WO2009122245A1

WO2009122245A1 - Wound electrode body manufacturing method and apparatus, and electrode winding apparatus

Info

Publication number: WO2009122245A1
Application number: PCT/IB2009/000406
Authority: WO
Inventors: Kenji Tsuchiya; Shigetaka Nagamatsu; Masataka Takeda
Original assignee: Toyota Jidosha Kabushiki Kaisha
Priority date: 2008-04-03
Filing date: 2009-03-03
Publication date: 2009-10-08
Also published as: KR101156831B1; KR20100133400A; CN102089920A; JP4656451B2; CN102089920B; JP2009252425A

Abstract

A method for manufacturing a wound electrode body includes a first step of winding a predetermined length of strip electrodes (11, 13) and the strip separators (12, 14), one on top of the other, onto a winding shaft (121) from among a plurality of winding shafts (121, 122) provided on a turret (110), a second step of cutting the strip electrodes (11, 13) with cutters (131, 132), and a third step of winding the remaining tail ends of the strip electrodes (11, 13) cut in the second step by rotating the winding shafts (121, 122) while rotating the turret (110), and feeding the strip separators (12, 14).

Description

WOUND ELECTRODE BODY MANUFACTURING METHOD AND APPARATUS, AND ELECTRODE WINDING APPARATUS

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The invention relates to a method and apparatus for manufacturing a wound electrode body in which a strip electrode and a strip separator are wound, one on top of the other, onto a winding shaft. The invention also relates to an electrode winding apparatus.

2. Description of the Related Art

[0002] Japanese Patent Application Publication No. 9-194091 (JP-A-9-194091) and Japanese Patent Application Publication No. 2007-329059 (JP-A-2007-329059), for example, each describe a method of manufacturing a wound electrode body in which a strip electrode and a strip separator are wound, one on top of the other, onto a winding shaft.

[0003] In JP-A-9-194091, predetermined amounts of a strip electrode and a strip separator (hereinafter simply referred to as the "strip electrode and the like") are wound by a winding shaft on a turret when the winding shaft is in a predetermined first position. Next, the winding shaft is stopped and the turret is rotated such that the winding shaft moves to a second position. Then in this second position, the strip electrode and the like is cut and the winding shaft is rotated again to wind up the cut strip electrode and the like (so-called remaining winding). Also, when the winding shaft is moved to the second position, another winding shaft is moved to the first position. Then when the remaining winding step is performed in the second position, a predetermined amount of the strip electrode and the like is wound by the other winding shaft in the first position. Also, JP-A-2007-329059 describes a method for conveying a wound electrode group by rotating a turret, while setting a strip separator in a state so that it is ready for the next winding process in which it will be wound onto a winding core. [0004] In JP-A-9-194091, the strip electrode and the like is wound on the winding shaft that is in a first position. Then the winding shaft is temporarily stopped and the turret is rotated so as to move the winding shaft to a second position. Then in this second position, the cut strip electrode and the like is wound. With this method, the overall number of processes is large so productivity is poor. In contrast, productivity can be improved if by the strip electrode and the like is wound by rotating the winding shaft while the turret is being rotated. However, this also tends to result in- a large fluctuation in the tension on the strip electrode and the like. If the tension on the strip electrode and the like fluctuates greatly when the strip electrode and the like is being wound while manufacturing a wound electrode body such as a lithium-ion secondary battery, it may result in lower battery performance. Therefore, productivity is unable to be improved by rotating the winding shaft to wind the strip electrode and the like while the turret is being rotated.

SUMMARY OF THE INVENTION

[0005] This invention thus provides a wound electrode body manufacturing method and apparatus that efficiently manufactures a wound electrode body with little weaving. [0006] A first aspect of the invention relates to a method for manufacturing a wound electrode body in which at least one strip electrode and at least one strip separator are alternately wound, one on top of the other. This method includes a first step of winding a predetermined length of the strip electrode and the strip separator, one on top of the other, onto a winding shaft from among a plurality of winding shafts provided on a turret; a second step of cutting the strip electrode; and a third step of winding a remaining tail end of the strip electrode cut in the second step by rotating the winding shaft while rotating the turret, and feeding the strip separator.

[0007] According to this aspect, the remaining tail end of the strip element cut in the second step is wound by rotating the winding shaft while the turret is being rotated, thus improving productivity. Also, in the third step, the strip separator is fed so fluctuation in the tension on the strip separator can also be kept low. As a result, a wound electrode body with little weaving can be manufactured efficiently.

[0008] In the aspect described above, the third step may include the step of winding the fed strip separator by rotating the winding shaft, and the speed at which the strip separator is wound by rotating the winding shaft may be equal to or greater than the speed at which the strip separator is fed.

[0009] The manufacturing method described above may also include a fourth step of cutting the strip separator. [0010] In the third step of the structure described above, the speed at which the winding shaft is rotated may be adjusted based on a length of the remaining tail end of the strip electrode cut in the second step and a length of the strip electrode that will be unwound or wound by rotating the turret.

[0011] According to this structure, a predetermined length of the remaining tail end of the cut strip electrode is able to be more reliably wound by adjusting the speed at which the winding shaft rotates. As a result, a wound electrode body can be manufactured efficiently.

[0012] Also, in the third step of the structure described above, the speed at which the strip separator is fed may be adjusted based on a length of the remaining tail end of the strip electrode cut in the second step, a length of the strip electrode that will be unwound or wound by rotating the turret, and a length of the strip separator that will be pulled out by rotating the turret.

