Method for manufacturing a wound electrode body, manufacturing apparatus, and energy storage device

Abstract

This relieves the stress on the curved portion of the wound electrode body. [Solution] The method for manufacturing a wound electrode body includes a winding step in which a laminated sheet 2, in which a strip-shaped positive electrode sheet 3, a negative electrode sheet 4, a first separator sheet 5, and a second separator sheet 6 are stacked in a predetermined order, is fed, and a winding shaft 21 having an oval-shaped outer surface having a pair of opposing flat surfaces 21a and a pair of arcuate surfaces 21b connecting both sides of the pair of flat surfaces 21a is rotated to wind the laminated sheet 2 around the outer surface of the winding shaft 21; and a pressing step in which the laminated sheet formed into an oval shape in the winding step is pressed so that the pair of flat surfaces are pressed together. In the winding step, for each rotation of the winding shaft 21, the laminated sheet 2 is fed for a length longer than the outer surface length corresponding to the number of turns of the laminated sheet 2 wound on the winding shaft 21.

Description

Technical Field

[0004] , , , ,

[0005] , , , , , ,

[0001] The present invention relates to a method for manufacturing a wound electrode body, a manufacturing apparatus for a wound electrode body, and a power storage device including the wound electrode body.

Background Art

[0002] For example, Patent Document 1 discloses a method for manufacturing a lithium ion secondary battery having a wound electrode body in which a strip-shaped positive electrode sheet, a negative electrode sheet, and a separator sheet are overlapped and wound. In the method described in Patent Document 1, the winding core rotates while tension is applied to each sheet by a tension roller, and each sheet is wound around the winding core. According to Patent Document 1, when the tension is released after cutting each sheet or at the end of winding, the sheet may swim and may not be wound well. Therefore, the winding device described in Patent Document 1 includes a support roller that continuously applies tension to the positive electrode sheet that is finally wound until the end of winding of the end portion.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When pressing and molding a wound body of a sheet formed by winding around a winding shaft, the curved portion of the sheet is deformed. Therefore, a large stress is applied to the curved portion of the sheet during pressing. It is preferable that the stress applied to the curved portion of such a sheet is small.

Means for Solving the Problems

[0005] A method for manufacturing a wound electrode body disclosed herein includes a winding step and a pressing step. In the winding step, a laminated sheet in which a strip-shaped positive electrode sheet, a strip-shaped negative electrode sheet, a strip-shaped first separator sheet, and a strip-shaped second separator sheet are stacked in a predetermined order is fed, and a winding shaft having an oval-shaped outer surface having a pair of opposing flat surfaces and a pair of arcuate surfaces connecting both sides of the pair of flat surfaces is rotated to wind the laminated sheet around the outer surface of the winding shaft. In the winding step, for each rotation of the winding shaft, the laminated sheet is fed for a length longer than the outer surface length corresponding to the number of turns of the laminated sheet wound on the winding shaft. In the pressing step, the laminated sheet formed into an oval shape in the winding step is pressed so that the pair of flat surfaces are pressed together.

[0006] According to the above method for manufacturing a wound electrode, in the winding process, for each rotation of the winding shaft, the laminated sheet is fed a distance longer than the outer circumference length corresponding to the number of turns of the laminated sheet wound on the winding shaft. Therefore, with each rotation of the winding shaft, a gap is created between the laminated sheet already wound on the winding shaft and the laminated sheet being wound on the outside. In the pressing process, the pressed laminated sheet can escape into this gap. Therefore, according to the above method for manufacturing a wound electrode, the stress applied to the curved portion of the laminated sheet formed by the arcuate surface of the winding shaft during the pressing process can be relieved.

[0007] Furthermore, the apparatus for manufacturing a wound electrode body disclosed herein is an apparatus for manufacturing a wound electrode body in which a laminated sheet is wound, in which a strip-shaped positive electrode sheet, a strip-shaped negative electrode sheet, a strip-shaped first separator sheet, and a strip-shaped second separator sheet are stacked in a predetermined order, and the apparatus comprises: a winding shaft having an oval-shaped outer peripheral surface having a pair of opposing flat surfaces and a pair of arcuate surfaces connecting both sides of the pair of flat surfaces, the laminated sheet being wound around the outer peripheral surface; a winding shaft drive device for rotating the winding shaft; a feeding device for feeding the laminated sheet toward the winding shaft; and a control device that controls the winding shaft drive device to control the rotation of the winding shaft and controls the amount of the laminated sheet being fed by the feeding device. The control device controls the feeding device to feed the laminated sheet by a length longer than the outer peripheral length corresponding to the number of turns of the laminated sheet wound on the winding shaft per rotation of the winding shaft.

[0008] The above-described manufacturing apparatus for wound electrode bodies can achieve the same effects as the above-described method for manufacturing wound electrode bodies.

[0009] The energy storage device disclosed herein comprises a wound electrode body in which a laminated sheet is wound multiple times, in which a strip-shaped positive electrode sheet, a strip-shaped negative electrode sheet, a strip-shaped first separator sheet, and a strip-shaped second separator sheet are stacked in a predetermined order. The wound electrode body is wound in an oval shape having a pair of opposing flat portions and a pair of arc-shaped R portions connecting both sides of the pair of flat portions. The laminated sheet includes a plurality of curved portions that form the R portions and are stacked radially in the direction of the R portions. Of the plurality of curved portions, the inner circumference of one curved portion is longer than the outer circumference of the curved portion one step inside the first curved portion.

[0010] In the above energy storage device, the inner circumference of one curved section is longer than the outer circumference of the curved section immediately inside it. Therefore, for the same reasons mentioned above, the stress on the curved portion of the wound electrode body is reduced. [Brief explanation of the drawing]

[0011] [Figure 1]This is a schematic side view of the winding device and the feeding device. [Figure 2] This is a schematic front view of a press machine. [Figure 3] This is a flowchart showing part of the manufacturing process for wound electrode bodies. [Figure 4] This is a side view of the winding and feeding device when the winding shaft is in the 3 o'clock position. [Figure 5] This is a side view of the winding and feeding device when the winding shaft is located between the 3 o'clock and 6 o'clock positions. [Figure 6] This is a side view of the winding and feeding device when the winding shaft is positioned at the 6 o'clock position. [Figure 7] This is a schematic cross-sectional view of a lithium-ion secondary battery. [Modes for carrying out the invention]

[0012] The following describes one embodiment of a manufacturing apparatus for producing wound electrode bodies of energy storage devices. It should be noted that the embodiment described herein is not intended to limit the present invention. Furthermore, the figures are schematic diagrams and do not necessarily faithfully reflect actual implementations.

[0013] [Configuration of the wound electrode manufacturing apparatus] Figure 1 is a schematic side view of a part of the wound electrode manufacturing apparatus 10 according to one embodiment, more specifically, of the winding device 20 and the feeding device 30. Figure 2 is a schematic front view of another part of the wound electrode manufacturing apparatus 10, more specifically, of the pressing device 40. The wound electrode manufacturing apparatus 10 according to this embodiment is an apparatus for manufacturing a wound electrode 1 (see Figure 7) in which a laminated sheet 2 is wound, in which a strip-shaped positive electrode sheet 3, a strip-shaped negative electrode sheet 4, a strip-shaped first separator sheet 5, and a strip-shaped second separator sheet 6 are stacked in a predetermined order. The winding device 20 winds the laminated sheet 2 multiple times around the outer surface of the winding shaft 21 to form the laminated sheet 2 into an oval shape. The feeding device 30 feeds the laminated sheet 2 in accordance with the operation of the winding device 20. The pressing device 40 presses the oval-shaped laminated sheet 2 to further flatten it. The wound electrode manufacturing apparatus 10 also includes a press device (not shown) that further presses the wound electrode 1, which has been pressed by the press device 40.

