sheet S via the second circumferential surface 4a. The first circumferential surface 2a has an Str of 0.5 or less, and the second circumferential surface 4a has an Str of more than 0.5.

Description

Manufacturing apparatus for electrode mixture sheet

[0001] The present disclosure relates to a manufacturing apparatus for an electrode mixture sheet.

[0002] Patent Document 1 describes a method for manufacturing a coated film product in which a wet electrode mixture paint is introduced into the gap between a first roll and a second roll, and a coating film is formed on the surface of the second roll and conveyed.

[0003] Japanese Patent Application Laid-Open No. 2016-59870

[0004] Regarding dry electrode mixtures, there are cases where they are formed into a sheet shape and conveyed using a plurality of rolls as in the above-described manufacturing method. As a result of intensive studies on a manufacturing apparatus for a dry electrode mixture sheet, the inventors have found a technique for improving the performance of the manufacturing apparatus such as the transportability of the electrode mixture sheet.

[0005] The present disclosure has been made in view of such circumstances, and an object thereof is to provide a technique for improving the performance of a manufacturing apparatus for an electrode mixture sheet.

[0006] One aspect of the present disclosure is a manufacturing apparatus for an electrode mixture sheet. This apparatus includes a first roll and a second roll that are adjacent to each other with a predetermined interval, and a dry electrode mixture is placed on the first circumferential surface of the first roll and the second circumferential surface of the second roll and supplied into the gap between the two rolls. The dry electrode mixture is compressed into a sheet shape to form an electrode mixture sheet, and the apparatus includes the first roll and the second roll that support and convey the electrode mixture sheet on the second circumferential surface. The first circumferential surface has an aspect ratio Str of the surface property measured in accordance with JIS B 0601:2001 standard of 0.5 or less. The second circumferential surface has an Str of more than 0.5.

[0007] Any combination of the above components, and those obtained by converting the expression of the present disclosure among a method, an apparatus, a system, etc. are also effective as an aspect of the present disclosure.

[0008] According to the present disclosure, it is possible to improve the performance of the manufacturing apparatus for an electrode mixture sheet.

[0009] It is a schematic diagram of a manufacturing apparatus for an electrode mixture sheet according to an embodiment. It is a diagram showing the results of a transferability evaluation test.

[0010] The present disclosure will be described below with reference to the drawings, based on preferred embodiments. The embodiments are illustrative and not limiting, and not all features or combinations thereof described in the embodiments are necessarily essential to the present disclosure. The same or equivalent components, members, and processes shown in each drawing are denoted by the same reference numerals, and redundant descriptions are omitted where appropriate. The scale and shape of each part shown in each drawing are set for convenience to facilitate explanation and are not to be interpreted restrictively unless otherwise specified. Furthermore, where terms such as "first," "second," etc. are used in this specification or claims, unless otherwise specified, these terms do not indicate any order or importance, but are used to distinguish one configuration from another. In addition, some components that are not important for explaining the embodiments are omitted in each drawing.

[0011] Figure 1 is a schematic diagram of an electrode mixture sheet manufacturing apparatus 1 according to an embodiment. The electrode mixture sheet manufacturing apparatus 1 comprises a first roll 2, a second roll 4, a third roll 6, and a storage section 8. Hereinafter, the electrode mixture sheet manufacturing apparatus 1 will be abbreviated as "manufacturing apparatus 1" as appropriate. In the manufacturing apparatus 1 of this embodiment, as an example, the first roll 2, the second roll 4, and the third roll 6 are arranged in the horizontal direction.

[0012] The storage section 8 has a known structure, such as a combination of a hopper and a feeder, and stores the dry electrode mixture P, which is the raw material for the electrode mixture sheet S. The dry electrode mixture P contains an electrode active material and a binder. It also contains a conductive agent and a solvent as needed. The binder and solvent function as binding components that bind the electrode active materials together.

[0013] In typical lithium-ion secondary batteries, the electrode active material is lithium cobalt oxide or lithium iron phosphate for the positive electrode, and graphite for the negative electrode. The binder is polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), etc. The conductive agent is graphite, carbon black, acetylene black, etc. When dry electrode mixture P is used as the negative electrode, the solvent is water, alcohols, N-methylpyrrolidone (NMP), toluene, dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), etc. When dry electrode mixture P is used as the positive electrode, the solvent is amine-based solvent, ether-based solvent, ketone-based solvent, ester-based solvent, amide-based solvent, etc. As an example, the solvent content of dry electrode mixture P is 5% by mass or less, 3% by mass or less, 0.1% by mass, or substantially 0% of the total mass of dry electrode mixture P.