[0013] According to this structure, fluctuation in the tension on the strip separator can be kept even lower by adjusting the speed at which the strip separator is fed, thereby enabling a wound electrode body with little weaving to be manufactured efficiently.

[0014] A second aspect of the invention relates to an apparatus for manufacturing a wound electrode body in which at least one strip electrode and at least one strip separator are alternately wound, one on top of the other. This apparatus includes a turret; a plurality of winding shafts provided on the turret; a cutter that cuts the strip electrode; and a controller that controls the turret, the winding shafts, and the cutter. The controller executes the steps in the method for manufacturing a wound electrode body according to the first aspect described above. [0015] A third aspect of the invention relates to an electrode winding apparatus that alternately winds at least one strip electrode and at least one strip separator, one on top of the other, onto a winding shaft. This electrode winding apparatus includes a turret; a plurality of winding shafts provided on the turret; a cutter that cuts the strip electrode; and a controller that controls the turret, the winding shafts, and the cutter. The controller performs a first process that involves winding a predetermined length of the strip electrode and the strip separator, one on top of the other, onto the winding shafts, a second process that involves cutting the strip electrode with the cutter, and a third process that involves winding a remaining tail end of the strip electrode cut in the second process by rotating the winding shaft while rotating the turret, and feeding the strip separator.

[0016] According to this aspect, the strip electrode is cut by a cutter, and then the processes of rotating the turret and winding the remaining tail end of the cut strip electrode are performed simultaneously. Therefore, the number of processes can be reduced which improves productivity. Also, the strip separator is fed which enables fluctuation in the tension on the strip separator to be kept low.

[0017] In the aspect described above, the third process may include a winding process that winds the fed strip separator by rotating the winding shaft, and the speed at which the strip separator is wound by rotating the winding shaft may be equal to or greater than the speed at which the strip separator is fed. [0018] In the aspect described above, the electrode winding apparatus may further include a second cutter that cuts the strip separator. And the controller may perform a fourth process that involves cutting the strip separator.

[0019] In the foregoing third process of the structure described above, a first controlled variable for controlling the rotation of the winding shafts may be set based on a length of the remaining tail end of the strip electrode cut in the second process and a length of the strip electrode that will be unwound or wound by rotating the turret.

[0020] According to the structure described above, a predetermined length of the remaining tail end of the cut strip electrode is able to be more reliably wound by adjusting the controlled variable for rotating the winding shaft.

[0021] Furthermore, in the foregoing third process of the structure described above, a second controlled variable for feeding the strip separator may be set based on a length of the remaining tail end of the strip electrode cut in the second process, a length of the strip electrode that will be unwound or wound by rotating the turret, and a length of the strip separator that will be pulled out by rotating the turret.

[0022] Fluctuation in the tension on the strip separator can be kept lower by setting the controlled variable for feeding the strip separator in the structure described above.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The foregoing and further objects, features and advantages of the invention will become apparent from the following description of preferred embodiments with reference to the accompanying drawings, wherein like numerals are used to represent like elements and wherein:

FIG. 1 is a view showing the structure of a wound electrode body manufactured using an electrode winding apparatus according to an example embodiment of the invention;

FIG. 2 is a sectional view showing the electrode structure of the wound electrode body manufactured using the electrode winding apparatus according to the example embodiment of the invention;

FIG. 3 is a view showing the structure of the electrode winding apparatus according to the example embodiment of the invention;

FIG. 4 is view showing part of the structure of the electrode winding apparatus according to the example embodiment of the invention;

FIG. 5 is a view showing a state of the electrode winding apparatus according to the example embodiment of the invention in use;

FIG. 6 is view showing another state of the electrode winding apparatus according to the example embodiment of the invention in use;

FIG. 7 is a view showing yet another state of the electrode winding apparatus according to the example embodiment of the invention in use;

FIG. 8 is a chart showing a controlled variable for rotating a winding shaft of the electrode winding apparatus according to the example embodiment of the invention; FIG. 9 is another chart showing the controlled variable for rotating the winding shaft of the electrode winding apparatus according to the example embodiment of the invention;

FIG. 10 is a chart showing a controlled variable for feeding a strip separator of the electrode winding apparatus according to the example embodiment of the invention; and

FIG. 11 is another chart showing the controlled variable for feeding the strip separator of the electrode winding apparatus according to the example embodiment of the invention.

DETAILED DESCRIPTION OF AN EMBODIMENT

[0024] Hereinafter, a wound electrode body manufacturing method and an electrode winding apparatus according to an example embodiment of the invention will be described with reference to the drawings. Incidentally, in this example embodiment, the wound electrode body manufacturing method and the electrode winding apparatus will be described using a method for manufacturing a wound electrode body of a lithium-ion secondary battery as an example.

[0025] In a wound electrode body 10 of a lithium-ion secondary battery or the like, a strip anode 11, a first strip separator 12, a strip cathode 13, and a second strip separator 14 are wound, one on top of the other in that order, for example, as shown in FIG. 1. Incidentally, in the following description, the strip anode 11 and the strip cathode 13 may be collectively referred to as "strip electrodes" when appropriate. Also, the strip electrodes 11 and 13 and the strip separators 12 and 14 may collectively be referred to as "strip members" when appropriate.