[0014] The wound electrode manufacturing apparatus 10 here manufactures the wound electrode 1, which is a power generation element of the lithium-ion secondary battery 100 (see Figure 7). However, the wound electrode 1 is not limited to the wound electrode of the lithium-ion secondary battery 100, but may be a wound electrode of various known energy storage devices. The term "energy storage device" refers to all devices from which electrical energy can be extracted, and includes so-called storage batteries (chemical batteries) such as lithium-ion secondary batteries and nickel-metal hydride batteries, and capacitors (physical batteries) such as electric double-layer capacitors.

[0015] The positive electrode sheet 3 is a component in which a positive electrode active material layer containing a positive electrode active material is formed on the surface of a strip-shaped current collector foil (e.g., aluminum foil) of predetermined width and thickness. The positive electrode active material is a material that can release lithium ions during charging and absorb lithium ions during discharge, such as a lithium transition metal composite material in a lithium-ion secondary battery. The negative electrode sheet 4 is a component in which a negative electrode active material layer containing a negative electrode active material is formed on the surface of a strip-shaped current collector foil (e.g., copper foil) of predetermined width and thickness. The negative electrode active material is a material that can absorb lithium ions during charging and release the absorbed lithium ions during discharge, such as natural graphite in a lithium-ion secondary battery. Various positive electrode active materials other than those described above have been proposed and are not particularly limited.

[0016] The first separator sheet 5 and the second separator sheet 6 are, for example, made of a porous resin sheet that has the required heat resistance and through which the electrolyte can pass. Various materials have been proposed for the separator and are not particularly limited. The wound electrode body 1 here is made by winding a laminated sheet 2, in which the first separator sheet 5, positive electrode sheet 3, second separator sheet 6, and negative electrode sheet 4 are stacked in this order, with the negative electrode sheet 4 being the outermost layer.

[0017] As shown in FIG. 1, the winding device 20 includes a winding shaft 21 around which the laminated sheet 2 is wound on its outer peripheral surface, a winding shaft driving device 22 that rotates the winding shaft 21, and a winding shaft moving device 23 that moves the winding shaft 21 so that the laminated sheet 2 before being wound around the winding shaft 21 hangs in the direction of gravity. The feeding device 30 includes a pair of nip rollers 31 that sandwich and rotate the laminated sheet 2, a nip roller driving device 32 that rotates the pair of nip rollers 31, a nip roller moving device 33 that moves the pair of nip rollers 31 closer or farther apart, a pressing roller 34 that presses the laminated sheet 2 toward the winding shaft 21, a pressing roller driving device 35 that rotates the pressing roller 34, a following device 36 that moves the pressing roller 34 so as to follow the movement of the winding shaft 21, and a pressing roller moving device 37 that brings the pressing roller 34 into contact with or separates it from the winding shaft 21. As shown in FIG. 1, the winding electrode body manufacturing apparatus 10 includes a control device 50 that controls the operations of the winding device 20 and the feeding device 30.

[0018] The winding shaft 21 has an oval outer peripheral surface having a pair of opposing flat surface portions 21a and a pair of arc surface portions 21b connecting both sides of the pair of flat surface portions 21a. The winding shaft 21 is configured in a flat shape in which the distance between the pair of arc surface portions 21b is longer than the distance between the pair of flat surface portions 21a. The laminated sheet 2 is wound around the outer peripheral surface of the winding shaft 21. The depth direction of the paper surface in FIG. 1 is the width direction of the laminated sheet 2. Although not shown, the outer peripheral surface of the winding shaft 21 has a predetermined width wider than the width of the laminated sheet 2 in the width direction of the laminated sheet 2.

[0019] The winding shaft 21 forms the laminated sheet 2 into an oval shape close to the finished wound electrode body 1. Hereinafter, the laminated sheet 2 formed into an oval shape by winding around the winding shaft 21 is also referred to as a wound body of the laminated sheet 2. The laminated sheet 2 is formed into a wound body having a shape corresponding to the outer peripheral surface of the winding shaft 21. As shown in FIG. 2, the wound body of the laminated sheet 2 has a pair of opposing flat portions 2a and a pair of arc-shaped R portions 2b connecting both sides of the pair of flat portions 2a. The pair of flat portions 2a are formed by the pair of flat surface portions 21a of the winding shaft 21. The pair of R portions 2b are formed by the pair of arc surface portions 21b of the winding shaft 21. The wound body of the laminated sheet 2 is also flat, and its longitudinal direction is the arrangement direction of the pair of R portions 2b.

[0020] In the following, in order to distinguish the flat portion and the R portion of the wound electrode body 1 after the pressing process from the flat portion 2a and the R portion 2b of the wound body of the laminated sheet 2 before pressing, they are respectively represented as a pair of flat portions 1a and R portions 1b (see FIG. 7). Also, in the wound electrode body 1 after pressing, each of the plurality of flat portions of the laminated sheet 2 that are overlapped to form the flat portion 1a is referred to as a straight portion urchased 2c. The flat portion 1a of the wound electrode body 1 is an aggregate in which a plurality of straight portions 2c are overlapped. Further, in the wound electrode body 1 after pressing, the plurality of curved portions of the laminated sheet 2 that are overlapped in the radial direction of the R portion 1b and form the R portion 1b are respectively represented as curved portions 2d. The R portion 1b of the wound electrode body 1 is an aggregate in which a plurality of curved portions 2d are overlapped.

[0021] As shown in FIG. 1, the winding shaft driving device 22 rotates the winding shaft 21 around a rotating shaft 22a extending in the width direction of the laminated sheet 2 (the depth direction of the paper surface of FIG. 1). The winding shaft driving device 22 includes a driving motor 22b that rotates the winding shaft 21. The rotation / stop, rotation speed, and rotation angle of the driving motor 22b are controlled by the control device 50.

[0022] The winding shaft moving device 23 moves the winding shaft 21 in accordance with the rotation of the winding shaft 21 so that the end of the portion of the laminated sheet 2 wound on the winding shaft 21 remains directly below the nip roller 31. The specific movement of the winding shaft 21 will be described later with reference to Figures 1 and 4 to 6. Due to the movement of the winding shaft 21 by the winding shaft moving device 23, the feeding direction of the laminated sheet 2 before it is wound on the winding shaft 21 becomes the direction of gravity. As will be described later, in this embodiment, the wound electrode manufacturing apparatus 10 does not apply tension to the laminated sheet 2 when winding the laminated sheet 2 onto the winding shaft 21. Therefore, the laminated sheet 2 before it is wound on the winding shaft 21 hangs in the direction of gravity.

