JP4600926B2 - Winding core and method for producing electrode body using the winding core - Google Patents

Description

  The present invention relates to a winding core for manufacturing an electrode body incorporated in a battery can of a lithium ion battery and a method for manufacturing an electrode body using the winding core.

  In Patent Documents 1 to 5, by rotating a winding core, a positive electrode, a negative electrode, and a separator are placed on the winding core in a state where a strip-shaped separator is interposed between the strip-shaped positive electrode and the strip-shaped negative electrode. It is disclosed that an electrode body is manufactured by winding.

JP-A-8-153519 (paragraph numbers 0009-0010, FIG. 6-10) JP 2003-282136 A (paragraph number 0017, FIG. 1) Japanese Patent No. 3536391 (paragraph number 0046, FIG. 2) Japanese Patent Laying-Open No. 2003-257475 (paragraph number 0008, FIG. 2) Japanese Patent Laying-Open No. 2004-127860 (paragraph numbers 0008-0011, FIG. 1-3)

  In Patent Documents 1 and 2, the separator is wound around the winding core in a state where the separator is passed through a slit provided in a through shape in the radial direction of the winding core. In Patent Document 3, the positive electrode, the negative electrode, and the separator are directly wound around the outer peripheral surface of the winding core. For this reason, in patent documents 1-3, a separator slips at the time of winding, the positional relationship of a positive electrode and a negative electrode will shift, and it may cause the quality fall of an electrode body, etc.

  On the other hand, in Patent Documents 4 and 5, the separator is sandwiched and fixed by split winding cores to prevent the above-described separator from slipping. However, when the separator is sandwiched, the split surface of the winding core is the separator. Since it is pressed while moving in the surface direction, the separator may be torn off. Moreover, Patent Documents 4 and 5 tend to increase the cost of the winding core due to the complicated structure.

  Accordingly, an object of the present invention is to provide a winding core that sandwiches and fixes a separator without moving in the surface direction of the separator while having a simple structure, and a method for manufacturing an electrode body using the winding core.

  As shown in FIG. 5, the winding core 21 targeted by the present invention is used to manufacture the electrode body 2 by winding the belt-like positive electrode 6 and the belt-like negative electrode 7 with the belt-like separator 9 interposed therebetween. . As shown in FIGS. 1 and 2, the winding core 21 of the present invention includes a long rod-shaped outer shaft 22 around which the positive electrode 6, the negative electrode 7, and the separator 9 are wound, and a long rod-shaped inner shaft 25 for fixing the separator 9. And a receiving shaft 26 that is detachably attached to one end of the outer shaft 22. A space 23 extending in the axial direction of the outer shaft 22 and opened at one end of the outer shaft 22 is formed in the shaft core portion of the outer shaft 22. The middle shaft 25 has the shaft core of the middle shaft 25 as the outer shaft. It is arranged in the space 23 in a posture along the 22 axis. The receiving shaft 26 has a fitting portion 35 that is detachably fitted to the distal end portion 25 b of the middle shaft 25 when attached to one end of the outer shaft 22. The middle shaft 25 has a middle shaft slit 29 that is fixed to the inner portion of the space 23 and has a middle shaft slit 29 that extends in the axial direction of the middle shaft 25 and is opened at the tip of the middle shaft 25. 29 divides the tip side into a bifurcated shape. The outer shaft 22 has an outer shaft slit 27 that faces the middle shaft slit 29, and the separator 9 is introduced into the middle shaft slit 29 through the outer shaft slit 27. When 35 is externally fitted to the distal end portion 25b of the intermediate shaft 25, the outer peripheral surface of the distal end portion 25b of the intermediate shaft 25 is pushed in the width direction of the gap of the intermediate shaft slit 29 on the inner peripheral surface of the insertion portion 35, and the intermediate shaft slit 29 is closed. And the separator 9 is sandwiched. The outer shaft 22 here is formed in a cross-sectional shape such as a rhombus, ellipse, hexagon, or octagon. The outer shaft 22 is set in a tapered shape in which the end portion 25a side of the intermediate shaft 25 is wider in the width direction of the gap of the outer shaft slit 27 than the front end portion 25b side, and when the receiving shaft 26 is externally fitted to the intermediate shaft 25, It is also possible to set so that the width direction dimension of the slit gap between the end portion 25a side of the middle shaft 25 and the tip portion 25b side of the middle shaft 25 becomes substantially equal.

