Winding core and winding device

Abstract

To provide a winding core and a winding device that can reduce the acceleration and deceleration speed during rotation, while preventing looseness of a material on the innermost periphery.SOLUTION: A winding core of an embodiment extends along a first central axis C1 that is the center of rotation. The winding core has a pair of outer peripheral surfaces 42 formed at a predetermined radius of curvature, and a pair of corner parts 41 extending along the first central axis C1 at symmetrical positions in a circumferential direction. Belt-like materials 101, 102, 103, 104 are wound around the outer peripheral surfaces 42 of the winding core.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a winding core and a winding device. [Background technology]

[0002] A winding device is known that winds a plurality of foil-like strip materials in a stacked state to produce a wound body. The winding device includes a winding core. The winding device rotates the winding core to wind the material for the wound body around the winding core and complete the wound body. The shape of such winding cores can be broadly divided into circular and non-circular shapes, each of which has advantages and disadvantages.

[0003] For example, a circular core can be wound at a high speed because there is little need to change the speed when it rotates. However, there is a high possibility that the material on the innermost periphery will loosen after winding is completed, and there is a high possibility that the material on the innermost periphery will crease after the wound body is pressed.

[0004] Although a non-circular core is less likely to loosen the material at the innermost periphery, fluctuations in foil speed occur, resulting in large accelerations and decelerations in the rotation of the core. For this reason, non-circular cores require core rotation control to suppress foil speed fluctuations while achieving a high winding speed.

[0005] Therefore, there is a demand for a winding core that can reduce acceleration and deceleration while suppressing loosening of the innermost circumference. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2017-091667 [Patent Document 2] Japanese Patent Application Publication No. 2021-160895 Summary of the Invention [Problem to be solved by the invention]

[0007] The problem to be solved by the present invention is to provide a winding core and a winding device that can reduce acceleration and deceleration during rotation while suppressing loosening of the material at the innermost periphery. [Means for solving the problem]

[0008] The winding core of the embodiment extends along a first central axis that is the center of rotation. The winding core has a pair of outer peripheral surfaces formed with a predetermined radius of curvature and a pair of corners that extend along the first central axis at circumferentially symmetrical positions. A strip-shaped material is wound around the outer peripheral surface of the winding core. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an explanatory diagram that schematically shows the configuration of an example of a winding device according to an embodiment. [Figure 2] FIG. 2 is a block diagram showing an example of a control configuration of the winding device according to the embodiment. [Figure 3] FIG. 3 is a cross-sectional view that schematically shows the configuration of a winding core of the winding device according to the embodiment. [Figure 4] FIG. 4 is an explanatory view schematically illustrating an example of a wound body produced using the winding core according to the embodiment. [Figure 5] FIG. 5 is an explanatory diagram that schematically shows the configuration of the winding core according to the embodiment. [Figure 6] FIG. 6 is a flow chart showing an example of a method for manufacturing a wound body using the winding device according to the embodiment. [Figure 7] FIG. 7 is a cross-sectional view that schematically shows the configuration of the winding core according to Comparative Example 1. As shown in FIG. [Figure 8] FIG. 8 is a cross-sectional view that schematically shows the configuration of the winding core according to Comparative Example 2. As shown in FIG. [Figure 9] FIG. 9 is a cross-sectional view schematically showing the configuration of the winding core according to Comparative Example 3. As shown in FIG. [Figure 10] FIG. 10 is a cross-sectional view schematically showing the configuration of the winding core according to Comparative Example 4. As shown in FIG. [Figure 11] FIG. 11 is an explanatory view schematically illustrating an example of a wound body manufactured using the winding core according to Comparative Example 1. As shown in FIG. [Figure 12] FIG. 12 is an explanatory diagram showing an example of winding a material using a winding core according to the embodiment. [Figure 13] FIG. 13 is an explanatory diagram showing an example of winding a material using a winding core according to Comparative Example 2. As shown in FIG. [Figure 14] FIG. 14 is an explanatory diagram showing the relationship between the winding shaft speed and the foil speed with respect to the winding shaft angle of the winding core according to the embodiment. [Figure 15] FIG. 15 is an explanatory diagram showing the relationship between the winding shaft speed and the foil speed and the winding shaft angle of the winding core according to Comparative Example 2. [Figure 16] FIG. 16 is an explanatory diagram showing the relationship between the winding shaft speed and the foil speed with respect to the winding shaft angle of the winding core according to the embodiment. [Figure 17] FIG. 17 is an explanatory diagram showing the relationship between the winding shaft speed and the foil speed and the winding shaft angle of the winding core according to Comparative Example 2. [Figure 18] FIG. 18 is an explanatory diagram showing the results of an evaluation test of the winding core according to the embodiment and the winding core according to Comparative Example 1. [Figure 19] FIG. 19 is an explanatory diagram showing the state of the material at the innermost periphery of the wound body produced using the winding core according to the embodiment. [Figure 20] FIG. 20 is an explanatory diagram showing the state of the material at the innermost periphery of the wound body produced using the winding core according to Comparative Example 1. As shown in FIG. [Figure 21] FIG. 21 is an exploded perspective view showing the configuration of an example of a nonaqueous electrolyte battery according to this embodiment. [Figure 22] FIG. 22 is a perspective view showing a partially developed configuration of an electrode group used in a nonaqueous electrolyte battery according to an embodiment. [Figure 23] FIG. 23 is a flowchart showing the manufacturing process of the secondary battery according to the embodiment. [Figure 24] FIG. 24 is a cross-sectional view that schematically shows the configuration of a winding core according to another embodiment. Embodiment

[0010] The configuration of the winding device 1 and the winding core 40 according to the embodiment will be described below with reference to the drawings. Note that in the drawings, the configuration is enlarged, reduced, or omitted as appropriate for the sake of convenience.

[0011] Fig. 1 is an explanatory diagram schematically showing the configuration of an example of a winding device 1 according to an embodiment, and Fig. 2 is a block diagram showing an example of a control configuration of the winding device 1. Fig. 3 is a cross-sectional diagram schematically showing the configuration of a winding core 40 used in the winding device 1. Fig. 4 is an explanatory diagram schematically showing an example of a wound body 100 produced using the winding core 40. Fig. 5 is an explanatory diagram schematically showing the configuration of the winding core 40.

[0012] 1, the winding device 1 is a device that winds a plurality of overlapping strip-shaped materials (foils) around a winding core 40 to produce a wound body 100. The wound body 100 produced by the winding device 1 is a wound body in which at least one of the plurality of strip-shaped materials is a foil made of a metal material.

