Wound electrode body manufacturing method, manufacturing apparatus, and power storage device

Abstract

To relieve the stress applied to a curved portion of a wound electrode body.SOLUTION: A manufacturing method of a wound electrode body includes a winding step of feeding 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, while rotating a winding shaft 21 having an oval-shaped outer peripheral surface with a pair of opposing flat surface portions 21a and a pair of arcuate surface portions 21b connecting both sides of the pair of flat surface portions 21a, and winding the laminated sheet 2 around the outer peripheral surface of the winding shaft 21, and a pressing step of pressing the laminated sheet formed into an oval shape in the winding step so as to press the pair of flat portions together. In the winding step, the laminated sheet 2 is fed by a length longer than the outer peripheral length corresponding to the number of turns of the laminated sheet 2 wound around the winding shaft 21 per rotation of the winding shaft 21.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method and apparatus for manufacturing a wound electrode body, and an electricity storage device including a wound electrode body. [Background technology]

[0002] For example, Patent Document 1 discloses a method for manufacturing a lithium ion secondary battery having a wound electrode body in which strip-shaped positive electrode sheets, negative electrode sheets, and separator sheets are superimposed and wound. In the method described in Patent Document 1, the core rotates in a state in which each sheet is tensioned by a tension roller, and each sheet is wound around the core. According to Patent Document 1, in a tension-free state after cutting each sheet or at the end of winding, the sheet may move and may not be wound well. For this reason, the winding device described in Patent Document 1 is equipped with a support roller that applies tension consistently to the positive electrode sheet that is wound last, all the way to the end of the winding at the end. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-302034 A Summary of the Invention [Problem to be solved by the invention]

[0004] When the sheet wound around a reel is pressed to form a roll of the sheet, 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 the sheet is small. [Means for solving the problem]

[0005] The manufacturing method of the 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 peripheral surface with a pair of opposing flat surface portions and a pair of arcuate surface portions connecting both sides of the pair of flat surface portions is rotated to wind the laminated sheet around the outer peripheral surface of the winding shaft. In the winding step, the laminated sheet is fed by a length longer than the outer peripheral length corresponding to the number of turns of the laminated sheet wound around the winding shaft per rotation of the winding shaft. In the pressing step, the laminated sheet formed into an oval shape in the winding step is pressed so as to press a pair of flat portions together.

[0006] According to the above-mentioned method for manufacturing a wound electrode body, in the winding step, the laminate sheet is fed a distance longer than the outer circumferential length corresponding to the number of turns of the laminate sheet wound around the winding shaft per rotation of the winding shaft. Therefore, with each rotation of the winding shaft, a gap is generated between the laminate sheet already wound around the winding shaft and the laminate sheet to be wound around it. In the pressing step, the pressed laminate sheet can escape into this gap. Therefore, according to the above-mentioned method for manufacturing a wound electrode body, the stress applied in the pressing step to the curved portion of the laminate sheet formed by the arc surface portion of the winding shaft can be alleviated.

[0007] The present disclosure also provides a wound electrode body manufacturing 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 includes a winding shaft having an oval-shaped outer peripheral surface with a pair of opposing flat surface portions and a pair of arcuate surface portions connecting both sides of the pair of flat surface portions, on which the laminated sheet is wound, a winding shaft driving device for rotating the winding shaft, a feeding device for feeding the laminated sheet toward the winding shaft, and a control device for controlling the winding shaft driving device to control the rotation of the winding shaft and the feeding device to control the feeding amount of the laminated sheet. 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 around the winding shaft per rotation of the winding shaft.

[0008] According to the above-mentioned manufacturing apparatus for a wound electrode body, it is possible to achieve the same effects as those of the above-mentioned manufacturing method for a wound electrode body.

[0009] The electric storage device disclosed herein includes a wound electrode body in which 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 wound multiple times. The wound electrode body is wound into an oval shape having a pair of opposing flat parts and a pair of arc-shaped R parts connecting both sides of the pair of flat parts. The laminated sheet includes a plurality of curved parts that form the R parts and are stacked in the radial direction of the R parts. Of the plurality of curved parts, the inner periphery of one curved part is longer than the outer periphery of the curved part one part further inward than the first curved part.

[0010] In the power storage device, the inner periphery of one curved portion is longer than the outer periphery of the next curved portion on the inside, and therefore, for the same reason as above, less stress is applied to the curved portion of the wound electrode body. [Brief description of the drawings]

[0011] [Figure 1]FIG. 2 is a schematic side view of a winding device and a feeding device. [Diagram 2] FIG. 2 is a schematic front view of a press device. [Diagram 3] 4 is a flowchart showing a part of a manufacturing process of a wound electrode body. [Figure 4] FIG. 2 is a side view of the winding device and the feeding device when the winding shaft is located at the 3 o'clock position. [Diagram 5] FIG. 2 is a side view of the winding device and the feeding device when the winding shaft is located between the 3 o'clock position and the 6 o'clock position. [Figure 6] FIG. 2 is a side view of the winding device and the feeding device when the winding shaft is located at the 6 o'clock position. [Figure 7] FIG. 1 is a schematic cross-sectional view of a lithium-ion secondary battery. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, one embodiment of a manufacturing apparatus for manufacturing a wound electrode body of an electricity storage device will be described. Note that the embodiment described here is, of course, not intended to limit the present invention in particular. Also, each figure is a schematic diagram and does not necessarily faithfully reflect an actual product.