  The outer shaft slit 27 extends in the axial direction of the outer shaft 22 and is opened at one end of the outer shaft 22, so that one end side of the outer shaft 22 is divided into two. The fitting portion 35 of the receiving shaft 26 is formed so as to fit into the space 23 from one end side of the outer shaft 22 and to be fitted to the distal end portion 25 b of the middle shaft 25, and the fitting portion 35 of the receiving shaft 26 is formed in the space 23. When removed from the inside, one end of the outer shaft 22 becomes free and the gap between the outer shaft slits 27 becomes narrower.

  The middle shaft 25 is formed with a pair of cut surfaces 30 and 31 facing the middle shaft slit 29, and one cut surface 30 is provided with a protrusion 32 extending in the length direction of the cut surface 30. The other cut surface 31 has a recess 33 extending in the length direction of the cut surface 31 and facing the protrusion 32. The protrusion 32 may be anything that bites into the separator 9 so as not to break the separator 9. The cross-sectional shape of the protrusion 32 is preferably an arc shape or a triangular shape. The protrusions 32 and the recesses 33 may be provided in two or more rows, or may be provided intermittently in the length direction of the cut surfaces 30 and 31.

  The manufacturing method of the present invention is a manufacturing method of an electrode body using the above-described winding core 21, and as shown in FIG. The first step of inserting the two separators 9 and 9 into the outer shaft slit 27 and the middle shaft slit 29 of the outer shaft 22 and the receiving shaft 26 from the one end side of the outer shaft 22 By fitting in the space 23 of the shaft 22 and externally fitting to the tip 25b of the middle shaft 25, the pair of cut surfaces 30 and 31 facing the middle slit 29 of the middle shaft 25 are sandwiched and fixed. The second step of rotating the winding core 21 to wind the two-layer separators 9, 9 around the winding core 21, and then either the positive electrode 6 or the negative electrode 7 between the two-layer separators 9, 9. If one of the electrodes is placed To be arranged in the other state in which the electrode was allowed to face the one electrode across the one of the separators 9, and a third step of winding the two electrodes 6, 7 to the winding core 21 together with the separator 9.

  Furthermore, when the winding in the third step is completed, the fourth step for stopping the rotation of the winding core 21, and the receiving shaft 26 is removed from the tip 25b of the middle shaft 25 to widen the gap between the middle shaft slits 29. In addition to releasing the sandwiching of the two-layer separators 9 and 9 between the pair of cut surfaces 30 and 31, the receiving shaft 26 is removed from the space 23 of the outer shaft 22 to free one end of the outer shaft 22 and A fifth step of narrowing the gap of the slit 27 and a sixth step of extracting the electrode body 2 that has been wound from the winding core 21 are included. As described above, when the outer shaft 22 has a tapered shape in which the end portion 25a side of the middle shaft 25 is wider in the width direction of the outer shaft slit 27 than the tip portion 25b side, the receiving shaft 26 is extracted in the fifth step. The extraction of the electrode body 2 in the sixth step can be easily performed along the taper.

  One end side of the outer shaft 22 is bifurcated by the outer shaft slit 27, and the middle shaft 25 is bifurcated by the middle shaft slit 29. Prior to the third step, the outer shaft slit 27 and the middle shaft slit are formed. A portion 9 a of the two-layer separators 9 and 9 drawn out from the gap 29 to the side opposite to the side where the electrodes are arranged is cut to a predetermined length by the cutting blade 39.

  A protrusion 32 extending in the length direction of the cut surface 30 is provided on one cut surface 30 of the pair of cut surfaces 30 and 31, and the length of the cut surface 31 is provided on the other cut surface 31. A recess 33 that extends in the direction and faces the protrusion 32 is formed, and when the two separators 9 and 9 are sandwiched between the pair of cut surfaces 30 and 31 in the second step, the protrusion 32 bites into the separator 9. Can be.

