Electrode mixture stretching device and method for manufacturing electrode mixture sheet

Abstract

This stretching device for an electrode mixture used to manufacture an electrode mixture sheet of a secondary battery is provided with a wave roller that stretches the electrode mixture containing a resin, wherein the wave roller has a plurality of crests and troughs alternately provided along the axial direction of a roller rotating shaft on the outer peripheral surface of the wave roller. The wave roller is formed such that the cross-sectional shape along the axial direction thereof is line-symmetric with respect to the roller rotating shaft.

Description

Electrode composite stretching apparatus and manufacturing method for producing electrode composite sheet

[0001] The present invention relates to an electrode composite sheet stretching apparatus used in the production of electrode composite sheets for secondary batteries, and to a manufacturing method for producing electrode composite sheets.

[0002] As electrode composites, mixed materials containing electrode active materials, resins, and additives such as conductive enhancers are known. The electrode composites are formed into electrode composite sheets by pressing or other means and used as electrode active material layers in secondary batteries.

[0003] WO2020 / 127215 discloses a manufacturing method for forming an electrode mixture sheet by rolling, pressing, or extrusion of an electrode mixture that has been mixed using a crushing, worm shaft or calendering roll device, a mixing device, a mortar device, or a combination thereof.

[0004] Incidentally, electrode mixtures that have been softened by mixing equipment tend to have a low fibrillated resin content. When such electrode mixtures are formed into thin sheets (hereinafter referred to as sheet molding), the sheet's breaking strength cannot be sufficiently ensured, making it prone to tearing during sheet molding.

[0005] On the other hand, while extending the mixing time makes it possible to prepare an electrode mixture containing a large amount of fibrillated material, the electrode mixture tends to harden. When forming such an electrode mixture into a sheet, it is possible to improve the sheet's breaking strength, but it can be difficult to form it to the desired thinness efficiently in a short amount of time.

[0006] Therefore, the object of the present invention is to provide an electrode composite stretching apparatus that can efficiently form an electrode composite sheet while improving the breaking strength of the electrode composite sheet by promoting the fibrillation of the resin.

[0007] According to one aspect of the present invention, an electrode mixture stretching apparatus for use in the production of electrode mixture sheets for secondary batteries is provided. This stretching apparatus comprises a roller for stretching an electrode mixture containing resin, and includes a wave roller having a plurality of peaks and valleys alternately provided on the outer circumferential surface of the roller along the axial direction of the roller rotation axis. The wave roller is formed such that its cross-sectional shape along its axial direction is symmetrical with respect to the roller rotation axis.

[0008] Figure 1 is a perspective view of a stretching device according to the first embodiment. Figure 2 is a longitudinal cross-sectional view of the wave rollers of the stretching device. Figure 3 is a partial longitudinal cross-sectional view of the first roll section of the stretching device according to the first embodiment, illustrating the state in which a pair of wave rollers are interlocked. Figure 4 is a partial longitudinal cross-sectional view of a pair of stretching rollers of the stretching device, illustrating the contact state between the electrode mixture and the stretching rollers immediately after the electrode mixture is fed between the stretching rollers. Figure 5 is a partial longitudinal cross-sectional view of the first roll section of the stretching device according to the first embodiment, illustrating the state in which the electrode mixture is stretched between a pair of wave rollers. Figure 6 is a perspective view of a stretching device according to a modified example. Figure 7 is a perspective view of a stretching device according to the second embodiment.

[0009] Embodiments of the present invention will be described below with reference to the drawings.

[0010] (First Embodiment) Figure 1 is a perspective view of the stretching device 1 according to the first embodiment. Figure 2 is a longitudinal cross-sectional view of the wave roller 3 provided in the stretching device 1. Figure 3 is a partial longitudinal cross-sectional view of the first roll section 2 of the stretching device 1, illustrating the state in which a pair of wave rollers 3 are interlocked with each other.

[0011] As shown in Figure 1, the stretching device 1 according to the first embodiment includes a first roll section 2, a frame section 4 on which the first roll section 2 is rotatably supported, and leg sections 6 that support the frame section 4 from below.

[0012] The leg portion 6 is, for example, placed on the floor surface and is configured as a frame with a roughly rectangular shape, and has a support base 6a on the upper surface of the frame. A pair of frame portions 4 are arranged on the upper surface of this support base 6a at predetermined intervals.