[0014] A first roll 2 and a second roll 4 are positioned at the powder outlet of the storage section 8. The orientation of the first roll 2 and the second roll 4 is determined so that their respective rotation axes are parallel to each other, and they are adjacent to each other with a predetermined distance between them. The second roll 4 is positioned downstream of the first roll 2 in the direction of conveying the electrode mixture sheet S. Dry electrode mixture P is supplied from the storage section 8 into the gap between the first roll 2 and the second roll 4. In this embodiment, the first roll 2 and the second roll 4 function as feed rolls. That is, the first roll 2 supplies the dry electrode mixture P from the storage section 8 into the gap between the two rolls by placing it on its first circumferential surface 2a. The second roll 4 supplies the dry electrode mixture P from the storage section 8 into the gap between the two rolls by placing it on its second circumferential surface 4a.

[0015] The first roll 2 and the second roll 4 rotate in opposite directions, compressing the dry electrode mixture P supplied into the gap into a sheet. This forms the electrode mixture sheet S. Therefore, the first roll 2 and the second roll 4 also function as forming rolls. The electrode mixture sheet S is continuously fed out from the gap between the first roll 2 and the second roll 4. Therefore, the electrode mixture sheet S is a long strip in the conveying direction. The electrode mixture sheet S is conveyed downstream while being supported by the second circumferential surface 4a of the second roll 4. Therefore, the second roll 4 also functions as a conveying roll.

[0016] A third roll 6 is positioned downstream of the second roll 4. The second roll 4 and the third roll 6 are positioned adjacent to each other with a predetermined distance between them, so that their respective axes of rotation are parallel to each other. The electrode mixture sheet S is supported and conveyed by the second circumferential surface 4a of the second roll 4 and transported into the gap between the second roll 4 and the third roll 6. The second roll 4 and the third roll 6 can feed the electrode mixture sheet S downstream by rotating in opposite directions with the electrode mixture sheet S sandwiched between them. As the electrode mixture sheet S passes through the gap between the second roll 4 and the third roll 6, it is transferred from the second circumferential surface 4a to the third circumferential surface 6a of the third roll 6 at the position where the second roll 4 and the third roll 6 face each other. The electrode mixture sheet S is then supported by the third circumferential surface 6a of the third roll 6 and transported downstream. Therefore, the third roll 6 functions as a transport roll.

[0017] The electrode mixture sheet S may be stretched as it passes through the gap between the second roll 4 and the third roll 6. In other words, the second roll 4 and the third roll 6 may function as stretching rolls. For example, the second roll 4 and the third roll 6 rotate at different peripheral speeds. Specifically, the rotation speed of the third roll 6 is faster than the rotation speed of the second roll 4. This allows the second roll 4 and the third roll 6 to transport the electrode mixture sheet S and stretch it due to the difference in their peripheral speeds. Alternatively, the electrode mixture sheet S can also be stretched by making the gap between the second roll 4 and the third roll 6 narrower than the thickness of the incoming electrode mixture sheet S.

[0018] The first circumferential surface 2a has a surface texture aspect ratio Str of 0.5 or less. The second circumferential surface 4a has a Str value greater than 0.5. Str is measured using a contact-type roughness meter in accordance with the JIS B 0601:2001 standard. This allows the anisotropy of contact between each circumferential surface and the electrode mixture sheet S to be adjusted to a degree suitable for transferring the electrode mixture sheet S to the second circumferential surface 4a. Therefore, the transferability of the electrode mixture sheet S to the second circumferential surface 4a can be improved. Consequently, the transportability of the electrode mixture sheet S in the manufacturing apparatus 1 can be improved.

[0019] Preferably, the first circumferential surface 2a is polished, and the second circumferential surface 4a is blast-treated. This makes it easy to adjust the Str of the first circumferential surface 2a to 0.5 or less, and easy to adjust the Str of the second circumferential surface 4a to more than 0.5. Furthermore, preferably, the arithmetic mean roughness Ra of the first circumferential surface 2a is lower than the Ra of the second circumferential surface 4a. For example, the Ra of the first circumferential surface 2a is 0.2 or less, and the Ra of the second circumferential surface 4a is 0.5 or more.

[0020] The configuration of the manufacturing apparatus 1 can be modified as appropriate. For example, the arrangement direction of the first roll 2, the second roll 4, and the third roll 6 is not particularly limited. For example, the third roll 6 may be arranged vertically or diagonally with respect to the second roll 4. In addition, one or more transport rolls may be arranged downstream of the third roll 6. Furthermore, a lamination roll may be arranged adjacent to the downstream transport roll. In this case, the electrode mixture sheet S can be laminated onto a sheet material such as a current collector plate that is transported by the lamination roll. The third roll 6 may also be omitted. In other words, the transport of the electrode mixture sheet S downstream of the second circumferential surface 4a may be carried out by another device.