[0026] In this example embodiment, the strip anode 11 has electrode material 32 (anode active materiel) that includes lithium applied to both sides of a strip sheet 31 (i.e., an anode collector) made of aluminum foil. Examples of the electrode material 32 include lithium manganese oxide (LiMn2O4), lithium cobalt oxide (LiCoO2), and lithium nickel oxide (LiNiO2) and the like. In this example embodiment, the strip cathode 13 has electrode material 42 (cathode active materiel) applied to both side.s of a strip sheet 41 (i.e., a cathode collector) made of copper foil. Examples of preferable cathode active material in the electrode material 42 include carbon-based material such as graphite and amorphous carbon, as well as lithium-containing transition metal oxides and transition metal nitrides and the like. The strip separators 12 and 14 are films through which ionic material can pass. In this example embodiment, polypropylene microporous films are used.

[0027] In this example embodiment, the anode strip electrodes 11 and 13 are formed by applying the electrode material 32 and 42 to the strip sheets 31 and 41, respectively. The electrode material 32 and 42 is applied to both sides of the strip sheets 31 and 41, as described above, on all but one edge portion in the width direction of the strips sheets 31 and 41. Of the anode strip electrodes 11 and 13, the portions where the electrode material 32 and 42 is applied to the strip sheets 31 and 41 will be referred to as applied portions 11a and 13a, and the portions where the electrode material 32 and 42 is not applied to the strip sheets 31 and 41 will be referred to as unapplied portions lib and 13b.

[0028] FIG. 2 is a sectional view in the width direction showing the strip anode 11, the first strip separator 12, the strip cathode 13, and the second strip separator 14, one on top of the other in that order and is also a sectional view of the line thorough II-II shown in FIG. 1. The applied portion 11a of the strip anode 11 and the applied portion 13a of the strip cathode 13 oppose one another across the strip separators 12 and 14. As shown in FIGS. 1 and 2, the unapplied portions lib and 13b of the strip anode 11 and the strip cathode 13 protrude out from the strip separators 12 and 14 at both ends in the direction orthogonal to the winding direction of the wound electrode body 10 (i.e., in the direction of the winding axis). The unapplied portion lib of the strip anode 11 forms an anode collector llbl of the wound collector 10, and the unapplied portion 13b of the strip cathode 13 forms a cathode collector 13bl of the wound collector 10.

[0029] In the lithium-ion secondary battery, lithium ions move back and forth thiough the strip separators 12 and 14 between the applied portion 11a of the strip anode 11 and the applied portion 13a of the strip cathode 13 when discharging and charging. In order to prevent the deposition of lithium ions at this time, it is preferable that the applied portion 11a of the strip anode 11 not protrude from the applied portion 13a of the strip cathode 13. The applied portion 11a of the strip anode 11 is able to prevent the deposition of lithium ions during discharging and charging by not protruding out from the applied portion 13a of the strip cathode 13. In this example embodiment, the edges of the applied portion 13a of the strip cathode 13 protrudes out from the edges of the applied portion 11a of the strip anode 11 by preset difference (b-a), as shown in FIGS. 1 and 2.

[0030] Also, the applied portion 11a of the strip anode 11 and the applied portion 13a of the strip cathode 13 do not protrude out from the strip separators 12 and 14, thus preventing internal shorting from occurring. The edges of the strip separators 12 and 14 protrudes out from the edges of the applied portion 11a of the strip anode 11 by preset protruding distance dl and d2, as shown in FIGS. 1 and 2. There may be some manufacturing error in the width of the applied portion 11a of the strip anode 11 and the width of the applied portion 13a of the strip cathode 13, or those widths may become off in the width direction when the strip anode 11, the strip cathode 13, and the strip separators 12 and 14 are on top of one another. Therefore, in order to allow for this error or offset, a distance is set that is necessary for the difference (b - a), between the width b of the applied portion 13a of the strip cathode 13 and the width a of the applied portion 11a of the strip anode 11, and the difference ((cl, c2) - b) between the widths cl and c2 of the first strip separator 12 and the second strip separator 14 and the width b of the applied portion 13a of the strip cathode 13.

[0031] In this example embodiment, manufacturing error or offset during winding is allowed for by setting the distances dl and d2 and the difference (b - a) and the difference ((cl, c2) - b), as described above. When the manufacturing error or offset during winding is large, the distances dl and d2, the difference (b - a), and the difference ((cl, c2) - b) must be set large. Also, if the manufacturing error or offset during winding can be reduced, the difference (b - a) and the difference ((cl, c2) - b) can be set smaller, which enables the material cost to be reduced by that amount. In this way, it is preferable to minimize weaving (i.e., offset during winding) of the strip electrodes 11 and 13 and the strip separators 12 and 14 when manufacturing the wound electrode body 10.

[0032] An electrode winding apparatus 100 is an apparatus that winds the strip anode 11 (i.e., a first strip electrode), the first strip separator 12, the strip cathode 13 (i.e., a second strip electrode), and the second strip separator 14 on top of one another in that order on winding shafts 121 and 122. The strip anode 11 (i.e., the first strip electrode), the first strip separator 12, the strip cathode 13 (i.e., the second strip electrode), and the second strip separator 14 are each supplied from a separate supply reel 21 to 24. [0033] This electrode winding apparatus 100 includes a turret 110, the winding shafts 121 and 122, dancer rollers 311 to 314, edge detecting devices 321 to 324, and correcting mechanisms 331 to 334. In addition, the electrode winding apparatus 100 is also provided with a controller 400. This controller 400 includes a calculating portion formed of a CPU and the like, and a storage element formed of nonvolatile memory and the like. This controller 400 controls the electrode winding apparatus 100 by performing various electronic calculations according to a program set beforehand.