[0023] The winding shaft moving device 23 includes, for example, a slide guide (not shown) into which the rotating shaft 22a of the winding shaft 21 is engaged so as to be slidable in the left-right direction as shown in Figure 1, a drive motor 23a for moving the rotating shaft 22a along the slide guide, and a ball screw mechanism (not shown) connected to the drive motor 23a. However, the configuration of the winding shaft moving device 23 is not particularly limited. The drive / stop, rotation speed, and rotation angle of the drive motor 23a are controlled by the control device 50.

[0024] The pair of nip rollers 31 of the feed device 30 are configured to grip and rotate the laminated sheet 2. The pair of nip rollers 31 feed the laminated sheet 2 toward the winding shaft 21. Each of the pair of nip rollers 31 is configured to rotate around an axis 31a extending in the width direction of the laminated sheet 2. The pair of nip rollers 31 are located above the winding shaft 21. The laminated sheet 2 fed by the pair of nip rollers 31 is not under tension and therefore moves downward due to gravity. The nip roller drive device 32 rotates the pair of nip rollers 31. The nip roller drive device 32 here includes a drive motor 32a that rotates one of the pair of nip rollers 31. The other nip roller 31 rotates passively in response to the rotation of the driven nip roller 31. However, the nip roller drive device 32 may be configured to drive both of the pair of nip rollers 31. The drive / stop, rotation speed, and rotation angle of the drive motor 32a are controlled by the control device 50.

[0025] The nip roller moving device 33 brings a pair of nip rollers 31 closer together to grip the laminated sheet 2, or separates the pair of nip rollers 31 to release the laminated sheet 2. In this case, the nip roller moving device 33 moves the left nip roller 31. The left nip roller 31 moves between a position where it can grip the laminated sheet 2 together with the right nip roller 31, and a position further to the left in Figure 1, separated from the right nip roller 31. The nip roller moving device 33 includes, for example, an air cylinder (not shown) that moves the left nip roller 31 in the left-right direction. However, the nip roller 31 moved by the nip roller moving device 33 may be the right nip roller 31, or both the left and right nip rollers 31. Also, the nip roller moving device 33 is not limited to one driven by an air cylinder. The configuration of the nip roller moving device 33 is not particularly limited. The operation of the nip roller moving device 33 is controlled by the control device 50.

[0026] The pressing roller 34 presses the laminated sheet 2, which is wound around the arcuate surface portion 21b of the winding shaft 21, toward the arcuate surface portion 21b. When pressed by the pressing roller 34, the laminated sheet 2, which includes a metal current collector foil, undergoes plastic deformation, and the shape of the laminated sheet 2 conforms to the shape of the outer surface of the winding shaft 21. This makes it possible to make the shape of the laminated sheet 2 conform to the shape of the outer surface of the winding shaft 21 without applying tension to the laminated sheet 2.

[0027] The press roller drive device 35 rotates the press roller 34. The press roller drive device 35 rotates the press roller 34 around a rotation axis 35a that extends in the width direction of the laminated sheet 2. The press roller drive device 35 is equipped with a drive motor 35b that rotates the winding shaft 21. The rotation / stopping, rotation speed, and rotation angle of the drive motor 35b are controlled by the control device 50. The press roller 34 is thus configured to rotate by the driving force of the drive motor 35b. The press roller 34 is a member for making the shape of the laminated sheet 2 conform to the shape of the outer surface of the winding shaft 21, and at the same time, is a member for feeding the laminated sheet 2 on the arcuate surface portion 21b by its rotation. However, the press member that makes the shape of the laminated sheet 2 conform to the shape of the outer surface of the winding shaft 21 does not have to be related to feeding the laminated sheet 2. Such a press member may be, for example, a plate-shaped member that does not rotate but flexes in accordance with the movement of the arcuate surface portion 21b.

[0028] The tracking device 36 moves the pressing roller 34 along the arcuate surface 21b of the winding shaft 21 in accordance with the movement of the arcuate surface 21b of the winding shaft 21. By moving the pressing roller 34, the tracking device 36 keeps the pressing roller 34 in contact with the arcuate surface 21b, which moves due to the rotation of the winding shaft 21 and the drive of the winding shaft moving device 23. Here, the tracking device 36 keeps the pressing roller 34 in contact with the winding shaft 21 while the laminated sheet 2 is wound around the winding shaft 21 for approximately half a rotation. The timing of when the tracking device 36 brings the pressing roller 34 into contact with the winding shaft 21 will be described later.

[0029] The tracking device 36 includes, for example, a slide guide (not shown) with a press roller 34 engaged so as to be slidable in the vertical direction, a drive motor 36a for moving the press roller 34 along the slide guide, and a ball screw mechanism (not shown) connected to the drive motor 36a. However, the configuration of the tracking device 36 is not particularly limited. The drive / stop, rotation speed, and rotation angle of the drive motor 36a are controlled by the control device 50.

[0030] The press roller moving device 37 brings the press roller 34 into contact with the arcuate surface portion 21b of the winding shaft 21, or moves it away from the arcuate surface portion 21b. The press roller moving device 37 moves the press roller 34 between a position where it can contact the winding shaft 21 directly below the nip roller 31, and a position to the right of that position in Figure 1 where it does not contact the winding shaft 21. The press roller moving device 37 includes, for example, an air cylinder (not shown) for moving the press roller 34 in the left-right direction. However, the configuration of the press roller moving device 37 is not particularly limited. The operation of the press roller moving device 37 is controlled by the control device 50.

[0031] The control device 50 controls the rotation of the winding shaft 21 by controlling the winding shaft drive device 22, and also controls the amount of laminated sheet 2 fed by controlling the feed device 30. Specifically, the control device 50 controls the feed device 30 to feed the laminated sheet 2 by a length longer than the outer circumference length corresponding to the number of turns of laminated sheet 2 wound on the winding shaft 21 for each rotation of the winding shaft 21. By feeding the laminated sheet 2 in this way, the circumference length of the laminated sheet 2 wound on the outside (hereinafter also referred to as the outer layer laminated sheet 2) becomes longer than the outer circumference length of the laminated sheet 2 already wound on the winding shaft 21 (hereinafter also referred to as the inner layer laminated sheet 2), so a gap is created between the inner layer laminated sheet 2 and the outer layer laminated sheet 2 for each rotation of the winding shaft 21. The effects of this gap will be described later.

[0032] The outer circumference of the laminated sheet 2 wound on the winding shaft 21 increases with each additional turn. The control device 50 increases the length of the laminated sheet 2 fed by the feeding device 30 as the number of turns of the laminated sheet 2 increases. In this embodiment, the control device 50 calculates the length obtained by adding the increase in circumference due to the increase in the number of turns and a predetermined additional length to create a gap to the circumference of the inner layer laminated sheet 2, and uses this as the length of the outer layer laminated sheet 2. In this embodiment, the additional length to create a gap is constant regardless of the number of turns of the laminated sheet 2. However, the additional length to create a gap does not have to be constant.

[0033] The additional length described above is set to a length such that a gap 1c with a gap G1 obtained by multiplying the thickness of the laminated sheet 2 by a predetermined factor is created between the multiple curved portions 2d of the laminated sheet 2 (see Figure 7). Note that the gap 1c is the gap after pressing. For example, if the thickness of the laminated sheet 2 is 0.3 mm and the factor is 50%, the gap G1 is set to 0.15 mm. The above factor is preferably, for example, 30% or more and 100% or less. However, the above factor is not limited. In calculating the additional length, the gap G1 is considered to be the additional radius of the curved portion 2d. Therefore, the additional length is twice the length obtained by multiplying the gap G1 by pi (multiplied by 2 because there are curved portions 2d on both sides). However, the above method of setting the additional length is an example and is not limited thereto.