[0021] The embodiments of this disclosure have been described in detail above. The embodiments described above are merely examples of how to implement this disclosure. The content of the embodiments does not limit the technical scope of this disclosure, and many design changes, such as changes, additions, and deletions of components, are possible, as long as they do not deviate from the idea of ​​this disclosure as defined in the claims. A new embodiment with design changes will have the effects of both the combined embodiment and the variation. In the embodiments described above, the content in which such design changes are possible is emphasized with notations such as "of this embodiment" or "in this embodiment," but design changes are also permitted even if there are no such notations. Any combination of components included in each embodiment is also valid as an embodiment of this disclosure. The hatching applied to the cross-section in the drawings does not limit the material of the object to which the hatching is applied.

[0022] The embodiments may be specified by the items described below. [Item 1] A manufacturing apparatus (1) for an electrode mixture sheet (S), comprising a first roll (2) and a second roll (4) adjacent to each other at a predetermined interval, wherein a dry electrode mixture (P) is placed on the first circumferential surface (2a) of the first roll (2) and the second circumferential surface (4a) of the second roll (4) and supplied into the gap between the two rolls (2,4), the dry electrode mixture (P) is compressed into a sheet to form an electrode mixture sheet (S), and the electrode mixture sheet (S) is supported and conveyed by the second circumferential surface (2a), wherein the aspect ratio Str of the surface properties measured in accordance with the JIS B 0601:2001 standard is 0.5 or less, and the Str of the second circumferential surface (4a) is greater than 0.5. [Item 2] The first circumferential surface (2a) is polished, and the second circumferential surface (4a) is blast-treated, in the manufacturing apparatus (1) for the electrode mixture sheet (S) of Item 1.

[0023] The following describes embodiments of the present invention, but these embodiments are merely illustrative examples for suitably illustrating the present invention and do not limit the present invention in any way.

[0024] (Example 1) A manufacturing apparatus was prepared that included a first roll 2, a second roll 4, and a storage section 8, that is, the manufacturing apparatus 1 shown in Figure 1 with the third roll 6 omitted. The first circumferential surface 2a had a Str of 0.35 and a Ra of 0.2. The second circumferential surface 4a had a Str of 0.85 and a Ra of 0.5. The Str and Ra of each circumferential surface were measured using a contact-type roughness meter (SURFTEST SJ-210: manufactured by Mitutoyo Corporation).

[0025] The following evaluation test was performed using the manufacturing apparatus according to Example 1. Specifically, an electrode mixture sheet S was formed from the dry electrode mixture P and conveyed, and the transferability of the electrode mixture sheet S was evaluated to see whether it could be transferred to the second circumferential surface 4a through the gap between the first roll 2 and the second roll 4. In the evaluation of transferability, a ○ was given if the electrode mixture sheet S was transferred to the second circumferential surface 4a, and a × was given if it was not transferred. The results are shown in Figure 2.

[0026] (Comparative Example 1) An evaluation test was conducted in the same manner as in Example 1, except that the Str of the first circumferential surface 2a was set to 0.87. The results are shown in Figure 2.

[0027] Figure 2 shows the results of the transferability evaluation test. As shown in Figure 2, in Example 1, where the Str of the first circumferential surface 2a was 0.5 or less and the Str of the second circumferential surface 4a was greater than 0.5, the transferability was good (○). On the other hand, in Comparative Example 1, where the Str of the second circumferential surface 4a was greater than 0.5, but the Str of the first circumferential surface 2a was also greater than 0.5, the transferability was poor (×). In Comparative Example 1, even when the electrode mixture sheet S passed through the gap between the first roll 2 and the second roll 4, it did not adhere to the second circumferential surface 4a. From the above, it was confirmed that by setting the Str of the first circumferential surface 2a to 0.5 or less and the Str of the second circumferential surface 4a to greater than 0.5, the electrode mixture sheet S can be stably transferred to the second circumferential surface 4a, and the transportability of the electrode mixture sheet S can be improved.

[0028] This disclosure can be used in a manufacturing apparatus for electrode mixture sheets.

[0029] 1 Manufacturing apparatus, 2 First roll, 2a First surface, 4 Second roll, 4a Second surface, P Dry electrode mixture, S Electrode mixture sheet.

Claims

1. An apparatus for manufacturing an electrode mixture sheet, comprising a first roll and a second roll adjacent to each other at a predetermined interval, wherein a dry electrode mixture is placed on the first circumferential surface of the first roll and the second circumferential surface of the second roll and supplied into the gap between the two rolls, the dry electrode mixture is compressed into a sheet to form an electrode mixture sheet, and the electrode mixture sheet is supported and conveyed by the second circumferential surface, wherein the aspect ratio Str of the surface properties measured in accordance with the JIS B 0601:2001 standard is 0.5 or less, and the Str of the second circumferential surface is greater than 0.

5.

2. The apparatus for manufacturing an electrode mixture sheet according to claim 1, wherein the first circumferential surface is polished and the second circumferential surface is blast-treated.

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