[0034] The dancer rollers 311 to 314 are devices that adjust the tension on the strip members 11 to 14 to be wound around the winding shafts 121 to 122. The edge detecting devices 321 to 324 are devices that detect the positions of the edges of the strip members 11 to 14 to be wound on the winding shafts 121 and 122. The correcting mechanisms 331 to 334 are mechanisms that correct the position in the width direction of the strip members 11 to 14 to be wound on the winding shafts 121 and 122.

[0035] The controller 400 controls the dancer rollers 311 to 314. An appropriate amount of frictional force is created between the conveyer rollers and the strip members 11 to 14 by applying adequate tension to the strip members 11 to 14. This inhibits the strip members from weaving in the width direction along their trajectories. Also, the controller 400 controls the correcting mechanisms 331 to 334 based on detections signals from the edge detecting devices 321 to 324. The strip members 11 to 14 are wound onto the winding shafts 121 and 122 while their positions in the width direction are corrected by the correcting mechanisms 331 to 334. In this way, the electrode winding apparatus 100 winds the strip members 11 to 14 onto the winding shafts 121 to 122 while minimizing weaving of the strip members 11 to 14 using the dancer rollers 311 to 314 and the correcting mechanisms 331 to 334 and the like described above. Incidentally, any of various suitable structures can be employed for the specific methods of controlling the dancer rollers 311 to 314 and the correcting mechanisms 331 to 334, as well as the specific mechanical structures of the dancer rollers 331 to 314, the edge detecting devices 321 to 324, and the correcting mechanisms 331 to 334, and the like. [0036] This electrode winding apparatus 100 winds a predetermined length of the strip electrodes 11 and 13 and the second strip separators 12 and 14 on top of one another onto the winding shafts 121 and 122, and then performs a plurality of processes such as cutting the strip electrodes 11 and 13 and winding up the cut strip electrodes 11 and 13. The plurality of winding shafts 121 and 122 of this electrode winding apparatus 100 are provided on the turret 110 so that their positions can be changed according to the process to be performed. That is, the plurality of processes is performed with the winding shafts 121 and 122 in different positions for each process, which improves productivity.

[0037] The turret 110 is arranged rotatable with respect to the electrode winding apparatus 100. A rotating shaft 111 is arranged at the rotational center of the turret 110. In this example embodiment, the two winding shafts 121 and 121 are positioned on the turret 110 180° apart from each other in the circumferential direction of the turret 110. As shown in FIG. 4, the turret 110 rotates such that one winding shaft 121 or 122 is in a first position Xl where the winding shaft 121 or 122 winds the strip members 11 to 14, and the other winding shaft 121 or 122 is in a second position X2 where the wound strip members 11 to 14 are pulled off of the winding shaft 121 or 122. The first position Xl and the second position X2 are positioned 180° apart from each other in the circumferential direction of the turret 110. Accordingly, the winding shaft 121 or 122 that winds the strip members 11 to 14 can be changed by rotating the turret 110.

[0038] As shown in FIG. 3, the trajectories of the strip electrodes 11 and 13 and the strip separators 12 and 14 are set so they are in the direction of the first position Xl from the supply reels 21 to 24. The strip electrodes 11 and 13 and the strip separators 12 and 14 are bound one on top of the other in a predetermined order in the first position Xl.

[0039] In this example embodiment, the winding shafts 121 and 122 are formed by a pair of shaft members that bind and retain the strip electrodes 11 and 13 and the strip separators 12 and 14. Although not shown in the drawings, the winding shafts 121 and 122 have mechanisms that enable them to protrude or retract with respect to the turret 110. The winding shafts 121 and 122 are made to protrude from the turret 110 and bind and retain the strip electrodes 11 and 13 and the strip separators 12 and 14 at one end. Then by having the winding shafts 121 and 122 rotate (by autorotation), the strip electrodes 11 and 13 and the strip separators 12 and 14 can be wound onto the outer peripheral surfaces of the winding shafts 121 and 122. Also, the resultant wound electrode body can be removed from the winding shafts 121 and 122 by retracting the winding shafts 121 and 122 into the turret 110.

[0040] Cutters 131 and 132 that cut the strip electrodes 11 and 13 are arranged along the trajectories of the strip electrodes 11 and 13 that are supplied to the first position Xl, as shown in FIG. 4. In this example embodiment, retaining portions 141 and 142 that retain the end portions of the cut strip electrodes 11 and 13 are provided near the cutters 131 and 132. Also, a cutter 133 that cuts the strip separators 12 and 14 is arranged near the rotating shaft 111 of the turret 110. The turret 110, the winding shafts 121 and 122, and the cutters 131, 132, and 133 are all controlled by the controller 400.

[0041] The controller 400 performs a first process of winding a predetermined length of the strip electrodes 11 and 13 and the strip separators 12 and 14, one on top of the other, onto the winding shafts 121 and 122. In this example embodiment, of the winding shafts 121 and 122, the winding shaft 121 is moved to the first position Xl, and the other winding shaft 122 is moved to the second position X2, as shown in FIG. 4. Then the strip electrodes 11 and 13 and the strip separators 12 and 14 are placed one top of the other in a predetermined order and the end portions of those strip electrodes and strip separators are retained by the winding shaft 121 in the first position Xl. The winding shaft 121 is then rotated and a predetermined length of the strip electrodes 11 and 13 and the strip separators 12 and 14 is wound.