  After the sixth step, the electrode body 2 can be accommodated in the thin rectangular tube-shaped battery can 1 by crushing the electrode body 2 into an oval cross section.

  According to the present invention, just by fitting the receiving shaft 26 to the front end portion 25 b of the intermediate shaft 25, the intermediate shaft 25 is pushed in the width direction of the clearance of the intermediate shaft slit 29 by the receiving shaft 26, and the intermediate shaft slit 29 is The separator 9 is closed in a direction substantially perpendicular to the back surface, and the separator 9 is sandwiched and fixed by the middle shaft 25. Therefore, when the sandwiching is performed, the pair of cut surfaces 30 and 31 of the middle shaft 25 facing the middle shaft slit 29 are separated from each other. There is almost no movement in the surface direction. Therefore, the separator 9 is not easily torn off during the sandwiching, and the positive electrode 6, the negative electrode 7, and the separator 9 are reliably wound by the winding core 21. Damage at the winding start portion of the separator 9 can be suppressed. The positional relationship between the positive electrode 6 and the negative electrode 7 is shifted during winding, and the active material of the positive electrode 6 and the negative electrode 7 is not peeled off, and the quality deterioration of the electrode body 2 can be well prevented. In addition, the structure of the winding core 21 is not so complicated. Further, the separator at the winding start end can be shortened, and the cost of the electrode body 2 can be suppressed.

  When the protrusions 32 and the recesses 33 are respectively provided on the pair of cut surfaces 30 and 31 of the middle shaft 25, the protrusions 32 firmly bite into the separator 9 and are separated from the winding core 21 during winding. Can be more reliably prevented from slipping.

  3 and 4, a thin sealed prismatic battery according to the present invention includes a bottomed rectangular tube-shaped battery can 1 having a horizontally long opening on the upper surface, an electrode body 2 housed in the battery can 1, and a non- It includes a water electrolyte, a horizontally long lid 3 that closes the upper surface of the opening of the battery can 1, and a plastic insulator 5 that is disposed inside the lid 3. The battery can 1 is formed in a vertically thin shape by deep drawing a clad material made of nickel and aluminum. The battery can 1 has a lateral width of 34 mm, a vertical height of 50 mm, and a longitudinal thickness of 3.8 mm.

  The electrode body 2 is manufactured by spirally winding a strip-shaped separator 9 made of a microporous polyethylene film between a strip-shaped positive electrode 6 and a strip-shaped negative electrode 7. The electrode body 2 is crushed and formed into an oval cross section after winding. On the positive electrode 6, a coating film containing a positive electrode active material is disposed on both the front and back surfaces of a strip-shaped positive electrode current collector. On the negative electrode 7, a coating film containing a negative electrode active material is disposed on both the front and back surfaces of a strip-shaped negative electrode current collector. From the positive electrode current collector of the positive electrode 6, a thin plate-shaped positive electrode current collecting lead 10 is led out. From the negative electrode current collector of the negative electrode 7, a thin plate-shaped negative electrode current collecting lead 11 is led out. The width of the positive electrode 6 is smaller than that of the negative electrode 7, and the difference in the width dimension between the positive electrode 6 and the negative electrode 7 is 0.6 mm.

  The lid 3 is a press-formed product of a plate material such as an aluminum alloy, and the outer peripheral edge of the lid 3 is seam welded to the opening peripheral edge of the battery can 1 by a laser. In the center of the lid 3, a negative electrode terminal 15 is attached in a penetrating manner via an upper insulating packing 12 and a lower insulating plate 13. Near the right end of the lid 3 in the left-right direction, a circular injection hole 16 for injecting the electrolyte into the battery can 1 is formed in a vertically penetrating manner. The liquid injection hole 16 is closed and sealed with a plug 17 after the electrolyte is injected.