[0013] First, a specific example of a wound body 100 manufactured by the winding device 1 will be described. The winding device 1 manufactures the wound body 100 by winding a plurality of strip-shaped materials (strips). The wound body 100 is used, for example, for an electrode group used in a secondary battery such as a lithium-ion battery. In this embodiment, an example will be described in which the winding device 1 manufactures the wound body 100 for an electrode group of a secondary battery using four strip-shaped materials: a positive electrode sheet 101, a separator sheet 102, a negative electrode sheet 103, and a separator sheet 104.

[0014] FIG. 22 shows an example of an electrode group 155 using the wound body 100 formed by the winding device 1 of the embodiment shown in FIG. 1. As shown in FIG. 22, the winding device 1 winds four strip-shaped materials in a state in which the four strip-shaped materials are stacked one on top of the other, thereby forming the electrode group 155. The winding device 1 winds the four strip-shaped materials, i.e., the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104, in a state in which the four strip-shaped materials are stacked one on top of the other in this order. In the electrode group 155, the positive electrode sheet 101 forms a positive electrode 156, and the negative electrode sheet 103 forms a negative electrode 157. In the electrode group 155, the separator sheets 102 and 104 form a separator that electrically insulates the positive electrode 156 from the negative electrode 157.

[0015] The electrode group 155 may be configured so that the negative electrode sheet 103 is on the inner side when rolled and the positive electrode sheet 101 is on the outer side when rolled, or so that the positive electrode sheet 101 is on the inner side when rolled and the negative electrode sheet 103 is on the outer side when rolled.

[0016] The positive electrode sheet 101 is an electrode sheet that forms the positive electrode of the secondary battery. The positive electrode sheet 101 is an example of a strip-shaped material. The positive electrode sheet 101 is a strip-shaped positive electrode current collector. The positive electrode sheet 101 is formed of, for example, aluminum foil or aluminum alloy foil. The positive electrode sheet 101 also has a positive electrode active material-containing layer provided on at least one surface. The positive electrode active material-containing layer contains a positive electrode active material.

[0017] The negative electrode sheet 103 is an electrode sheet that forms the negative electrode of the secondary battery. The negative electrode sheet 103 is an example of a strip-shaped material. The negative electrode sheet 103 is a strip-shaped negative electrode current collector. The negative electrode sheet 103 is formed of, for example, copper foil. The negative electrode sheet 103 may also be formed of aluminum foil or aluminum alloy foil. The negative electrode sheet 103 also has a negative electrode active material-containing layer provided on at least one surface. The negative electrode active material-containing layer contains a negative electrode active material.

[0018] The separator sheets 102 and 104 are disposed between the positive electrode sheet 101 and the negative electrode sheet 103. The separator sheets 102 and 104 constitute insulating layers. Therefore, in an electrode assembly 155 manufactured by rolling the positive electrode sheet 101 and the negative electrode sheet 103, the separator sheets 102 and 104 serve as a separator 158 that electrically insulates the positive electrode 156 from the negative electrode 157. Note that instead of the separator sheets 102 and 104, a solid electrolyte-containing layer may be formed integrally with one of the positive electrode sheet 101 and the negative electrode sheet 103. In this case, in the manufactured electrode assembly, the solid electrolyte-containing layer electrically insulates the positive electrode from the negative electrode.

[0019] Next, we will explain the winding device 1. As shown in Fig. 1, the winding device 1 includes, for example, four supply units 5 to 8, four conveying units 11 to 14, a winding core 40, a motor 50, an adjustment mechanism 60, a cutting device 70, and a control device 80.

[0020] Each of the supply units 5 and 6 has, for example, two reels 10 arranged therein, and each of the supply units 7 and 8 has, for example, one reel 10 arranged therein. The reels 10 hold rolls of raw material around which a strip-shaped material is wound. Each of the reels 10 carries a corresponding one of the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 wound in roll form. In the supply unit 5, the negative electrode sheet 103 is sent from one of the two reels 10 to the conveying unit 11, and in the supply unit 6, the positive electrode sheet 101 is sent from one of the two reels 10 to the conveying unit 12. In the supply unit 7, the separator sheet 102 is sent from the reel 10 to the conveying unit 13, and in the supply unit 8, the separator sheet 104 is sent from the reel 10 to the conveying unit 14. Each of the supply units 5 to 8 intermittently delivers a corresponding one of the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 to a corresponding one of the conveying units 11 to 14. Each of the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 is delivered by a predetermined length in the longitudinal direction along a pair of long side edges in each delivery.

[0021] A conveying path is formed by each of the conveying units 11 to 14. The conveying unit 11 conveys the negative electrode sheet 103 delivered from the supply unit 5 to the winding core 40 via the conveying path, and the conveying unit 12 conveys the positive electrode sheet 101 delivered from the supply unit 6 to the winding core 40 via the conveying path. The conveying unit 13 conveys the separator sheet 102 delivered from the supply unit 7 to the winding core 40 via the conveying path, and the conveying unit 14 conveys the separator sheet 104 delivered from the supply unit 8 to the winding core 40 via the conveying path. In each of the conveying units (conveying paths) 11 to 14, the conveying direction in which the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 are conveyed, i.e., the direction toward the winding core 40, is the downstream side. In each of the conveying sections 11 to 14, the upstream side is the direction opposite to the conveying direction, i.e., the direction toward the corresponding one of the supplying sections 5 to 8. In the example of FIG. 1, the arrow X1 side is the downstream side of the conveying section 11, and the arrow X2 side is the upstream side of the conveying section 11.

[0022] One or more guide rollers 15 are arranged in each of the conveying units (conveying paths) 11 to 14, and in the example of FIG. 1, multiple guide rollers 15 are arranged in each of the conveying units 11 to 14. In each of the conveying units 11 to 14, that is, in each of the four conveying paths, the guide rollers 15 guide a corresponding one of the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 to the winding core 40. Note that the number and arrangement of the guide rollers 15 in each of the conveying units 11 to 14 are not limited to the example of FIG. 1 and can be changed as appropriate depending on the arrangement of the supply units 5 to 8 and the arrangement of the winding core 40.

[0023] Pinch rollers 16 and detectors 17 and 18 are disposed in each of the conveying units 11 and 12. The pinch roller 16 is made of, for example, rubber. The pinch roller 16 of the conveying unit 11 sandwiches the conveyed negative electrode sheet 103 between itself and a guide roller 15A, which is one of the guide rollers 15, and abuts against the negative electrode sheet 103 from the side opposite the guide roller 15A. The pinch roller 16 of the conveying unit 12 sandwiches the conveyed positive electrode sheet 101 between itself and a guide roller 15B, which is one of the guide rollers 15, and abuts against the positive electrode sheet 101 from the side opposite the guide roller 15B. In each of the conveying units (conveying paths) 11 and 12, the pinch rollers 16 convey the strip (the corresponding one of 51 and 52) to the winding core 40 at a stable conveying speed. Among the pinch rollers 16, the one disposed in the conveying section 11 is referred to as a pinch roller 16A, and the one disposed in the conveying section 12 is referred to as a pinch roller 16B.

