Method and apparatus for manufacturing wound electrode body, and power storage device

Abstract

The present invention relates to a method for manufacturing a wound electrode body, an apparatus for manufacturing a wound electrode body, and a power storage device provided with a wound electrode body, capable of relaxing stress applied to a bent portion of a wound electrode body. This method for manufacturing a wound electrode body comprises: a winding step in which a laminated sheet in which a belt-shaped positive electrode sheet, a negative electrode sheet, a first separator sheet, and a second separator sheet are stacked in a predetermined order is conveyed, and a reel having an elliptical outer peripheral surface is rotated to wind the laminated sheet around the outer peripheral surface of the reel, the elliptical outer peripheral surface is provided with a pair of flat surface parts which face each other and a pair of arc surface parts which connect the two sides of the pair of flat surface parts; and a pressing step for pressing the laminated sheet formed in the elliptical shape in the winding step so as to press the pair of flat portions. In the winding step, each time the reel rotates for one circle, a laminated sheet having a length longer than the outer circumference corresponding to the number of turns of the laminated sheet wound around the reel is conveyed.

Description

Technical Field

[0001] The present invention relates to a method for producing a wound electrode body, an apparatus for producing a wound electrode body, and an electric storage device including the wound electrode body. Background Art

[0002] For example, Japanese Patent Application Publication No. 2001-302034 discloses a method for manufacturing a lithium-ion secondary battery having a wound electrode body, wherein the wound electrode body is formed by overlapping and winding a strip-shaped positive electrode sheet, a negative electrode sheet, and a separator sheet. In the method described in Japanese Patent Application Publication No. 2001-302034, the winding core rotates while tension is applied to each sheet by a tension roller, thereby winding each sheet on the winding core. According to Japanese Patent Application Publication No. 2001-302034, after each sheet is cut and wound, in a tension-free state, there is a situation where the sheet becomes loose and cannot be wound well. Therefore, the winding device described in Japanese Patent Application Publication No. 2001-302034 is equipped with a support roller that always applies tension to the last wound positive electrode sheet until the winding of the terminal portion is completed.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2001-302034

[0004] When the rolled body of the sheet body formed by winding around the reel is punched and formed, the bent part of the sheet body is deformed. Therefore, during the punching, a large stress is applied to the bent part of the sheet body. The smaller the stress applied to the bent part of the sheet body, the better. Summary of the invention

[0005] The method for manufacturing a wound electrode body disclosed herein includes a winding process and a punching process. In the winding process, a laminated sheet having a strip-shaped positive electrode sheet, a strip-shaped negative electrode sheet, a strip-shaped first diaphragm sheet, and a strip-shaped second diaphragm sheet overlapped in a predetermined order is conveyed, and a reel having an elliptical outer peripheral surface is rotated to wind the laminated sheet on the outer peripheral surface of the reel, wherein the elliptical outer peripheral surface has a pair of opposed flat face portions and a pair of arc face portions connecting the two sides of the pair of flat face portions. In the winding process, when the reel rotates once, the laminated sheet having a length longer than the outer peripheral length corresponding to the number of rolls of the laminated sheet wound on the reel is conveyed. In the punching process, the laminated sheet formed into an elliptical shape in the winding process is punched by pushing a pair of flat portions.

[0006] According to the above-mentioned method for manufacturing a wound electrode body, in the winding process, when the reel rotates one circle, the laminated sheet is transported at a distance longer than the outer circumference corresponding to the number of rolls of the laminated sheet wound on the reel. Therefore, when the reel rotates one circle, a gap is generated between the laminated sheet already wound on the reel and the laminated sheet wound on the outside thereof. In the stamping process, the stamped laminated sheet can escape into the gap. Therefore, according to the above-mentioned method for manufacturing a wound electrode body, the stress applied to the bent portion of the laminated sheet formed by the arc surface of the reel in the stamping process can be alleviated.

[0007] In addition, the manufacturing device of the wound electrode body disclosed herein is a device for manufacturing a wound electrode body formed by winding a laminated sheet, wherein the laminated sheet is overlapped with 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, wherein the manufacturing device of the wound electrode body comprises: a reel having an elliptical outer peripheral surface and winding the laminated sheet on the outer peripheral surface, wherein the elliptical outer peripheral surface has a pair of opposed flat surface portions and a pair of arc surface portions connecting the two sides of the pair of flat surface portions; a reel driving device for rotating the reel; a conveying device for conveying the laminated sheet toward the reel; and a control device for controlling the reel driving device to control the rotation of the reel and controlling the conveying device to control the conveying amount of the laminated sheet. The control device controls the conveying device so that when the reel rotates once, the laminated sheet having a length longer than the outer peripheral length corresponding to the number of turns of the laminated sheet wound on the reel is conveyed.

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

[0009] The storage device disclosed herein has a wound electrode body formed by winding a laminated sheet multiple times, wherein the laminated sheet is overlapped with a strip-shaped positive electrode sheet, a strip-shaped negative electrode sheet, a strip-shaped first diaphragm sheet, and a strip-shaped second diaphragm sheet in a predetermined order. The wound electrode body is wound into an elliptical shape, and the elliptical shape has a pair of opposing flat portions and a pair of arc-shaped arc portions connecting the two sides of the pair of flat portions. The laminated sheet includes a plurality of curved portions that form the arc-shaped portion and overlap in the radial direction of the arc-shaped portion. The inner circumference of one of the plurality of curved portions is longer than the outer circumference of the curved portion immediately inside the one curved portion.

[0010] In the above-mentioned electric storage device, the inner circumference of one curved portion is longer than the outer circumference of the curved portion immediately inside the curved portion. Therefore, for the same reason as above, the stress applied to the curved portion of the wound electrode body is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1is a schematic side view of a winding device and a conveying device.

[0012] Figure 2 It is a schematic front view of the punching device.

[0013] Figure 3 This is a flow chart showing a part of the manufacturing process of the wound electrode body.

[0014] Figure 4 It is a side view of the winding device and the conveying device when the reel is at the 3 o'clock position.

[0015] Figure 5 It is a side view of the winding device and the conveying device when the reel is located between the 3 o'clock position and the 6 o'clock position.

[0016] Figure 6 It is a side view of the winding device and the conveying device when the reel is at the 6 o'clock position.

[0017] Figure 7 is a schematic cross-sectional view of a lithium-ion secondary battery.

[0018] Description of Reference Numerals

[0019] 1… wound electrode body; 1a… flat portion; 1b… arcuate portion; 1c… gap; 2… laminated sheet; 2a… flat portion; 2b… arcuate portion (arc-shaped portion); 2c… straight portion; 2d… curved portion; 3… positive electrode sheet; 4… negative electrode sheet; 5… first diaphragm sheet; 6… second diaphragm sheet; 10… wound electrode body manufacturing device; 20… winding device; 21… reel; 21a… flat surface; 21b… arcuate surface; 22… reel drive device; 22a… rotating shaft; 22b… drive motor; 23… reel moving device; 23a… drive motor; 30… conveying device; 31… clamping roller ; 31a…axis line; 32…clamping roller driving device; 32a…driving motor; 33…clamping roller moving device; 34…pressing roller; 35…pressing roller driving device; 35a…rotating shaft; 35b…driving motor; 36…following device; 36a…driving motor; 37…pressing roller moving device; 40…stamping device; 41…stamping component; 42…leaf spring; 43…driving unit; 50…control device; 100…lithium ion secondary battery (electricity storage device); G1…gap; S10…winding process; S20…stamping process; S21…first stamping process; S22…second stamping process. DETAILED DESCRIPTION

[0020] Hereinafter, an embodiment of a manufacturing apparatus for manufacturing a wound electrode body of an electrical storage device will be described. It is to be understood that the embodiment described here is not intended to limit the present invention in particular. In addition, each of the drawings is a schematic diagram and does not necessarily reflect the actual implementation components.