  Connected to the lower end of the negative electrode terminal 15 is a lead body 19 made of a horizontally long thin plate on the inner surface of the lid 3. The lead body 19 extends to the opposite side of the liquid injection hole 16 and is insulated from the lid 3 by the lower insulating plate 13. The negative electrode current collector lead 11 is laser welded to the lower surface of the lead body 19. The positive electrode current collecting lead 10 is laser-welded in the space between the insulating plate 13 and the liquid injection hole 16 on the back surface of the lid 3. Thus, the positive electrode current collecting lead 10 is conducted to the lid 3 and the battery can 1, and the lid 3 and the battery can 1 are charged to the positive electrode potential. A cleaving vent 20 is formed near one end of the lid 3 in the left-right direction (near the left end in FIG. 3), and the cleaving vent 20 is cleaved to release the battery internal pressure when the battery internal pressure rises abnormally.

  When assembling the battery, the negative electrode terminal 15, the insulating packing 12, the insulating plate 13 and the lead body 19 are attached to the lid 3 as described above, and the electrode body 2 is accommodated in the battery can 1. The electric lead 11 is welded to the lead body 19 and the positive electrode current collecting lead 10 is welded to the lid 3 as described above. Next, the lid 3 is seam welded to the periphery of the opening of the battery can 1 with a laser, the electrolyte is injected from the injection hole 16, and the injection hole 16 is sealed by the plug 17, thereby completing the battery.

  The positive electrode 6, the negative electrode 7, and the separator 9 are wound using a winding core 21. As shown in FIGS. 2A and 2B, the winding core 21 is formed on a long rod-shaped outer shaft 22 around which the positive electrode 6, the negative electrode 7, and the separator 9 are wound, and an axial core portion of the outer shaft 22. A long shaft-like middle shaft 25 that is disposed in the space 23 and fixes the separator 9, and a receiving shaft 26 that is detachably attached to one end of the outer shaft 22 (left end in FIG. 2).

  As shown in FIG. 1, the outer shaft 22 is formed in a substantially rhombic cross-sectional shape. As shown in FIG. 2A, the space 23 extends in the axial direction of the outer shaft 22 and is open at one end of the outer shaft 22. The middle shaft 25 is contained in the space 23 in a posture in which the shaft center of the middle shaft 25 is along the shaft core of the outer shaft 22.

  The outer shaft 22 is provided with an outer shaft slit 27 for guiding the separator 9 into the space 23. The outer shaft slit 27 is formed so as to pass on the minor axis in the cross section of the outer shaft 22, and extends from one end of the outer shaft 22 to the vicinity of the other end in the axial direction of the outer shaft 22 to end one end of the outer shaft 22. Is open. The outer shaft 22 is formed in a bifurcated shape by the outer shaft slit 27. The other end of the outer shaft 22 (the right end in FIG. 2) is supported by driving means (not shown), and the outer shaft 22 is rotationally driven by the driving means. The length of the outer shaft 22 is larger than the width of the separator 9.

  The end portion 25 a of the middle shaft 25 is fixed to the inner portion of the space 23. The middle shaft 25 is provided with a middle shaft slit 29 for sandwiching the separator 9. The middle shaft slit 29 extends in the axial direction of the middle shaft 25 from the front end of the middle shaft 25 to the vicinity of the end, and is open at the front end of the middle shaft 25 (the left end in FIG. 2). The middle shaft 25 is formed in a bifurcated shape by the middle shaft slit 29. The outer shaft slit 27 faces the middle shaft slit 29.

  The tip of the middle shaft 25 is closer to the back side of the space 23 than the open end of the space 23 of the outer shaft 22. The outer peripheral surface of the middle shaft 25 is pressed against the inner surface of the space 23 by the elastic force of the middle shaft 25 itself. In order to fit the concave portion 37 of the receiving shaft 26 to the distal end portion 25 b of the intermediate shaft 25, the outer diameter of the distal end portion 25 b of the intermediate shaft 25 is smaller than the outer diameter of the terminal end side of the intermediate shaft 25. That is, as shown in FIG. 2A, a gap is formed between the tip 25 b of the middle shaft 25 and the peripheral surface of the space 23 of the outer shaft 22.

  As shown in FIG. 1, the middle shaft 25 is formed with a pair of upper and lower cut surfaces 30, 31 facing the middle shaft slit 29. A projection 32 having a semicircular cross section extending in the length direction is provided on the lower cut surface 30. The upper cut surface 31 is formed with a recess 33 that extends in the length direction of the upper cut surface 31 and faces the protrusion 32. That is, when the central slit 29 is closed, the protrusion 32 is fitted into the recess 33.