[0024] In each of the conveying sections 11 and 12, a detection section (first detection section) 17 is disposed upstream of the pinch roller 16 and is disposed between the pinch roller 16 and the supply section (the corresponding one of 5 and 6). In each of the conveying sections 11 and 12, a detection section (second detection section) 18 is disposed downstream of the pinch roller 16 and is disposed between the pinch roller 16 and the winding core 40. In each of the conveying sections (conveying paths) 11 and 12, the detection section 17 detects an abnormal shape portion formed on the strip (the corresponding one of 51 and 52) at a position upstream of the pinch roller 16. In each of the conveying sections (conveying paths) 11 and 12, the detection section 18 detects an abnormal shape portion formed on the strip (the corresponding one of 51 and 52) at a position downstream of the pinch roller 16. In each of the detection sections 17 and 18, for example, a CCD camera or a laser displacement meter is used to detect the abnormal shape portion. Furthermore, examples of shape abnormalities formed on the negative electrode sheet 103 and the positive electrode sheet 101 include unevenness, kinks, wrinkles, etc. Among the detection units 17 and 18, those that perform detection in the conveying unit 11 are referred to as detection units 17A and 18A, and those that perform detection in the conveying unit 12 are referred to as detection units 17B and 18B.

[0025] The winding core 40 is attached to a frame or the like (not shown). As shown in FIG. 2, the winding core 40 is connected to a motor 50. The winding core 40 rotates when driven by the motor 50. The winding core 40 has a first central axis C1, which is the center of rotation. When driven by the motor 50, the winding core 40 rotates around the first central axis C1 relative to the frame or the like.

[0026] The winding core 40 holds the stacked positive electrode sheet 101, separator sheet 102, negative electrode sheet 103, and separator sheet 104, and rotates around the first central axis C1 to wind the positive electrode sheet 101, separator sheet 102, negative electrode sheet 103, and separator sheet 104 around its outer circumferential surface.

[0027] The winding core 40 is formed in a columnar shape extending along the first central axis C1. At least the portions of the winding core 40 around which the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 are wound are formed to have the same or substantially the same shape along the first central axis C1. As shown in FIG. 3 , the winding core 40 has two corners 41 formed at two circumferentially symmetrical positions, and two outer peripheral surfaces 42 formed between the vertices of the two corners 41. In other words, the winding core 40 is formed in a point-symmetric shape about the first central axis C1, or in a symmetric shape about a second central axis C2 connecting the two corners 41. Furthermore, it is preferable that the winding core 40 does not have a straight portion extending in a direction intersecting the first central axis C1 in the outer peripheral portion around which the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 are wound. In other words, it is preferable that the winding core 40 does not have a straight portion on its outer surface along the circumferential direction.

[0028] For example, as shown in FIG. 4, the corner portion 41 forms a folding line 100a on at least the positive electrode sheet 101 or the negative electrode sheet 103, which is the innermost one of the wound body 100 formed by winding a positive electrode sheet 101, a separator sheet 102, a negative electrode sheet 103, and a separator sheet 104.

[0029] The angle θ of the tangent to the corner 41 shown in FIG. 3 is set to an angle that does not cause a large fluctuation in angular velocity and that allows the formation of a folding line 100a. As a specific example, the angle θ of the tangent to the corner 41 is formed to be 120° or less. The corner 41 is preferably set to be 90°. By setting the angle θ of the tangent to the corner 41 to be 120° or less, the actual angle of the corner 41 becomes an acute angle that allows the formation of a folding line 100a in the material. Therefore, as shown in FIG. 4, the innermost periphery of a wound body 100 wound around a winding core 40 having such a corner 41 forms a folding line 100a, and the portion of the wound body 100 where the folding line 100a is formed is substantially acute-angled.

[0030] The apex of the corner 41 is formed so as not to damage the contacting positive electrode sheet 101 or negative electrode sheet 103 and so as to be able to form the folding line 100a. For example, the apex of the corner 41 is formed into a curved surface with a curvature radius r of 1 mm or less. As one example, the apex of the corner 41 is formed into a curved surface with a curvature radius r of 0.5 mm.

[0031] The outer peripheral surface 42 extends along the first center axis C1. The outer peripheral surface 42 is formed, for example, with a single radius of curvature. The pair of outer peripheral surfaces 42 are formed with a radius of curvature such that the angle θ of the tangent to the corner portion 41 is 120° or less. The two ridges formed by the pair of outer peripheral surfaces 42 constitute the pair of corner portions 41.

[0032] As in the cross-sectional shape of the winding core 40 schematically shown in Fig. 3, the centers of curvature C0 of the two outer peripheral surfaces 42 are shifted from the second central axis C2 in a direction perpendicular or substantially perpendicular to the first central axis C1 and in a direction perpendicular to the second central axis C2 connecting the two corners 41. That is, as shown in Fig. 5, the cross-sectional shape of the winding core 40 in a cross section perpendicular or substantially perpendicular to the first central axis C1 is formed to have the same shape or substantially the same shape as the shape of an intersection of two imaginary circles CI when the centers C0 of two imaginary circles CI having predetermined radii are positioned at shifted positions, or more specifically, when the centers C0 of two imaginary circles CI having predetermined radii are positioned at shifted positions from the second central axis C2 in a direction perpendicular to each of the first central axis C1 and the second central axis C2 connecting the two corners 41.

[0033] In the example of the winding core 40 shown in Fig. 5, the center C0 of one imaginary circle CI is located on the outer periphery of the other imaginary circle CI. That is, in the configuration of the winding core 40 shown in Fig. 5, the distance between the centers C0 of the two imaginary circles CI is the same as the radii of the imaginary circles CI.

[0034] Next, a specific example of the winding core 40 will be described. The winding core 40 has, for example, a pair (two) of core pieces 45. The winding core 40 holds a positive electrode sheet 101, a separator sheet 102, a negative electrode sheet 103, and / or a separator sheet 104 that are arranged in a slit 45a between the opposing surfaces of the pair of core pieces 45. For example, the winding core 40 has a clamp 46 that holds the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 that are arranged in the slit 45a.

[0035] The pair of core pieces 45 have opposing surfaces spaced apart to form a slit 45a therebetween. Each of the pair of core pieces 45 has one corner 41. The pair of core pieces 45 are held in a predetermined positional relationship to form the pair of corners 41 and the pair of outer circumferential surfaces 42. The winding core 40 may also have a movement mechanism or drive source that varies the distance between the pair of core pieces 45. For example, the winding core 40 may be configured to move the pair of core pieces 45 so that the width of the slit 45a decreases when the wound body 100 is removed from the winding core 40.

[0036] The opposing surfaces of the pair of core pieces 45 are, for example, inclined surfaces that are inclined (intersecting) with respect to the second central axis C2. Therefore, the slits 45a are inclined with respect to the second central axis C2.