[0021] [Structure of wound electrode body manufacturing apparatus]

[0022] Figure 1 It is a schematic side view of a part of a wound electrode body production apparatus 10 according to one embodiment, specifically, a winding apparatus 20 and a conveying apparatus 30 . Figure 2 FIG. 1 is a schematic front view of another part of the wound electrode body manufacturing device 10, specifically, a punching device 40. The wound electrode body manufacturing device 10 according to the present embodiment is a device for manufacturing a wound electrode body 1 (see FIG. 1 ) in which the laminated sheets 2 are wound. Figure 7 ) device, the laminated sheet 2 is overlapped with 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 in a predetermined order. The winding device 20 winds the laminated sheet 2 multiple times on the outer peripheral surface of the winding shaft 21 and forms the laminated sheet 2 into an elliptical shape. The conveying device 30 conveys the laminated sheet 2 according to the action of the winding device 20. The punching device 40 punches the laminated sheet 2 formed into an elliptical shape and further forms it into a flat shape. The wound electrode body manufacturing device 10 also has a formal punching device (not shown) for further punching the wound electrode body 1 punched by the punching device 40.

[0023] Here, the wound electrode assembly manufacturing apparatus 10 manufactures a lithium ion secondary battery 100 (see Figure 7 ) is a wound electrode body 1 of a power generation element. 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 power storage devices. The power storage device is a term for all devices that can extract electrical energy, including so-called storage batteries (chemical batteries) such as lithium ion secondary batteries and nickel-metal hydride batteries, and capacitors (physical batteries) such as double-layer capacitors.

[0024] The positive electrode sheet 3 is a component having a positive electrode active material layer formed on the surface of a strip-shaped collector foil (e.g., aluminum foil) of a predetermined width and thickness. In a lithium-ion secondary battery, the positive electrode active material is a material that can release lithium ions during charging and absorb lithium ions during discharge, such as a lithium transition metal composite material. The negative electrode sheet 4 is a component having a negative electrode active material layer formed on the surface of a strip-shaped collector foil (e.g., copper foil) of a predetermined width and thickness. In a lithium-ion secondary battery, the negative electrode active material is a material that can absorb lithium ions during charging and release the lithium ions absorbed during discharge, such as natural graphite. In addition to the above-mentioned materials, various positive electrode active materials and negative electrode active materials have been proposed and are not particularly limited.

[0025] The first separator sheet 5 and the second separator sheet 6 are composed of, for example, a porous resin sheet having the required heat resistance and capable of allowing electrolyte to pass. Various materials for the separator are proposed, and are not particularly limited. Here, the wound electrode body 1 is wound in such a way that the negative electrode sheet 4 becomes the outermost circumference, and the laminated sheet 2 formed by stacking the first separator sheet 5, the positive electrode sheet 3, the second separator sheet 6, and the negative electrode sheet 4 in sequence is wound.

[0026] like Figure 1 As shown, the winding device 20 comprises: a reel 21, on which the laminated sheet 2 is wound around the outer circumference; a reel driving device 22, which rotates the reel 21; and a reel moving device 23, which moves the reel 21 in such a way that the laminated sheet 2 before being wound on the reel 21 droops in the direction of gravity. The conveying device 30 comprises: a pair of clamping rollers 31, which clamp the laminated sheet 2 and rotate; a clamping roller driving device 32, which rotates the pair of clamping rollers 31; a clamping roller moving device 33, which moves the pair of clamping rollers 31 closer to or farther away from the reel 21; a pressing roller 34, which presses the laminated sheet 2 toward the reel 21; a pressing roller driving device 35, which rotates the pressing roller 34; a following device 36, which moves the pressing roller 34 in such a way as to follow the movement of the reel 21; and a pressing roller moving device 37, which makes the pressing roller 34 contact or separate from the reel 21. As shown in FIG. Figure 1 As shown, the wound electrode body production apparatus 10 includes a control device 50 that controls the operations of the winding device 20 and the conveying device 30 .

[0027] The reel 21 has an elliptical outer peripheral surface, which has a pair of opposed flat surface parts 21a and a pair of arc surface parts 21b connecting the two sides of the pair of flat surface parts 21a. The reel 21 is configured in a flat shape in which the distance between the pair of arc surface parts 21b is longer than the distance between the pair of flat surface parts 21a. The laminated sheet 2 is wound around the outer peripheral surface of the reel 21. Figure 1 The paper depth direction 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 wider than the width of the laminated sheet 2 in the width direction of the laminated sheet 2.

[0028] The winding shaft 21 forms the laminated sheet 2 into an elliptical shape close to the finished wound electrode body 1. Hereinafter, the laminated sheet 2 formed into an elliptical shape by winding on the winding shaft 21 is also referred to as a wound body of the laminated sheet 2. The laminated sheet 2 is formed into a wound body having a shape corresponding to the outer peripheral surface of the winding shaft 21. Figure 2 As shown, the roll of the laminated sheet 2 has a pair of opposed flat portions 2a and a pair of arc-shaped arc portions 2b connecting the two 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 reel 21. The pair of arc-shaped portions 2b are formed by a pair of arc surface portions 21b of the reel 21. The roll of the laminated sheet 2 is also flat, and its long side direction is the arrangement direction of the pair of arc-shaped portions 2b.

[0029] In addition, in order to distinguish the flat portion 2a and the arc-shaped portion 2b of the wound body of the laminated sheet 2 before punching, the flat portion and the arc-shaped portion of the wound electrode body 1 after the punching process are respectively represented as a pair of flat portions 1a and arc-shaped portions 1b (see Figure 7 ). In addition, in the wound electrode body 1 after punching, the multiple flat portions of the laminated sheets 2 that overlap and form the flat portion 1a are respectively referred to as straight portions 2c. The flat portion 1a of the wound electrode body 1 is a collection of multiple overlapping straight portions 2c. And, in the wound electrode body 1 after punching, the multiple curved portions of the laminated sheets 2 that overlap in the radial direction of the arc-shaped portion 1b and form the arc-shaped portion 1b are respectively represented as curved portions 2d. The arc-shaped portion 1b of the wound electrode body 1 is a collection of multiple overlapping curved portions 2d.

[0030] like Figure 1 As shown, the reel drive device 22 causes the reel 21 to reel in the width direction ( Figure 1 The reel drive device 22 is provided with a drive motor 22b for rotating the reel 21. The rotation / stop, rotation speed and rotation angle of the drive motor 22b are controlled by the control device 50.