[0042] After a predetermined length of the strip electrodes 11 and 13 and the strip separators 12 and 14 has been wound on the winding shaft 121 by the first process, a second process is performed in which the strip electrodes 11 and 13 are cut by the cutters 131 and 132, as shown in FIG. 5. In this example embodiment, the strip electrodes 11 and 13 are cut while being retained by the retaining portions 141 and 142 near the cutters 131 and 132. Of the end portions of the cut strip electrodes 11 and 13, the end portions that are connected to the supply reels 21 and 23 are retained by the retaining portions 141 jond 142. Meanwhile, the end portions of the strip electrodes 11 and 13 that are wound on the winding shafts 121 are free ends. [0043] Next, a third process is performed in which the winding shaft 121 is rotated (by autorotation) while the turret 110 is rotated so that the remaining tail ends of the strip electrodes 11 and 13 cut in the second process are wound, while the strip separators 12 and 14 are fed, as shown in FIG. 6. That is, even though the strip electrodes 11 and 13 are cut in the second process, the strip separators 12 and 14 that are being wound onto the winding shaft 121 are still connected to the supply reels 21 to 24. Therefore, the controller 400 rotates the supply reels 22 and 24 of the strip separators 12 and 14 to feed the strip separators 12 and 14 while the remaining tail ends of the strip electrodes 11 and 13 cut in the second process are wound.

5 [0044] In this third process, the winding shaft 121 moves to the second position X2, as shown in FIG. 7. Meanwhile, the winding shaft 122, which had been in the second position X2, moves to the first position Xl. Then, in the first position Xl, the strip electrodes 11 and 13 and the strip separators 12 and 14 are set on the winding shaft 122 and the winding of the strip members 11 to 14 starts anew. Also, the strip

10 separators 12 and 14 are connected to the winding shaft 121 that has moved to the second position X2. In this example embodiment, when the winding shaft 121 moves to the second position X2, the strip separators 12 and 14 become strung around the rotating shaft 111 of the turret 110, as shown in FIG. 7, and are cut by the cutter 133 that is arranged near the rotating shaft 111. At this second position X2, the end portions of the

15 cut strip separators 12 and 14 are fastened to the outer peripheral surface of the wound electrode body with tape or the like. Then the wound electrode body is removed from the winding shaft 121 by retracting the winding shaft 121 into the turret 110.

[0045] In this way, in the first position Xl, the strip electrodes 11 and 13 are cut after a predetermined length of the strip electrodes 11 and 13 and the strip separators

20 12 and 14 has been wound on the winding shaft 121, as shown in FIG. 5. Then, the remaining tail ends of the cut strip electrodes 11 and 13 are wound by rotating the winding shaft 121 while the turret 110 is rotated, as shown in FIG. 6. That is, the

_ remaining tail ends of the cut strip electrodes 11 and 13 are wound while moving the winding shaft 121 from the first position Xl to the second position X2. In the second

25 position X2, the strip separators 12 and 14 are cut, the end portions of the strip separators 12 and 14 are fixed, and the wound electrode body is removed from the winding shaft 121. The electrode winding apparatus 100 repeats these operations while changing the positions of the winding shafts 121 and 122 by rotating the turret 110 at the appropriate timing. The technology according to which the strip electrodes 11 and 13 and the strip separators 12 and 14 are wound on the winding shafts 121 and 122 again after being cut is known technology that is described in JP-A-9-194091, for example, and so will not be described here.

[0046] In this example embodiment, in the third process described above, the remaining tail ends of the cut strip electrodes 11 and 13 are wound by rotating (by autorotation) the winding shaft 121 while the winding shaft 121 is being moved by rotating the turret 110. Therefore, according to this electrode winding apparatus 100, the process of rotating the turret 110 and the process of winding up the remaining tail ends of the cut strip electrodes 11 and 13 are performed simultaneously. Accordingly, the number of processes can be reduced, thereby increasing productivity. Furthermore, in the third process, the strip separators 12 and 14 are fed so fluctuation in the tension on the strip separators 12 and 14 can kept low.

[0047] In this example embodiment, the rotation (autorotation) of the winding shaft 121 and the feeding out of the strip separators 12 and 14 are appropriately controlled in the third process. In this third process described above, a first controlled variable Vl for controlling the rotation of the winding shaft 121 and a second controlled variable C2 for feeding the strip separators 12 and 14 are set as described below.

[0048] The first controlled variable Vl for controlling the rotation of the winding shaft 121 is set based on i) the lengths of the remaining tail ends of the strip electrodes 11 and 13 cut in the second process, and ii) the lengths of the strip electrodes 11 and 13 that will be wound or unwound by rotating the turret 110.