[0037] The slit 45a is a gap or opening formed between the opposing surfaces of the pair of core pieces 45. The slit 45a extends along the first central axis C1. The slit 45a is formed in a shape that allows the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and / or the separator sheet 104 to be inserted therein. It is preferable that the width of the slit 45a in the circumferential direction of the winding core 40 is large enough to allow the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and / or the separator sheet 104 to be inserted therein, and that the width is as small as possible.

[0038] In this winding core 40, the slits 45a are inclined with respect to the second central axis C2, and therefore the cross-sectional shape of the winding core 40 including the slits 45a is point-symmetrical about the first central axis C1. Also, part of the outer peripheral surface 42 of the winding core 40 is intermittently formed by the slits 45a.

[0039] Furthermore, by forming the slits 45a in a shape that is inclined with respect to the second center axis C2, the outer surface portions that form the pair of outer peripheral surfaces 42 of the core piece 45 are configured to have a first outer peripheral portion 45b and a second outer peripheral portion 45c that is longer in the circumferential direction than the first outer peripheral portion 45b. The first outer peripheral portion 45b of one core piece 45 and the second outer peripheral portion 45c of the other core piece 45 form one outer peripheral surface 42 having the slits 45a. The second outer peripheral portion 45c of one core piece 45 and the first outer peripheral portion 45b of the other core piece 45 form the other outer peripheral surface 42 having the slits 45a.

[0040] Clamp 46 is, for example, a chuck that holds positive electrode sheet 101, separator sheet 102, negative electrode sheet 103, and / or separator sheet 104 arranged in slit 45a. Clamp 46 opens and closes by power from a motor or the like, as shown by the arrows in Fig. 3. In Fig. 3, clamp 46 in an open state is indicated by a solid line, and clamp 46 in a closed state is indicated by a dashed line.

[0041] The motor 50 is, for example, a servo motor, and the rotation speed of the motor 50 is controlled by a control device 80.

[0042] The adjustment mechanism 60 includes a roller 61 and a drive device 65. The roller 61 adjusts the insertion angle of the positive electrode sheet 101, separator sheet 102, negative electrode sheet 103, and separator sheet 104 supplied to the winding core 40 relative to the roller 61. In other words, the roller 61 determines the insertion angle of the positive electrode sheet 101, separator sheet 102, negative electrode sheet 103, and separator sheet 104 relative to the winding core 40. The drive device 65 drives the roller 61 to move it. Specifically, the drive device 65 moves the roller 61 between a reference position and a winding position.

[0043] As one example, the driving device 65 includes a slider and a servo motor, and the driving of the slider and the servo motor moves the roller 61 in a predetermined direction. As another example, the driving device 65 includes an arm and an air cylinder, one end of the arm is rotatably attached to a frame or the like, and the roller 61 is fixed to the other end of the arm. In addition, an air cylinder is connected to the arm. The air cylinder rotates the arm by expanding and contracting in a predetermined direction. Then, as the arm rotates, the roller 61 moves along an arc centered on the rotation axis of the arm.

[0044] The reference position is a position where the roller 61 is placed when the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 are attached to the winding core 40. When the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 are attached to the winding core 40, for example, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 are inserted between the outer peripheral surface of the winding core 40 and the positive electrode sheet 101, with the end of the positive electrode sheet 101 being gripped by the winding core 40.

[0045] The winding position is a position where the roller 61 is disposed when the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 are wound around the winding core 40. When the positive electrode sheet 101 and the negative electrode sheet 103 are attached to the winding core 40, for example, the roller 61 moves to the winding position and determines the insertion angle of the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 relative to the winding core 40.

[0046] The cutting device 70 cuts the positive electrode sheet 101, separator sheet 102, negative electrode sheet 103, and separator sheet 104 that have been supplied to the winding core 40. For example, the cutting device 70 includes a cutter 71 that performs the cutting, and a drive source 72 such as a motor that moves the cutter 71. The cutting device 70 moves the cutter 71 between a standby position and a cutting position using the drive source 72, and cuts the positive electrode sheet 101, separator sheet 102, negative electrode sheet 103, and separator sheet 104 at the cutting position.

[0047] The control device 80 is, for example, a processing device such as a computer. The control device 80 includes a processor or integrated circuit (control circuit) including a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or the like, and a storage medium such as a memory. The control device 80 may include only one integrated circuit or the like, or may include multiple integrated circuits or the like. The control device 80 performs processing by executing a program or the like stored in a storage medium or the like. The control device 80 controls the operation of each element provided in the winding device 1. The control device 80 controls the driving of, for example, the four supply units 5 to 8, the four conveying units 11 to 14, the clamp 46, the motor 50, the drive unit 65 of the adjustment mechanism 60, the cutting device 70, and the like. The control device 80 may further include an input unit through which an operator or the like inputs process conditions and operating conditions, a display unit that displays the operating status and abnormality indications, and the like.

[0048] The control device 80 performs rotation control to reduce the difference in angular velocity in one rotation (half rotation) of the winding core 40 by varying the rotation speed of the motor 50 depending on the distance from the rotation center of the winding core 40 to the outer surface where the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 come into contact.

[0049] Next, an example of a method for manufacturing an electrode group using the winding device 1 of this embodiment will be described with reference to FIG.

[0050] First, the control device 80 performs an attachment step. As a specific example, the control device 80 controls the four supply units 5 to 8 and the four conveying units 11 to 14 to insert the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and / or the separator sheet 104 into the slit 45a between the pair of core pieces 45 (step ST1). Next, the control device 80 controls the clamp 46 to hold the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and / or the separator sheet 104 inserted into the slit 45a (step ST2). When the positive electrode sheet 101, separator sheet 102, negative electrode sheet 103, and / or separator sheet 104 are held by the winding core 40, the control device 80 controls the cutting device 70 to cut the portions of the positive electrode sheet 101, separator sheet 102, negative electrode sheet 103, and / or separator sheet 104 inserted into the slits 45a that will become the leading edge sides of the sheets (step ST3). These steps complete the attachment process.

[0051] For example, the strip-shaped material inserted into the slit 45a and held by the clamp 46 may be any one of the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104, or may be all of the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104. For example, when any one of the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 is held in the slit 45a, the control device 80 may include a step of inserting another strip-shaped material between the winding core 40 and the held strip-shaped material.

[0052] Next, as a moving step, the control device 80 controls the driving of the drive unit 65 to move the roller 61 from the reference position to the winding position. Next, as a winding step, the control device 80 controls the driving of the motor 50 to rotate the winding core 40 and wind the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 a predetermined number of turns (step ST4). For example, in the winding step, after the start of winding, the winding core 40 is rotated in a direction in which the material passes through the first outer peripheral portion 45b, which has a shorter circumferential length of the core piece 45, and reaches the corner portion 41. In the winding step, the control device 80 controls the motor 50 to rotate the winding core 40 so as to reduce the difference in angular velocity occurring at the winding axis angle during one rotation (half rotation) of the winding core 40.