[0013] [Configuration of wound electrode manufacturing equipment] FIG. 1 is a schematic side view of a part of a wound electrode manufacturing apparatus 10 according to an embodiment, specifically, a winding device 20 and a feeding device 30. FIG. 2 is a schematic front view of another part of the wound electrode manufacturing apparatus 10, specifically, a pressing device 40. The wound electrode manufacturing apparatus 10 according to this embodiment is an apparatus for manufacturing a wound electrode 1 (see FIG. 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 circumferential surface of a 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 laminated sheet 2 formed into an oval shape, and further forms it into a flat shape. The wound electrode body manufacturing apparatus 10 also includes a main pressing device (not shown) that further presses the wound electrode body 1 pressed by the pressing device 40 .

[0014] Here, the wound electrode body manufacturing apparatus 10 manufactures a wound electrode body 1 which is a power generating element of a lithium ion secondary battery 100 (see FIG. 7). However, the wound electrode body 1 is not limited to the wound electrode body of the lithium ion secondary battery 100, and may be a wound electrode body of various known electricity storage devices. The term "electricity storage device" refers to devices in general that can extract electric energy, 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 member 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 a predetermined width and thickness. The positive electrode active material is, for example, a material that can release lithium ions during charging and absorb lithium ions during discharging, such as a lithium transition metal composite material, in a lithium ion secondary battery. The negative electrode sheet 4 is a member 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 a predetermined width and thickness. The negative electrode active material is, for example, a material that can absorb lithium ions during charging and release the absorbed lithium ions during discharging, such as natural graphite, in a lithium ion secondary battery. The positive electrode active material and the negative electrode active material are not particularly limited, and various materials other than those mentioned above have been proposed.

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

[0017] 1, the winding device 20 includes a reel 21 around which the laminated sheet 2 is wound, a reel drive device 22 that rotates the reel 21, and a reel movement device 23 that moves the reel 21 so that the laminated sheet 2 before being wound around the reel 21 hangs down in the direction of gravity. The feed device 30 includes a pair of nip rollers 31 that rotate while holding the laminated sheet 2, a nip roller drive device 32 that rotates the pair of nip rollers 31, a nip roller movement device 33 that moves the pair of nip rollers 31 closer to or farther apart, a pressure roller 34 that presses the laminated sheet 2 toward the reel 21, a pressure roller drive device 35 that rotates the pressure roller 34, a follower device 36 that moves the pressure roller 34 to follow the movement of the reel 21, and a pressure roller movement device 37 that brings the pressure roller 34 into contact with or away from the reel 21. As shown in FIG. 1, the wound electrode 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-shaped outer peripheral surface having a pair of opposing flat surface portions 21a and a pair of arcuate 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 arcuate 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 in the figure, the outer peripheral surface of the winding shaft 21 has a predetermined width in the width direction of the laminated sheet 2 that is wider than the width 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 being wound 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 circumferential 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 a pair of flat surface portions 21a of the winding shaft 21. The pair of R portions 2b are formed by a 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, the flat portion and R portion of the wound electrode body 1 after the pressing process will be referred to as a pair of flat portion 1a and R portion 1b, respectively, in order to distinguish them from the flat portion 2a and R portion 2b of the wound body of the laminated sheet 2 before pressing (see FIG. 7). In addition, in the wound electrode body 1 after pressing, the multiple flat portions of the laminated sheet 2 that are stacked to form the flat portion 1a will be referred to as straight portions 2c. The flat portion 1a of the wound electrode body 1 is an assembly of multiple straight portions 2c stacked. Furthermore, in the wound electrode body 1 after pressing, the multiple curved portions of the laminated sheet 2 that are stacked in the radial direction of the R portion 1b to form the R portion 1b will be referred to as curved portions 2d. The R portion 1b of the wound electrode body 1 is an assembly of multiple curved portions 2d stacked.

[0021] 1, the reel driving device 22 rotates the reel 21 around a rotation axis 22a extending in the width direction of the laminated sheet 2 (the depth direction of the paper in FIG. 1). The reel driving device 22 is equipped with a drive motor 22b that rotates the reel 21. The rotation / stop, rotation speed, and rotation angle of the drive motor 22b are controlled by a control device 50.

[0022] The reel moving device 23 moves the reel 21 in accordance with the rotation of the reel 21 so that the end of the portion of the laminated sheet 2 wound around the reel 21 remains positioned directly below the nip roller 31. Specific movements of the reel 21 will be described later with reference to FIG. 1 and FIGS. 4 to 6. As a result of the movement of the reel 21 by the reel moving device 23, the feed direction of the laminated sheet 2 before being wound around the reel 21 becomes the direction of gravity. As will be described later, the wound electrode body manufacturing apparatus 10 according to this embodiment does not apply tension to the laminated sheet 2 when winding the laminated sheet 2 around the reel 21. Therefore, the laminated sheet 2 before being wound around the reel 21 sags in the direction of gravity.

[0023] The reel moving device 23 includes, for example, a slide guide (not shown) with which the rotating shaft 22a of the reel 21 is engaged so as to be slidable in the left-right direction in Fig. 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 reel moving device 23 is not particularly limited. The drive / stop, rotation speed, and rotation angle of the drive motor 23a are controlled by a control device 50.

[0024] The pair of nip rollers 31 of the feed device 30 are configured to rotate while holding the laminated sheet 2. The pair of nip rollers 31 feed the laminated sheet 2 toward the winding shaft 21. The pair of nip rollers 31 are configured to be rotatable about an axis 31a extending in the width direction of the laminated sheet 2. The pair of nip rollers 31 are provided above the winding shaft 21. The laminated sheet 2 fed by the pair of nip rollers 31 advances downward by the action of gravity since no tension is applied thereto. The nip roller drive device 32 rotates the pair of nip rollers 31. Here, the nip roller drive device 32 includes a drive motor 32a that rotates one of the pair of nip rollers 31. The other nip roller 31 rotates following 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 a control device 50.