[0049] The lengths of the remaining tail ends of the strip electrodes 11 and 13 cut in the second process are the lengths of the remaining tail ends of the cut strip electrodes 11 and 13 when the strip electrodes 11 and 13 have been cut by the cutters 131 and 132 in the second process, as shown in FIG. 5. In this case, the distance along the trajectory of the strip electrodes 11 and 13 from the position where the strip electrodes 11 and 13 are wound onto the winding shafts 121 and 122 in the first position Xl to the position where the strip electrodes 11 and 13 are cut by the cutters 131 and 132 may be obtained. [0050] In this example embodiment, the position where the strip electrodes 11 and 13 are wound on the winding shafts 121 and 122 in the first position Xl is calculated in advance according to the positions where pulleys are arranged and the like, and the length wound on the winding shafts 121 and 122. Also, the positions where the strip electrodes 11 and 13 are cut by the cutters 131 and 132 are obtained by the positions where the cutters 131 and 132 are arranged. The trajectory of the strip electrodes 11 and 13 may be obtained by the positions where the pulleys and the like are arranged. The lengths of the remaining tail ends of the cut strip electrodes 11 and 13 when the strip electrodes 11 and 13 are cut by the cutters 131 and 132 in the second process are the lengths described above. The lengths of the strip electrodes 11 and 13 and the strip separators 12 and 14 to be wound may be set after the cutting in the second process is performed, based on the lengths of the remaining tail ends of the cut strip electrodes 11 and 13.

[0051] Also, as shown in FIG. 5, the position in the circumferential direction on the winding shaft 121 where the strip electrodes 11 and 13 start to wind onto the winding shaft 121 (hereinafter this position will simply be referred to as the "winding point") is different when the winding shaft 121 is in the first position Xl than it is when the winding shaft 121 is in the second position X2. In this example embodiment, the winding point where the strip electrodes 11 and 13 wind onto the winding shaft 121 in the second position X2 is behind, in the rotational direction of the winding shaft 121, the winding point when the winding shaft 121 is in the first position Xl. That is, in FIGS. 5 and 7, the winding point of the strip electrodes 11 and 13 that are being wound onto the winding shaft 121 is farther back in the rotational direction of the winding shaft 121. Therefore, as the winding shaft 121 moves from the first position Xl to the second position X2, the strip electrodes 11 and 13 already wound on the winding shaft 121 are unwound from the winding shaft 121 in the second position X2. Accordingly, when winding the remaining tail ends of the cut strip electrodes 11 and 13 onto the winding shaft 121 while the winding shaft 121 is being moved from the first position Xl to the second position X2, it is necessary to take into account the length that the strip electrodes 11 and 13, which are already wound on the winding shaft 121, will unwind and wind that much more.

[0052] Incidentally, although not shown in the drawings, if the rotational direction of the winding shaft 121 is the same as is shown in FIG. 5 and the rotational direction of the turret 110 is opposite that described above, the strip electrodes 11 and 13 that are already wound on the strip electrodes 11 and 13 would wind further when the winding shaft 121 is moved from the first position Xl to the second position X2. Also, if the rotational direction of the turret 110 is the same as is shown in FIG. 5 and the rotational direction of the winding shaft 121 is opposite that described above, the strip electrodes 11 and 13 that are already wound on the winding shaft 121 would wind further when the winding shaft 121 is moved from the first position Xl to the second position X2. Also, if the rotational direction of the turret 110 and the rotational direction of the winding shaft 121 are both opposite that shown in FIG. 5, the electrodes 11 and 13 that are already wound on the winding shaft 121 would unwind when the winding shaft 121 is moved from the first position Xl to the second position X2.

[0053] In this example embodiment, the lengths of the strip electrodes 11 and 13 that are unwound or wound by rotating the turret 110 is obtained and the first controlled variable Vl that controls the rotation of the winding shaft 121 is determined in the third process described above based on this knowledge. [0054] That is, in this example embodiment, with the time that it takes for the turret 110 to rotate 180° designated tl, the first controlled variable Vl for controlling the rotation of the winding shaft 121 is set as shown in FIG. 8 while the winding shaft 121 moves from the first position Xl to the second position X2. In FIG. 8, VIl is the controlled variable that is set based on the lengths of the remaining tail ends of the strip electrodes 11 and 13 cut in the second process, and V12 is the controlled variable that is set based on the lengths of the strip electrodes 11 and 13 that will be unwound by rotating the turret 110. Vl is obtained by adding VIl and V12 together. Incidentally, in this example embodiment, the strip electrodes 11 and 13 are unwound by rotating the turret 110, as shown in FIGS. 5 to 7, so V12 is a positive controlled variable. In contrast, when the strip electrodes 11 and 13 are wound on the winding shaft 121 by rotating the turret 110, the V12 becomes a negative controlled variable. Incidentally, in this example embodiment, as shown in FIG. 9, the first controlled variable Vl is divided up per unit control time, and the controlled variable is calculated for each unit control time. Also, in this example embodiment, the first controlled variable Vl is calculated by the speed at which the strip electrodes 11 and 13 are wound on the winding shaft 121.