[0053] This forms a wound body 100 in which the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 are wound a predetermined number of times. Once the wound body 100 is formed, the control device 80 ends the winding process.

[0054] Next, the control device 80 controls the clamps 46 to release the holding of the manufactured wound body 100, and controls the cutting device 70 to cut the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104, and removes the wound body 100 from the winding core 40. In the attachment process of step ST1, the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 to be manufactured next are attached to the winding core. Note that in the attachment process of the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 of the wound body 100 to be manufactured next, the cutting of the positive electrode sheet 101, the separator sheet 102, the negative electrode sheet 103, and the separator sheet 104 described in step ST3 may be performed, and the manufactured wound body 100 may be separated from the positive electrode sheet 101 and the negative electrode sheet 103.

[0055] For example, as shown in FIG. 4, the wound body 100 produced by the winding device 1 is pressed by a press or the like in a direction perpendicular or substantially perpendicular to the second central axis C2 (step ST5). For example, the pressing performed by the press is a flat press. As an example of pressing conditions, a load of 1 t is applied to the wound body 100 for several tens of seconds at a temperature of 100°C to press the wound body 100. As a result, the wound body 100 is formed into a flat shape. Through these exemplary steps, the wound body 100 such as an electrode group is produced.

[0056] Next, the effects of the winding device 1 and the winding core 40 of this embodiment will be described. The winding core 40 has a pair of corners 41 whose tangents are formed at a predetermined angle, and a pair of outer peripheral surfaces 42 with a predetermined radius of curvature between the pair of corners 41. The pair of corners 41 of the winding core 40 can form a folding line 100a in at least the innermost material. For example, the pair of corners 41 of the winding core 40 can form a folding line 100a in at least one of the positive electrode sheet 101 and the negative electrode sheet 103. The folding line 100a is formed by plastic deformation of the innermost material during pressing. The folding line 100a becomes a fold when the wound body 100 is pressed, and guides the deformation of the positive electrode sheet 101 and the negative electrode sheet 103 (material) during press-molding of the wound body 100.

[0057] Furthermore, the folding lines 100a can increase the coefficient of friction at the overlapping portion between the innermost layer (material) where the folding lines 100a are formed and the layer (material) adjacent to this innermost layer. For example, the folding lines 100a can increase the coefficient of friction at the overlapping portion between the positive electrode sheet 101 and the negative electrode sheet 103, which are adjacent to each other via the separator sheets 102 and 104. This allows the end of the strip-shaped material (positive electrode sheet 101 or negative electrode sheet 103) on the innermost side of the wound body 100 to be fixed by the folding lines 100a. In the wound body 100 manufactured on the winding core 40, the material (positive electrode sheet 101 or negative electrode sheet 103) on the innermost side is fixed, thereby preventing the material (positive electrode sheet 101 or negative electrode sheet 103) on the innermost side from shifting. That is, when the material is wound around the winding core 40, the corners 41 serving as edges impart a crease to the innermost foil of the wound body 100, making it difficult for the innermost foil to shift.

[0058] Therefore, the shape of the manufactured wound body 100 is maintained as it is when the winding core 40 is removed from the wound body 100. This makes it possible to prevent loosening of the positive electrode sheet 101 or the negative electrode sheet 103 on the innermost periphery of the wound body 100. Furthermore, because the shape of the wound body 100 is maintained, the positive electrode sheet 101 or the negative electrode sheet 103 on the innermost periphery can be pressed without shifting during pressing, which makes it possible to prevent creases or steps from occurring in the positive electrode sheet 101 or the negative electrode sheet 103 on the innermost periphery that are plastically deformed during pressing.

[0059] Furthermore, after winding begins, the winding device 1 rotates the winding core 40 in a direction in which the material passes through the first outer peripheral portion 45b, which has a shorter circumferential length of the core piece 45, and reaches the corner 41, thereby forming a folding line 100a on the end side of the material. This allows the winding device 1 and winding core 40 to better prevent loosening of the innermost end of the material. Therefore, the winding device 1 and winding core 40 can produce a wound body 100 of excellent quality.

[0060] Furthermore, the winding core 40 has a pair of outer peripheral surfaces 42 between a pair of corners 41 that are curved with a single radius of curvature, so that the winding core 40 does not have a straight portion, and the change in the distance from the center of rotation of the winding core 40 to the outer surface in the circumferential direction can be minimized.

[0061] That is, when a winding core with a non-circular circumferential shape (cross-sectional shape) of the outer periphery is used, the distance between the point on the winding core where the strip-shaped material is wrapped and the winding core's center of rotation fluctuates during one rotation (half rotation). That is, the distance between the point on the winding core where the strip-shaped material is wrapped and the winding core's center of rotation changes depending on the angle of the winding shaft. Therefore, when winding the material, the angular velocity fluctuates depending on the radius of the winding core. Fluctuations in the moving speed of the material (the object to be wound) can cause the moving speed of the object to shift or bounce, making it difficult to wind the object neatly. To solve this problem, the rotation of the winding core is adjusted using a control device 80 or the like to slow down the rotational speed of the winding core when the angular velocity increases and speed up the rotation of the winding core when the angular velocity decreases, thereby suppressing fluctuations in the winding speed. However, when controlling the rotational speed of the winding core, sudden fluctuations in the angular velocity require sudden acceleration or deceleration of the winding core. When the winding core is suddenly accelerated or decelerated, it becomes difficult for the motor 50 to follow, making it difficult to wind material at high speed, and the productivity of the wound body decreases.

[0062] However, the winding core 40 of the embodiment can minimize the change in the distance from the rotation center of the winding core 40 to the outer surface in the circumferential direction, so the acceleration / deceleration rate per rotation (half rotation) of the winding core 40 can be reduced. In other words, by using the winding core 40, the speed change of the winding shaft is reduced. Therefore, the winding core 40 does not need to be suddenly accelerated or decelerated, and material can be wound at high speed. Therefore, the winding core 40 and the winding device 1 can suppress a decrease in productivity.

[0063] Next, the winding core 40 of this embodiment will be compared with conventional winding cores of comparative examples. First, winding core 40A of comparative example 1 to winding core 40D of comparative example 4 will be described with reference to Figs. 7 to 10.

[0064] [Comparative Example 1] As shown in FIG. 7, the winding core 40A of Comparative Example 1 is formed so that the cross-sectional shape (circumferential shape) perpendicular to the first center axis C1 is circular.

[0065] Comparative Example 2 As shown in FIG. 8, the winding core 40B of Comparative Example 2 has a cross-sectional shape (circumferential shape) perpendicular to the first center axis C1 that is formed into a flat hexagonal shape.

