JP6955201B2 - Manufacturing method of bag-shaped separator - Google Patents

Description

The present invention relates to a method for manufacturing a bag-like separator Ru with the negative electrode and the bag-like separator in case the stacked electrode assembly alternately.

Vehicles such as EV (Electric Vehicle) and PHV (Plug in Hybrid Vehicle) are equipped with a secondary battery as a power storage device for storing power supplied to a traveling motor. As a secondary battery, a battery provided with a laminated electrode assembly is known. The laminated electrode assembly is configured by laminating a large number of sheet-shaped positive electrode and negative electrode with a separator insulating between them. The positive electrode has a positive electrode active material layer on both sides of the metal foil of the positive electrode, and the negative electrode has a negative electrode active material layer on both sides of the metal foil of the negative electrode.

Further, the positive electrode electrode has an uncoated portion in which the metal foil is exposed for connection with the outside, and typically has a positive electrode tab having a shape protruding from one end edge of the metal foil. A positive electrode terminal is electrically connected to the positive electrode tab via a conductive member. Similarly, the negative electrode has a negative electrode having a shape protruding from one end edge of the metal foil. The negative electrode terminal is electrically connected to the negative electrode tab via a conductive member. A part of these positive electrode terminals and negative electrode terminals penetrates the lid of the case and projects to the outside of the case.

Further, in a secondary battery, if there is a portion between the positive electrode active material layer and the negative electrode active material layer where the positive electrode active material layer and the negative electrode active material layer do not face each other due to misalignment or the like, the capacity is reduced. Invite. Further, in a lithium ion battery, in order to suppress the precipitation of metallic lithium on the surface of the negative electrode active material layer generated by the concentration of lithium ions during charging, the area of the negative electrode active material layer is compared with the area of the positive electrode active material layer. Is getting bigger. For these reasons, at the time of manufacturing the electrode assembly, the negative electrode active material layer is aligned with the positive electrode active material layer so as to be accurately opposed to the positive electrode active material layer via the separator.

By the way, since the laminated structure of the electrode assembly goes through a manufacturing process in which the positive electrode, the negative electrode, and the separator are stacked in order, the number of stacking steps is large, the production tact time is long, and the productivity is not good. There was a problem. Therefore, a method is known in which the positive electrode is stored in advance inside the bag-shaped separator, and the bag-shaped separator and the negative electrode are stacked to increase productivity.

Further, as a method for manufacturing the electrode assembly, for example, Patent Document 1 is mentioned. In Patent Document 1, the electrode assembly is surrounded while dropping the electrode assembly in which the positive electrode, the separator, and the negative electrode are laminated. The plurality of aligning members are moved toward the electrode assembly. Then, the side surface of the electrode assembly is pushed by the aligning member to align the positive electrode, the separator, and the negative electrode. In addition, Patent Document 1 suggests that the separator has a form of wrapping one electrode (generally a positive electrode) in addition to an independent sheet-shaped separator.

Japanese Unexamined Patent Publication No. 2017-76489

However, in the method disclosed in Patent Document 1, for example, the aligning member may come into contact with the tab. In such a case, since the tab is made of a thin metal foil, the tab may be deformed and the amount of movement of the electrodes or the like may be insufficient. Therefore, there is a method in which the aligning member is brought into contact with the separator wrapping one of the electrodes instead of the tab to push the separator. However, even in this case, the separator may be deformed. In particular, when the contact portion of the alignment member is miniaturized by using, for example, a piston-shaped actuator, such deformation of the separator becomes more remarkable, and the deformation of the separator may result in insufficient movement of the electrode. ..

An object of the present invention, during manufacturing of the electrode assembly, in the case of moving the positive electrode by the contact is to provide a method for manufacturing a bag-like separator that can suppress the movement shortage due to the deformation of the bag-like separator.