[0031] The reel moving device 23 moves the reel 21 in accordance with the rotation of the reel 21 so that the terminal end of the portion of the laminated sheet 2 wound around the reel 21 is continuously located directly below the clamping roller 31. The specific behavior of the reel 21 will be described later. Figure 1 and Figures 4 to 6 By moving the reel 21 by the reel moving device 23, the conveying direction of the laminated sheet 2 wound in front of the reel 21 becomes the direction of gravity. The wound electrode body manufacturing device 10 involved in this embodiment does not apply tension to the laminated sheet 2 when winding the laminated sheet 2 on the reel 21, and the details will be described later. Therefore, the laminated sheet 2 wound in front of the reel 21 sags in the direction of gravity.

[0032] The reel moving device 23 includes, for example, a sliding guide (not shown) so as to be able to Figure 1 The reel moving device 23 is provided with a rotating shaft 22a of the reel 21 in a manner that the reel 21 slides in the left-right direction; a driving motor 23a is used to move the rotating shaft 22a along the sliding guide; and a ball screw mechanism (not shown) is connected to the driving motor 23a. However, the structure of the reel moving device 23 is not particularly limited. The driving / stopping, the rotation speed and the rotation angle of the driving motor 23a are controlled by the control device 50.

[0033] A pair of clamping rollers 31 of the conveying device 30 is configured to clamp the laminated sheet 2 and rotate. The pair of clamping rollers 31 convey the laminated sheet 2 toward the reel 21. The pair of clamping rollers 31 are respectively configured to be able to rotate around an axis 31a extending in the width direction of the laminated sheet 2. The pair of clamping rollers 31 are arranged at a position above the reel 21. The laminated sheet 2 conveyed by the pair of clamping rollers 31 is not subjected to tension, so it moves downward by the action of gravity. The clamping roller driving device 32 rotates the pair of clamping rollers 31. Here, the clamping roller driving device 32 is provided with a driving motor 32a that rotates one of the pair of clamping rollers 31. The other clamping roller 31 rotates in a driven manner according to the rotation of the driven clamping roller 31. However, the clamping roller driving device 32 may also be configured to drive both of the pair of clamping rollers 31. The driving / stopping, rotation speed and rotation angle of the driving motor 32a are controlled by the control device 50.

[0034] The clamping roller moving device 33 moves the pair of clamping rollers 31 closer to clamp the laminated sheet 2, or separates the pair of clamping rollers 31 to release the laminated sheet 2. Here, the clamping roller moving device 33 moves the left clamping roller 31. The left clamping roller 31 is at a position where it can clamp the laminated sheet 2 together with the right clamping roller 31, and is offset from this position. Figure 1 The clamping roller moving device 33 moves between a position to the left of the clamping roller 31 and separated from the clamping roller 31 on the right. The clamping roller moving device 33, for example, includes a cylinder (not shown) that moves the clamping roller 31 on the left to the left and right. However, the clamping roller 31 moved by the clamping roller moving device 33 may be the clamping roller 31 on the right, or may be the clamping roller 31 on both the left and right. In addition, the clamping roller moving device 33 is not limited to a device driven by a cylinder. The structure of the clamping roller moving device 33 is not particularly limited. The operation of the clamping roller moving device 33 is controlled by the control device 50.

[0035] The pressing roller 34 presses the laminated sheet 2 wound on the arc surface 21b of the winding shaft 21 toward the arc surface 21b. The laminated sheet 2 including the metal collector foil is plastically deformed by being pressed by the pressing roller 34, and the shape of the laminated sheet 2 follows the shape of the outer peripheral surface of the winding shaft 21. Thus, the shape of the laminated sheet 2 can follow the shape of the outer peripheral surface of the winding shaft 21 without applying tension to the laminated sheet 2.

[0036] The pressing roller driving device 35 rotates the pressing roller 34. The pressing roller driving device 35 rotates the pressing roller 34 around a rotating shaft 35a extending in the width direction of the laminated sheet 2. The pressing roller driving device 35 includes a driving motor 35b for rotating the pressing roller 34. The rotation / stop, rotation speed and rotation angle of the driving motor 35b are controlled by the control device 50. In this way, the pressing roller 34 is configured to rotate with the driving force of the driving motor 35b. The pressing roller 34 is a component for making the shape of the laminated sheet 2 follow the shape of the outer peripheral surface of the reel 21, and is also a component for conveying the laminated sheet 2 on the arc surface 21b by its rotation. However, the pressing component for making the shape of the laminated sheet 2 follow the shape of the outer peripheral surface of the reel 21 may have nothing to do with the conveying of the laminated sheet 2. The pressing component may also be a plate-shaped component that follows the movement of the arc surface 21b and flexes without rotating.

[0037] The following device 36 moves the pressing roller 34 in a manner that moves along the arc surface 21b in accordance with the movement of the arc surface 21b of the reel 21. The following device 36 moves the pressing roller 34 so that the pressing roller 34 is continuously in contact with the arc surface 21b that is moved by the rotation of the reel 21 and the drive of the reel moving device 23. Here, the following device 36 brings the pressing roller 34 into contact with the reel 21 during a period of approximately half a rotation of the laminated sheet 2 wound around the reel 21. The timing when the following device 36 brings the pressing roller 34 into contact with the reel 21 will be described later.

[0038] The following device 36 includes, for example, a sliding guide (not shown) with which the pressing roller 34 is engaged in a manner that allows sliding in the up-down direction; a driving motor 36a for moving the pressing roller 34 along the sliding guide; and a ball screw mechanism (not shown) connected to the driving motor 36a. However, the structure of the following device 36 is not particularly limited. The driving / stopping, rotation speed, and rotation angle of the driving motor 36a are controlled by the control device 50.

[0039] The pressing roller moving device 37 causes the pressing roller 34 to contact the arc surface 21b of the winding shaft 21 or to separate from the arc surface 21b. The pressing roller moving device 37 causes the pressing roller 34 to contact the winding shaft 21 directly below the clamping roller 31 or to move away from the arc surface 21b. Figure 1 The pressing roller moving device 37 is configured to move the pressing roller 34 to the right of the roller 34 and not in contact with the reel 21. The pressing roller moving device 37 includes, for example, an air cylinder (not shown) for moving the pressing roller 34 in the left-right direction. However, the structure of the pressing roller moving device 37 is not particularly limited. The operation of the pressing roller moving device 37 is controlled by the control device 50.

[0040] The control device 50 controls the reel drive device 22 to control the rotation of the reel 21, and controls the conveying device 30 to control the conveying amount of the laminated sheet 2. Specifically, the control device 50 controls the conveying device 30 so that the laminated sheet 2 having a length longer than the outer circumference corresponding to the number of rolls of the laminated sheet 2 wound on the reel 21 can be conveyed every time the reel 21 rotates one circle. By conveying the laminated sheet 2 in this way, the circumference of the laminated sheet 2 wound on the outside (hereinafter also referred to as the outer layer laminated sheet 2) becomes longer than the outer circumference of the laminated sheet 2 already wound on 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 every time the reel 21 rotates one circle. The effect of the gap will be described later.