[0013] The first roll section 2 has a pair of wave rollers 3. In Figure 1, the upper wave roller 3 is designated as the first wave roller 3a, and the lower wave roller 3 is designated as the second wave roller 3b.

[0014] Each wave roller 3 is positioned between a pair of frame sections 4, and both ends of each are supported by the frame section 4 so that they can rotate along their central axis. The pair of wave rollers 3 stretch the electrode composite material 100 (see Figure 4(B)) containing resin by a mechanism described later.

[0015] Each frame section 4 is provided with a first adjustment screw 4a at its upper part for adjusting the pressing force of the wave roller 3. By changing the height position of the first wave roller 3a using the first adjustment screw 4a, and thereby changing the distance between the first wave roller 3a and the second wave roller 3b, the pressing force of the wave roller 3 can be adjusted.

[0016] One of the frame sections 4 is provided with a power transmission mechanism 5a and a drive unit 5b. The power transmission mechanism 5a consists of gears provided on the rotation shafts of the drive unit 5b, the first wave roller 3a, and the second wave roller 3b, and a plurality of gears that mesh with these gears.

[0017] The drive unit 5b is a device whose rotating shaft is driven by, for example, an electric motor. When the drive unit 5b is driven by rotation, its power is transmitted to the first wave roller 3a and the second wave roller 3b via the gears of the power transmission mechanism 5a. As a result, the first wave roller 3a and the second wave roller 3b rotate at the same rotational speed.

[0018] At this time, the first wave roller 3a and the second wave roller 3b are configured to rotate in different directions from each other so that the electrode mixture 100 (see Figure 4(B)) can be stretched. In other words, when viewing the first roll section 2 from the right side of the apparatus in Figure 1 (the side where the power transmission mechanism 5a and the drive device 5b are located), the first wave roller 3a rotates counterclockwise and the second wave roller 3b rotates clockwise.

[0019] The drive unit 5b is connected to a control device (not shown). This control device controls the rotational speed of the drive unit 5b. The drive unit 5b is not limited to being driven by an electric motor, as long as it is capable of rotating each gear of the power transmission mechanism 5a and a set of wave rollers 3. In addition to an electric motor, the drive unit 5b can also employ a system that rotates its rotating shaft hydraulically or manually.

[0020] By passing the electrode composite material 100 (see Figure 4(B)) at least once between the two wave rollers 3, which rotate using the mechanism described above, along the stretching direction A in Figure 1, the electrode composite material 100 is stretched into a sheet. If the sheet discharged from the first roll section 2 is thicker than the desired thickness, the stretching operation by the first roll section 2 is repeated until the sheet reaches the desired thickness.

[0021] Here, each wave roller 3 has a wave-shaped outer surface. As shown in Figure 2, the wave roller 3 has a plurality of peaks 31 and a plurality of valleys 32 alternately arranged on its outer surface (roller surface) along the axial direction of the roller rotation axis X. The plurality of peaks 31 and valleys 32 are formed such that the cross-sectional shape along the axial direction of the wave roller 3 is symmetrical with respect to the roller rotation axis X. In other words, the outer surface of the wave roller 3 is not helical.

[0022] Furthermore, the set of wave rollers 3 in the stretching device 1 are arranged such that the peaks 31 and troughs 32 of the first wave roller 3a interlock with the troughs 32 and peaks 31 of the second wave roller 3b. As shown in Figure 3, the peaks 31 of the first wave roller 3a, shown on the upper side, are positioned to fit into the troughs 32 of the second wave roller 3b, shown on the lower side, and the peaks 31 of the second wave roller 3b are positioned to fit into the troughs 32 of the first wave roller 3a.

[0023] The electrode active material layer of a secondary battery uses an electrode composite sheet, which is made by forming an electrode composite material into a thin sheet. Electrode composite materials are generally prepared by kneading a mixture containing electrode active material, resin, and additives in a kneading device. Electrode composite sheets are produced by stretching the prepared electrode composite material to the desired thickness using, for example, a stretching device equipped with a set of roughly cylindrical stretching rollers.

[0024] Incidentally, it is desirable for electrode composite sheets to have high tensile strength, from the standpoint of ease of handling during manufacturing and ensuring good charge / discharge characteristics of the battery. Furthermore, from the standpoint of improving production efficiency, it is desirable to form the sheets in the shortest possible time.