[0034] In this embodiment, the control device 50 is configured to control the feed device 30 at least for a portion of the time during which the laminated sheet 2 is wound around the arcuate surface portion 21b, so that the feed speed of the laminated sheet 2 is faster than the speed at which the laminated sheet 2 is wound around the arcuate surface portion 21b. As a result, when the laminated sheet 2 is wound around the arcuate surface portion 21b, the laminated sheet 2 is fed for a length longer than the outer circumference length corresponding to the number of turns of the laminated sheet 2 wound around the arcuate surface portion 21b. As a result, gaps caused by the excess feed of the laminated sheet 2 are more likely to form in the R portion 2b of the wound body of the laminated sheet 2. In this embodiment, the control device 50 is configured to make the speed at which the laminated sheet 2 is wound around the winding shaft 21 the same as the feed speed of the laminated sheet 2 at other times. As a result, gaps caused by the excess feed of the laminated sheet 2 are reduced in the flat portion 2a of the laminated sheet 2.

[0035] More specifically, the control device 50 controls the nip roller moving device 33 to separate the pair of nip rollers 31 for at least a portion of the time during which the laminated sheet 2 is being wrapped around the arcuate surface 21b. At the same time, the control device 50 controls the press roller moving device 37 and the press roller driving device 35 to rotate the press roller 34 while it is in contact with the arcuate surface 21b. In this state, the feeding speed of the laminated sheet 2 is controlled by the rotational speed of the press roller 34. The control device 50 is configured to set the feeding speed of the laminated sheet 2 by the press roller 34 to be faster than the speed at which the laminated sheet 2 is being wrapped around the arcuate surface 21b.

[0036] Furthermore, at other times, the control device 50 controls the press roller moving device 37 to move the press roller 34 away from the winding shaft 21. Simultaneously, the control device 50 controls the nip roller moving device 33 and the nip roller drive device 32 to grip and feed the laminated sheet 2 between the pair of nip rollers 31. In this state, the feeding speed of the laminated sheet 2 is controlled by the rotational speed of the nip rollers 31. The control device 50 is configured to set the feeding speed of the laminated sheet 2 by the pair of nip rollers 31 to be the same as the speed at which the laminated sheet 2 is wound onto the winding shaft 21.

[0037] The press device 40 presses the wound body of the laminated sheet 2 so as to press a pair of flat portions 2a together. As shown in Figure 2, the press device 40 comprises a pair of opposing press members 41 that each press the pair of flat portions 2a of the laminated sheet 2, a pair of leaf springs 42 provided on each of the pair of press members 41, and a drive unit 43 that brings the pair of press members 41 closer together and presses the laminated sheet 2. Each leaf spring 42 is curved so as to convex toward the side of the opposing press member 41, and is positioned so that the apex of the convex portion is located in the center of the press member 41 (the longitudinal center of the wound body of the laminated sheet 2). The press device 40 is configured to press the flat portions 2a of the wound body of the laminated sheet 2 by the press members 41 via the leaf springs 42.

[0038] In this embodiment, the rolled laminated sheet 2 is further pressed by a separate press device from the press device 40 and compressed to a predetermined thickness. This press device does not have a leaf spring and presses the laminated sheet 2 using a pressing member. However, the final pressing may also be performed by the press device 40. The press device 40 may constitute part of or all of a broad-sense press device that presses the rolled laminated sheet 2 to form the rolled electrode body 1 by pressing a pair of flat portions 2a together.

[0039] [Manufacturing process for wound electrode bodies] Figure 3 is a flowchart showing part of the manufacturing process of the wound electrode body 1. As shown in Figure 3, the manufacturing process of the wound electrode body 1 includes a winding step S10 in which a laminated sheet 2, in which a strip-shaped positive electrode sheet 3, a strip-shaped negative electrode sheet 4, a strip-shaped first separator sheet 5, and a strip-shaped second separator sheet 6 are stacked in a predetermined order, is fed, and a winding shaft 21 having an oval-shaped outer surface is rotated to wind the laminated sheet 2 around the outer surface of the winding shaft 21; and a pressing step S20 in which the laminated sheet 2 (winding body of laminated sheet 2) formed into an oval shape in the winding step S10 is pressed so that a pair of flat portions 2a are pressed together. The pressing step S20 includes a first pressing step S21 using a press device 40 and a second pressing step S22 using the same press device.

[0040] First, the details of the winding process S10 will be explained. Figures 4 to 6 are side views of the winding device 20 and the feeding device 30 at an intermediate point in the winding process S10. Hereafter, the rotational position of the winding shaft 21 will be represented by the direction of the end 21c (here, one of the arcuate surfaces 21b) of the winding shaft 21 that is facing upward (to the 12 o'clock position) in Figure 1. Figure 1 shows the winding device 20 and the feeding device 30 when the winding shaft 21 is at the 12 o'clock position. In Figure 1, the winding shaft 21 in a state slightly rotated from the 12 o'clock position is also shown by a dashed line. The direction of rotation of the winding shaft 21 is clockwise, as shown in Figure 1. Figure 4 shows the winding device 20 and the feeding device 30 when the winding shaft 21 is at the 3 o'clock position. Figure 5 shows the winding device 20 and the feeding device 30 when the winding shaft 21 is located between the 3 o'clock and 6 o'clock positions. Figure 6 shows the winding device 20 and the feed device 30 when the winding shaft 21 is in the 6 o'clock position.

[0041] As shown in Figure 3, the winding process S10 includes steps S11 to S17. In step S11, the winding shaft 21 is started to rotate, and the nip rollers 31 are rotated to feed the laminated sheet 2 onto the winding shaft 21. As shown in Figure 1, at this time, the pair of nip rollers 31 are holding the laminated sheet 2. In step S11, the nip rollers 31 rotate to feed the laminated sheet 2 at the same speed as the laminated sheet 2 is wound onto the winding shaft 21. Because the laminated sheet 2 is fed at the same speed as the laminated sheet 2 is wound onto the winding shaft 21, no tension is applied to the laminated sheet 2. As shown in Figure 1, at this time, the retaining roller 34 is retracted to the right.

[0042] In step S11, as shown in Figure 1, the position of the end 21c of the winding shaft 21 relative to the rotation axis 22a gradually moves to the right. In step S11, the winding shaft 21 is gradually moved to the left in order to maintain the leftward position of the end 21c of the winding shaft 21 directly below the pair of nip rollers 31. This control allows the laminated sheet 2, which is hanging down in the direction of gravity because no tension is applied, to be wound onto the winding shaft 21. In step S11, one of the flat portions 2a is formed by the flat surface portion 21a.

[0043] In step S12, it is determined whether the winding shaft 21 has reached the 3 o'clock position. If the winding shaft 21 has not reached the 3 o'clock position (the result of step S12 is NO), step S11 continues.

[0044] When the winding shaft 21 reaches the 3 o'clock position (if the result of step S12 is YES), in step S13, the pair of nip rollers 31 separate, and the gripping of the laminated sheet 2 by the nip rollers 31 is released (see Figure 4). In step S14, as shown in Figure 4, the press roller 34 moves to the left and contacts the arcuate surface portion 21b of the winding shaft 21, sandwiching the laminated sheet 2. Steps S13 and S14 may be performed in reverse order or simultaneously.