[0041] As the number of rolls increases, the outer circumference of the laminated sheet 2 wound on the reel 21 becomes longer. As the number of rolls of the laminated sheet 2 increases, the control device 50 lengthens the length of the laminated sheet 2 conveyed by the conveying device 30. Here, the control device 50 calculates the length of the circumference increase caused by the increase in the number of rolls and the additional length specified for generating the gap and the circumference of the inner layer laminated sheet 2, and uses it as the length of the outer layer laminated sheet 2. In this embodiment, the additional length for generating the gap is constant regardless of the number of rolls of the laminated sheet 2. However, the additional length for generating the gap may not be constant.

[0042] The 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 factor is generated between the plurality of bent portions 2d of the laminated sheet 2 (see Figure 7 ). In addition, the gap 1c is a gap after punching. 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, not less than 30% and not more than 100%. However, the above-mentioned magnification is not limited. In the calculation of the additional length, the gap G1 is regarded as the 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 the pi (since the curved portion 2d exists on both sides, it is twice). However, the above-mentioned method of setting the additional length is an example and is not limited to this.

[0043] In the present embodiment, the control device 50 is configured to control the conveying device 30 to make the conveying speed of the laminate 2 faster than the speed of winding the laminate 2 on the arc surface 21b at least in a part of the time when the laminate 2 is wound on the arc surface 21b. Thus, when the laminate 2 is wound on the arc surface 21b, the laminate 2 having a length longer than the outer circumference corresponding to the number of rolls of the laminate 2 wound on the arc surface 21b is conveyed. As a result, a gap caused by the excess amount of the laminate 2 being conveyed can be easily formed in the arc-shaped portion 2b of the winding body of the laminate 2. In the present embodiment, the control device 50 is configured to make the speed of winding the laminate 2 on the reel 21 the same as the conveying speed of the laminate 2 at other times. Thus, the gap caused by the excess amount of the laminate 2 being conveyed is reduced in the flat portion 2a of the laminate 2.

[0044] In more detail, the control device 50 controls the clamping roller moving device 33 to separate the pair of clamping rollers 31 at least for a portion of the time when the laminated sheet 2 is wound around the arc surface 21b. At the same time, the control device 50 controls the pressing roller moving device 37 and the pressing roller driving device 35 to rotate the pressing roller 34 in a state of contact with the arc surface 21b. In this state, the conveying speed of the laminated sheet 2 is controlled by the rotation speed of the pressing roller 34. The control device 50 is configured to make the conveying speed of the laminated sheet 2 by the pressing roller 34 faster than the speed of winding the laminated sheet 2 around the arc surface 21b.

[0045] In addition, the control device 50 controls the pressing roller moving device 37 to separate the pressing roller 34 from the reel 21 at other times. At the same time, the control device 50 controls the clamping roller moving device 33 and the clamping roller driving device 32 to clamp and convey the laminated sheet 2 with the pair of clamping rollers 31. In this state, the conveying speed of the laminated sheet 2 is controlled by the rotation speed of the clamping rollers 31. The control device 50 is configured to make the conveying speed of the laminated sheet 2 by the pair of clamping rollers 31 the same as the speed of winding the laminated sheet 2 on the reel 21.

[0046] The punching device 40 punches the wound body of the laminated sheet 2 by pushing the pair of flat portions 2a. Figure 2 As shown, the punching device 40 includes: a pair of opposing punching parts 41, which respectively press a pair of flat portions 2a of the laminated sheet 2; a pair of leaf springs 42, which are respectively provided on the pair of punching parts 41; and a driving part 43, which makes the pair of punching parts 41 approach and punch the laminated sheet 2. Each leaf spring 42 is configured to be bent in a manner convex toward one side of the opposing punching parts 41, and the vertex of the convex portion is located at the center of the punching part 41 (the center of the long side direction of the wound body of the laminated sheet 2). The punching device 40 is configured to press the flat portion 2a of the wound body of the laminated sheet 2 through the punching parts 41 via the leaf springs 42.

[0047] In this embodiment, the wound body of the laminated sheet 2 after the punching is further punched by a formal punching device different from the punching device 40, and is compressed to a predetermined thickness. The formal punching device does not have a leaf spring, but punches the laminated sheet 2 by a punching member. However, the final punching can also be performed by the punching device 40. The punching device 40 can constitute a part of a broad punching device that punches the wound body of the laminated sheet 2 by pushing a pair of flat portions 2a to form the wound electrode body 1, or it can constitute the whole.

[0048] [Wound Electrode Body Manufacturing Process]

[0049] Figure 3 1 is a flow chart showing a part of the manufacturing process of the wound electrode body 1. Figure 3 As shown, the manufacturing process of the wound electrode body 1 includes: a winding process S10, conveying a laminated sheet 2 formed by stacking 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 in a predetermined order, and rotating a reel 21 having an elliptical outer peripheral surface to wind the laminated sheet 2 on the outer peripheral surface of the reel 21; and a punching process S20, punching the laminated sheet 2 (the wound body of the laminated sheet 2) formed into an elliptical shape in the winding process S10 by pushing a pair of flat portions 2a. The punching process S20 includes a first punching process S21 using a punching device 40, and a second punching process S22 using a formal punching device.

[0050] First, the details of the winding step S10 will be described. Figures 4 to 6 FIG. 2 is a side view of the winding device 20 and the conveying device 30 at a time in the middle of the winding process S10. Figure 1 The direction in which the end 21 c (here, one arc surface portion 21 b ) of the spool 21 facing upward (in the direction of 0 o'clock) is directed indicates the rotational position of the spool 21 . Figure 1 The winding device 20 and the conveying device 30 are shown when the reel 21 is at the zero position. Figure 1 In FIG. 1 , the reel 21 is also shown by a two-dot chain line in a state where it is slightly rotated from the 0 o'clock position. Figure 1 As shown, the rotation direction of the reel 21 is clockwise. Figure 4 The winding device 20 and the conveying device 30 are shown when the reel 21 is located at the 3 o'clock position. Figure 5 The winding device 20 and the conveying device 30 are shown when the winding shaft 21 is located between the 3 o'clock position and the 6 o'clock position. Figure 6 The winding device 20 and the conveying device 30 are shown when the reel 21 is located at the 6 o'clock position.

[0051] like Figure 3As shown, the winding process S10 includes steps S11 to S17. In step S11, the rotation of the winding shaft 21 is started, and the clamping roller 31 is rotated to convey the laminated sheet 2 to the winding shaft 21. Figure 1 As shown, at this time, the pair of clamping rollers 31 clamp the laminated sheet 2. In step S11, the clamping rollers 31 rotate in such a manner that the laminated sheet 2 is conveyed at the same speed as the speed at which the laminated sheet 2 is wound around the reel 21. By conveying the laminated sheet 2 at the same speed as the speed at which the laminated sheet 2 is wound around the reel 21, no tension is applied to the laminated sheet 2. Figure 1 As shown, at this time, the pressing roller 34 retreats to the right position.

