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 for manufacturing a wound electrode body, an 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 assembly in which strip-shaped positive electrode sheets, negative electrode sheets, and separator sheets are stacked and wound. In the method described in Patent Document 1, a winding core is rotated 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, if each sheet is in a tension-free state after cutting or at the end of winding, the sheet may move and may not be wound properly. 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, which is wound last, all the way to the end of the winding. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-302034 Summary of the Invention [Problem to be solved by the invention]

[0004] When a roll of a sheet formed by winding the sheet around a reel is pressed to form the roll, 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 method for manufacturing a wound electrode assembly disclosed herein includes a winding step and a pressing step. In the winding step, a laminate sheet 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 is fed, and a winding shaft having an oval-shaped outer circumferential 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 laminate sheet around the outer circumferential surface of the winding shaft. In the winding step, the laminate sheet is fed per rotation of the winding shaft by a length longer than the outer circumferential length corresponding to the number of turns of the laminate sheet wound around the winding shaft. In the pressing step, the laminate sheet formed into an oval shape in the winding step is pressed so that the pair of flat portions are pressed together.

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

[0007] The presently disclosed device for manufacturing a wound electrode body is an apparatus for manufacturing a wound electrode body in which a laminate 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 device 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, around which the laminate sheet is wound, a winding shaft drive device for rotating the winding shaft, a feeding device for feeding the laminate sheet toward the winding shaft, and a control device for controlling the winding shaft drive device to control the rotation of the winding shaft and the feeding device to control the feed amount of the laminate sheet. The control device controls the feeding device to feed the laminate sheet per rotation of the winding shaft a length longer than the outer peripheral length corresponding to the number of turns of the laminate sheet wound around the winding shaft.

[0008] The above-described manufacturing device for a wound electrode body can achieve the same effects as the above-described manufacturing method for a wound electrode body.

[0009] The energy storage device disclosed herein includes a wound electrode body formed by winding a laminated sheet multiple times, the laminated sheet being made 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. The wound electrode body is wound into 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 of the R portions. Of the plurality of curved portions, the inner peripheral length of one curved portion is longer than the outer peripheral length of the curved portion immediately inside the first curved portion.

[0010] In the above-described electricity storage device, the inner periphery of one curved portion is longer than the outer periphery of the curved portion immediately inside it, and therefore, for the same reason as above, less stress is applied to the curved portion of the wound electrode body. [Brief explanation of the drawings]

[0011] [Figure 1]FIG. 2 is a schematic side view of a winding device and a feeding device. [Figure 2] FIG. 2 is a schematic front view of a press device. [Figure 3] 10 is a flowchart showing a part of the manufacturing process of the wound electrode body. [Figure 4] FIG. 10 is a side view of the winding device and the feeding device when the winding shaft is located at the 3 o'clock position. [Figure 5] FIG. 10 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. 10 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 INVENTION

[0012] Hereinafter, one embodiment of a manufacturing apparatus for manufacturing a wound electrode body for an electricity storage device will be described. Note that the embodiment described here is, of course, not intended to particularly limit the present invention. Furthermore, 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 portion of a wound electrode manufacturing apparatus 10 according to one embodiment, specifically a winding device 20 and a feeding device 30. FIG. 2 is a schematic front view of another portion of the wound electrode manufacturing apparatus 10, specifically a press 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 reel 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 press device 40 presses the oval-shaped laminated sheet 2 to further flatten it. 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] In this case, 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 the wound electrode body of various known electricity storage devices. The term "electricity storage device" refers to any device that can extract electrical 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. In a lithium-ion secondary battery, the positive electrode active material is, for example, a material such as a lithium transition metal composite material that can release lithium ions during charging and absorb lithium ions during discharging. 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. In a lithium-ion secondary battery, the negative electrode active material is, for example, a material such as natural graphite that can absorb lithium ions during charging and release the absorbed lithium ions during discharging. The positive electrode active material and the negative electrode active material are not particularly limited, and various materials other than those described 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 that has the required heat resistance and allows the electrolyte to pass through. Various separator materials have been proposed, and there is no particular limitation. 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, winding device 20 includes reel 21 around which laminate sheet 2 is wound, reel drive device 22 that rotates reel 21, and reel movement device 23 that moves reel 21 so that laminate sheet 2 hangs down in the direction of gravity before being wound around reel 21. Feeding device 30 includes a pair of nip rollers 31 that rotate while sandwiching laminate sheet 2, nip roller drive device 32 that rotates pair of nip rollers 31, nip roller movement device 33 that moves pair of nip rollers 31 toward or away from each other, pressure roller 34 that presses laminate sheet 2 toward reel 21, pressure roller drive device 35 that rotates pressure roller 34, follower device 36 that moves pressure roller 34 to follow the movement of reel 21, and pressure roller movement device 37 that moves pressure roller 34 toward or away from 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 reel 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 reel 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 laminate sheet 2 is wound around the outer peripheral surface of the reel 21. The depth direction of the paper in FIG. 1 is the width direction of the laminate sheet 2. Although not shown in the figure, the outer peripheral surface of the reel 21 has a predetermined width in the width direction of the laminate sheet 2 that is wider than the width of the laminate sheet 2.