  The receiving shaft 26 is detachably fitted to the distal end portion 25b of the middle shaft 25 when attached to one end of the outer shaft 22, and a support portion 36 that is rotatably supported by a support member (not shown). including. That is, the aforementioned concave portion 37 is provided on the distal end surface of the fitting portion 35.

  As shown in FIG. 2B, the fitting portion 35 of the receiving shaft 26 is fitted into the space 23 from one end side of the outer shaft 22, and the distal end portion 25 b of the middle shaft 25 is inserted into the concave portion 37 of the fitting portion 35 of the receiving shaft 26. Is inserted, the outer peripheral surface of the distal end portion 25b of the intermediate shaft 25 is pushed in the width direction of the clearance of the intermediate shaft slit 29 on the inner peripheral surface of the concave portion 37 of the insertion portion 35, and the upper and lower cut surfaces 30 and 31 of the intermediate shaft 25 are pressed. As the two approach, the central shaft slit 29 is closed and the two-layer separators 9 and 9 are sandwiched. A tapered surface is formed at the opening of the recess 37, a tapered surface is formed at the tip of the tip 25b of the middle shaft 25, and the tip 25b of the middle shaft 25 is easily fitted into the opening of the recess 37. .

The electrode body 2 is manufactured through the following steps in order.
(First Step) Remove the receiving shaft 26 from the tip 25b of the middle shaft 25, and, as shown in FIG. 5 (a), two sheets with the clearance of the middle shaft slit 29 of the middle shaft 25 widened by the elastic force of the middle shaft 25 itself. The overlapping separators 9 and 9 are inserted into the outer shaft slit 27 of the outer shaft 22 and the middle shaft slit 29 of the middle shaft 25. The separators 9 and 9 are inserted into the outer shaft slits 27 and the middle shaft slits 29 as the outer shaft 22 and the middle shaft 25 move in the width direction of the separators 9 and 9.

(Second Step) The fitting portion 35 of the receiving shaft 26 is fitted into the space 23 of the outer shaft 22 from one end side of the outer shaft 22, and the fitting portion 35 is fitted onto the distal end portion 25 b of the middle shaft 25, As shown in FIG. 5B, the two separators 9, 9 are sandwiched and fixed by the pair of cut surfaces 30, 31 of the central shaft 25. At this time, the protrusions 32 of the lower cut surface 30 are fitted into the recesses 33 of the upper cut surface 31 in a state of biting into the two stacked separators 9, 9, so that the separator 9. No slip between 31.

  Next, a portion 9a of the two-layer separators 9 and 9 drawn out from the gap between the outer shaft slit 27 and the middle shaft slit 29 to the side opposite to the side where the electrodes 6 and 7 are arranged is shown in FIG. As shown, the cutting blade 39 is cut so that the dimension from the axis of the winding core 21 is a predetermined length. The cutting blade 39 is disposed at a position where the predetermined length is about 5 to 30 mm in consideration of interference with the winding core 21 and the like.

(Third Step) The winding core 21 is rotated, and as shown in FIG. 5C, the two-layer separators 9 and 9 are wound around the winding core 21 by a half rotation, and then the two-layer separators are wound. 9 and 9, the positive electrode 6 is disposed, and the negative electrode 7 is disposed so as to face the positive electrode 6 with one separator 9 interposed therebetween. As shown in FIG. It winds around the winding core 21 with the separator 9. The negative electrode 7 is set to be wound around the winding core 21 before the positive electrode 6. The negative electrode 7 may be disposed between the two stacked separators 9 and 9, and the positive electrode 6 may be disposed in a state of facing the negative electrode 7 with one separator 9 interposed therebetween.

(Fourth Step) As shown in FIG. 2B, the positive electrode 6, the negative electrode 7, and the separator 9 are wound a predetermined number of times, and when the winding is completed, the rotation of the winding core 21 is stopped. The positive electrode 6 and the negative electrode 7 are cut with a predetermined dimension.