[0045] In step S15, the winding shaft 21 is rotated, and the pressing roller 34 is also rotated. In step S15, the formation of one of the R portions 2b is mainly carried out by the arcuate surface portion 21b. As shown in Figure 5, in step S15, the winding shaft 21 is gradually moved to the right by the winding shaft moving device 23. This maintains the left-right position of the end 21c of the winding shaft 21 directly below the pair of nip rollers 31. At the same time, the pressing roller 34 is gradually moved downward by the follow device 36. This causes the pressing roller 34 to move along the arcuate surface portion 21b in accordance with the movement of the arcuate surface portion 21b of the winding shaft 21. As the pressing roller 34 moves along the arcuate surface portion 21b of the winding shaft 21 with the laminated sheet 2 in between, the laminated sheet 2 is formed to conform to the shape of the arcuate surface portion 21b.

[0046] In step S15, the press roller 34 is rotating and feeding the laminated sheet 2 downward. Upstream of the press roller 34, tension is applied to the laminated sheet 2. However, downstream of the press roller 34, there is no tension applied to the laminated sheet 2. In step S15, the press roller 34 rotates to feed the laminated sheet 2 at a speed faster than the speed at which the laminated sheet 2 is wound onto the winding shaft 21. This causes slack in the laminated sheet 2 wound onto the arcuate surface portion 21b. This control allows the shape of the laminated sheet 2 to be formed into an arc while creating a gap between the curved portion 2d of the inner layer and the curved portion 2d of the outer layer.

[0047] In step S16, it is determined whether the winding shaft 21 has reached the 6 o'clock position. If the winding shaft 21 has not reached the 6 o'clock position (the result of step S16 is NO), step S15 continues. When the winding shaft 21 reaches the 6 o'clock position (the result of step S16 is YES), in step S17, the pressing roller 34 is separated from the winding shaft 21 (see Figure 6). Also in step S17, the pair of nip rollers 31 move closer together, and the laminated sheet 2 is gripped again by the pair of nip rollers 31 (see Figure 6). With the end of step S17, the winding process S10 for half a rotation of the winding shaft 21 is completed. The winding process S10 for the remaining half rotation is the same as the first half, so the explanation is omitted. The winding process S10 for one rotation is repeated, thereby winding the laminated sheet 2 onto the winding shaft 21 multiple times.

[0048] In the first pressing step S21, pressing is started from a part of the pair of flat portions 2a of the laminated sheet 2 (in this case, the longitudinal center of the wound body), and the pressing area is carried out so that it expands toward the pair of R portions 2b of the laminated sheet 2 which are formed in an oval shape.

[0049] In the first pressing step S21, when the leaf spring 42 is sandwiched between the pressing member 41 and the winding body of the laminated sheet 2, it gradually collapses outward from the apex of the convex portion. As a result, pressing begins from a part of the pair of flat portions 2a of the laminated sheet 2 (in this case, the central portion), and the pressing area expands toward the pair of curved portions 2b of the laminated sheet 2. Consequently, the gaps between the multiple laminated sheets 2 that also existed in the flat portions 2a of the winding body of the laminated sheet 2 are compressed. The excess laminated sheet 2 generated by the compression of the gaps is absorbed by the multiple curved portions 2d. As a result, the gaps between the multiple curved portions 2d expand, and as shown in Figure 7, a gap 1c with a target gap value of G1 is formed. The first pressing step S21 is a step to collect the gaps toward the curved portions 1b.

[0050] In the second pressing step S22, the wound laminated sheet 2 is further pressed until it reaches a predetermined thickness. This forms the wound electrode body 1.

[0051] Figure 7 is a schematic cross-sectional view of a lithium-ion secondary battery 100 equipped with a wound electrode body 1. However, in Figure 7, components other than the wound electrode body 1 of the lithium-ion secondary battery 100 are omitted from the illustration. As shown in Figure 7, in the wound electrode body 1 after the pressing process S20, the lengths of the multiple straight sections 2c of the laminated sheet 2 are equal, and there is almost no gap between the multiple straight sections 2c. In contrast, the inner circumference length of the curved section 2d of 1 is longer than the outer circumference length of the curved section 2d immediately inside it. A gap 1c with a gap of G1 (target value) is formed between the curved section 2d of 1 and the curved section 2d immediately inside it.

[0052] [Effects of the Embodiment] The following describes the effects and advantages that can be achieved by the wound electrode manufacturing apparatus 10 and the method for manufacturing the wound electrode 1 according to this embodiment.

[0053] The wound electrode manufacturing apparatus 10 according to this embodiment is an apparatus for manufacturing a wound electrode body 1 in which a laminated sheet 2 is wound, in which a strip-shaped positive electrode sheet 3, a strip-shaped negative electrode sheet 4, a strip-shaped first separator sheet 5, and a strip-shaped second separator sheet 6 are stacked in a predetermined order. The apparatus comprises a winding shaft 21 having an oval-shaped outer peripheral surface having a pair of opposing flat surfaces 21a and a pair of arcuate surfaces 21b connecting both sides of the pair of flat surfaces 21a, on which the laminated sheet 2 is wound; a winding shaft drive device 22 for rotating the winding shaft 21; a feed device 30 for feeding the laminated sheet 2 toward the winding shaft 21; and a control device 50 that controls the winding shaft drive device 22 to control the rotation of the winding shaft 21 and controls the amount of the laminated sheet 2 fed by the feed device 30. The control device 50 controls the feed device 30 to feed the laminated sheet 2 by a length longer than the outer peripheral length corresponding to the number of turns of the laminated sheet 2 wound on the winding shaft 21 for each rotation of the winding shaft 21.

[0054] In this wound electrode manufacturing apparatus 10, for each rotation of the winding shaft 21, the laminated sheet 2 is fed a distance longer than the outer circumference length corresponding to the number of turns of the laminated sheet 2 wound on the winding shaft 21. As a result, with each rotation of the winding shaft 21, a gap is created between the inner layer laminated sheet 2 already wound on the winding shaft 21 and the outer layer laminated sheet 2 wound on the outside. In the pressing process S20, the pressed laminated sheet 2 can escape into this gap. Therefore, with this wound electrode manufacturing apparatus 10, the stress applied to the R portion 2b of the laminated sheet 2 in the pressing process S20 can be relieved.

[0055] When tension is applied to the laminated sheet 2 and the laminated sheet 2 is wound onto the winding shaft 21, no gap is created between the inner layer laminated sheet 2 and the outer layer laminated sheet 2. Therefore, when the R portion 2b of the laminated sheet 2 is deformed during the pressing process, a large stress is applied to the R portion 2b of the laminated sheet 2. In addition, the wound electrode body 1 expands and contracts during charging and discharging of the energy storage device. This expansion and contraction of the wound electrode body 1 also applies a large stress to the R portion 2b of the laminated sheet 2. If the number of turns of the laminated sheet 2 is increased to increase the capacity of the energy storage device, the expansion and contraction of the wound electrode body 1 will become even larger. From the viewpoint of durability and reliability of the R portion 2b, it is preferable that the stress applied to the R portion 2b of the laminated sheet 2 be small. According to the wound electrode body manufacturing apparatus 10 of this embodiment, the stress applied to the R portion 2b of the laminated sheet 2 can be alleviated by forming a gap between the inner layer laminated sheet 2 and the outer layer laminated sheet 2.