[0052] In step S11, Figure 1 As shown in FIG. 1 , the position of the end portion 21c relative to the rotation axis 22a of the reel 21 gradually moves to the right. In step S11, the reel 21 is gradually moved to the left in order to maintain the left and right positions of the end portion 21c of the reel 21 directly below the pair of clamping rollers 31. By this control, the laminated sheet 2 that sags in the direction of gravity due to the lack of tension is wound around the reel 21. In step S11, one flat portion 2a is formed by the flat surface portion 21a.

[0053] In step S12, it is determined whether the reel 21 has reached the 3 o'clock position. If the reel 21 has not reached the 3 o'clock position (if the result of step S12 is NO), the process proceeds to step S11.

[0054] If the reel 21 reaches the 3 o'clock position (if the result of step S12 is yes), then in step S13, the pair of clamping rollers 31 separate and release the clamping rollers 31 from the laminated sheet 2 (see Figure 4 ). In step S14, as Figure 4 As shown, the pressing roller 34 moves to the left, sandwiches the laminated sheet 2, and comes into contact with the arc surface 21b of the winding shaft 21. Steps S13 and S14 may be performed in reverse order or simultaneously.

[0055] In step S15, the reel 21 is rotated and the pressing roller 34 is rotated. In step S15, the arc-shaped portion 2b is formed mainly by the arc surface portion 21b. Figure 5 As shown, in step S15, the reel 21 is gradually moved to the right by the reel moving device 23. Thus, the left and right positions of the end 21c of the reel 21 are maintained directly below the pair of clamping rollers 31. At the same time, the pressing roller 34 is gradually moved downward by the following device 36. Thus, the pressing roller 34 moves along the arc surface 21b according to the movement of the arc surface 21b of the reel 21. The pressing roller 34 moves on the arc surface 21b of the reel 21 while sandwiching the laminated sheet 2, so that the laminated sheet 2 is formed into a shape imitating the arc surface 21b.

[0056] In step S15, the pressing roller 34 rotates to convey the laminated sheet 2 downward. At a position on the upstream side of the pressing roller 34, tension is applied to the laminated sheet 2. However, at a position on the downstream side of the pressing roller 34, no tension is applied to the laminated sheet 2. In step S15, the pressing roller 34 rotates in a manner that conveys the laminated sheet 2 at a speed faster than the speed at which the laminated sheet 2 is wound on the reel 21. As a result, looseness is generated in the laminated sheet 2 wound on the arc surface 21b. Through this control, the shape of the laminated sheet 2 can be arranged into an arc shape, and a gap can be formed between the curved portion 2d of the inner layer and the curved portion 2d of the outer layer.

[0057] 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 (if the result of step S16 is No), the process proceeds to step S15. If the reel 21 has reached the 6 o'clock position (if the result of step S16 is Yes), in step S17, the pressing roller 34 is separated from the reel 21 (refer to Figure 6 ). In addition, in step S17, the pair of clamping rollers 31 approach each other, and the laminated sheet 2 is clamped again by the pair of clamping rollers 31 (refer to Figure 6 ). With the completion of step S17, the winding process S10 of half a rotation of the reel 21 is completed. The winding process S10 of the remaining half a rotation is the same as the first half, so the description is omitted. The winding process S10 of one rotation is repeated, thereby winding the laminated sheet 2 on the reel 21 multiple times.

[0058] In the first punching step S21, punching starts from a portion of a pair of flat portions 2a of the stacking sheet 2 (here, the central portion in the long side direction of the winding body), and punching is performed in a manner such that the punching area expands toward a pair of arc-shaped portions 2b of the stacking sheet 2 formed into an elliptical shape.

[0059] In the first stamping process S21, if the leaf spring 42 is clamped by the stamping component 41 and the wound body of the laminated sheet 2, it is slowly compressed from the top of the convex portion toward the outside. Thus, stamping starts from a part of a pair of flat portions 2a of the laminated sheet 2 (here, the central portion), and the stamping area expands toward a pair of arc-shaped portions 2b of the laminated sheet 2. As a result, the gaps between the multiple laminated sheets 2 that also exist in the flat portion 2a of the wound body of the laminated sheet 2 are squeezed out. The excess laminated sheets 2 generated by squeezing out the gaps are absorbed by the multiple bent portions 2d. As a result, the gaps between the multiple bent portions 2d are enlarged, as shown in FIG. Figure 7 As shown, a gap 1c having a target gap value G1 is formed. The first pressing step S21 is a step for gathering the gaps at the arc-shaped portion 1b.

[0060] In the second punching step S22 , the wound body of the laminated sheet 2 is further punched out until it reaches a predetermined thickness. Thus, the wound electrode body 1 is formed.

[0061] Figure 7 FIG. 1 is a schematic cross-sectional view of a lithium-ion secondary battery 100 including a wound electrode body 1. Figure 7 In the figure, components other than the wound electrode body 1 of the lithium ion secondary battery 100 are omitted from the figure. Figure 7 As shown, in the wound electrode body 1 after the stamping step S20, the lengths of the plurality of straight portions 2c of the laminated sheet 2 are equal, and there is almost no gap between the plurality of straight portions 2c. In contrast, the inner circumference of one curved portion 2d is longer than the outer circumference of the curved portion 2d immediately inside it. A gap 1c having a gap of G1 (target value) is formed between one curved portion 2d and the curved portion 2d immediately inside it.

[0062] [Effects of the Embodiments]

[0063] Hereinafter, 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 the present embodiment will be described.

[0064] The wound electrode body manufacturing device 10 involved in the present embodiment is a device for manufacturing a wound electrode body 1 formed by winding a laminated sheet 2, wherein the laminated sheet 2 is overlapped with 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 in a predetermined order, wherein the wound electrode body manufacturing device 10 comprises: a winding shaft 21 having an elliptical outer peripheral surface and winding the laminated sheet 2 around the outer peripheral surface, the elliptical outer peripheral surface having a pair of opposing flat surface portions 21a and a pair of arc surface portions 21b connecting the two sides of the pair of flat surface portions 21a; a winding shaft driving device 22 for rotating the winding shaft 21; a conveying device 30 for conveying the laminated sheet 2 toward the winding shaft 21; and a control device 50 for controlling the winding shaft driving device 22 to control the rotation of the winding shaft 21, and controlling the conveying device 30 to control the conveying amount of the laminated sheet 2. The control device 50 controls the conveying device 30 so that the laminated sheet 2 having a length longer than the outer circumference corresponding to the number of turns of the laminated sheet 2 wound around the reel 21 is conveyed every time the reel 21 rotates once.

[0065] According to the wound electrode body manufacturing device 10, when the winding shaft 21 rotates once, the laminated sheet 2 is fed by a distance longer than the outer perimeter corresponding to the number of turns of the laminated sheet 2 wound on the winding shaft 21, so that when the winding shaft 21 rotates once, a gap is generated between the inner layer laminated sheet 2 already wound on the winding shaft 21 and the outer layer laminated sheet 2 wound on the outside thereof. In the punching step S20, the punched laminated sheet 2 escapes into the gap. Therefore, according to the wound electrode body manufacturing device 10, the stress applied to the arc-shaped portion 2b of the laminated sheet 2 in the punching step S20 can be alleviated.