(Fifth Step) The receiving shaft 26 is removed from the tip 25b of the middle shaft 25, the receiving shaft 26 is extracted from the space 23 of the outer shaft 22, and the clearance of the middle shaft slit 29 is widened by the elastic force of the middle shaft 25 itself. Thereby, the sandwiching of the two stacked separators 9 and 9 between the pair of cut surfaces 30 and 31 is released, and the electrode body 2 can be moved to one end side of the outer shaft 22.

(Sixth Step) The electrode body 2 that has been wound is extracted from the one end side of the outer shaft 22. When the outer shaft 22 is tapered such that the end portion 25a side of the middle shaft 25 is wider in the width direction of the gap of the outer shaft slit 27 than the tip portion 25b side, the movement of the electrode body 2 in the fifth step, The extraction of the electrode body 2 in the sixth step can be easily performed along the taper.

  Thereafter, the outermost peripheral surface of the electrode body 2 is bonded and fixed with an adhesive tape. Next, the electrode body 2 is completed by being crushed and formed into an oval cross section as shown in FIG. 4 so that the electrode body 2 can be accommodated in the battery can 1. A positive electrode current collector lead 10 is welded to the positive electrode 6, and a negative electrode current collector lead 11 is welded to the negative electrode 7.

  The outer shaft 22 may have a cross-sectional shape such as an ellipse, a hexagon, or an octagon. On the inner peripheral side of the electrode body 2, the winding start portions of the separators 9 and 9 wound around the winding core 21 prior to the positive electrode 6 and the negative electrode 7 have a length dimension of 0. It is preferably 1 to 1.5 times, and more preferably 0.2 to 1.0 times. If the length dimension of the winding start portion is smaller than 0.1 times the major axis dimension of the electrode body 2, the distance between the cutting blade 39 for cutting the separators 9 and 9 and the winding core 21 becomes too close, If it is larger than 1.5 times the major axis dimension of the electrode body 2, the effect of reducing the length of the separators 9 and 9 at the initial winding stage is hardly obtained.

  The width dimension between which the separators 9 and 9 are sandwiched by the middle shaft 25 is preferably 0.1 to 0.5 times the short diameter dimension of the electrode body 2, and more preferably 0.2 to 0.4 times. If the width dimension between which the separators 9 and 9 are sandwiched is smaller than 0.1 times the minor axis dimension of the electrode body 2, it is difficult to fix the separators 9 and 9, and the minor axis dimension of the electrode body 2 is 0.5. If it is larger than twice, the space 23 becomes too small, the movable width of the central slit becomes small, and it becomes difficult to sandwich the separators 9 and 9. The protrusions 32 and the recesses 33 arranged on the cut surfaces 30 and 31 of the middle shaft 25 may be omitted as shown in FIG.

Longitudinal front view of winding core Vertical side view of winding core Cross section of the main part of a sealed prismatic battery Disassembled perspective view of sealed prismatic battery Schematic sectional view explaining the operation of the winding core Longitudinal front view showing another embodiment of the winding core

Explanation of symbols

2 Electrode body 6 Positive electrode 7 Negative electrode 9 Separator 21 Winding core 22 Outer shaft 23 Space 25 Middle shaft 25a Middle shaft end portion 25b Middle shaft tip 26 Receiving shaft 27 Outer shaft slit 29 Middle shaft slit 30 Lower cut surface 31 Upper cut Surface 39 Cutting blade

Claims (8)