[0025] The nip roller moving device 33 brings the pair of nip rollers 31 closer to each other to clamp the laminated sheet 2, or separates the pair of nip rollers 31 to release the laminated sheet 2. Here, the nip roller moving device 33 moves the left nip roller 31. The left nip roller 31 moves between a position where it can clamp the laminated sheet 2 together with the right nip roller 31 and a position to the left of that in FIG. 1 and 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. The nip roller moving device 33 is not limited to being 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 pressure roller 34 presses the laminate sheet 2 wound around the arcuate surface portion 21b of the winding shaft 21 against the arcuate surface portion 21b. When pressed by the pressure roller 34, the laminate sheet 2 including the metal current collecting foil is plastically deformed, and the shape of the laminate sheet 2 follows the shape of the outer circumferential surface of the winding shaft 21. This allows the shape of the laminate sheet 2 to follow the shape of the outer circumferential surface of the winding shaft 21 without applying tension to the laminate sheet 2.

[0027] The pressure roller driving device 35 rotates the pressure roller 34. The pressure roller driving device 35 rotates the pressure roller 34 around a rotation axis 35a extending in the width direction of the laminated sheet 2. The pressure roller driving device 35 includes a drive motor 35b that rotates the winding shaft 21. The rotation / stop, rotation speed, and rotation angle of the drive motor 35b are controlled by the control device 50. The pressure roller 34 is thus configured to rotate by the driving force of the drive motor 35b. The pressure roller 34 is a member for making the shape of the laminated sheet 2 conform to the shape of the outer circumferential surface of the winding shaft 21, and at the same time, is a member for feeding the laminated sheet 2 on the arc surface portion 21b by its rotation. However, the pressure member for making the shape of the laminated sheet 2 conform to the shape of the outer circumferential surface of the winding shaft 21 does not have to be related to the feeding of the laminated sheet 2. For example, the pressure member may be a plate-like member that does not rotate and bends following the movement of the arc surface portion 21b.

[0028] The follow-up device 36 moves the pressure roller 34 so that it moves along the arcuate surface portion 21b in accordance with the movement of the arcuate surface portion 21b of the reel 21. By moving the pressure roller 34, the follow-up device 36 keeps the pressure roller 34 in contact with the arcuate surface portion 21b that moves due to the rotation of the reel 21 and the driving of the reel moving device 23. Here, the follow-up device 36 keeps the pressure roller 34 in contact with the reel 21 while the laminated sheet 2 is being wound around the reel 21 for approximately half a rotation. The timing at which the follow-up device 36 brings the pressure roller 34 into contact with the reel 21 will be described later.

[0029] The tracking device 36 includes, for example, a slide guide (not shown) with which the pressure roller 34 is engaged so as to be slidable in the vertical direction, a drive motor 36a for moving the pressure 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 pressure roller moving device 37 brings the pressure roller 34 into contact with the arcuate surface portion 21b of the winding shaft 21 or separates it from the arcuate surface portion 21b. The pressure roller moving device 37 moves the pressure roller 34 between a position directly below the nip roller 31 where it can come into contact with the winding shaft 21 and a position to the right of that in FIG. 1 where it does not come into contact with the winding shaft 21. The pressure roller moving device 37 includes, for example, an air cylinder (not shown) that moves the pressure roller 34 left and right. However, the configuration of the pressure roller moving device 37 is not particularly limited. The operation of the pressure roller moving device 37 is controlled by a control device 50.

[0031] The control device 50 controls the reel drive device 22 to control the rotation of the reel 21, and controls the feed device 30 to control the feed amount of the laminated sheet 2. More specifically, the control device 50 controls the feed device 30 to feed the laminated sheet 2 by a length longer than the outer circumferential length corresponding to the number of turns of the laminated sheet 2 wound around the reel 21 per rotation of the reel 21. By feeding the laminated sheet 2 in this manner, the circumferential 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 circumferential length of the laminated sheet 2 already wound around the reel 21 (hereinafter also referred to as the inner layer laminated sheet 2), so that a gap is generated between the inner layer laminated sheet 2 and the outer layer laminated sheet 2 per rotation of the reel 21. The effect of this gap will be described later.

[0032] The outer circumferential length of the laminate sheet 2 wound around the reel 21 increases with the number of turns. The control device 50 increases the length of the laminate sheet 2 fed by the feed device 30 with each increase in the number of turns of the laminate sheet 2. Here, the control device 50 calculates a length obtained by adding the increase in circumferential length due to the increase in the number of turns and a predetermined additional length for generating a gap to the circumferential length of the inner layer laminate sheet 2, and sets this length as the length of the outer layer laminate sheet 2. In this embodiment, the additional length for generating a gap is constant regardless of the number of turns of the laminate sheet 2. However, the additional length for generating a gap does not have to be constant.

[0033] The above-mentioned additional length is set to a length such that a gap 1c having a gap G1 obtained by multiplying the thickness of the laminated sheet 2 by a predetermined magnification is generated between the curved portions 2d of the laminated sheet 2 (see FIG. 7). The gap 1c is the gap after pressing. For example, when the thickness of the laminated sheet 2 is 0.3 mm and the magnification is 50%, the gap G1 is set to 0.15 mm. The above-mentioned magnification is preferably, for example, 30% or more and 100% or less. However, the above-mentioned magnification is not limited. In calculating the additional length, the gap G1 is regarded as an additional amount of the radius of the curved portion 2d. Therefore, the additional length is twice the length obtained by multiplying the gap G1 by pi (doubled because the curved portions 2d are present on both sides). However, the above-mentioned method of setting the additional length is only one example, and is not limited thereto.