[0066] If tension is applied to the laminated sheet 2 and the laminated sheet 2 is wound on the reel 21, no gap is generated between the inner laminated sheet 2 and the outer laminated sheet 2. Therefore, if the arcuate portion 2b of the laminated sheet 2 is deformed in the punching process, a large stress is applied to the arcuate portion 2b of the laminated sheet 2. In addition, the wound electrode body 1 expands and contracts during the charging and discharging of the storage device. The expansion and contraction of the wound electrode body 1 also applies a large stress to the arcuate portion 2b of the laminated sheet 2. If an attempt is made to increase the number of turns of the laminated sheet 2 to increase the capacity of the storage device, the expansion and contraction of the wound electrode body 1 becomes further increased. From the viewpoint of durability and reliability of the arcuate portion 2b, it is preferred that the stress applied to the arcuate portion 2b of the laminated sheet 2 is small. According to the wound electrode body manufacturing device 10 involved in this embodiment, by forming a gap between the inner laminated sheet 2 and the outer laminated sheet 2, the stress applied to the arcuate portion 2b of the laminated sheet 2 can be alleviated.

[0067] The wound electrode body manufacturing apparatus 10 according to the present embodiment includes a pressing roller 34 that presses the laminated sheet 2 wound on the arc surface 21b of the winding shaft 21 toward the arc surface 21b. According to this structure, by pressing the laminated sheet 2 with the pressing roller 34, the shape of the laminated sheet 2 can be made to follow the shape of the outer peripheral surface of the winding shaft 21 without applying tension to the laminated sheet 2.

[0068] In the present embodiment, the control device 50 controls the conveying device 30 so that the conveying speed of the laminated sheet 2 is faster than the speed of winding the laminated sheet 2 on the circular arc surface 21b, at least in a part of the time when the laminated sheet 2 is wound on the circular arc surface 21b. According to this control, when the laminated sheet 2 is wound on the circular arc surface 21b, the laminated sheet 2 having a length longer than the outer circumference corresponding to the number of rolls of the laminated sheet 2 wound on the circular arc surface 21b can be conveyed. As a result, the laminated sheet 2 wound on the circular arc surface 21b becomes loose, so that a gap can be formed between the curved portion 2d of the inner layer and the curved portion 2d of the outer layer. Here, in the second half of the time when the laminated sheet 2 is wound on the circular arc surface 21b ( Figure 5 The conveying speed of the laminated sheet 2 is made faster than the speed of winding the laminated sheet 2 around the arc surface portion 21b.

[0069] In the present embodiment, the conveying device 30 comprises: a pair of clamping rollers 31, which are configured to clamp the laminated sheet 2 and rotate, and convey the laminated sheet 2 toward the reel 21; a clamping roller driving device 32, which rotates the pair of clamping rollers 31; a clamping roller moving device 33, which brings the pair of clamping rollers 31 closer to clamp the laminated sheet 2, or separates the pair of clamping rollers 31 to release the laminated sheet 2; a pressing roller 34, which presses the laminated sheet 2 wound on the arc surface 21b of the reel 21 toward the arc surface 21b; a pressing roller driving device 35, which rotates the pressing roller 34; and a pressing roller moving device 37, which makes the pressing roller 34 abut against the arc surface 21b, or separates from the arc surface 21b.

[0070] The control device 50 controls the clamping roller moving device 33 to separate the pair of clamping rollers 31 at least in a part of the time when the laminated sheet 2 is wound on the arc surface 21b, and controls the pressing roller moving device 37 and the pressing roller driving device 35 to rotate the pressing roller 34 in a state of contact with the arc surface 21b. At other times, the control device 50 controls the pressing roller moving device 37 to separate the pressing roller 34 from the reel 21, and controls the clamping roller moving device 33 and the clamping roller driving device 32 to clamp and convey the pair of clamping rollers 31. The control device 50 makes the conveying speed of the pair of clamping rollers 31 for the laminated sheet 2 the same as the speed of winding the laminated sheet 2 on the reel 21. The control device 50 makes the conveying speed of the pressing roller 34 for the laminated sheet 2 faster than the speed of winding the laminated sheet 2 on the arc surface 21b.

[0071] According to this structure, at least in a part of the time when the laminated sheet 2 is wound around the arc surface 21b, the conveying speed of the laminated sheet 2 is controlled according to the rotation speed of the pressing roller 34. Therefore, by controlling the rotation speed of the pressing roller 34 in the above-mentioned part of the time, the conveying speed of the laminated sheet 2 can be made faster than the speed of winding the laminated sheet 2 around the arc surface 21b.

[0072] The wound electrode body manufacturing device 10 according to the present embodiment starts punching from a part of a pair of flat portions 2a of the laminated sheet 2, and punches in a manner that the punching area expands toward a pair of arc-shaped portions 2b of the laminated sheet 2. According to this structure, through the above-mentioned process, the gaps between the plurality of laminated sheets 2 that also exist in the flat portion 2a of the wound body of the laminated sheet 2 are squeezed out, thereby forming the gap 1c of the desired gap G1 between the plurality of curved portions 2d. As a result, the stress applied to the arc-shaped portion 2b can be further alleviated.

[0073] In more detail, the wound electrode body manufacturing device 10 according to the present embodiment further includes a punching device 40, which punches the wound body of the laminated sheet 2 in a manner of pushing the pair of flat portions 2a. The punching device 40 includes: a pair of punching parts 41, which respectively press the pair of flat portions 2a of the laminated sheet 2 and are opposed to each other; and a pair of leaf springs 42, which are respectively provided on the pair of punching parts 41 and are bent in a manner of convex toward one side of the opposed punching parts 41. According to this structure, it is possible to start punching from a part of the pair of flat portions 2a of the laminated sheet 2, and to expand the punching area toward the pair of arc-shaped portions 2b of the laminated sheet 2.

[0074] In the present embodiment, a storage device (here, a lithium ion secondary battery 100) having a wound electrode body 1 can be obtained, wherein the wound electrode body 1 is wound with a laminated sheet 2 multiple times, and the laminated sheet 2 is overlapped with 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 in a predetermined order. In the lithium ion secondary battery 100 involved in the present embodiment, the wound electrode body 1 is wound into an elliptical shape, and the elliptical shape has a pair of opposing flat portions 1a, and a pair of arc-shaped arc portions 1b that connect the two sides of the pair of flat portions 1a. The laminated sheet 2 includes a plurality of curved portions 2d that form the arc portion 1b and overlap in the radial direction of the arc portion 1b. The inner circumference of one of the plurality of curved portions 2d is longer than the outer circumference of the curved portion 2d that is adjacent to the inner side of the one curved portion 2d. According to the lithium ion secondary battery 100 , the stress applied to the arc-shaped portion 1 b of the wound electrode body 1 can be relaxed for the reasons described above.

[0075] In the lithium ion secondary battery 100 according to the present embodiment, a gap 1c is provided between one curved portion 2d and the curved portion 2d immediately inside thereof. According to the lithium ion secondary battery 100, stress applied to the arcuate portion 1b of the wound electrode body 1 can be relaxed for the reasons described above.