A winding core for producing an electrode body by winding a strip-shaped positive electrode and a strip-shaped negative electrode with a strip-shaped separator interposed therebetween,
A long rod-shaped outer shaft around which the positive electrode, the negative electrode, and the separator are wound, a long rod-shaped inner shaft for fixing the separator, and a receiving shaft that is detachably attached to one end of the outer shaft,
A space extending in the axial direction of the outer shaft and opened at one end of the outer shaft is formed in the shaft portion of the outer shaft. Is arranged in the space in a posture along the axis of
The receiving shaft has a fitting portion that is detachably fitted to the tip of the middle shaft when attached to one end of the outer shaft;
The middle shaft has a middle shaft slit that is fixed at the inner end of the space and extends in the axial direction of the middle shaft and is opened at the tip of the middle shaft. The tip side is divided into two forks,
The outer shaft has an outer shaft slit facing the middle shaft slit, and the separator is introduced into the middle shaft slit through the outer shaft slit,
When the fitting portion of the receiving shaft is externally fitted to the tip portion of the middle shaft, the outer peripheral surface of the tip portion of the middle shaft is pushed in the width direction of the gap of the middle shaft slit on the inner circumferential surface of the fitting portion, A winding core characterized in that the separator is sandwiched by closing a central shaft slit. The outer shaft slit extends in the axial direction of the outer shaft and is opened at one end of the outer shaft, so that one end side of the outer shaft is divided into two forks,
The insertion portion of the receiving shaft is formed so as to be fitted into the space from one end side of the outer shaft and to be fitted to the distal end portion of the middle shaft,
2. The winding core according to claim 1, wherein when the fitting portion of the receiving shaft is removed from the space, one end of the outer shaft is freed and a gap of the outer shaft slit is narrowed. The middle shaft is formed with a pair of cut surfaces facing the middle shaft slit,
One cut surface is provided with a protrusion extending in the length direction of the cut surface,
The winding core according to claim 2, wherein the other cut surface is formed with a recess extending in the length direction of the cut surface and facing the protrusion. The middle shaft having a middle shaft slit, the outer shaft having a space containing the middle shaft and having an outer shaft slit facing the middle shaft slit, and the open end of the space provided at one end of the outer shaft are fitted into the outer shaft. Using a winding core that includes a receiving shaft that is detachably fitted to the tip of the middle shaft, the middle shaft slit being opened at the tip of the middle shaft, and the outer shaft slit being opened at one end of the outer shaft. A method of manufacturing an electrode body that is wound with a strip-shaped separator interposed between a strip-shaped positive electrode and a strip-shaped negative electrode,
A first step of inserting the two-layered separator into the outer shaft slit and the middle shaft slit in a state in which the receiving shaft is removed from the tip of the middle shaft and the gap of the middle shaft slit is widened;
By fitting the receiving shaft into the space from one end side of the outer shaft and by fitting the outer end to the tip of the middle shaft, the two-layer separator is formed with a pair of cut surfaces facing the middle shaft slit of the middle shaft. A second step of pinching and fixing;
The winding core is rotated, and the separator is wound around the winding core. Then, one of the positive electrode and the negative electrode is disposed between the two stacked separators, and the other electrode is placed on one of the winding cores. An electrode body using a winding core comprising: a third step in which the electrode is disposed in a state of being opposed to the one electrode with a separator interposed therebetween, and the electrodes are wound around the winding core together with the separator. Manufacturing method. A fourth step of stopping rotation of the winding core when the winding in the third step is completed;
The receiving shaft is removed from the front end portion of the middle shaft to widen the gap between the middle shaft slits to release the two-layer separator between the pair of cut surfaces, and from the space of the outer shaft. A fifth step of extracting the receiving shaft and freeing one end of the outer shaft to narrow the gap of the outer shaft slit;
A method for producing an electrode body using a wound core according to claim 4, further comprising a sixth step of extracting the wound electrode body from the winding core. The outer shaft is formed in a forked shape by the outer shaft slit, the middle shaft is formed in a forked shape by the middle shaft slit,
Prior to the third step, the two-layer separator part drawn out from the gap between the outer shaft slit and the middle shaft slit to the side opposite to the side where the electrodes are arranged is made a predetermined length by a cutting blade. The manufacturing method of the electrode body using the winding core of Claim 5 cut | disconnected. One cut surface of the pair of cut surfaces is provided with a protrusion extending in the length direction of the cut surface, and the other cut surface is extended in the length direction of the cut surface and extends to the protrusion. A concavity to face is formed,
The method of manufacturing an electrode body using a wound core according to claim 6, wherein, when the two stacked separators are sandwiched between the pair of cut surfaces in the second step, the protrusions bite into the separator.   8. The manufacturing of an electrode body using a wound core according to claim 7, wherein after the sixth step, the electrode body is crushed and formed into an oval cross section so as to be accommodated in a thin rectangular tube-shaped battery can. Method.

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