[0025] However, conventional stretching devices employ flat rollers with smooth outer surfaces as stretching rollers, and with such stretching devices, it was sometimes difficult to achieve both improved fracture strength of electrode composite sheets and rapid sheet formation.

[0026] To explain in more detail, electrode composites that have been softened by mixing equipment tend to have fewer fibrillated portions (fibrous portions) of the resin. When such soft electrode composites are formed into sheets using a pair of flat rollers with smooth outer surfaces, it is easy to form them to the desired thickness in a short time, but the sheet's breaking strength cannot be sufficiently ensured, making it prone to tearing. In other words, handling during sheet forming can be difficult. Furthermore, because it is prone to tearing during battery manufacturing and use, it can be a factor that worsens yield and reduces the charge and discharge characteristics of the battery.

[0027] On the other hand, while extending the mixing time can produce an electrode mixture containing a large amount of fibrillated resin, the electrode mixture tends to become hard. When forming such a hard electrode mixture into a sheet using a pair of flat rollers, it is possible to improve the sheet's breaking strength, but it can be difficult to efficiently form it to the desired thinness in a short time. In other words, when trying to form a hard block of electrode mixture into a thin sheet, in the initial stage of stretching, it is necessary to stretch with a sufficiently wide gap between the rollers to ensure that the hard electrode mixture is securely contained between them, and then stretch it multiple times while gradually narrowing the gap between the rollers. As a result, it takes time to form it to the desired thinness, which reduces the production efficiency of electrode mixture sheets.

[0028] In contrast, the stretching apparatus 1 according to this embodiment enables efficient sheet forming in a short time while improving the breaking strength of the electrode composite sheet.

[0029] Referring to Figures 4 and 5, the stretching of the electrode mixture by the stretching device 1 will be described in more detail. Figure 4 is a partial longitudinal cross-sectional view of a pair of stretching rollers of the stretching device, and is a diagram for explaining the contact state between the electrode mixture 100 and the stretching rollers immediately after the electrode mixture 100 is fed between the stretching rollers. Figure 4(A) shows the state immediately after the electrode mixture 100 is fed between a pair of flat rollers with smooth outer surfaces. Figure 4(B) shows the state immediately after the electrode mixture 100 is fed between a pair of wave rollers 3 of the stretching device 1 according to this embodiment.

[0030] As shown in Figure 4(A), when a set of flat rollers is used, the electrode mixture 100 immediately after being introduced is in uniform contact with each roller. In other words, because the flat rollers are cylindrical rollers with smooth outer surfaces, gaps are unlikely to form between each roller and the electrode mixture 100.

[0031] In contrast, as shown in Figure 4(B), when a stretching device 1 having a set of wave rollers 3 is used, the electrode mixture 100 immediately after being fed into contact with the peaks 31 of each wave roller 3, while a gap is created between it and the valleys 32. In other words, compared to flat rollers, using wave rollers 3 results in a smaller contact area between the outer surface of the wave rollers 3 and the electrode mixture 100.

[0032] In other words, even when the pressing force of the rollers is the same, using the corrugated roller 3 will apply a greater pressure to the electrode composite material 100. Therefore, the electrode composite material 100 will more easily enter between the rollers, and as a result, the time required for sheet forming will be shortened. Also, even a hard electrode composite material 100 that has been kneaded in advance to contain many fibrillated portions of the resin will easily enter between the rollers. Therefore, efficient sheet forming can be realized without widening the interval between a set of rollers more than necessary or stretching an excessive number of times.

[0033] Subsequently, FIG. 5 is a partial longitudinal sectional view of the first roll portion 2 of the stretching device 1, and is a view showing a state in which the electrode composite material 100 is being stretched between a set of corrugated rollers 3.

[0034] As shown in FIG. 5, when the electrode composite material 100 is stretched by a set of corrugated rollers 3, ridges 31 and valleys 32 of each corrugated roller 3 bite into the electrode composite material 100, generating a force in the direction of shearing the electrode composite material 100 (the direction of the white arrow in FIG. 5). Due to this shearing force, the resin contained in the electrode composite material 100 is loosened into fibrous form, promoting the fibrillation of the resin. That is, during the process of stretching the electrode composite material 100, the fibrillation of the resin is simultaneously promoted. Thereby, the formation of an electrode composite material sheet with high breaking strength and low tear resistance is realized.