[0019] The winding shaft 21 forms the laminate sheet 2 into an oval shape similar to the finished wound electrode body 1. Hereinafter, the laminate sheet 2 formed into an oval shape by winding it around the winding shaft 21 will also be referred to as a wound body of the laminate sheet 2. The laminate 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 laminate sheet 2 has a pair of opposing flat portions 2a and a pair of arc-shaped rounded 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 rounded portions 2b are formed by a pair of arc-shaped surface portions 21b of the winding shaft 21. The wound body of the laminate sheet 2 is also flat, and its longitudinal direction is the arrangement direction of the pair of rounded 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, 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). Furthermore, 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 each be referred to as a straight portion 2c. The flat portion 1a of the wound electrode body 1 is an assembly of multiple stacked straight portions 2c. 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 each be referred to as a curved portion 2d. The R portion 1b of the wound electrode body 1 is an assembly of multiple stacked curved portions 2d.

[0021] 1, reel drive device 22 rotates reel 21 around rotation axis 22a extending in the width direction of laminated sheet 2 (depth direction in the plane of FIG. 1). Reel drive device 22 is equipped with drive motor 22b that rotates reel 21. The rotation / stop, rotation speed, and rotation angle of drive motor 22b are controlled by 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 laminate 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 laminate 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 laminate sheet 2 when winding the laminate sheet 2 around the reel 21. Therefore, the laminate sheet 2 before being wound around the reel 21 sags in the direction of gravity.

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

[0024] The pair of nip rollers 31 of the feeding device 30 are configured to rotate while sandwiching the laminated sheet 2. The pair of nip rollers 31 feed the laminated sheet 2 toward the reel 21. Each of the pair of nip rollers 31 is 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 reel 21. The laminated sheet 2 fed by the pair of nip rollers 31 is not subjected to tension and therefore moves downward due to the action of gravity. The nip roller driving device 32 rotates the pair of nip rollers 31. Here, the nip roller driving device 32 includes a drive motor 32a that rotates one of the pair of nip rollers 31. The other nip roller 31 rotates in response to the rotation of the driven nip roller 31. However, the nip roller driving 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 moves the pair of nip rollers 31 closer to each other to clamp the laminated sheet 2, or moves the pair of nip rollers 31 apart to release the laminated sheet 2. In this example, 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 position in FIG. 1 and spaced apart 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 left and right. 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 a control device 50.

[0026] The pressure roller 34 presses the laminate sheet 2 wound around the arcuate surface 21b of the reel 21 toward the arcuate surface 21b. When pressed by the pressure roller 34, the laminate sheet 2, which includes a metal current collector foil, undergoes plastic deformation, and the shape of the laminate sheet 2 follows the shape of the outer circumferential surface of the reel 21. This allows the shape of the laminate sheet 2 to follow the shape of the outer circumferential surface of the reel 21 without applying tension to the laminate sheet 2.