[0055] Also, in this example embodiment, the second controlled variable C2 that feeds out the strip separators 12 and 14 is set so that the strip separators 12 and 14 are fed appropriately in the third process. This second controlled variable C2 is obtained based on the first controlled variable Vl and the lengths of the strip separators 12 and 14 that will be pulled out by rotating the turret 110. Even if the winding shaft 121 was not rotated, the strip separators 12 and 14 would still be pulled out when the turret 110 is rotated, as shown in FIGS. 5 to 7. Also, compared to when the winding shaft 121 is in the first position Xl, as shown in FIG. 5, the strip separators 12 and 14 are pulled out when the turret 110 rotates approximately 90°, as shown in FIG. 6. Furthermore, as shown in FIG. 7, the strip separators 12 and 14 are pulled out further when the winding shaft 121 moves to the second position X2. In this example embodiment, the second controlled variable V2 that feeds out the strip separators 12 and 14 is set in the third process based on this knowledge. [0056] That is, with the time it takes for the turret 110 to rotate 180° designated tl, the second controlled variable V2 that feeds out the strip separators 12 and 14 is set as shown in FIG. 10 while the winding shaft 121 moves from the first position Xl to the second position X2. In FIG. 10, Vl is the first controlled variable Vl described above. The rotation of the winding shaft 121 is controlled based on this first controlled variable Vl so that the remaining tail ends of the cut strip electrodes 11 and 13 are wound appropriately. The strip separators 12 and 14 must be fed according to the rotation of the winding shaft 121. Also, in FIG. 10, V21 is a controlled variable that is set based on the lengths of the strip separators 12 and 14 that will be pulled out by rotating the turret 110. V2 is obtained by adding Vl and V21 together. Incidentally, more specifically, in this example embodiment the first controlled variable Vl is divided up per unit control time, as shown in FlG. 11, and the controlled variable is calculated for each unit control time. Also, in this example embodiment, the second controlled variable V2 is calculated by the speed at which the strip separators 12 and 14 are fed. [0057] Also, in this example embodiment, the amount that the strip separators

12 and 14 are fed is adjusted by controlling the rotation of the supply reels 22 and 24 of the strip separators 12 and 14. At this time, the remaining amounts of the strip separators 12 and 14 wound on the supply reels 22 and 24 gradually change. Therefore, the controller 400 detects the outer diameter of the strip separators 12 and 14 wound on the supply reels 22 and 24 when necessary, and calculates the rotation speed of the supply reels 22 and 24 to feed the strip separators 12 and 14 at a predetermined rate. Then the controller 400 controls the rotation of the supply wheels 22 and 24 based on the calculation results.

[0058] Incidentally, in the example embodiment described above, the second controlled variable C2 that feeds out the strip separators 12 and 14 is obtained in the third process based on the first controlled variable Vl and the lengths of the strip separators 12 and 14 that will be pulled out by rotating the turret 110. The second controlled variable C2 may also be obtained based on the lengths VIl (refer to FIG. 8) of the remaining tail ends of the strip electrodes 11 and 13 cut in the second process and the lengths V12 (refer to FIG. 8) of the strip electrodes 11 and 13 that will be unwound or wound by rotating the turret 110, instead of based on the first controlled variable Vl. That is, the second controlled variable C2 may also be set based on i) the lengths VIl (refer to FIG. 8) of the remaining tail ends of the strip electrodes 11 and 13 cut in the second process, ii) the lengths V12 (refer to FIG. 8) of the strip electrodes 11 and 13 that will be unwound or wound by rotating the turret 110, and iii) the lengths V21 (see FIG. 10) of the strip separators 12 and 14 that will be pulled out by rotating the turret 110.

[0059] In the example embodiment described above, the wound electrode body that is manufactured may be used as a wound electrode body of a lithium-ion secondary battery. Incidentally, any of various suitable methods for manufacturing a lithium-ion secondary battery that uses the manufactured wound electrode body may be used.

[0060] The method for manufacturing the wound electrode body that is employed by the electrode winding apparatus 100 described above includes the following three steps. The first step involves winding a predetermined length of strip electrodes 11 and 13 and strip separators 12 and 14, one on top of the other, onto one winding shaft from among a plurality of winding shafts 121 and 122 provided on the turret 110. The second step involves cutting the strip electrodes 11 and 13 with cutters 131 and 132. The third step involves winding the remaining tail ends of the strip electrodes 11 and 13 cut in the second step by rotating the winding shafts 121 and 122 while rotating the turret 110, and feeding out the strip separators 12 and 14. According to the method of manufacturing a wound electrode body that includes the first, second, and third steps, the remaining tail ends of the strip electrodes 11 and 13 cut in the second step are wound by rotating winding shafts 121 and 122 while the turret 110 is being rotated. As a result, productivity is good. Also, in the third step, the strip separators 12 and 14 are fed out so fluctuation in the tension on the strip separators 12 and 14 can be kept low. Therefore, a wound electrode body in which there is little weaving can be manufactured efficiently. Also, a battery having good performance can be efficiently provided by using this wound electrode body.

[0061] In this case, in the third step, the speed at which the winding shafts 121 and 122 are rotated may be adjusted based on the lengths of the remaining tail ends of the strip electrodes 11 and 13 cut in the second step, and the lengths of the strip electrodes 11 and 13 that will be unwound or wound by rotating the turret 110. Adjusting the speed at which the winding shafts 121 and 122 are wound in this way makes it possible to more reliably wind predetermined lengths of the remaining tail ends of the cut strip electrodes 11 and 13. As a result, a wound electrode can be manufactured efficiently, thereby enabling a battery having good performance to be efficiently provided.

[0062] Also, in the third step described above, the speed at which the strip separators 12 and 14 are fed out may also be adjusted based on i) the lengths of the remaining tail ends of the strip electrodes 11 and 13 cut in the second step, ii) the lengths of the strip electrodes 11 and 13 that will be unwound or wound by rotating the turret 110, and iii) the lengths of the strip separators 12 and 14 that will be pulled out by rotating the turret 110. Adjusting the speed at which the strip separators 12 and 14 are fed out in this way enables fluctuation in the tension on the strip separators 12 and 14 to be kept low, which enables a wound electrode body in which there is little weaving to be efficiently manufactured. As a result, a battery having good performance can be efficiently provided by using this wound electrode body.