[0056] The wound electrode manufacturing apparatus 10 according to this embodiment is equipped with a pressing roller 34 that presses the laminated sheet 2 wound on the arcuate surface portion 21b of the winding shaft 21 toward the arcuate surface portion 21b. With this configuration, by pressing the laminated sheet 2 with the pressing roller 34, the shape of the laminated sheet 2 can be made to conform to the shape of the outer surface of the winding shaft 21 without applying tension to the laminated sheet 2.

[0057] In this embodiment, the control device 50 controls the feed device 30 to make the feed speed of the laminated sheet 2 faster than the speed at which the laminated sheet 2 is wound around the arcuate surface portion 21b, at least for a portion of the time during which the laminated sheet 2 is wound around the arcuate surface portion 21b. With this control, when winding the laminated sheet 2 around the arcuate surface portion 21b, the laminated sheet 2 can be fed for a length longer than the outer circumference length corresponding to the number of turns of the laminated sheet 2 wound around the arcuate surface portion 21b. As a result, slack occurs in the laminated sheet 2 wound around the arcuate surface portion 21b, and a gap can be formed between the curved portion 2d of the inner layer and the curved portion 2d of the outer layer. Here, in the latter half of the time during which the laminated sheet 2 is wound around the arcuate surface portion 21b (the time period shown in Figure 5), the feed speed of the laminated sheet 2 is faster than the speed at which the laminated sheet 2 is wound around the arcuate surface portion 21b.

[0058] In this embodiment, the feeding device 30 is configured to grip and rotate the laminated sheet 2 and includes a pair of nip rollers 31 that feed the laminated sheet 2 toward the winding shaft 21, a nip roller drive device 32 that rotates the pair of nip rollers 31, a nip roller moving device 33 that brings the pair of nip rollers 31 closer together to grip the laminated sheet 2, or separates the pair of nip rollers 31 to release the laminated sheet 2, a press roller 34 that presses the laminated sheet 2 wound on the arcuate surface portion 21b of the winding shaft 21 toward the arcuate surface portion 21b, a press roller drive device 35 that rotates the press roller 34, and a press roller moving device 37 that brings the press roller 34 into contact with the arcuate surface portion 21b or separates it from the arcuate surface portion 21b.

[0059] The control device 50 controls the nip roller moving device 33 to separate the pair of nip rollers 31 for at least a portion of the time during which the laminated sheet 2 is being wound around the arcuate surface 21b, and controls the press roller moving device 37 and the press roller drive device 35 to rotate the press roller 34 in contact with the arcuate surface 21b. For the rest of the time, the control device 50 controls the press roller moving device 37 to separate the press roller 34 from the winding shaft 21, and controls the nip roller moving device 33 and the nip roller drive device 32 to grip and feed the laminated sheet 2 between the pair of nip rollers 31. The control device 50 sets the feeding speed of the laminated sheet 2 by the pair of nip rollers 31 to be the same as the speed at which the laminated sheet 2 is being wound around the winding shaft 21. The control device 50 sets the feeding speed of the laminated sheet 2 by the press roller 34 to be faster than the speed at which the laminated sheet 2 is being wound around the arcuate surface 21b.

[0060] With this configuration, for at least a portion of the time during which the laminated sheet 2 is wrapped around the arcuate surface portion 21b, the feed speed of the laminated sheet 2 is controlled by the rotation speed of the press roller 34. Therefore, by controlling the rotation speed of the press roller 34 for the aforementioned portion of time, the feed speed of the laminated sheet 2 can be made faster than the speed at which the laminated sheet 2 is wrapped around the arcuate surface portion 21b.

[0061] In this embodiment, the wound electrode manufacturing apparatus 10 starts pressing from a portion of a pair of flat portions 2a of the laminated sheet 2, and presses so that the pressing area expands toward a pair of curved portions 2b of the laminated sheet 2. With this configuration, the aforementioned process eliminates the gaps between the multiple laminated sheets 2 that also existed in the flat portions 2a of the wound laminated sheet 2, and a gap 1c of the desired gap G1 is formed between the multiple curved portions 2d. This further reduces the stress applied to the curved portions 2b.

[0062] More specifically, the wound electrode manufacturing apparatus 10 according to this embodiment further includes a press device 40 for pressing a wound laminated sheet 2 against a pair of flat portions 2a. The press device 40 includes a pair of opposing press members 41 that each press the pair of flat portions 2a of the laminated sheet 2, and a pair of leaf springs 42 provided on each of the press members 41 and curved to protrude toward the opposing press members 41. With this configuration, pressing can be started from a part of the pair of flat portions 2a of the laminated sheet 2, and the pressing area can be expanded toward the pair of R portions 2b of the laminated sheet 2.

[0063] In this embodiment, a power storage device (here, a lithium-ion secondary battery 100) can be obtained, which comprises a wound electrode body 1 in which a laminated sheet 2, in which a strip-shaped positive electrode sheet 3, a strip-shaped negative electrode sheet 4, a strip-shaped first separator sheet 5, and a strip-shaped second separator sheet 6 are stacked in a predetermined order, is wound multiple times. In the lithium-ion secondary battery 100 according to this embodiment, the wound electrode body 1 is wound in an oval shape having a pair of opposing flat portions 1a and a pair of arc-shaped R portions 1b connecting both sides of the pair of flat portions 1a. The laminated sheet 2 includes a plurality of curved portions 2d that form the R portions 1b and are stacked radially on the R portions 1b. Of the plurality of curved portions 2d, the inner circumference length of one curved portion 2d is longer than the outer circumference length of the curved portion 2d one position inward from that curved portion 2d. With such a lithium-ion secondary battery 100, the stress applied to the R portions 1b of the wound electrode body 1 can be relieved for the reasons described above.

[0064] In the lithium-ion secondary battery 100 according to this embodiment, a gap 1c is provided between the curved portion 2d 1 and the curved portion 2d one position inward from it. With such a lithium-ion secondary battery 100, the stress applied to the R portion 1b of the wound electrode body 1 can be relieved for the reasons described above.

[0065] In the lithium-ion secondary battery 100 according to this embodiment, the laminated sheet 2 includes a plurality of straight portions 2c that are stacked to form a flat portion 1a. The lengths of the plurality of straight portions 2c are equal. With this configuration, even if the laminated sheet 2 expands and contracts due to charging and discharging of the lithium-ion secondary battery 100, there is no difference in the lengths of the plurality of straight portions 2c. Therefore, gaps (peeling) are less likely to occur between the plurality of straight portions 2c, and the lithium-ion secondary battery 100 is less likely to deteriorate.

[0066] [Other embodiments] The above describes one embodiment of the manufacturing apparatus for wound electrode bodies proposed herein. However, the above embodiment is merely an example, and it can be implemented in other ways. For example, in the above embodiment, by increasing the feed speed of the laminated sheet 2 when winding the laminated sheet 2 onto the arcuate surface portion 21b of the winding shaft 21, the laminated sheet 2 was fed for a length longer than the outer circumference length corresponding to the number of turns of the laminated sheet 2 wound on the winding shaft 21. However, the feed speed of the laminated sheet 2 may be faster than the speed at which the laminated sheet 2 is wound onto the winding shaft 21 when winding the laminated sheet 2 onto the flat surface portion 21a of the winding shaft 21. Alternatively, the laminated sheet 2 may be fed in advance and loosened before being wound onto the winding shaft 21.