[0027] The pressure roller drive device 35 rotates the pressure roller 34. The pressure roller drive 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 drive device 35 is equipped with a drive motor 35b that rotates the reel 21. The rotation / stop, rotation speed, and rotation angle of the drive motor 35b are controlled by a control device 50. The pressure roller 34 is configured to rotate by the driving force of the drive motor 35b. The pressure roller 34 is a member that conforms the shape of the laminated sheet 2 to the shape of the outer surface of the reel 21, and at the same time, it is a member that feeds the laminated sheet 2 over the arcuate surface portion 21b by its rotation. However, the pressure member that conforms the shape of the laminated sheet 2 to the shape of the outer surface of the reel 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 but bends in accordance with the movement of the arcuate surface portion 21b.

[0028] The tracking device 36 moves the pressure roller 34 so that it moves along the arcuate surface 21b in accordance with the movement of the arcuate surface 21b of the reel 21. By moving the pressure roller 34, the tracking device 36 keeps the pressure roller 34 in contact with the arcuate surface 21b, which moves due to the rotation of the reel 21 and the driving of the reel moving device 23. Here, the tracking 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 tracking 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 up and down 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 a 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 reel 21 or moves it away 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 reel 21 and a position to the right of that position in FIG. 1 where it does not come into contact with the reel 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 also controls the feeding device 30 to control the feed amount of the laminate sheet 2. Specifically, the control device 50 controls the feeding device 30 to feed the laminate sheet 2 by a length longer than the outer circumferential length corresponding to the number of turns of the laminate sheet 2 wound around the reel 21 per rotation of the reel 21. By feeding the laminate sheet 2 in this manner, the outer circumferential length of the laminate sheet 2 wound on the outside (hereinafter also referred to as the outer layer laminate sheet 2) becomes longer than the outer circumferential length of the laminate sheet 2 already wound around the reel 21 (hereinafter also referred to as the inner layer laminate sheet 2), and therefore a gap is generated between the inner layer laminate sheet 2 and the outer layer laminate sheet 2 with each 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 feeding device 30 with each increase in the number of turns of the laminate sheet 2. Here, the control device 50 calculates the length obtained by adding the increase in circumferential length due to the increase in the number of turns and a predetermined additional length for creating 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 creating a gap is constant regardless of the number of turns of the laminate sheet 2. However, the additional length for creating a gap does not have to be constant.

[0033] The additional length is set, for example, to a length that creates gaps 1c between the curved portions 2d of the laminated sheet 2, with gaps G1 equal to the thickness of the laminated sheet 2 multiplied by a predetermined magnification (see FIG. 7). The gaps 1c are the gaps after pressing. For example, if 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 magnification is preferably, for example, 30% or more and 100% or less. However, the magnification is not limited. In calculating the additional length, the gap G1 is considered to be an additional amount to 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 method for setting the additional length described above is merely an example and is not limited thereto.

[0034] In this embodiment, the control device 50 is configured to control the feeding device 30 to make the feeding speed of the laminate sheet 2 faster than the speed at which the laminate sheet 2 is wound around the arcuate surface portion 21b, at least during a portion of the time during which the laminate sheet 2 is being wound around the arcuate surface portion 21b. As a result, when the laminate sheet 2 is wound around the arcuate surface portion 21b, the laminate sheet 2 is fed a length longer than the outer circumferential length corresponding to the number of turns of the laminate sheet 2 wound around the arcuate surface portion 21b. As a result, gaps due to excess feeding of the laminate sheet 2 are likely to occur in the curved portion 2b of the wound laminate sheet 2. In this embodiment, the control device 50 is configured to make the speed at which the laminate sheet 2 is wound around the reel 21 and the feeding speed of the laminate sheet 2 the same during other times. As a result, gaps due to excess feeding of the laminate sheet 2 are reduced in the flat portion 2a of the laminate 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 for a portion of the time during which the laminated sheet 2 is being 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 while it is 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 set the feed 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.