[0063] Although an electrode winding apparatus and a method for manufacturing a wound electrode body according to an example embodiment of the invention are described above, the electrode winding apparatus and the method for manufacturing an wound electrode body according to the invention are not limited to this example embodiment.

[0064] For example, the structure of the electrode winding apparatus is not limited to the example embodiment described above. More specifically, the provisions of the dancer rollers, the edge detecting devices, and the correcting mechanisms are not limited to the example embodiment described above. To the contrary, various modifications are possible. Also, in the electrode winding apparatus 100 described above, two winding shafts 121 and 122 are provided on the turret 110. However, the number of winding shafts provided on the turret 110 is not limited to two. That is, two or more winding shafts may be provided on the turret 110. Incidentally, as in the example embodiment described above, in the invention, the remaining tail ends of the cut strip electrodes are wound at the same time the turret is rotated, thereby consolidating operations. Accordingly, two winding shafts can be provided on the turret 110. Also, strip electrodes and strip separators of a wound electrode body that is used in a lithium-ion secondary battery are given as examples of strip electrodes and strip separators. However, the electrode winding apparatus and the method for manufacturing a wound electrode body according to the invention may also be used to manufacture a wound electrode body used in another type of battery other than a lithium-ion secondary battery. In this case, the structures of the strip electrodes and the strip separators may be changed so that they are suitable for the battery.

[0065] While the invention has been described with reference to example embodiments thereof, it is to be understood that the invention is not limited to the described embodiments or constructions. To the contrary, the invention is intended to cover various modifications and equivalent arrangements. In addition, while the various elements of the disclosed invention are shown in various example combinations and configurations, other combinations and configurations, including more, less or only a single element, are also within the scope of the appended claims.

Claims

CLAIMS:

1. A method for manufacturing a wound electrode body in which at least one strip electrode and at least one strip separator are alternately wound, one on top of the other, characterised by comprising: a first step of winding a predetermined length of the strip electrode and the strip separator, one on top of the other, onto a winding shaft from among a plurality of winding shafts provided on a turret; a second step of cutting the strip electrode; and a third step of winding a remaining tail end of the strip electrode cut in the second step by rotating the winding shaft while rotating the turret, and feeding the strip separator.

2. The manufacturing method according to claim 1, wherein: the third step includes the step of winding the fed strip separator by rotating the winding shaft; and the speed at which the strip separator is wound by rotating the winding shaft is equal to or greater than the speed at which the strip separator is fed.

3. The manufacturing method according to claim 1 or 2, further comprising a fourth step of cutting the strip separator.

4. The manufacturing method according to any one of claims 1 to 3, wherein in the third step, the speed at which the winding shaft is rotated is adjusted based on a length of the remaining tail end of the strip electrode cut in the second step and a length of the strip electrode that will be unwound or wound by rotating the turret.

5. The manufacturing method according to any one of claims 1 to 4, wherein in the third step, the speed at which the strip separator is fed is adjusted based on a length of the remaining tail end of the strip electrode cut in the second step, a length of the strip electrode that will be unwound or wound by rotating the turret, and a length of the strip separator that will be pulled out by rotating the turret.

6. An apparatus for manufacturing a wound electrode body in which at least one strip electrode and at least one strip separator are alternately wound, one on top of the other, characterised by comprising: a turret; a plurality of winding shafts provided on the turret; a cutter that cuts the strip electrode; and a controller that controls the turret, the winding shafts, and the cutter, wherein the controller executes the steps in the method for manufacturing a wound electrode body according to any one of claims 1 to 5.

7. An electrode winding apparatus that alternately winds at least one strip electrode and at least one strip separator, one on top of the other, onto a winding shaft, characterised by comprising: a turret; a plurality of winding shafts provided on the turret; a cutter that cuts the strip electrode; and a controller that controls the turret, the winding shafts, and the cutter, wherein the controller performs a first process that involves winding a predetermined length of the strip electrode and the strip separator, one on top of the other, onto the winding shafts, a second process that involves cutting the strip electrode with the cutter, and a third process that involves winding a remaining tail end of the strip electrode cut in the second process by rotating the winding shaft while rotating the turret, and feeding the strip separator.

8. The electrode winding apparatus according to claim 7, wherein the third process includes a winding process that winds the fed strip separator by rotating the winding shaft; and the speed at which the strip separator is wound by rotating the winding shaft is equal to or greater than the speed at which the strip separator is fed.

9. The electrode winding apparatus according to claim 7 or 8, further comprising a second cutter that cuts the strip separator, wherein the controller performs a fourth process that involves cutting the strip separator with the second cutter.

10. The electrode winding apparatus according to any one of claims 7 to 9, wherein in the third process, a first controlled variable for controlling the rotation of the winding shafts is set based on a length of the remaining tail end of the strip electrode cut in the second process and a length of the strip electrode that will be unwound or wound by rotating the turret.

11. The electrode winding apparatus according to any one of claims 7 to 10, wherein in the third process, a second controlled variable for feeding the strip separator is set based on a length of the remaining tail end of the strip electrode cut in the second process, a length of the strip electrode that will be unwound or wound by rotating the turret, and a length of the strip separator that will be pulled out by rotating the turret.