[0067] In the embodiment described above, the feeding device 30 was configured to rotate the press roller 34 and feed the laminated sheet 2 by the press roller 34 as well. However, the feeding device 30 may be configured to feed the laminated sheet 2 by only a pair of nip rollers 31. The press roller 34 may rotate passively, and may be omitted if the configuration allows the laminated sheet 2 to be wound onto the winding shaft 21 without the press roller 34.

[0068] In the embodiment described above, the press device 40 was equipped with a pair of leaf springs 42 for bringing the slack of the laminated sheet 2 outward from the center of the flat portion 2a. However, the press device 40 does not necessarily have a configuration for bringing the slack of the laminated sheet 2 inward, such as a pair of leaf springs 42. Even without bringing the slack of the laminated sheet 2 towards the R portion 2b, it is possible to some extent to alleviate the stress applied to the R portion 2b by feeding the laminated sheet 2 for a length longer than the outer circumference length corresponding to the number of turns of the laminated sheet 2.

[0069] Furthermore, the embodiments described above do not limit the present invention unless specifically mentioned. The technologies disclosed herein can be modified in various ways, and each component and each process mentioned herein may be omitted or combined as appropriate, unless no particular problems arise.

[0070] This Specification includes the disclosures set forth in the following sections:

[0071] Section 1: A winding process involves feeding a laminated sheet in which a strip-shaped positive electrode sheet, a strip-shaped negative electrode sheet, a strip-shaped first separator sheet, and a strip-shaped second separator sheet are stacked in a predetermined order, and rotating a winding shaft having an oval-shaped outer surface having a pair of opposing flat surfaces and a pair of arc-shaped surfaces connecting both sides of the pair of flat surfaces, thereby winding the laminated sheet around the outer surface of the winding shaft. The process includes a pressing step in which the laminated sheet, which has been formed into an oval shape in the winding step, is pressed together by pressing a pair of flat portions together. In the winding process, for each rotation of the winding shaft, the laminated sheet is fed by a length longer than the outer circumference length corresponding to the number of turns of the laminated sheet wound on the winding shaft. A method for manufacturing a wound electrode body.

[0072] Section 2: In the winding process, when winding the laminated sheet onto the arcuate surface, the laminated sheet is fed for a length longer than the outer circumference length corresponding to the number of turns of the laminated sheet wound onto the arcuate surface. A method for manufacturing a wound electrode body as described in item 1.

[0073] Section 3: The pressing process includes a first pressing step in which pressing is started from a part of the pair of flat portions of the laminated sheet and the pressing area expands toward the pair of arc-shaped portions of the laminated sheet. A method for manufacturing a wound electrode body as described in item 1 or 2.

[0074] Section 4: In the first pressing process described above, A pair of opposing press members that press the pair of flat portions of the laminated sheet, A press device is used which has a pair of leaf springs provided on each of the pair of press members and curved so as to protrude toward the side of the opposing press member. A method for manufacturing a wound electrode body as described in item 3.

[0075] Section 5: An apparatus for manufacturing a wound electrode body, in which a laminated sheet is wound, in which a strip-shaped positive electrode sheet, a strip-shaped negative electrode sheet, a strip-shaped first separator sheet, and a strip-shaped second separator sheet are stacked in a predetermined order, A winding shaft having an oval-shaped outer surface having a pair of opposing flat surfaces and a pair of arcuate surfaces connecting both sides of the pair of flat surfaces, the laminated sheet being wound around the outer surface, A winding shaft drive device for rotating the winding shaft, A feeding device that feeds the laminated sheet toward the winding shaft, The system includes a control device that controls the winding shaft drive device to control the rotation of the winding shaft, and controls the feed device to control the feed amount of the laminated sheet, The control device controls the feeding device to feed the laminated sheet by a length longer than the outer circumference length corresponding to the number of turns of the laminated sheet wound on the winding shaft, per rotation of the winding shaft. Manufacturing equipment for wound electrode bodies.

[0076] Item 6: The winding shaft is further equipped with a pressing roller that presses the laminated sheet wound around the arcuate surface toward the arcuate surface. A manufacturing apparatus for wound electrode bodies as described in item 5.

[0077] Section 7: The control device controls the feed device to make the feed speed of the laminated sheet faster than the speed at which the laminated sheet is wound onto the arcuate surface, at least for a portion of the time during which the laminated sheet is wound onto the arcuate surface. A manufacturing apparatus for wound electrode bodies as described in item 5 or 6.

[0078] Section 8: The aforementioned feeding device is A pair of nip rollers configured to hold and rotate the laminated sheet, and to feed the laminated sheet toward the winding shaft, A nip roller drive device for rotating the pair of nip rollers, A nip roller moving device that brings the pair of nip rollers closer together to clamp the laminated sheet, or separates the pair of nip rollers to release the laminated sheet, A pressing roller that presses the laminated sheet wound on the arcuate surface of the winding shaft toward the arcuate surface, A pressing roller drive device that rotates the aforementioned pressing roller, The system includes a pressing roller moving device that brings the pressing roller into contact with the arcuate surface or separates it from the arcuate surface, The control device is During at least a portion of the time while the laminated sheet is wrapped around the arcuate surface, the nip roller moving device is controlled to separate the pair of nip rollers, and the press roller moving device and the press roller driving device are controlled to rotate the press roller while it is in contact with the arcuate surface. At other times, the system controls the press roller moving device to separate the press roller from the winding shaft, and controls the nip roller moving device and the nip roller driving device to clamp and feed the laminated sheet between the pair of nip rollers. The feeding speed of the laminated sheet by the pair of nip rollers is set to be the same as the speed at which the laminated sheet is wound onto the winding shaft. The feeding speed of the laminated sheet by the pressing roller is made faster than the speed at which the laminated sheet is wound onto the arcuate surface. A manufacturing apparatus for wound electrode bodies as described in item 7.

[0079] Section 9: The press device further comprises a press that presses the laminated sheet, which has been formed into an oval shape by winding it onto the aforementioned winding shaft, by pressing a pair of flat portions together. The aforementioned press device is A pair of opposing press members that press the pair of flat portions of the laminated sheet, The pair of press members each have a pair of leaf springs provided on them, which are curved so as to protrude toward the side of the opposing press member, A manufacturing apparatus for wound electrode bodies as described in any one of items 5 to 8.

[0080] Section 10: The device comprises a wound electrode body in which a laminated sheet is formed by stacking a strip-shaped positive electrode sheet, a strip-shaped negative electrode sheet, a strip-shaped first separator sheet, and a strip-shaped second separator sheet in a predetermined order, and winding the laminated sheet multiple times. The wound electrode body is wound in an oval shape having a pair of opposing flat portions and a pair of arc-shaped R portions connecting both sides of the pair of flat portions, and the laminated sheet includes a plurality of curved portions that form the R portions and are superimposed in the radial direction of the R portions. Of the aforementioned multiple curved portions, the inner circumference of one curved portion is longer than the outer circumference of the curved portion one step inside the first curved portion. Energy storage device.