[0035] Also, since it is possible to increase the fibrillated portion of the resin simultaneously with sheet forming, it is not necessary to knead the electrode composite material 100 in advance so that the fibrillated portion of the resin is increased. That is, the time required for kneading the electrode composite material 100 can be shortened, enabling efficient sheet forming.

[0036] Further, when using the corrugated roller 3, the electrode composite material 100 will be deformed along the corrugated shape of the corrugated roller 3. At this time, a tensile stress that stretches the electrode composite material 100 along the width direction of the corrugated roller 3 is generated. That is, the electrode composite material 100 can be efficiently stretched in the width direction of the corrugated roller 3. Therefore, an electrode composite material sheet of a desired thickness can be produced in a shorter time than when using flat rollers.

[0037] As described above, according to the stretching device 1 according to the present embodiment, efficient sheet forming can be achieved in a short time while improving the breaking strength of the electrode composite material sheet by promoting fibrillation of the resin.

[0038] In addition, the number of the peak portions 31 and the valley portions 32 of the corrugated roller 3 is not particularly limited and can be changed as appropriate. However, in the present embodiment, it is preferable that the number of the peak portions 31 of the first corrugated roller 3a is the same as the number of the valley portions 32 of the second corrugated roller 3b. Further, it is preferable that the number of the peak portions 31 of the second corrugated roller 3b is the same as the number of the valley portions 32 of the first corrugated roller 3a. Further, a flat portion may be present between the peak portion 31 and the valley portion 32 on a part of the outer peripheral surface of the corrugated roller 3.

[0039] Further, from the viewpoint of realizing miniaturization of the battery, the thickness of the electrode composite material sheet produced by the stretching device 1 according to the present embodiment is preferably as thin as possible within a range that does not inhibit the performance of the battery. The thickness of the electrode composite material sheet is, for example, 0.01 to 1 mm, preferably 0.05 to 0.5 mm.

[0040] In addition, the electrode composite material is a general term for a positive electrode composite material containing a positive electrode active material and a negative electrode composite material containing a negative electrode active material. As the positive electrode active material, for example, a lithium metal composite oxide represented by the chemical formula LiMO ４ , ２ , ５ , ４ is used. Examples of the lithium metal composite oxide include layered rock salt type compounds such as LiCoO ２ , LiMnO ２ , LiNiO ２ , LiVO ２ , and Li(Ni - Mn - Co)O ２ etc., spinel type compounds such as LiMn ２ O ４ , and LiNi ０．５ Mn １．５ O ４ etc., olivine type compounds such as LiFePO ４ , and LiMnPO [[ID=3x]] ４ etc., or Si-containing compounds such as Li ２ FeSiO ４ , and Li ２ MnSiO ４ etc. Further, Li ４ Ti ５ O１２ Other options can also be used.

[0041] Furthermore, the negative electrode active material can be, for example, lithium metal, silicon materials, tin materials, compounds containing silicon or tin (oxides, nitrides, alloys with other metals), and carbon materials (graphite, etc.).

[0042] Furthermore, the resin contained in the electrode mixture 100 plays a role in binding the various components of the electrode mixture 100 together, and for example, PTFE (polytetrafluoroethylene) is used.

[0043] Furthermore, additives are added to the electrode mixture 100 according to various purposes. Examples of additives include conductive additives.

[0044] The above describes the stretching apparatus 1 according to the first embodiment. Next, the effects and advantages of the stretching apparatus 1 according to the first embodiment will be summarized.

[0045] The stretching apparatus 1 according to the first embodiment is a roller for stretching an electrode mixture 100 containing resin, and includes a wave roller 3 having a plurality of peaks 31 and valleys 32 alternately provided on the outer circumferential surface of the roller along the axial direction of the roller rotation axis. The wave roller 3 is formed such that its cross-sectional shape along its axial direction is symmetrical with respect to the roller rotation axis.

[0046] With this configuration, the tensile strength of the electrode composite sheet can be improved by promoting the fibrillation of the resin, while efficient sheet molding can be performed in a short time.

[0047] Furthermore, the stretching device 1 according to the first embodiment includes a first roll section 2 having a pair of wave rollers 3. The pair of wave rollers 3 are arranged such that the peaks 31 and troughs 32 of one wave roller 3 (first wave roller 3a) interlock with the troughs 32 and peaks 31 of the other wave roller 3 (second wave roller 3b).