[0034] In this embodiment, the control device 50 is configured to control 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 during a part of the time during 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 by a length longer than the outer circumferential length corresponding to the number of turns of the laminated sheet 2 wound around the arcuate surface portion 21b. As a result, gaps due to the excess of the feed of the laminated sheet 2 are easily formed in the R portion 2b of the roll 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 reel 21 and the feed speed of the laminated sheet 2 the same during the other time. As a result, gaps due to the excess of the 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 at least during a part of the time during which the laminated sheet 2 is wound around the arcuate surface portion 21b. At the same time, the control device 50 controls the pressure roller moving device 37 and the pressure roller driving device 35 to rotate the pressure roller 34 in contact with the arcuate surface portion 21b. In this state, the feed speed of the laminated sheet 2 is controlled by the rotation speed of the pressure roller 34. The control device 50 is configured to make the feed speed of the laminated sheet 2 by the pressure roller 34 faster than the speed at which the laminated sheet 2 is wound around the arcuate surface portion 21b.

[0036] During other times, the control device 50 controls the pressure roller moving device 37 to move the pressure roller 34 away from the reel 21. At the same time, the control device 50 controls the nip roller moving device 33 and the nip roller driving device 32 to nip the laminated sheet 2 between the pair of nip rollers 31 and feed the laminated sheet 2. In this state, the feed speed of the laminated sheet 2 is controlled by the rotation speed of the nip rollers 31. The control device 50 is configured to make the feed speed of the laminated sheet 2 by the pair of nip rollers 31 the same as the speed at which the laminated sheet 2 is wound around the reel 21.

[0037] The press device 40 presses the roll of the laminated sheet 2 so as to press the pair of flat parts 2a together. As shown in FIG. 2, the press device 40 includes a pair of opposing press members 41 that press the pair of flat parts 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 moves the pair of press members 41 closer to each other to press the laminated sheet 2. Each leaf spring 42 is curved so as to protrude toward the opposing press member 41, and is arranged so that the apex of the protrusion is located at the center of the press member 41 (the center of the roll of the laminated sheet 2 in the longitudinal direction). The press device 40 is configured to press the flat parts 2a of the roll of the laminated sheet 2 by the press members 41 via the leaf springs 42.

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

[0039] [Manufacturing process of wound electrode body] Fig. 3 is a flow chart showing a part of the manufacturing process of the wound electrode body 1. As shown in Fig. 3, the manufacturing process of the wound electrode body 1 includes a winding process 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, a winding shaft 21 having an oval outer peripheral surface is rotated, and the laminated sheet 2 is wound around the outer peripheral surface of the winding shaft 21, and a pressing process S20 in which the laminated sheet 2 (wound body of the laminated sheet 2) formed into an oval shape in the winding process S10 is pressed so as to press a pair of flat portions 2a together. The pressing process S20 includes a first pressing process S21 using a pressing device 40 and a second pressing process S22 using this pressing device.

[0040] First, the details of the winding step S10 will be described. FIGS. 4 to 6 are side views of the winding device 20 and the feeding device 30 at the midpoint of the winding step S10. Hereinafter, the rotational position of the winding shaft 21 will be represented by the direction in which the end 21c (here, one of the arcuate surface portions 21b) of the winding shaft 21, which faces upward (in the direction of 0 o'clock) in FIG. 1, faces. FIG. 1 shows the winding device 20 and the feeding device 30 when the winding shaft 21 is located at the 0 o'clock position. FIG. 1 also shows the winding shaft 21 in a state where it has rotated slightly from the 0 o'clock position by a two-dot chain line. The rotational direction of the winding shaft 21 is clockwise as shown in FIG. 1. FIG. 4 shows the winding device 20 and the feeding device 30 when the winding shaft 21 is located at the 3 o'clock position. FIG. 5 shows the winding device 20 and the feeding device 30 when the winding shaft 21 is located between the 3 o'clock position and the 6 o'clock position. FIG. 6 shows the winding device 20 and the feeding device 30 when the winding shaft 21 is located at the 6 o'clock position.

[0041] As shown in FIG. 3, the winding process S10 includes steps S11 to S17. In step S11, the winding shaft 21 starts to rotate, and the nip roller 31 is rotated to feed the laminated sheet 2 to the winding shaft 21. As shown in FIG. 1, at this time, the pair of nip rollers 31 holds the laminated sheet 2. In step S11, the nip roller 31 rotates so as to feed the laminated sheet 2 at the same speed as the speed at which the laminated sheet 2 is wound around the winding shaft 21. By feeding the laminated sheet 2 at the same speed as the speed at which the laminated sheet 2 is wound around the winding shaft 21, no tension is applied to the laminated sheet 2. As shown in FIG. 1, at this time, the pressure roller 34 is retracted to a right position.

[0042] In step S11, as shown in Fig. 1, the position of end 21c of winding shaft 21 relative to rotation axis 22a gradually moves to the right. In step S11, winding shaft 21 is gradually moved to the left in order to maintain the lateral position of end 21c of winding shaft 21 directly below the pair of nip rollers 31. By such control, it is possible to wind up laminated sheet 2, which is sagging in the direction of gravity due to the absence of tension, around winding shaft 21. In step S11, one flat portion 2a is formed by flat surface portion 21a.