[0076] In the lithium-ion secondary battery 100 involved in this embodiment, the laminate 2 includes a plurality of straight portions 2c that overlap to form a flat portion 1a. The lengths of the plurality of straight portions 2c are equal. According to this structure, even if the laminate 2 expands and contracts due to the charging and discharging of the lithium-ion secondary battery 100, the lengths of the plurality of straight portions 2c will not differ. Therefore, it is not easy to generate gaps (peeling) between the plurality of straight portions 2c, and the lithium-ion secondary battery 100 is not easy to deteriorate.

[0077] [Other embodiments]

[0078] In the above, an embodiment of the manufacturing device of the wound electrode body proposed here is described. However, the above embodiment is only an example and can also be implemented in other ways. For example, in the above embodiment, when the laminated sheet 2 is wound on the arc surface 21b of the reel 21, the conveying speed of the laminated sheet 2 is increased, thereby conveying the laminated sheet 2 having a length longer than the outer circumference corresponding to the number of rolls of the laminated sheet 2 wound on the reel 21. However, when the laminated sheet 2 is wound on the flat surface 21a of the reel 21, the conveying speed of the laminated sheet 2 can also be faster than the speed of winding the laminated sheet 2 on the reel 21. Alternatively, the laminated sheet 2 can be conveyed in advance and relaxed before winding the laminated sheet 2 on the reel 21.

[0079] In the above-mentioned embodiment, the conveying device 30 is configured to rotate the pressing roller 34 and convey the laminated sheet 2 by the pressing roller 34. However, the conveying device 30 may be configured to convey the laminated sheet 2 only by the pair of clamping rollers 31. The pressing roller 34 may be rotated only in a driven manner, and may be omitted if the laminated sheet 2 can be wound around the reel 21 without the pressing roller 34.

[0080] In the above-mentioned embodiment, the punching device 40 is provided with a pair of leaf springs 42 for gathering the looseness of the laminated sheet 2 from the central portion of the flat portion 2a toward the outside. However, the punching device 40 may not be provided with a structure for gathering the looseness of the laminated sheet 2, such as a pair of leaf springs 42. Even if the looseness of the laminated sheet 2 is not gathered at the arc-shaped portion 2b, by conveying the laminated sheet 2 having a length longer than the outer circumference corresponding to the number of turns of the laminated sheet 2, the stress applied to the arc-shaped portion 2b can be relieved to a certain extent.

[0081] In addition, the above-mentioned embodiments do not limit the present invention unless otherwise specified. In addition, the technology disclosed herein can be modified in various ways, and each component and each process described herein can be appropriately omitted or appropriately combined as long as no particular problem occurs.

[0082] This specification includes the disclosure described in the following items.

[0083] Item 1:

[0084] A method for manufacturing a wound electrode body, wherein the method for manufacturing the wound electrode body comprises: a winding step of conveying a laminated sheet having 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 overlapped in a predetermined order, and rotating a reel having an elliptical outer peripheral surface to wind the laminated sheet around the outer peripheral surface of the reel, wherein the elliptical outer peripheral surface has a pair of opposing flat surface portions and a pair of arc surface portions connecting the two sides of the pair of flat surface portions; and a punching step of punching the laminated sheet formed into an elliptical shape in the winding step by pushing a pair of flat portions, wherein in the winding step, when the reel rotates one circle, the laminated sheet having a length longer than the outer peripheral length corresponding to the number of turns of the laminated sheet wound around the reel is conveyed.

[0085] Item 2:

[0086] According to the method for manufacturing a wound electrode body described in item 1, in the winding step, when the stacked sheet is wound around the arc surface, the stacked sheet is fed to have a length longer than the outer circumference corresponding to the number of turns of the stacked sheet wound around the arc surface.

[0087] Item 3:

[0088] A method for manufacturing a wound electrode body according to item 1 or 2, wherein the stamping process includes a first stamping process, in which stamping is started from a portion of the pair of flat portions of the stacked sheet, and stamping is performed in a manner such that the stamping area expands toward a pair of arc-shaped portions of the stacked sheet.

[0089] Item 4:

[0090] According to the method for manufacturing a wound electrode body described in item 3, in the above-mentioned first stamping step, a stamping device is used, which comprises: a pair of opposing stamping parts, respectively pressing the above-mentioned pair of flat portions of the above-mentioned stacked sheets; and a pair of leaf springs, respectively arranged on the above-mentioned pair of stamping parts and bent in a manner of convex toward one side of the opposing stamping parts.

[0091] Item 5:

[0092] A device for manufacturing a wound electrode body is a device for manufacturing a wound electrode body with a laminated sheet, wherein the laminated sheet is overlapped with 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, wherein the device for manufacturing the wound electrode body comprises: a winding shaft having an elliptical outer peripheral surface and winding the laminated sheet on the outer peripheral surface, the elliptical outer peripheral surface having a pair of opposing flat surface portions and a pair of arc surface portions connecting the two sides of the pair of flat surface portions; a winding shaft driving device for rotating the winding shaft; a conveying device for conveying 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 controlling the conveying device to control the conveying amount of the laminated sheet, wherein the control device controls the conveying device to convey the laminated sheet having a length longer than the outer peripheral length corresponding to the number of turns of the laminated sheet wound on the winding shaft each time the winding shaft rotates one circle.

[0093] Item 6:

[0094] The apparatus for producing a wound electrode body according to Item 5, further comprising a pressing roller for pressing the laminated sheet wound around the arcuate surface of the winding shaft toward the arcuate surface.

[0095] Item 7:

[0096] A device for manufacturing a wound electrode body according to item 5 or 6, wherein, during at least a portion of the time when the stacked sheet is wound around the arc surface, the control device controls the conveying device so that the conveying speed of the stacked sheet is faster than the speed of winding the stacked sheet around the arc surface.

[0097] Item 8:

[0098] According to the manufacturing device of the wound electrode body recorded in item 7, the above-mentioned conveying device comprises: a pair of clamping rollers, which are configured to clamp the above-mentioned laminated sheet and rotate, and convey the above-mentioned laminated sheet toward the above-mentioned winding shaft; a clamping roller driving device to rotate the above-mentioned pair of clamping rollers; a clamping roller moving device to bring the above-mentioned pair of clamping rollers closer to clamp the above-mentioned laminated sheet, or to separate the above-mentioned pair of clamping rollers to release the above-mentioned laminated sheet; a pressing roller, which presses the above-mentioned laminated sheet on the above-mentioned arc surface wound on the above-mentioned winding shaft toward the above-mentioned arc surface; a pressing roller driving device to rotate the above-mentioned pressing roller; and a pressing roller moving device to make the above-mentioned pressing roller abut against the above-mentioned arc surface, or to separate from the above-mentioned arc surface, and the above-mentioned control device is configured to: at least when the above-mentioned laminated sheet is being conveyed to the winding shaft During a part of the time when the sheet is wound on the arc surface, the clamping roller moving device is controlled to separate the pair of clamping rollers, and the pressing roller moving device and the pressing roller driving device are controlled to rotate the pressing roller in contact with the arc surface. During the rest of the time, the pressing roller moving device is controlled to separate the pressing roller from the reel, and the clamping roller moving device and the clamping roller driving device are controlled to clamp and convey the stacked sheet, so that the conveying speed of the pair of clamping rollers for the stacked sheet is the same as the speed of winding the stacked sheet on the reel, and the conveying speed of the pressing roller for the stacked sheet is faster than the speed of winding the stacked sheet on the arc surface.