[0048] With this configuration, the tensile strength of the electrode composite sheet can be improved by promoting the fibrillation of the resin, while efficient sheet molding can be performed in a short time.

[0049] Next, a stretching device 1 with a configuration different from that shown in Figure 1 will be described with reference to a modified example. Note that detailed explanations will be omitted for aspects where the same configuration as the previously described embodiment can be adopted.

[0050] (Modified Version) Figure 6 is a perspective view of the stretching device 1 according to a modified version. As shown in Figure 6, the stretching device 1 according to this modified version further includes a second roll section 7 in addition to the first roll section 2 described above. The second roll section 7 has a pair of flat rollers 8 with smooth outer surfaces. In Figure 6, the upper flat roller 8 of the pair of flat rollers 8 is referred to as the first flat roller 8a, and the lower flat roller 8 is referred to as the second flat roller 8b.

[0051] As shown in Figure 6, a pair of flat rollers 8, like the wave rollers 3, are positioned between a pair of frame sections 4, and both ends of each roller are supported by the frame section 4 so that they can rotate along their central axis.

[0052] A second adjustment screw 4b for adjusting the pressing force of the flat roller 8 is provided separately from the first adjustment screw 4a at the top of each frame section 4. By changing the height position of the first flat roller 8a using the second adjustment screw 4b, and thereby changing the distance between the first flat roller 8a and the second flat roller 8b, the pressing force of the flat roller 8 can be adjusted. In other words, the pressing force of each roller in the first roll section 2 and the second roll section 7 can be individually and appropriately changed.

[0053] Furthermore, the power transmission mechanism 5a is additionally equipped with gears on the rotation axes of the first flat roller 8a and the second flat roller 8b, and is arranged to mesh with the gears described above. As a result, the power from the drive device 5b is transmitted to the first flat roller 8a and the second flat roller 8b via the gears. Consequently, the first flat roller 8a and the second flat roller 8b rotate at the same rotational speed as the first wave roller 3a and the second wave roller 3b.

[0054] At this time, the first flat roller 8a and the second flat roller 8b are configured to rotate in different directions from each other so that the electrode mixture 100 can be stretched. In other words, when the second roll section 7 is viewed from the right side of the apparatus in Figure 6 (the side where the power transmission mechanism 5a and the drive device 5b are located), the first flat roller 8a rotates counterclockwise and the second flat roller 8b rotates clockwise.

[0055] Here, the second roll section 7 is located downstream of the first roll section 2 when viewed along the stretching direction A of the electrode mixture 100. In this modified example, the second roll section 7 is located behind the first roll section 2 in the front-rear direction of the stretching device 1.

[0056] When using a stretching device 1 with such a configuration, the electrode mixture 100 is stretched by a pair of wave rollers 3 in the first roll section 2, and then stretched again in the second roll section 7 between the first flat roller 8a and the second flat roller 8b.

[0057] The electrode composite sheet 101 stretched by the first roll section 2 will have a wavy surface that follows the shape of the outer surface of the wave roller 3. Subsequently, by stretching it by the flat roller 8 of the second roll section 7, an electrode composite sheet 101 with a smooth surface is produced.

[0058] This results in the production of an electrode composite sheet 101 that has high tensile strength due to the promotion of fibrillation of the resin and also has a smooth surface.

[0059] If the sheet discharged from the second roll section 7 is thicker than the desired thickness, the stretching operation by the first roll section 2 and the second roll section 7 is repeated until the desired thickness is achieved.

[0060] Furthermore, in Figure 6, the first roll section 2 and the second roll section 7 are arranged side by side in the front-to-back direction of the stretching device 1. However, the arrangement is not limited to this, as long as the second roll section 7 is provided downstream of the first roll section 2 along the stretching direction A of the electrode composite material 100. For example, the first roll section 2 and the second roll section 7 may be arranged side by side in the vertical direction of the stretching device 1. That is, the first roll section 2 may be located above the device and the second roll section 7 may be located below the device. In this case, gravity will act along the stretching direction (vertical direction) of the electrode composite material 100, thus enabling more efficient sheet forming in a shorter time.

[0061] Alternatively, two drive devices 5b may be provided, with one device driving the first roll section 2 and the other device driving the second roll section 7. By driving the first roll section 2 and the second roll section 7 individually in this way, it becomes possible to individually and appropriately change the rotation speed of each roller in the first roll section 2 and the second roll section 7 to suit various purposes.