[0036] At 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 it. 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 laminate sheet 2 so as to press the pair of flat portions 2a together. As shown in FIG. 2, the press device 40 includes a pair of opposing press members 41 that respectively press the pair of flat portions 2a of the laminate 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 laminate sheet 2. Each leaf spring 42 is curved so as to convex toward the opposing press member 41, and is positioned so that the apex of the convex portion is located at the center of the press member 41 (the center in the longitudinal direction of the roll of the laminate sheet 2). The press device 40 is configured so that the press members 41 press the flat portions 2a of the roll of the laminate sheet 2 via the leaf springs 42.

[0038] In this embodiment, the rolled laminate 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 laminate sheet 2 using a press member. However, the final pressing may also be performed by the press device 40. The press device 40 may constitute part or all of a broadly defined press device that presses the rolled laminate 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 flowchart showing 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 while a reel 21 having an oval-shaped outer peripheral surface is rotated to wind the laminated sheet 2 around the outer peripheral surface of the reel 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 that a pair of flat portions 2a are pressed together. The pressing process S20 includes a first pressing process S21 using a press device 40 and a second pressing process S22 using this press 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 points midway through 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 (toward 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 with a two-dot chain line. As shown in FIG. 1, the rotation direction of the winding shaft 21 is clockwise. 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, rotation of the reel 21 is started, and the nip roller 31 is rotated to feed the laminate sheet 2 onto the reel 21. As shown in FIG. 1, at this time, the pair of nip rollers 31 holds the laminate sheet 2 between them. In step S11, the nip roller 31 rotates so as to feed the laminate sheet 2 at the same speed as the speed at which the laminate sheet 2 is wound around the reel 21. By feeding the laminate sheet 2 at the same speed as the speed at which the laminate sheet 2 is wound around the reel 21, no tension is applied to the laminate 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 Figure 1, the position of end 21c of reel 21 relative to rotation axis 22a gradually moves to the right. In step S11, reel 21 is gradually moved to the left to maintain the lateral position of end 21c of reel 21 directly below the pair of nip rollers 31. This control allows the laminated sheet 2, which is drooping in the direction of gravity due to the absence of tension, to be wound around reel 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 reel 21 has reached the 3 o'clock position. If reel 21 has not reached the 3 o'clock position (the result of step S12 is NO), step S11 continues.

[0044] When the reel 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 its grip (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 reel 21, sandwiching the laminated sheet 2. Steps S13 and S14 may be performed in reverse order, or may be performed simultaneously.

[0045] In step S15, the reel 21 is rotated and the pressure roller 34 is rotated. In step S15, the formation of one of the rounded portions 2b by the arcuate surface portion 21b is primarily performed. As shown in FIG. 5, in step S15, the reel 21 is gradually moved to the right by the reel movement device 23. This maintains the lateral position of the end portion 21c of the reel 21 directly below the pair of nip rollers 31. At the same time, the pressure roller 34 is gradually moved downward by the tracking device 36. This causes the pressure roller 34 to move along the arcuate surface portion 21b in accordance with the movement of the arcuate surface portion 21b of the reel 21. As the pressure roller 34 moves over the arcuate surface portion 21b of the reel 21 with the laminated sheet 2 sandwiched between them, 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. Tension is applied to the laminate sheet 2 upstream of the pressure roller 34. However, tension is not applied to the laminate sheet 2 downstream of the pressure roller 34. In step S15, the pressure roller 34 rotates 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 reel 21 has reached the 6 o'clock position. If the reel 21 has not reached the 6 o'clock position (the result of step S16 is NO), step S15 continues. If the reel 21 has reached the 6 o'clock position (the result of step S16 is YES), in step S17, the pressure roller 34 is moved away from the reel 21 (see FIG. 6). Also in step S17, the pair of nip rollers 31 approaches each other, and the laminated sheet 2 is again sandwiched between the pair of nip rollers 31 (see FIG. 6). With the completion of step S17, the winding step S10 for one half rotation of the reel 21 is completed. The winding step S10 for the remaining half rotation is the same as the first half, and therefore will not be described here. The winding step S10 for one rotation is repeated, and the laminated sheet 2 is thereby wound around the reel 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 (here, the longitudinal center portion of the wound body), and pressing is performed so that the pressing area 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 press member 41 and the roll of the laminate sheet 2, it is gradually crushed from the apex of the convex portion outward. As a result, pressing begins from a portion (here, the center portion) of the pair of flat portions 2a of the laminate sheet 2, and the pressing area expands toward the pair of curved portions 2b of the laminate sheet 2. As a result, the gaps between the multiple laminate sheets 2 that existed in the flat portions 2a of the roll of the laminate sheet 2 are crushed. The excess laminate sheet 2 generated by the crushing of the gaps is absorbed by the multiple curved portions 2d. As a result, the gaps between the multiple curved portions 2d expand, and gaps 1c with a target gap value G1 are formed, as shown in FIG. 7. The first pressing step S21 is a step for concentrating the gaps in 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, 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 of the lithium-ion secondary battery 100 other than the wound electrode body 1 are omitted. As shown in FIG. 7, in the wound electrode body 1 after the pressing step S20, the straight portions 2c of the laminated sheet 2 are all equal in length, and there are almost no gaps between the straight portions 2c. In contrast, the inner peripheral length of one curved portion 2d is longer than the outer peripheral length of the curved portion 2d immediately inside it. A gap 1c with a gap G1 (target value) is formed between the first curved portion 2d and the curved portion 2d immediately inside 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 this embodiment is an apparatus for manufacturing a wound electrode 1 having a laminate sheet 2 wound thereon, the laminate sheet 2 being made up of 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 superimposed 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, around which the laminate sheet 2 is wound, a reel drive device 22 that rotates the reel 21, a feed device 30 that feeds the laminate 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 the feed device 30 to control the feed amount of the laminate sheet 2. The control device 50 controls the feed device 30 to feed the laminate sheet 2 per rotation of the reel 21 by a length longer than the outer peripheral length corresponding to the number of turns of the laminate sheet 2 wound around the reel 21.