[0099] Item 9:

[0100] A device for manufacturing a wound electrode body according to any one of items 5 to 8, which further comprises a punching device for punching the stacked sheet formed into an elliptical shape by winding on the winding shaft by pushing a pair of flat portions, the punching device comprising: a pair of opposing punching parts for respectively pressing the pair of flat portions of the stacked sheet; and a pair of leaf springs respectively arranged on the pair of punching parts and bent in a manner protruding toward one side of the opposing punching parts.

[0101] Item 10:

[0102] A storage device, comprising a wound electrode body wound with multiple layers of laminated sheets, wherein the laminated sheets are overlapped with 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 elliptical shape, the elliptical shape having a pair of opposing flat portions, and a pair of arc-shaped arc portions connecting the two sides of the pair of flat portions, the laminated sheets include a plurality of curved portions forming the arc portions and overlapping in the radial direction of the arc portions, and the inner circumference of one of the plurality of curved portions is longer than the outer circumference of a curved portion adjacent to the inner side of the one curved portion.

[0103] Item 11:

[0104] The power storage device according to Item 10, wherein a gap is provided between the one bent portion and the bent portion immediately inside the one bent portion.

[0105] Item 12:

[0106] The power storage device according to item 10 or 11, wherein the laminated sheet includes a plurality of straight portions which are overlapped to form the flat portion, and the plurality of straight portions have the same length.

Claims

1. A method for producing a wound electrode body, wherein: The method for manufacturing the wound electrode body comprises: A winding step of conveying a laminated sheet on 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 overlapped in a predetermined order, and rotating a reel having an elliptical outer peripheral surface to wind the laminated sheet around the outer peripheral surface of the reel, wherein the elliptical outer peripheral surface has a pair of opposed flat surface portions and a pair of arc surface portions connecting both sides of the pair of flat surface portions; and a punching step of punching the laminated sheet formed into an elliptical shape in the winding step by pressing a pair of flat portions, In the winding step, the laminated sheet having a length longer than the outer circumference corresponding to the number of turns of the laminated sheet wound around the winding shaft is fed every time the winding shaft rotates once.

2. The method for producing a wound electrode body according to claim 1, wherein: In the winding step, when the laminated sheet is wound around the arcuate surface portion, the laminated sheet is fed to have a length longer than the outer circumference corresponding to the number of turns of the laminated sheet wound around the arcuate surface portion.

3. The method for producing a wound electrode body according to claim 1, wherein: The punching step includes a first punching step in which punching is started from a part of the pair of flat portions of the laminated sheet and punching is performed so that a punching area spreads toward a pair of arc-shaped portions of the laminated sheet.

4. The method for producing a wound electrode body according to claim 3, wherein: In the first punching step, a punching device is used, and the punching device has: a pair of opposing punching members, respectively pressing the pair of flat portions of the laminated sheet; and A pair of leaf springs are respectively provided on the pair of punching parts and are bent in a manner of protruding toward one side of the opposing punching parts.

5. A device for manufacturing a wound electrode body, the device being a device for manufacturing a wound electrode body formed by winding a laminated sheet, wherein the laminated sheet is stacked in a predetermined order with 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, wherein: The wound electrode assembly manufacturing apparatus includes: A reel having an elliptical outer peripheral surface and on which the laminated sheet is wound, wherein the elliptical outer peripheral surface has a pair of opposed flat surface portions and a pair of arc surface portions connecting both sides of the pair of flat surface portions; A reel driving device for rotating the reel; a conveying device for conveying the laminated sheets toward the reel; as well as a control device for controlling the reel drive device to control the rotation of the reel and controlling the conveying device to control the conveying amount of the laminated sheet, The control device controls the conveying device so as to convey the laminated sheet having a length longer than the outer circumference corresponding to the number of turns of the laminated sheet wound around the reel every time the reel rotates once.

6. The apparatus for producing a wound electrode body according to claim 5, wherein: The invention further includes a pressing roller that presses the laminated sheet wound around the arcuate surface of the winding shaft toward the arcuate surface.

7. The apparatus for producing a wound electrode body according to claim 5, wherein: At least in a part of the time when the laminated sheet is wound around the arcuate surface, the control device controls the conveying device so that the conveying speed of the laminated sheet is faster than the speed of winding the laminated sheet around the arcuate surface.

8. The apparatus for producing a wound electrode body according to claim 7, wherein: The conveying device comprises: a pair of clamping rollers configured to clamp the laminated sheet and rotate to convey the laminated sheet toward the reel; A clamping roller driving device causes the pair of clamping rollers to rotate; A clamping roller moving device, which moves the pair of clamping rollers closer to clamp the laminated sheet, or separates the pair of clamping rollers to release the laminated sheet; a pressing roller for pressing the laminated sheet wound on the circular arc surface of the reel toward the circular arc surface; A pressing roller driving device for rotating the pressing roller; as well as A pressing roller moving device is provided to make the pressing roller contact with the arc surface part or separate from the arc surface part. The control device is composed of: At least during a portion of the time when the laminated sheet is wound around the arc surface, the clamping roller moving device is controlled to separate the pair of clamping rollers, and the pressing roller moving device and the pressing roller driving device are controlled to rotate the pressing roller in contact with the arc surface. At other times, the pressing roller moving device is controlled to separate the pressing roller from the reel, and the clamping roller moving device and the clamping roller driving device are controlled to clamp and convey the laminated sheet with the pair of clamping rollers. The conveying speed of the laminated sheet by the pair of clamping rollers is made equal to the speed at which the laminated sheet is wound around the reel. The conveyance speed of the laminated sheet by the pressing roller is set to be faster than the speed of winding the laminated sheet around the arcuate surface portion.

9. The apparatus for producing a wound electrode body according to claim 5, wherein: A punching device is further provided for punching the laminated sheet formed into an elliptical shape by winding around the reel so as to press a pair of flat portions. The punching device comprises: a pair of opposing punching members, respectively pressing the pair of flat portions of the laminated sheet; and A pair of leaf springs are respectively provided on the pair of punching parts and are bent in a manner of protruding toward one side of the opposing punching parts.

10. An electric storage device, wherein: A wound electrode body is provided in which a laminated sheet is wound multiple times, wherein a strip-shaped positive electrode sheet, a strip-shaped negative electrode sheet, a strip-shaped first separator sheet, and a strip-shaped second separator sheet are stacked in a predetermined order. The wound electrode body is wound in an elliptical shape having a pair of opposed flat portions and a pair of arc-shaped arc portions connecting both sides of the pair of flat portions, and the laminated sheet includes a plurality of curved portions that form the arc portions and overlap in a radial direction of the arc portions. The inner circumference of one of the plurality of curved portions is longer than the outer circumference of a curved portion immediately inside the one curved portion.

11. The power storage device according to claim 10, wherein A gap is provided between the one curved portion and the curved portion immediately inside the one curved portion.

12. The power storage device according to claim 10, wherein The laminate sheet includes a plurality of straight portions that overlap to form the flat portion, The plurality of straight portions have the same length.

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