[0062] The above describes the stretching device 1 according to a modified example of the first embodiment. Next, the effects and advantages of the stretching device 1 according to this modified example will be summarized.

[0063] The stretching device 1 according to this modified example further comprises a second roll section 7 having a pair of flat rollers 8 with smooth outer surfaces. The second roll section 7 is located downstream of the first roll section 2 when viewed along the stretching direction A of the electrode mixture 100.

[0064] With this configuration, an electrode composite sheet 101 having high tensile strength and a smooth surface can be efficiently produced in a short time by promoting fibrillation of the resin.

[0065] Next, we will describe the stretching device 1 according to the second embodiment. Note that detailed explanations will be omitted for aspects where the same configuration as in the previously described embodiment can be adopted.

[0066] (Second Embodiment) Figure 7 is a perspective view of the stretching device 1 according to the second embodiment. As shown in Figure 7, the stretching device 1 according to the second embodiment includes a support part 9, a stretching roller 10, a stretching table 11, a frame part 12, a shaft part 13, and a drive device 14.

[0067] The support section 9 is, for example, placed on the floor and is configured as a frame structured in a roughly rectangular shape. The stretching roller 10, stretching table 11, frame section 12, and shaft section 13 are housed inside the support section 9. The drive device 14 is fixed to the upper surface of the support section 9.

[0068] The stretching roller 10 includes a wave roller 3 and a flat roller 8 with a smooth outer surface. The wave roller 3 and the flat roller 8 are rotatable relative to each other so as to share the same axis of rotation.

[0069] The stretching table 11 is fixed to the lower surface of the support portion 9. The upper surface of the stretching table 11 is formed as a smooth surface (stretching surface 11a) and is located below the stretching roller 10. As will be described later, the electrode mixture 100 is stretched between the stretching roller 10 and the stretching surface 11a.

[0070] The frame portion 12 supports both ends of the stretching roller 10 so that the stretching roller 10 can rotate around its axis of rotation. The frame portion 12 has a base portion 12a that extends in the direction of the axis of rotation of the stretching roller 10, and a pair of arm portions 12b that extend downward from both ends of the base portion 12a, and the respective ends of the stretching roller 10 are supported by these arm portions 12b.

[0071] The lower end of the shaft portion 13 is fixed to the center of the frame portion 12 (i.e., the center of the base portion 12a in the direction of the rotation axis of the stretch roller 10). The shaft portion 13 extends in a direction perpendicular to the rotation axis of the stretch roller 10, and its upper end is connected to the drive device 14.

[0072] As previously described, the drive unit 14 is fixed to the upper surface of the support unit 9, and the upper end of the shaft unit 13 is connected to the rotational drive part inside the drive unit 14. When stretching the electrode mixture 100, the drive unit 14 rotates the shaft unit 13 with respect to its axial center (rotation axis Y). The frame unit 12 and the shaft unit 13 are configured to be movable relative to the drive unit 14 in the vertical direction. This allows the size of the gap between the stretching roller 10 supported by the frame unit 12 and the stretching surface 11a of the stretching table 11 to be adjusted as appropriate.

[0073] Here, as shown in Figure 7, the stretching roller 10 is configured such that, along its axis of rotation, one side from the center of the frame portion 12 becomes a wave roller 3, and the other side becomes a flat roller 8.

[0074] Furthermore, the wave roller 3 is composed of multiple wave roller sections arranged adjacent to each other in the direction of the rotation axis of the stretching roller 10. In other words, in this embodiment, the wave roller 3 is formed by integrating multiple wave roller sections. Each wave roller section shares the same rotation axis and is rotatable independently. The outer circumferential surface of each wave roller section has a wave shape similar to that of the outer circumferential surface of the wave roller 3 described in the first embodiment.

[0075] Similarly, the flat roller 8 is composed of multiple flat roller sections arranged adjacent to each other in the direction of the rotation axis of the stretching roller 10. In other words, in this embodiment, the flat roller 8 is formed by integrating multiple flat roller sections. Each flat roller section shares the same rotation axis and is rotatable independently. The outer surface of each flat roller section is smooth and does not have a wave shape.