[0054] With this wound electrode manufacturing apparatus 10, the laminate sheet 2 is fed per rotation of the reel 21 a distance longer than the outer circumferential length corresponding to the number of turns of the laminate sheet 2 wound around the reel 21, and therefore with each rotation of the reel 21 a gap is formed between the inner layer laminate sheet 2 already wound around the reel 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, with this wound electrode manufacturing apparatus 10, the stress applied to the curved 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 reel 21 under tension, no gap is formed between the inner and outer laminate sheets 2. Therefore, when the curved portion 2b of the laminate sheet 2 is deformed during the pressing process, a large stress is applied to the curved portion 2b of the laminate sheet 2. Furthermore, 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 curved portion 2b of the laminate sheet 2. Increasing the number of turns of the laminate sheet 2 to increase the capacity of the electricity storage device further increases the expansion and contraction of the wound electrode body 1. From the viewpoint of the durability and reliability of the curved portion 2b, it is preferable that the stress applied to the curved portion 2b of the laminate sheet 2 be small. According to the wound electrode body manufacturing apparatus 10 of this embodiment, a gap is formed between the inner and outer laminate sheets 2, thereby reducing the stress applied to the curved portion 2b of the laminate sheet 2.

[0056] The wound electrode manufacturing apparatus 10 according to this embodiment is equipped with 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. With 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 peripheral 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 being wound around the arcuate surface portion 21b. This control allows the laminated sheet 2 to be fed 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, slack occurs in the laminated sheet 2 wound around the arcuate surface portion 21b, forming a gap 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 during which the laminated sheet 2 is being wound around the arcuate surface portion 21b (the time period shown in FIG. 5 ).

[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 together 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] During at least a portion of the time during which the laminate sheet 2 is being wound around the arcuate surface portion 21b, the control device 50 controls the nip roller moving device 33 to separate the pair of nip rollers 31, and controls the pressure roller moving device 37 and the pressure roller driving device 35 to rotate the pressure roller 34 while it is in contact with the arcuate surface portion 21b. During the rest of the time, the control device 50 controls the pressure roller moving device 37 to separate the pressure roller 34 from the reel 21, and controls the nip roller moving device 33 and the nip roller driving device 32 to nip the laminate sheet 2 between the pair of nip rollers 31 and feed the laminate sheet 2. The control device 50 sets the feed speed of the laminate sheet 2 by the pair of nip rollers 31 to be the same as the speed at which the laminate sheet 2 is wound around the reel 21. The control device 50 sets the feed speed of the laminate sheet 2 by the pressure roller 34 to be faster than the speed at which the laminate 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 portion 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 curved 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 laminate sheet 2 are eliminated by the process described above, and 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 curved 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 laminate 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 laminate sheet 2, respectively, and a pair of leaf springs 42 that are provided on each of the pair of press members 41 and are curved so as to convexly face toward the opposing press member 41. With this configuration, pressing can be started from a part of the pair of flat portions 2a of the laminate sheet 2, and the pressed area can be expanded toward the pair of rounded portions 2b of the laminate sheet 2.