[0043] In step S12, it is determined whether or not 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 (the result of step S12 is YES), in step S13, the pair of nip rollers 31 separate and the nip rollers 31 release the laminated sheet 2 from the nip rollers 31 (see FIG. 4). In step S14, as shown in FIG. 4, the pressure roller 34 moves leftward and abuts against the arcuate surface portion 21b of the winding shaft 21, sandwiching the laminated sheet 2. Steps S13 and S14 may be performed in the opposite order, or simultaneously.

[0045] In step S15, the winding shaft 21 is rotated and the pressing roller 34 is rotated. In step S15, the formation of one of the R portions 2b by the arcuate surface portion 21b is mainly performed. As shown in FIG. 5, in step S15, the winding shaft 21 is gradually moved to the right by the winding shaft moving device 23. As a result, the left and right positions of the end portion 21c of the winding shaft 21 are maintained directly below the pair of nip rollers 31. At the same time, the pressing roller 34 is gradually moved downward by the following device 36. As a result, the pressing roller 34 moves 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 on the arcuate surface portion 21b of the winding shaft 21 with the laminated sheet 2 sandwiched therebetween, the laminated sheet 2 is shaped to follow the shape of the arcuate surface portion 21b.

[0046] In step S15, the pressure roller 34 is rotating and feeding the laminate sheet 2 downward. The laminate sheet 2 is under tension upstream of the pressure roller 34. However, the laminate sheet 2 is not under tension downstream of the pressure roller 34. In step S15, the pressure roller 34 rotates so as to feed the laminate sheet 2 at a speed faster than the speed at which the laminate sheet 2 is wound around the reel 21. This causes slack in the laminate sheet 2 wound around the arcuate surface portion 21b. This control allows the shape of the laminate sheet 2 to be adjusted to an arcuate shape while forming 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 (if the result of step S16 is NO), step S15 continues. If the winding shaft 21 has reached the 6 o'clock position (if the result of step S16 is YES), in step S17, the pressing roller 34 is moved away from the winding shaft 21 (see FIG. 6). Also, in step S17, the pair of nip rollers 31 approach each other, and the laminated sheet 2 is again sandwiched between the pair of nip rollers 31 (see FIG. 6). With the end of step S17, the winding step S10 for one half rotation of the winding shaft 21 is completed. The winding step S10 for the remaining half rotation is the same as the first half, so a description thereof will be omitted. The winding step S10 for one rotation is repeated, and the laminated sheet 2 is thereby wound around the winding shaft 21 multiple times.

[0048] In the first pressing process S21, pressing is started from a part of a pair of flat portions 2a of the laminated sheet 2 (here, the longitudinal center portion of the roll), and pressing is performed so that the pressing area expands toward a pair of R portions 2b of the laminated sheet 2 which are formed into an oval shape.

[0049] In the first pressing step S21, when the leaf spring 42 is sandwiched between the pressing member 41 and the roll of the laminated sheet 2, it is gradually crushed from the apex of the convex portion toward the outside. As a result, pressing starts from a part (here, the center) of the pair of flat portions 2a of the laminated sheet 2, and the pressing area expands toward the pair of R portions 2b of the laminated sheet 2. As a result, the gaps between the plurality of laminated sheets 2 that existed in the flat portions 2a of the roll of the laminated sheet 2 are crushed. The excess laminated sheet 2 generated by crushing the gaps is absorbed by the plurality of curved portions 2d. As a result, the gaps between the plurality of curved portions 2d are expanded, and as shown in FIG. 7, a gap 1c with a target gap value G1 is formed. The first pressing step S21 is a step for collecting the gaps in the R portions 1b.

[0050] In the second pressing step S22, the wound body of the laminated sheet 2 is further pressed until it has a predetermined thickness, thereby forming the wound electrode body 1.

[0051] FIG. 7 is a schematic cross-sectional view of a lithium-ion secondary battery 100 including a wound electrode body 1. However, in FIG. 7, components other than the wound electrode body 1 of the lithium-ion secondary battery 100 are omitted. As shown in FIG. 7, in the wound electrode body 1 after the pressing step S20, the straight parts 2c of the laminated sheet 2 have the same length, and there are almost no gaps between the straight parts 2c. In contrast, the inner periphery of the first curved part 2d is longer than the outer periphery of the curved part 2d next to it. A gap 1c having a gap G1 (target value) is formed between the first curved part 2d and the curved part 2d next to it.

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

[0053] The wound electrode manufacturing apparatus 10 according to the present 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, and includes a reel 21 having an oval-shaped outer peripheral surface with a pair of opposing flat surface portions 21a and a pair of arcuate surface portions 21b connecting both sides of the pair of flat surface portions 21a, and the laminated sheet 2 is wound around the outer peripheral surface, a reel drive device 22 that rotates the reel 21, a feed device 30 that feeds the laminated sheet 2 toward the reel 21, and a control device 50 that controls the reel drive device 22 to control the rotation of the reel 21 and controls the feed device 30 to control the feed amount of the laminated sheet 2. 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 around the reel 21 per rotation of the reel 21.

[0054] According to the wound electrode manufacturing apparatus 10, the laminate sheet 2 is fed a distance longer than the outer circumferential length corresponding to the number of turns of the laminate sheet 2 wound around the winding shaft 21 per rotation of the winding shaft 21, so that with each rotation of the winding shaft 21, a gap is generated between the inner layer laminate sheet 2 already wound around the winding shaft 21 and the outer layer laminate sheet 2 wound around it. In the pressing step S20, the pressed laminate sheet 2 can escape into this gap. Therefore, according to the wound electrode manufacturing apparatus 10, the stress applied to the R portion 2b of the laminate sheet 2 in the pressing step S20 can be alleviated.