[0076] Using a stretching device 1 with such a configuration, sheet forming can be achieved more efficiently and in a shorter amount of time.

[0077] The operation of the stretching device 1 will now be explained in detail. When the drive unit 14 is operated, the shaft 13 connected to the rotation drive part of the drive unit 14 rotates around the rotation axis Y. Accordingly, the frame 12 fixed to the lower end of the shaft 13, and the stretching roller 10 supported by the frame 12 also rotate around the rotation axis Y. If the electrode mixture 100 is placed in a suitable position on the stretching surface 11a of the stretching table 11 in advance, the electrode mixture 100 will be stretched between the stretching roller 10 of the stretching device 1, which is driven as described above, and the stretching surface 11a. At this time, since the stretching roller 10 has a wave roller 3 on one side and a flat roller 8 on the other side from the center position of the frame 12, the electrode mixture 100 will be stretched alternately and continuously by the wave roller 3 and the flat roller 8.

[0078] As shown in the stretching device 1 in Figure 6, when the part stretched by the wave roller 3 (first roll section 2) and the part stretched by the flat roller 8 (second roll section 7) are provided separately along the stretching direction, the stretching takes time because the electrode mixture 100 moves between the two roll sections. In addition, when stretching is performed multiple times, it is necessary to feed the sheet discharged from the second roll section 7 back into the first roll section 2, which can reduce the efficiency of sheet forming.

[0079] In contrast, when using the stretching apparatus 1 according to this embodiment, the electrode composite material 100 is stretched alternately and continuously by the wave roller 3 and the flat roller 8 provided on a single stretching roller 10, thus shortening the time required for stretching and improving the efficiency of sheet forming.

[0080] Furthermore, when the stretching roller 10 rotates around the rotation axis Y, the linear velocity is greater at the ends than at the center of rotation, which usually causes variations in breaking strength and thinness within the electrode composite sheet 101. However, in the stretching device 1 according to this embodiment, the stretching roller 10 consists of a wave roller 3 and a flat roller 8, each composed of multiple wave roller sections and multiple flat roller sections. In addition, each wave roller section and flat roller section is provided to be rotatable individually with the same rotation axis.

[0081] More specifically, unlike the rollers of the stretching device 1 shown in Figure 1 or Figure 6, the stretching roller 10 in this embodiment does not rotate on its axis of rotation. On the other hand, the multiple wave roller sections and multiple flat roller sections provided on the stretching roller 10 are configured to rotate freely around the axis of rotation of the stretching roller 10. Stretching with a stretching roller 10 having such a configuration suppresses variations in breaking strength and thinness within the electrode composite sheet 101, thereby achieving efficient sheet forming.

[0082] As described above, the stretching apparatus 1 according to the second embodiment enables efficient sheet forming in a shorter time.

[0083] Even when stretching between the wave roller 3 and the smooth stretching surface 11a, as in this embodiment, the electrode mixture 100 is stretched while being gripped by the peaks 31 and valleys 32 of the wave roller 3. Therefore, in this embodiment as well, the shear force described above is applied to the electrode mixture 100, and the fibrillation of the resin is promoted simultaneously with stretching.

[0084] Furthermore, although in this embodiment the electrode mixture 100 is described as being alternately stretched by the wave roller 3 and the flat roller 8 of the stretching roller 10, the stretching procedure is not limited to this. For example, in the initial stage of stretching, the drive device 14 can be driven so that the stretching roller 10 repeatedly rotates forward and in reverse, thereby stretching the electrode mixture 100 multiple times using only the wave roller 3.

[0085] Furthermore, the drive unit 14 may have a pressing mechanism that pushes the shaft portion 13 downward, in addition to the mechanism that rotates the shaft portion 13. This allows an appropriate load to be applied to the electrode mixture 100 according to its thickness and hardness, thereby achieving more efficient stretching of the electrode mixture 100. However, it should be noted that even without such a pressing mechanism, the stretching roller 10, frame portion 12, and shaft portion 13 have a certain amount of weight, so it is possible to apply a reasonable load to the electrode mixture 100.

[0086] The above describes the stretching apparatus 1 according to the second embodiment. Next, the effects and advantages of the stretching apparatus 1 according to the second embodiment will be summarized.