[0063] In this embodiment, an energy storage device (here, a lithium-ion secondary battery 100) can be obtained, which includes a wound electrode body 1 in which a laminate 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 into 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 laminate sheet 2 includes multiple curved portions 2d that form the R portions 1b and are overlapped in the radial direction of the R portions 1b. Of the multiple curved portions 2d, the inner circumferential length of one curved portion 2d is longer than the outer circumferential length of the curved portion 2d immediately inside the first curved portion 2d. With this lithium-ion secondary battery 100, stress applied to the R portions 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 thereof. 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, there is no difference in the lengths 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] The above describes one embodiment of the wound electrode manufacturing apparatus proposed herein. However, the above embodiment is merely an example, and other aspects are also possible. For example, in the above embodiment, the feed speed of the laminate sheet 2 is increased when winding the laminate sheet 2 around the arcuate surface portion 21b of the reel 21, thereby feeding the laminate sheet 2 a length longer than the outer circumferential length corresponding to the number of turns of the laminate sheet 2 wound around the reel 21. However, the feed speed of the laminate sheet 2 may be faster than the speed at which the laminate sheet 2 is wound around the reel 21 when winding the laminate sheet 2 around the flat surface portion 21a of the reel 21. Alternatively, the laminate sheet 2 may be fed and slackened in advance before being wound around the reel 21.

[0067] In the above-described 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 be driven to rotate, 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-described embodiment, the press device 40 is provided with a pair of leaf springs 42 for compressing the slack in the laminate sheet 2 from the center of the flat portion 2a outward. However, the press device 40 does not have to be provided with a configuration for compressing the slack in the laminate sheet 2, such as the pair of leaf springs 42. Even if the slack in the laminate sheet 2 is not compressed in 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 laminate sheet 2 a length longer than the outer periphery length corresponding to the number of turns of the laminate sheet 2.

[0069] 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 step of 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, while rotating a winding shaft having an oval-shaped outer peripheral surface that includes a pair of opposing flat surface portions and a pair of arcuate surface portions connecting both sides of the pair of flat surface portions, and winding the laminated sheet 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 reel by a length longer than the outer circumferential length corresponding to the number of turns of the laminated sheet wound around the reel. A method for manufacturing a wound electrode body.

[0072] Section 2: In the winding step, when the laminated sheet is wound around the arcuate surface, the laminated sheet is fed by a length longer than a circumferential length corresponding to the number of turns of the laminated sheet wound around the arcuate surface. Item 1. A method for manufacturing 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 the pressing area expands toward the pair of arc-shaped portions of the laminated sheet. Item 1 or 2. A method for producing a wound electrode body.

[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 pair of leaf springs provided on the pair of press members, respectively, and curved so as to convex toward the opposing press member; Item 4. A method for manufacturing 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, 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 outer peripheral surface around which the laminate sheet is wound; a reel drive device that rotates the reel; a feeding 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 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 circumferential length corresponding to the number of turns of the laminated sheet wound around the reel per rotation of the reel. Manufacturing equipment for wound electrode bodies.

[0076] Item 6: The winding machine further includes 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 feeding device to make the feeding speed of the laminated sheet faster than the speed at which the laminated sheet is wound around the arcuate surface, at least during a part of the time during which the laminated sheet is wound around the arcuate surface. Item 7. A manufacturing apparatus for a wound electrode body according to item 5 or 6.