[0081] Section 11: A gap is provided between the curved portion 1 and the curved portion one step inside it. The energy storage device described in item 10.

[0082] Section 12: The laminated sheet includes a plurality of straight sections that are stacked to form the flat section, The lengths of the aforementioned multiple straight sections are equal. Energy storage devices as described in item 10 or 11. [Explanation of symbols]

[0083] 1. Wrapped electrode body 1a Flat area 1b R section 1c gap 2 Laminated Sheets 2a Flat area 2b R section (arc-shaped portion) 2c Straight section 2D curved section 3 Positive electrode sheet 4 Negative electrode sheets 5. First separator sheet 6. Second Separator Sheet 10-wound electrode manufacturing apparatus 20 Winding device 21 windings 21a Flat surface part 21b Arc surface part 22. Winding shaft drive device 22a Rotation axis 22b Drive motor 23 Winding shaft moving device 23a Drive motor 30 Feed device 31 Nipple Roller 31a Axis 32. Nip roller drive unit 32a Drive motor 33. Nip roller moving device 34 Pressing roller 35 Pressing roller drive device 35a Rotation axis 35b Drive motor 36 Tracking device 36a Drive motor 37 Pressing roller moving device 40 Pressing device 41 Pressed parts 42 Leaf springs 43 Drive unit 50 Control device 100 Lithium-ion rechargeable batteries (energy storage devices) G1 Gap S10 Winding process S20 Pressing Process S21 First pressing process S22 Second pressing process

Claims

1. A winding process involves feeding a laminated sheet in which a strip-shaped positive electrode sheet, a strip-shaped negative electrode sheet, a strip-shaped first separator sheet, and a strip-shaped second separator sheet are stacked in a predetermined order, and rotating a winding shaft having an oval-shaped outer surface having a pair of opposing flat surfaces and a pair of arc-shaped surfaces connecting both sides of the pair of flat surfaces, thereby winding the laminated sheet around the outer surface of the winding shaft. The process includes a pressing step in which the laminated sheet, which has been formed into an oval shape in the winding step, is pressed together by pressing a pair of flat portions together. In the winding process, for each rotation of the winding shaft, the laminated sheet is fed by a length longer than the outer circumference length corresponding to the number of turns of the laminated sheet wound on the winding shaft. A method for manufacturing a wound electrode body.

2. In the winding process, when winding the laminated sheet onto the arcuate surface, the laminated sheet is fed for a length longer than the outer circumference length corresponding to the number of turns of the laminated sheet wound onto the arcuate surface. A method for manufacturing a wound electrode body according to claim 1.

3. The pressing process includes a first pressing step in which pressing is started from a part of the pair of flat portions of the laminated sheet and the pressing area expands toward the pair of arc-shaped portions of the laminated sheet. A method for manufacturing a wound electrode body according to claim 1.

4. In the first pressing process described above, A pair of opposing press members that press the pair of flat portions of the laminated sheet, A press device is used which has a pair of leaf springs provided on each of the pair of press members and curved so as to protrude toward the side of the opposing press member, A method for manufacturing a wound electrode body according to claim 3.

5. An apparatus for manufacturing a wound electrode body, in which a laminated sheet is wound, in which a strip-shaped positive electrode sheet, a strip-shaped negative electrode sheet, a strip-shaped first separator sheet, and a strip-shaped second separator sheet are stacked in a predetermined order, A winding shaft having an oval-shaped outer surface having a pair of opposing flat surfaces and a pair of arcuate surfaces connecting both sides of the pair of flat surfaces, the winding shaft on which the laminated sheet is wound, A winding shaft drive device for rotating the winding shaft, A feeding device that feeds the laminated sheet toward the winding shaft, The system includes a control device that controls the winding shaft drive device to control the rotation of the winding shaft, and controls the feed device to control the feed amount of the laminated sheet, The control device controls the feeding device to feed the laminated sheet by a length longer than the outer circumference length corresponding to the number of turns of the laminated sheet wound on the winding shaft, per rotation of the winding shaft. Manufacturing equipment for wound electrode bodies.

6. The winding shaft is further equipped with a pressing roller that presses the laminated sheet wound around the arcuate surface toward the arcuate surface. The apparatus for manufacturing a wound electrode body according to claim 5.

7. The control device controls the feed device to make the feed speed of the laminated sheet faster than the speed at which the laminated sheet is wound onto the arcuate surface, at least for a portion of the time during which the laminated sheet is wound onto the arcuate surface. The apparatus for manufacturing a wound electrode body according to claim 5.

8. The aforementioned feeding device is A pair of nip rollers configured to hold and rotate the laminated sheet, and to feed the laminated sheet toward the winding shaft, A nip roller drive device for rotating the pair of nip rollers, A nip roller moving device that brings the pair of nip rollers closer together to clamp the laminated sheet, or separates the pair of nip rollers to release the laminated sheet, A pressing roller that presses the laminated sheet wound on the arcuate surface of the winding shaft toward the arcuate surface, A pressing roller drive device that rotates the aforementioned pressing roller, The system includes a pressing roller moving device that brings the pressing roller into contact with the arcuate surface or separates it from the arcuate surface, The control device is During at least a portion of the time while the laminated sheet is wrapped around the arcuate surface, the nip roller moving device is controlled to separate the pair of nip rollers, and the press roller moving device and the press roller driving device are controlled to rotate the press roller while it is in contact with the arcuate surface. At other times, the system controls the press roller moving device to separate the press roller from the winding shaft, and controls the nip roller moving device and the nip roller driving device to clamp and feed the laminated sheet between the pair of nip rollers. The feeding speed of the laminated sheet by the pair of nip rollers is set to be the same as the speed at which the laminated sheet is wound onto the winding shaft. The feeding speed of the laminated sheet by the pressing roller is made faster than the speed at which the laminated sheet is wound onto the arcuate surface. The apparatus for manufacturing a wound electrode body according to claim 7.

9. The press device further comprises a press that presses the laminated sheet, which has been formed into an oval shape by winding it onto the aforementioned winding shaft, by pressing a pair of flat portions together. The aforementioned press device is A pair of opposing press members that press the pair of flat portions of the laminated sheet, The pair of press members each have a pair of leaf springs provided on them, which are curved so as to protrude toward the side of the opposing press member, The apparatus for manufacturing a wound electrode body according to claim 5.

10. The device comprises a wound electrode body in which a laminated sheet is formed by stacking a strip-shaped positive electrode sheet, a strip-shaped negative electrode sheet, a strip-shaped first separator sheet, and a strip-shaped second separator sheet in a predetermined order, and winding the laminated sheet multiple times. The wound electrode body is wound in an oval shape having a pair of opposing flat portions and a pair of arc-shaped R portions connecting both sides of the pair of flat portions, and the laminated sheet includes a plurality of curved portions that form the R portions and are superimposed in the radial direction of the R portions. Of the aforementioned multiple curved portions, the inner circumference of one curved portion is longer than the outer circumference of the curved portion one step inside the first curved portion. Energy storage device.

11. A gap is provided between the curved portion 1 and the curved portion one step inward. The energy storage device according to claim 10.

12. The laminated sheet includes a plurality of straight sections that are stacked to form the flat section, The lengths of the aforementioned multiple straight sections are equal. The energy storage device according to claim 10.

Images