[0087] The stretching device 1 according to the second embodiment includes a stretching roller 10 in which a wave roller 3 and a flat roller 8 with a smooth outer surface are rotatably mounted relative to each other so as to share the same axis of rotation; a stretching table 11 provided below the stretching roller 10 for stretching the electrode mixture 100 between itself and the stretching roller 10; a frame portion 12 that supports both ends of the stretching roller 10 so that the stretching roller 10 can rotate about its axis of rotation; a shaft portion 13 whose lower end is fixed at the center of the frame portion 12 and which extends perpendicularly from the frame portion 12 to the axis of rotation; and a drive device 14 connected to the upper end of the shaft portion 13 for rotating the shaft portion 13 about its axis. Furthermore, the stretching roller 10 has a wave roller 3 on one side of the frame portion 12 from the center along its axis of rotation, and a flat roller 8 on the other side. In addition, the wave roller 3 is composed of a plurality of wave roller portions arranged adjacent to each other in the direction of rotation, and the flat roller 8 is composed of a plurality of flat roller portions arranged adjacent to each other in the direction of rotation. In addition, the multiple wave roller sections and the multiple flat roller sections can each rotate individually around the rotation axis. Furthermore, the frame section 12 and the shaft section 13 can move relative to the drive device 14 in the vertical direction.

[0088] With this configuration, in addition to the effects of the first embodiment and its modified form, it becomes possible to perform sheet molding efficiently in an even shorter time.

[0089] Although embodiments of the present invention have been described above, the configurations described above represent only a part of the application examples of the present invention and are not intended to limit the technical scope of the present invention.

[0090] 1: Stretching device, 2: First roll section, 3: Wave roller, 31: Peak section, 32: Valley section, 3a: First wave roller, 3b: Second wave roller, 4: Frame section, 4a: First adjustment screw, 4b: Second adjustment screw, 5a: Power transmission mechanism, 5b: Drive unit, 6: Leg section, 6a: Support surface, 7: Second roll section, 8: Flat roller, 8a: First flat roller, 8b: Second flat roller, 9: Support section, 10: Stretching roller, 11: Stretching stand, 12: Frame section, 13: Shaft section, 14: Drive unit, 100: Electrode composite material, 101: Electrode composite material sheet, A: Stretching direction, X: Roller rotation axis, Y: Rotation axis

Claims

1. A stretching apparatus for electrode composites used in the manufacture of electrode composite sheets for secondary batteries, comprising a roller for stretching an electrode composite containing resin, the roller having a plurality of peaks and valleys alternately provided on its outer circumferential surface along the axial direction of the roller rotation axis, wherein the cross-sectional shape of the wave roller along the axial direction is formed to be symmetric with respect to the roller rotation axis.

2. A stretching device according to claim 1, comprising a first roll section having a pair of wave rollers, wherein the pair of wave rollers are arranged such that the peaks and valleys of one wave roller interlock with the valleys and peaks of the other wave roller.

3. A stretching apparatus according to claim 2, further comprising a second roll section having a pair of flat rollers with smooth outer surfaces, wherein the second roll section is provided downstream of the first roll section when viewed along the stretching direction of the electrode mixture.

4. A stretching device according to claim 1, comprising: a stretching roller in which a wave roller and a flat roller with a smooth outer surface are rotatable relative to each other so as to have the same axis of rotation; a stretching table provided below the stretching roller for stretching the electrode mixture between itself and the stretching roller; a frame portion supporting both ends of the stretching roller so as to be rotatable about the axis of rotation; a shaft portion having its lower end fixed at the center of the frame portion and extending perpendicularly from the frame portion to the axis of rotation; and a drive device connected to the upper end of the shaft portion for rotating the shaft portion about its axis, wherein the stretching roller has a wave roller on one side and a flat roller on the other side along the axis of rotation; the wave roller is composed of a plurality of wave roller portions arranged adjacent to each other in the direction of the axis of rotation; the flat roller is composed of a plurality of flat roller portions arranged adjacent to each other in the direction of the axis of rotation; and the plurality of wave roller portions and the plurality of flat roller portions are each individually rotatable about the axis of rotation. Stretching device.

5. An extension device according to claim 4, wherein the frame portion and the shaft portion are movable relative to the drive device in the vertical direction.

6. A manufacturing method for producing an electrode composite sheet using a stretching apparatus according to any one of claims 1 to 5, wherein the electrode composite sheet is produced by stretching the electrode composite at least once while gripping it with the wave roller of the stretching apparatus.

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