[0055] When the laminate sheet 2 is wound around the winding shaft 21 under tension, no gap is generated between the laminate sheet 2 of the inner layer and the laminate sheet 2 of the outer layer. Therefore, when the R portion 2b of the laminate sheet 2 is deformed in the pressing process, a large stress is applied to the R portion 2b of the laminate sheet 2. In addition, when the electricity storage device is charged and discharged, the wound electrode body 1 expands and contracts. This expansion and contraction of the wound electrode body 1 also applies a large stress to the R portion 2b of the laminate sheet 2. If the number of turns of the laminate sheet 2 is increased to increase the capacity of the electricity storage device, the expansion and contraction of the wound electrode body 1 becomes 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 laminate sheet 2 is small. According to the wound electrode body manufacturing apparatus 10 according to this embodiment, a gap is formed between the laminate sheet 2 of the inner layer and the laminate sheet 2 of the outer layer, so that the stress applied to the R portion 2b of the laminate sheet 2 can be alleviated.

[0056] The wound electrode body manufacturing apparatus 10 according to this embodiment includes a pressure roller 34 that presses the laminated sheet 2 wound around the arcuate surface portion 21b of the winding shaft 21 toward the arcuate surface portion 21b. According to this configuration, by pressing the laminated sheet 2 with the pressure roller 34, the shape of the laminated sheet 2 can be made to match the shape of the outer circumferential 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 during a part of the time during which the laminated sheet 2 is wound around the arcuate surface portion 21b. According to this control, when the laminated sheet 2 is wound around the arcuate surface portion 21b, the laminated sheet 2 can be fed by a length longer than the outer circumferential length according 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, the feed speed of the laminated sheet 2 is made faster than the speed at which the laminated sheet 2 is wound around the arcuate surface portion 21b during the latter half of the time (the time period shown in FIG. 5) during which the laminated sheet 2 is wound around the arcuate surface portion 21b.

[0058] In this embodiment, the feeding device 30 is configured to rotate while clamping the laminated sheet 2, and is equipped with a pair of nip rollers 31 that feed the laminated sheet 2 toward the reel 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 to each other to clamp the laminated sheet 2 or separates the pair of nip rollers 31 to release the laminated sheet 2, a pressure roller 34 that presses the laminated sheet 2 wound around the arcuate surface portion 21b of the reel 21 toward the arcuate surface portion 21b, a pressure roller drive device 35 that rotates the pressure roller 34, and a pressure roller moving device 37 that abuts the pressure roller 34 against the arcuate surface portion 21b or moves it away 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 during at least a part of the time during which the laminated sheet 2 is wound around the arcuate surface portion 21b, and controls the pressure roller moving device 37 and the pressure roller driving device 35 to rotate the pressure roller 34 in contact with the arcuate surface portion 21b. During the other time, the control device 50 controls the pressure roller moving device 37 to separate the pressure roller 34 from the winding shaft 21, and controls the nip roller moving device 33 and the nip roller driving device 32 to sandwich 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 wound around the winding shaft 21. The control device 50 sets the feeding speed of the laminated sheet 2 by the pressure roller 34 to be faster than the speed at which the laminated sheet 2 is wound around the arcuate surface portion 21b.

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

[0061] The wound electrode manufacturing apparatus 10 according to this embodiment starts pressing from a part of the pair of flat portions 2a of the laminate sheet 2, and performs pressing so that the pressing area expands toward the pair of R portions 2b of the laminate sheet 2. With this configuration, the gaps between the multiple laminate sheets 2 that existed in the flat portions 2a of the wound body of the laminate sheet 2 are eliminated by the above-mentioned process, and the gaps 1c of the desired gap G1 are formed between the multiple curved portions 2d. This makes it possible to further reduce the stress applied to the R portions 2b.

[0062] More specifically, the wound electrode body manufacturing apparatus 10 according to this embodiment further includes a press device 40 that presses the wound body of the laminated sheet 2 so as to press the pair of flat portions 2a together. The press device 40 includes a pair of opposing press members 41 that press the pair of flat portions 2a of the laminated sheet 2, respectively, and a pair of leaf springs 42 that are provided on the pair of press members 41, respectively, and are curved so as to convex toward the opposing press member 41 side. With this configuration, pressing can be started from a part of the pair of flat portions 2a of the laminated sheet 2, and the pressed area can be expanded toward the pair of R portions 2b of the laminated sheet 2.

[0063] In this embodiment, it is possible to obtain an electric storage device (here, a lithium ion secondary battery 100) including 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 parts 1a and a pair of arc-shaped R parts 1b connecting both sides of the pair of flat parts 1a. The laminated sheet 2 includes a plurality of curved parts 2d that form the R part 1b and are stacked in the radial direction of the R part 1b. Of the multiple curved parts 2d, the inner circumferential length of one curved part 2d is longer than the outer circumferential length of the curved part 2d that is one part on the inside of the one curved part 2d. According to the lithium ion secondary battery 100, the stress applied to the R part 1b of the wound electrode body 1 can be alleviated for the reasons described above.

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

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

[0066] [Other embodiments] An embodiment of the manufacturing device for a wound electrode body proposed here has been described above. However, the above embodiment is merely an example, and the present invention can be implemented in other ways. For example, in the above embodiment, the feed speed of the laminated sheet 2 is increased when the laminated sheet 2 is wound around the arc surface portion 21b of the winding shaft 21, so that the laminated sheet 2 is fed a length longer than the outer circumferential length corresponding to the number of turns of the laminated sheet 2 wound around 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 around the winding shaft 21 when the laminated sheet 2 is wound around the flat surface portion 21a of the winding shaft 21. Alternatively, the laminated sheet 2 may be fed and slackened in advance before the laminated sheet 2 is wound around the winding shaft 21.