[0066] Comparative Example 3 As shown in FIG. 9, the winding core 40C of Comparative Example 3 has a rhombic cross section (circumferential shape) perpendicular to the first center axis C1.

[0067] Comparative Example 4 As shown in FIG. 10, the winding core 40D of Comparative Example 4 has a cross-sectional shape (circumferential shape) perpendicular to the first center axis C1 that is formed into an elliptical shape.

[0068] Next, the winding cores 40A to 40D of the comparative examples and the winding core 40 of the embodiment will be compared and described.

[0069] [Comparison between the embodiment and the comparative example] First, we compare the winding core 40A of Comparative Example 1 with the winding core 40 of the embodiment. FIG. 11 shows an example of a wound body 100A manufactured using the winding core 40A of Comparative Example 1. The winding core 40A of Comparative Example 1 hardly requires varying the speed when rotating the winding core 40A, allowing for high winding speeds and high productivity. However, as in the wound body 100A in which material is wound around the winding core 40A shown in FIG. 11, the end of the material on the innermost periphery is not fixed, making it prone to loosening of the material on the innermost periphery. Loosening occurs when removing the winding core 40A from the wound body 100A, when moving the wound body 100A after removal, and when pressing the wound body 100A. Once the material has loosened, the wound body 100A cannot be corrected.

[0070] Furthermore, wound body 100A in which the material has loosened may become a defective product, depending on the characteristics. Furthermore, if the material is pressed in a loosened state, the loosened material has nowhere to go, and wrinkles, such as Z-shaped folds, occur. As a result, the wrinkles that occur when pressed become steps, and the steps act as foreign objects and break through other parts, resulting in poor characteristics for wound body 100A (electrode group).

[0071] As described above, wound body 100A in which loosened material occurs is likely to become a defective product. Furthermore, because the amount of deformation of wound body 100A is large during pressing, even if loosening does not occur, there is a risk that the shape of the material on the innermost periphery of wound body 100A will be distorted during pressing. Furthermore, there is a risk of damage due to the frequent rubbing between adjacent pieces of material in wound body 100A during pressing.

[0072] In contrast, with the winding core 40 of this embodiment, as shown in FIG. 4, the vertices of the pair of corners 41 can form folding lines 100a in at least the material on the innermost periphery of the wound body 100. Therefore, the winding core 40 of this embodiment can prevent slack from occurring on the innermost periphery of the wound body 100. Furthermore, by making the outer peripheral surface 42 of the winding core 40 a curved surface with a predetermined curvature radius, it is possible to prevent the speed of the winding core 40 from changing as it rotates, and therefore the rotation speed can be increased. Therefore, the winding core 40 of this embodiment can ensure high productivity.

[0073] Next, the winding core 40B of Comparative Example 2 and the winding core 40C of Comparative Example 3 are compared with the winding core 40 of the embodiment. After winding, the winding core 40B of Comparative Example 2 and the winding core 40C of Comparative Example 3 can form folding lines, which are traces of plastic deformation, in the material at the innermost periphery. This makes the wound body less likely to loosen. The winding core 40B of Comparative Example 2 and the winding core 40C of Comparative Example 3 can wind the wound body in a shape similar to the shape after pressing, so the amount of deformation and friction during pressing can be reduced, similar to the winding core 40 of the embodiment. The winding core 40B of Comparative Example 2 and the winding core 40C of Comparative Example 3 can reduce damage to the wound body, so the manufactured wound body is superior in quality. However, the winding core 40B of Comparative Example 2 and the winding core 40C of Comparative Example 3 have a straight portion formed on the outer circumferential surface in the cross-sectional shape (circumferential shape), which causes large fluctuations in angular velocity during winding, making it difficult to wind material at high speeds.

[0074] The winding core 40 of the embodiment and the winding core 40B of Comparative Example 2 will be described using specific examples in Figures 12 to 17. Figures 12 and 13 are diagrams respectively showing the state at each winding axis angle (rotation angle of the winding core) when the winding core 40 of the embodiment and the winding core 40B of Comparative Example 2 are rotated half a turn. Note that in Figures 12 and 13, the rotation direction R of the winding cores 40, 40B is indicated by arrows.

[0075] 14 and 15 are explanatory diagrams showing the relationship between the reel angle and the material speed (angular velocity) when the reel is rotated at a constant speed, for the reel 40 of the embodiment and the reel 40B of Comparative Example 2, respectively. Figs. 16 and 17 are explanatory diagrams showing the relationship between the reel angle and the reel speed (rotational speed) when the reel is rotated under controlled rotation so that the material speed is constant, for the reel 40 of the embodiment and the reel 40B of Comparative Example 2, respectively. Note that the reel 40C of Comparative Example 3 has similar characteristics to the reel 40B of Comparative Example 2, and therefore a detailed description thereof will be omitted.

[0076] As shown in Figures 13 and 15, when the winding core 40B of Comparative Example 2 is rotated, the angular velocity fluctuates greatly when material is wound around a portion (straight portion) of the outer peripheral surface that extends linearly in the circumferential direction. Therefore, as shown in Figure 17, when the winding core 40B is rotated under controlled rotation so that the angular velocity is constant, the range of adjustment of the winding shaft speed becomes large. The winding core 40B of Comparative Example 2 requires sudden acceleration and sudden stopping of the motor 50, but the performance of the motor 50 makes sudden acceleration and sudden stopping difficult, making it difficult to control the motor 50. Therefore, it is difficult to wind material at high speed around the winding core 40B of Comparative Example 2.

[0077] In contrast, as shown in FIGS. 12 and 14 , when the winding core 40 of the present embodiment is rotated, the fluctuation in angular velocity is smaller in the circumferential direction due to the outer peripheral surface 42 having a predetermined radius of curvature compared to Comparative Example 2. Therefore, as shown in FIG. 16 , when the winding core 40 is rotated under controlled conditions to maintain a constant angular velocity, the range of adjustment of the winding shaft speed is smaller compared to Comparative Example 2. The winding core 40 of the present embodiment does not require sudden acceleration or sudden stopping of the motor 50, allowing for smooth adjustment of the winding shaft speed. Therefore, the winding core 40 of the present embodiment is easier to control than the winding core 40B of Comparative Example 2, and can wind material at a higher speed than the winding core 40B of Comparative Example 2. Additionally, the winding core 40 of the present embodiment, like the winding core 40B of Comparative Example 2, can form a folding line 100a in the innermost material using a pair of corners 41.