[0078] Section 8: The feeding device is a pair of nip rollers configured to rotate while holding the laminated sheet and feed the laminated sheet toward the reel; a nip roller drive device that rotates 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 around the arcuate surface of the winding shaft toward the arcuate surface; a pressure roller drive device that rotates the pressure roller; a pressure roller moving device that causes the pressure roller to contact the arcuate surface portion or move away from the arcuate surface portion, The control device 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 a state of contact with the arcuate surface portion, At other times, the pressure roller moving device is controlled to move the pressure roller away from the winding shaft, and the nip roller moving device and the nip roller driving device are controlled to nip 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 reel and formed into an oval shape. The laminated sheet is pressed against the reel by a press device that presses 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 provided on the pair of press members, respectively, and curved so as to convex 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: The battery includes a wound electrode body in which a laminated sheet is wound multiple times, the laminated sheet being made up of 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 superimposed 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, 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 peripheral length of one curved portion is longer than an outer peripheral length of the curved portion immediately inside the one curved portion, Energy storage device.

[0081] Section 11: A gap is provided between the first curved portion and the next curved portion on the inside. 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 (arc-shaped 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 manufacturing equipment 20 Winding device 21 Reel 21a Flat surface part 21b Arc surface part 22 Reel drive device 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 device 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 Pressed 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 pressing process S22 Second pressing process

Claims

1. a winding step of 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, while rotating a winding shaft having an oval-shaped outer peripheral surface that includes a pair of opposing flat surface portions and a pair of arcuate surface portions connecting both sides of the pair of flat surface portions, and winding the laminated sheet 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, a roller for feeding the laminated sheet is rotated so that the feeding speed of the laminated sheet is faster than the speed at which the laminated sheet is wound around the arcuate surface portion during at least a part of the time during which the laminated sheet is wound around the arcuate surface portion, and the laminated sheet is fed per one rotation of the reel by a length longer than the outer circumferential length corresponding to the number of turns of the laminated sheet wound around the reel. A method for manufacturing a wound electrode body.

2. 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 the pair of arc-shaped portions of the laminated sheet. A method for manufacturing the wound electrode assembly according to claim 1 .

3. In the first pressing step, a pair of opposing press members that press the pair of flat portions of the laminated sheet, respectively; a pair of leaf springs provided on the pair of press members, respectively, and curved so as to convexly face the opposing press member; The method for manufacturing the wound electrode assembly according to claim 2 .

4. 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 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 laminate sheet being wound around the outer peripheral surface; a reel drive device that rotates the reel; a feeding 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 the feed device to control the feed amount of the laminated sheet, The feeding device is a roller for feeding the laminated sheet; a roller drive device that rotates the roller, the control device controls the roller drive device to rotate the roller so that the feed speed of the laminated sheet is faster than the speed at which the laminated sheet is wound around the arcuate surface portion, at least during a part of the time during which the laminated sheet is wound around the arcuate surface portion, and feeds the laminated sheet by a length per rotation of the reel that is longer than the outer circumferential length corresponding to the number of turns of the laminated sheet wound around the reel. Manufacturing equipment for wound electrode bodies.

5. The roller is a pressing roller that presses the laminated sheet wound on the arc surface portion of the reel toward the arc surface portion. The manufacturing apparatus for a wound electrode body according to claim 4.

6. The feeding device is a pair of nip rollers configured to rotate while sandwiching the laminated sheet and feed the laminated sheet toward the reel; a nip roller drive device that rotates 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 pressure roller moving device that causes the pressure roller to contact the arcuate surface portion or move away from the arcuate surface portion, The control device 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 roller driving device are controlled to rotate the pressure roller in a state of contact with the arcuate surface portion, At other times, the pressure roller moving device is controlled to move the pressure roller away from the winding shaft, and the nip roller moving device and the nip roller driving device are controlled to nip 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; The manufacturing apparatus for a wound electrode body according to claim 5 .

7. The laminated sheet is wound around the reel and formed into an oval shape. The laminated sheet is pressed against the reel by a press device that presses 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 provided on the pair of press members, respectively, and curved so as to convex toward the opposing press member; The manufacturing apparatus for a wound electrode body according to claim 4.

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