[0067] In the above embodiment, the feeding device 30 is configured to rotate the pressure roller 34 and feed the laminated sheet 2 also by the pressure roller 34. However, the feeding device 30 may be configured to feed the laminated sheet 2 only by the pair of nip rollers 31. The pressure roller 34 may simply rotate passively, and may be omitted as long as the laminated sheet 2 can be wound around the reel 21 without the pressure roller 34.

[0068] In the above embodiment, the press device 40 is provided with a pair of leaf springs 42 for compressing the slack in the laminated sheet 2 from the center of the flat portion 2a toward the outside. However, the press device 40 does not have to be provided with a configuration for compressing the slack in the laminated sheet 2, such as the pair of leaf springs 42. Even if the slack in the laminated sheet 2 is not compressed to the R portion 2b, the effect of alleviating the stress applied to the R portion 2b can be achieved to some extent by feeding the laminated sheet 2 a length longer than the outer circumferential length corresponding to the number of turns of the laminated sheet 2.

[0069] In addition, the above-described embodiments do not limit the present invention unless otherwise specified. Furthermore, the technology disclosed herein can be modified in various ways, and the components and processes described herein can be omitted or combined as appropriate, provided that no particular problems arise.

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

[0071] Section 1: a winding process in which 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 peripheral surface including a pair of opposing flat surface portions and a pair of arcuate surface portions connecting both sides of the pair of flat surface portions is rotated, and the laminated sheet is wound around the outer peripheral surface of the winding shaft; a pressing step of pressing the laminated sheet formed into an oval shape in the winding step so as to press a pair of flat portions together, In the winding step, the laminated sheet is fed per rotation of the winding shaft by a length longer than an outer circumferential length corresponding to the number of turns of the laminated sheet wound around the winding shaft. A method for manufacturing a wound electrode body.

[0072] Section 2: In the winding step, when winding the laminated sheet on the arcuate surface portion, the laminated sheet is fed by a length longer than an outer circumferential length corresponding to the number of turns of the laminated sheet wound on the arcuate surface portion. Item 1. A method for producing a wound electrode body according to item 1.

[0073] Section 3: The pressing step includes a first pressing step in which pressing is started from a part of the pair of flat portions of the laminated sheet and pressing is performed so that a pressing area expands toward a pair of arc-shaped portions of the laminated sheet. Item 3. A method for producing a wound electrode body according to item 1 or 2.

[0074] Section 4: In the first pressing step, A pair of opposing press members that press the pair of flat portions of the laminated sheet, respectively; A press device having a pair of leaf springs provided on the pair of press members, each of which is curved so as to protrude toward the opposing press member, is used. Item 4. A method for producing a wound electrode body according to 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, the apparatus comprising: a winding shaft having an oval-shaped outer peripheral surface including a pair of opposing flat surface portions and a pair of arcuate surface portions connecting both sides of the pair of flat surface portions, the laminated sheet being wound around the outer peripheral surface; a reel drive device that rotates the reel; a feed device for feeding the laminated sheet toward the winding shaft; a control device that controls the reel drive device to control the rotation of the reel 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 an outer circumferential length corresponding to the number of turns of the laminated sheet wound around the winding shaft per one rotation of the winding shaft. Manufacturing equipment for wound electrode bodies.

[0076] Item 6: The laminated sheet is wound on the arcuate surface portion of the winding shaft. The laminated sheet is further provided with a pressing roller that presses the laminated sheet wound on the arcuate surface portion of the winding shaft toward the arcuate surface portion. Item 6. A manufacturing apparatus for a wound electrode body according to item 5.

[0077] Section 7: the control device controls the feed device during at least a portion of the time during which the laminated sheet is wound around the arcuate surface portion to make the feed speed of the laminated sheet faster than the speed at which the laminated sheet is wound around the arcuate surface portion; Item 7. A manufacturing apparatus for a wound electrode body according to item 5 or 6.

[0078] Section 8: The feeding device includes: a pair of nip rollers configured to rotate while holding the laminated sheet and 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 to each other to sandwich 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 portion of the winding shaft toward the arcuate surface portion; a pressure roller drive device that rotates the pressure roller; a pressure roller moving device that brings the pressure roller into contact with the arcuate surface portion or moves the pressure roller away from the arcuate surface portion, The control device includes: During at least a part of the time during which the laminated sheet is wound around the arcuate surface portion, the nip roller moving device is controlled to separate the pair of nip rollers, and the pressure roller moving device and the pressure roller driving device are controlled to rotate the pressure roller in contact with the arcuate surface portion; At another time, the pressing roller moving device is controlled to move the pressing roller away from the winding shaft, and the nip roller moving device and the nip roller driving device are controlled to sandwich the laminated sheet between the pair of nip rollers and feed the laminated sheet, 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 around the reel; a feeding speed of the laminated sheet by the pressing roller is set to be faster than a speed at which the laminated sheet is wound around the arcuate surface portion; Item 8. A manufacturing apparatus for a wound electrode body according to item 7.

[0079] Section 9: The laminated sheet is wound around the winding shaft to form an oval shape. The laminated sheet is pressed against the winding shaft by pressing a pair of flat portions of the laminated sheet together. The press device is A pair of opposing press members that press the pair of flat portions of the laminated sheet, respectively; A pair of leaf springs are provided on the pair of press members, respectively, and are curved so as to protrude toward the opposing press member. Item 9. A manufacturing apparatus for a wound electrode body according to any one of Items 5 to 8.