[0078] Next, the winding core 40D of Comparative Example 4 is compared with the winding core 40 of the embodiment. Like the winding core 40 of the embodiment, the winding core 40D of Comparative Example 4 can reduce fluctuations in angular velocity, allowing for smooth adjustment of the winding shaft speed. Therefore, like the winding core 40 of the embodiment, the winding core 40D of Comparative Example 4 has good motor tracking. However, unlike the winding core 40 of the embodiment, the winding core 40D of Comparative Example 4 cannot form folding lines in the material at the innermost periphery of the wound body. Therefore, the wound body manufactured with the winding core 40D of Comparative Example 4 is prone to material loosening, as with Comparative Example 1, because the end of the innermost periphery is not fixed.

[0079] [Evaluation Test of the Embodiments and Comparative Examples] Next, a description will be given below of evaluation tests of the winding core 40 of the embodiment and the winding core 40A of Comparative Example 1. In the evaluation tests, wound bodies wound with the winding core 40 of the embodiment and the winding core 40A of Comparative Example 1 were pressed, and the material of the innermost periphery of the pressed wound body was visually inspected to determine whether wrinkles had occurred.

[0080] The evaluation test results are shown in Fig. 18. In addition, Fig. 19 shows an example of the material of the innermost periphery of the wound body 100 after pressing produced using the winding core 40 of the embodiment, and Fig. 20 shows an example of the material of the innermost periphery of the wound body 100A after pressing produced using the winding core 40A of Comparative Example 1.

[0081] As shown in Fig. 18, 247 wound bodies 100 were produced using the winding core 40 of the embodiment, but none of them had wrinkles at the bending position of the innermost periphery of the wound body 100 after pressing, as shown in Fig. 19. This is thought to be because, in the wound body 100 before pressing, the folding line 100a was formed in the material of the innermost periphery, and therefore, no bending or shifting occurred in the material of the innermost periphery.

[0082] In contrast, as shown in Fig. 18, when 29 wound bodies 100A were produced using the winding core 40A of Comparative Example 1, wrinkles, as indicated by the arrows in Fig. 20, occurred at the bending position of the material on the innermost periphery of the wound body 100A after pressing. Wrinkles occurred in 24% of the wound bodies produced using the winding core 40A of Comparative Example 1. This is thought to be because the winding core 40A of Comparative Example 1, which cannot form the folding line 100a, did not form a folding line in the wound body 100A.

[0083] The results of such evaluation tests clearly show that the winding core 40 of the embodiment can suppress the occurrence of wrinkles in the material by forming the folding lines 100a in the wound body 100. Therefore, the winding core 40 of the embodiment can maintain high productivity of the wound body 100 and improve quality.

[0084] Next, an example of a nonaqueous electrolyte battery 2 using the above-described wound body 100 as an electrode group 155 will be described with reference to Fig. 21. Fig. 21 is an exploded perspective view of one example of a nonaqueous electrolyte battery according to an embodiment.

[0085] The secondary battery shown in FIG. 21 is a sealed prismatic nonaqueous electrolyte battery 2. The nonaqueous electrolyte battery 2 shown in FIG. 21 includes an outer can 151, a lid 152, a positive electrode external terminal 153, a negative electrode external terminal 154, and an electrode group 155. The outer can 151 and the lid 152 form an outer casing member. The outer can 151 has a rectangular cylindrical shape with a bottom. The outer can 151 is made of a metal such as aluminum, an aluminum alloy, iron, or stainless steel.

[0086] The flat electrode group 155 is formed by winding a positive electrode 156 and a negative electrode 157 with a separator 158 interposed therebetween around a winding core 40, and then pressing the resultant into a flat shape. The positive electrode 156 is formed from a positive electrode sheet 101. The positive electrode 156 includes a strip-shaped positive electrode current collector 156a made of, for example, a metal foil, a positive electrode current collector tab 156b consisting of one end of the positive electrode current collector parallel to the long side, and a positive electrode material layer (positive electrode active material-containing layer) 156c formed on the positive electrode current collector excluding at least the portion of the positive electrode current collector tab 156b.

[0087] The negative electrode 157 is formed by a negative electrode sheet 103. The negative electrode 157 includes a strip-shaped negative electrode current collector 157a made of, for example, metal foil, a negative electrode current collector tab 157b consisting of one end of the negative electrode current collector parallel to the long side, and a negative electrode material layer (negative electrode active material-containing layer) 157c formed on the negative electrode current collector excluding at least the portion of the negative electrode current collector tab 157b. In FIG. 22, dots are drawn in the areas showing the active material-containing layers 156c and 157c to explain the configuration. The separator 158 is formed by separator sheets 102 and 104.

[0088] The positive electrode 156, separator 158, and negative electrode 157 are wound with the positive electrode 156 and negative electrode 157 offset from one another so that the positive electrode current collector tab 156b protrudes from the separator 158 in the direction of the winding axis of the electrode assembly, and the negative electrode current collector tab 157b protrudes from the separator 158 in the opposite direction. As a result of this winding, the electrode assembly 155 has the spirally wound positive electrode current collector tab 156b protruding from one end face, and the spirally wound negative electrode current collector tab 157b protruding from the other end face, as shown in FIG. 3. The electrode assembly 155 is impregnated with a nonaqueous electrolyte (not shown).

[0089] 21, the positive electrode current collector tabs 156b and the negative electrode current collector tabs 157b are each divided into two bundles, with the boundary near the center of the winding of the electrode group. The conductive clamping member 159 has first and second clamping portions 159a and 159b, each of which is substantially U-shaped, and a connecting portion 159c that electrically connects the first clamping portion 159a and the second clamping portion 159b. One bundle of the positive and negative electrode current collector tabs 156b and 157b is clamped by the first clamping portion 159a, and the other bundle is clamped by the second clamping portion 159b.

[0090] The positive electrode lead 160 has a substantially rectangular support plate 160a, a through-hole 160b opened in the support plate 160a, and strip-shaped current collecting portions 160c and 160d branching out in two directions from the support plate 160a and extending downward. On the other hand, the negative electrode lead 161 has a substantially rectangular support plate 161a, a through-hole 161b opened in the support plate 161a, and strip-shaped current collecting portions 161c and 161d branching out in two directions from the support plate 161a and extending downward.

[0091] The positive electrode lead 160 sandwiches the clamping member 159 between the current collecting portions 160c and 160d. The current collecting portion 160c is disposed in the first clamping portion 159a of the clamping member 159. The current collecting portion 160d is disposed in the second clamping portion 159b. The current collecting portions 160c and 160d, the first and second clamping portions 159a and 159b, and the positive electrode current collecting tab 156b are joined by, for example, ultrasonic welding. This electrically connects the positive electrode 156 of the electrode group 155 and the positive electrode lead 160 via the positive electrode current collecting tab 156b.

[0092] The negative electrode lead 161 has a clamping member 159 sandwiched between current collecting portions 161c and 161d. The current collecting portion 161c is disposed in a first clamping portion 159a of the clamping member 159. Meanwhile, the current collecting portion 161d is disposed in a second clamping portion 159b. The current collecting portions 161c and 161d, the first and second clamping portions 159a and 159b, and the negative electrode current collecting tab 157b are joined by, for example, ultrasonic welding. This electrically connects the negative electrode 157 of the electrode group 155 and the negative electrode lead 161 via the negative electrode current collecting tab 157b.

[0093] Although the materials of the positive and negative electrode leads 160, 161 and the clamping member 159 are not particularly specified, it is desirable that they be the same material as the positive and negative electrode external terminals 153, 154. For example, aluminum or an aluminum alloy is used for the positive electrode external terminal 153, and aluminum, an aluminum alloy, copper, nickel, nickel-plated iron, or the like is used for the negative electrode external terminal 154. For example, when the material of the external terminals is aluminum or an aluminum alloy, it is desirable that the material of the leads is aluminum or an aluminum alloy. Furthermore, when the external terminals are copper, it is desirable that the material of the leads is copper, or the like.

[0094] The rectangular plate-shaped lid 152 is seam-welded to the opening of the outer can 151, for example, by laser. The lid 152 is made of a metal such as aluminum, an aluminum alloy, iron, or stainless steel. The lid 152 and the outer can 151 are preferably made of the same type of metal. The positive electrode external terminal 153 is electrically connected to the support plate 160a of the positive electrode lead 160, and the negative electrode external terminal 154 is electrically connected to the support plate 161a of the negative electrode lead 161. The insulating gasket 162 is disposed between the positive and negative electrode external terminals 153, 154 and the lid 152, and electrically insulates the positive and negative electrode external terminals 153, 154 from the lid 152. The insulating gasket 162 is preferably a resin molded product.

[0095] Next, an example of a manufacturing method of the nonaqueous electrolyte battery 2 is shown in FIG. 22. First, a positive electrode 156 (positive electrode sheet 101) and a negative electrode 157 (negative electrode sheet 103) are subjected to slurry preparation, coating, slitting, roll pressing, and the like, and, if necessary, a porous layer is formed on the surface by electrospinning. These are then transported to the winding core 40 of the winding device 1 (steps 201 and 202). Next, the positive electrode sheet 101 and the negative electrode sheet 103 are wound around the winding core 40 with at least an insulating layer, a separator 158 (separator sheets 102 and 104), interposed between them to produce a wound body 100 (steps ST1 to ST4, step 203). The wound body 100 is then flat-pressed using a press or the like (step ST5, step 204). Through these steps, an electrode group 155 is manufactured. Next, the electrode group 155 is housed in an outer container, and after drying the electrode group 155 (step 205), the electrolyte is poured into the outer container (step 206). Next, the outer container is sealed, and after performing an aging treatment or the like, a degassing process is performed (step 207). Thereafter, the nonaqueous electrolyte battery 2 is charged and discharged (step 208), and a pre-shipment inspection of the nonaqueous electrolyte battery 2 is performed (step 209), and the nonaqueous electrolyte battery 2 is shipped (step 210). In this way, by manufacturing the electrode group 155 using the above-described winding core 40, a high-quality nonaqueous electrolyte battery 2 can be provided with high productivity.

[0096] According to the winding core 40 and the winding device 1 of the embodiment described above, by having a pair of corner portions 41 and a pair of outer peripheral surfaces 42, it is possible to suppress loosening of the innermost band-shaped material (positive electrode sheet 101 or negative electrode sheet 103) while reducing the acceleration / deceleration per rotation (half rotation) during rotation.

[0097] The above-described embodiment is merely illustrative, and the configuration is not limited thereto. For example, in the above example, the pair of outer peripheral surfaces 42 of the winding core 40 are formed with a single radius of curvature, but this is not limiting. For example, as in the winding core 40 of another embodiment shown in FIG. 23, each of the pair of outer peripheral surfaces 42 may be curved with a plurality of different radii of curvature. For example, in the example schematically shown in FIG. 23, the winding core 40 has an elliptical outer peripheral surface 42 and a pair of corners 41 at both ends in the longitudinal direction. Even with this winding core 40, it is possible to reduce the acceleration / deceleration per rotation (half rotation) during rotation while suppressing loosening of the innermost materials 101, 103.

[0098] Furthermore, as described above, the winding device 1 and the winding core 40 are made of a material capable of forming the folding line 100a, and as long as the wound body 100 is pressed to be flat, it is possible to manufacture wound bodies 100 for a variety of uses.

[0099] That is, in the above-described embodiment, as an example, a configuration has been described in which the wound body 100 used for the electrode group 155 of the secondary battery 2 is manufactured using the winding core 40 and the winding device 1, but the present invention is not limited thereto. That is, the winding device 1 can be used to manufacture wound bodies other than the electrode group 155 of the secondary battery 2, as long as it is configured to manufacture a wound body in a state in which multiple strips are stacked. For example, the wound body 100 manufactured by the winding device 1 may be used for a capacitor or a lithium ion capacitor. The wound body 100 may also be used for other purposes. That is, as long as the wound body 100 is manufactured by winding a strip-shaped material that undergoes plastic deformation in part around the winding core 40, it may also be used for purposes other than those described above. The number of strip-shaped material sheets used to manufacture the wound body can be set as appropriate. For example, although two or more strip-shaped material sheets are preferred, it may also be one sheet.

[0100] The relative positions of the positive electrode sheet 101, separator sheet 102, negative electrode sheet 103, and separator sheet 104 that are transported and wound in the winding device 1 can be set as appropriate. The innermost material (layer) where the folding line 100a of the wound body 100 is formed may be a separator or a current collecting foil (positive electrode sheet 101 and negative electrode sheet 103).

[0101] According to at least one of the embodiments of the winding core and winding device described above, by having a pair of corners and a pair of outer peripheral surfaces, it is possible to reduce acceleration and deceleration during rotation while suppressing loosening of the material at the innermost periphery.

[0102] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are intended to be included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims.

Claims

1. A winding core having a pair of outer peripheral surfaces extending along a first central axis that is a rotation center and formed with a predetermined radius of curvature, and a pair of corners extending along the first central axis at circumferentially symmetrical positions, the winding core having a strip-shaped material wound around the outer peripheral surfaces.

2. The winding core according to claim 1 , wherein the angle of the tangent of the corner portion is 120° or less.

3. the outer circumferential surface is defined by a radius of curvature; 3. The winding core according to claim 1, wherein the center of curvature of the outer peripheral surface is shifted from the second center axis in a direction perpendicular to the first center axis and the second center axis connecting the pair of corner portions.

4. a pair of core pieces extending along the first central axis and each having the corner portion; The pair of core pieces have slits inclined with respect to the second central axis, The winding core of claim 3 , which holds the material disposed in the slit.

5. The winding core according to any one of claims 1 to 4, a conveying unit that conveys the material to the core; A winding device comprising:

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