[0080] Section 10: a wound electrode body in which 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 wound 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 overlapped in a radial direction of the R portions, Among the plurality of curved portions, an inner circumferential length of one curved portion is longer than an outer circumferential length of a curved portion one position further inward than the one curved portion; Energy storage device.

[0081] Section 11: A gap is provided between the first curved portion and the inner curved portion. Item 11. The electricity storage device according to item 10.

[0082] Section 12: The laminated sheet includes a plurality of straight portions that are stacked to form the flat portion, The straight portions have equal lengths. Item 12. The electricity storage device according to item 10 or 11. [Explanation of symbols]

[0083] 1 Wound electrode body 1a Flat area 1b R section 1c Gap 2. Laminated Sheet 2a flat area 2b R section (arcuate section) 2c Straight section 2d Curved section 3 Positive electrode sheet 4. Negative electrode sheet 5 First separator sheet 6 Second separator sheet 10. Wound electrode body manufacturing equipment 20 Winding device 21 Reel 21a Flat surface part 21b Arc surface part 22 Reel drive unit 22a Rotation axis 22b Drive motor 23 Winding shaft moving device 23a Drive motor 30 Feeder 31 Nip roller 31a Axis 32 Nip roller drive unit 32a Drive motor 33 Nip roller moving device 34 Presser roller 35 Presser roller drive device 35a Rotation axis 35b Drive motor 36 Tracking device 36a Drive motor 37 Presser roller moving device 40 Press equipment 41 Press parts 42 Leaf spring 43 Drive unit 50 Control device 100 Lithium-ion secondary battery (energy storage device) G1 Gap S10 Winding process S20 Press process S21 First press process S22 Second pressing process

Claims

1. a winding process in which 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 peripheral surface including a pair of opposing flat surface portions and a pair of arcuate surface portions connecting both sides of the pair of flat surface portions is rotated, and the laminated sheet is wound around the outer peripheral surface of the winding shaft; a pressing step of pressing the laminated sheet formed into an oval shape in the winding step so as to press a pair of flat portions together, In the winding step, the laminated sheet is fed per rotation of the winding shaft by a length longer than an outer circumferential length corresponding to the number of turns of the laminated sheet wound around the winding shaft. A method for manufacturing a wound electrode body.

2. In the winding step, when winding the laminated sheet on the arcuate surface portion, the laminated sheet is fed by a length longer than an outer circumferential length corresponding to the number of turns of the laminated sheet wound on the arcuate surface portion. A method for manufacturing the wound electrode assembly according to claim 1 .

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

4. In the first pressing step, A pair of opposing press members that press the pair of flat portions of the laminated sheet, respectively; A press device having a pair of leaf springs provided on the pair of press members, each of which is curved so as to protrude toward the opposing press member, is used. A method for manufacturing the wound electrode assembly 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, the apparatus comprising: a winding shaft having an oval-shaped outer peripheral surface including a pair of opposing flat surface portions and a pair of arcuate surface portions connecting both sides of the pair of flat surface portions, the laminated sheet being wound around the outer peripheral surface; a reel drive device that rotates the reel; a feed device for feeding the laminated sheet toward the winding shaft; a control device that controls the reel drive device to control the rotation of the reel 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 an outer circumferential length corresponding to the number of turns of the laminated sheet wound around the winding shaft per one rotation of the winding shaft. Manufacturing equipment for wound electrode bodies.

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

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

8. The feeding device includes: a pair of nip rollers configured to rotate while holding the laminated sheet and 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 to each other to sandwich 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 portion of the winding shaft toward the arcuate surface portion; a pressure roller drive device that rotates the pressure roller; a pressure roller moving device that brings the pressure roller into contact with the arcuate surface portion or moves the pressure roller away from the arcuate surface portion, The control device includes: During at least a part of the time during which the laminated sheet is wound around the arcuate surface portion, the nip roller moving device is controlled to separate the pair of nip rollers, and the pressure roller moving device and the pressure roller driving device are controlled to rotate the pressure roller in contact with the arcuate surface portion; At another time, the pressing roller moving device is controlled to move the pressing roller away from the winding shaft, and the nip roller moving device and the nip roller driving device are controlled to sandwich the laminated sheet between the pair of nip rollers and feed the laminated sheet, 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 around the reel; a feeding speed of the laminated sheet by the pressing roller is set to be faster than a speed at which the laminated sheet is wound around the arcuate surface portion; An apparatus for manufacturing a wound electrode body according to claim 7.

9. The laminated sheet is wound around the winding shaft to form an oval shape. The laminated sheet is pressed against the winding shaft by pressing a pair of flat portions of the laminated sheet together. The press device is A pair of opposing press members that press the pair of flat portions of the laminated sheet, respectively; A pair of leaf springs are provided on the pair of press members, respectively, and are curved so as to protrude toward the opposing press member. An apparatus for manufacturing a wound electrode body according to claim 5.

10. 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 wound a plurality of times to form a wound electrode body; 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 overlapped in a radial direction of the R portions, Among the plurality of curved portions, an inner circumferential length of one curved portion is longer than an outer circumferential length of a curved portion one position on the inner side of the one curved portion, Energy storage device.

11. A gap is provided between the first curved portion and the inner curved portion. The power storage device according to claim 10.

12. The laminated sheet includes a plurality of straight portions that are stacked to form the flat portion, The straight portions have equal lengths. The power storage device according to claim 10.

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