Method for producing a bag-shaped separator to solve the above SL problems, a negative electrode having a negative electrode active material layer rectangular to the surface of a rectangular sheet-shaped negative electrode current collector, the facing is a rectangular sheet-shaped separator member The positive electrode electrode, which is housed in a bag-shaped separator having a welded portion whose edge is heat-welded and has a positive electrode active material layer on the surface of a rectangular sheet-shaped positive electrode current collector, is in the bag shape with respect to the positive electrode active material layer. A method for manufacturing the bag-shaped separator in a power storage device having an electrode assembly having a laminated structure in which the negative electrode active material layers are alternately stacked with each other via a separator. Two strip-shaped separator materials are stacked, and one end edge of the positive electrode and the other end edge, which is the opposite side of the one end edge, extend in the longitudinal direction of the strip-shaped separator material between the pair of strip-shaped separator materials. The arrangement step of arranging the positive electrode and the one end edge, the other end edge, and the pair of end edges connecting the one end edge and the other end edge of the arranged pair of strip-shaped separator materials. The first heater roller has a welding step of heat-welding the surrounding position using the first heater roller and the second heater roller, and the first heater roller is a pair of the pair of strip-shaped separator materials along the pair of end edges of the positive electrode. The second heater roller has a heater portion that heat-welds the end edge, and the second heater roller includes a first heater portion that heat-welds one end edge of the pair of strip-shaped separator materials along the one end edge of the positive electrode electrode, and the positive electrode. It has a second heater portion for heat-welding the other end edges of the pair of strip-shaped separator materials along the other end edge, and the dimension of the second heater portion in the direction in which the axis of the second heater roller extends is determined. It is formed longer than the first heater portion, and in the welding step, the other end edge of the pair of strip-shaped separator materials that are heat-welded by the second heater portion has a unit area as compared with other edge edges. The gist is to add a large amount of heat to the hit.

According to this, at least one of one end edge and the other end edge of the bag-shaped separator has a large amount of heat shrinkage and becomes harder than the other end edges. Therefore, in order to align one end edge of the negative electrode and one end edge of the bag-shaped separator in the height direction, when the positioning member is brought into contact with at least one of the one end edge and the other end edge of the bag-shaped separator, the bag-shaped separator It is possible to suppress deformation such as bending and bending near one end edge and the other end edge of the. As a result, when the positioning member is brought into contact with the bag-shaped separator to move the positive electrode, it is possible to suppress an insufficient movement amount due to deformation of the bag-shaped separator.

Further, a method for manufacturing the bag-shaped separator, the welding step includes a first welding step of heat welding positions surrounding the four edges of the positive electrode, Mininetsu the other edge of the pair of strip-shaped separator material It may be composed of the second welding step of adding.

According to this, by performing the second welding step after the first welding step, the amount of heat shrinkage of the other end edge of the pair of strip-shaped separator materials can be made larger than that of the other edge edges and hardened.

Further, regarding the method for manufacturing a bag-shaped separator, in the welding step, the temperature at the time of heat welding of the other end edge of the pair of strip-shaped separator materials may be set higher than the temperature at the time of heat welding of the other end edges. good.

According to this, the amount of heat shrinkage of the other end edge of the pair of strip-shaped separator materials can be made larger than that of the other end edges and can be made harder.

According to the present invention, when the positive electrode is moved by contact during the manufacture of the electrode assembly, it is possible to suppress the insufficient movement amount due to the deformation of the bag-shaped separator.

The cross-sectional view which shows the secondary battery of an embodiment. An exploded perspective view showing the components of the electrode assembly. The perspective view which shows the manufacturing apparatus of a bag-shaped separator. (A) is a perspective view showing a first heater roller, (b) is a perspective view showing a second heater roller, and (c) is a perspective view showing a third heater roller. The plan view which shows the manufacture of a bag-shaped separator. (A) is a diagram showing a state in which a bag-shaped separator and a negative electrode are housed in a positioning jig, (b) is a diagram showing a state of being pressed by a positioning member, and (c) is a diagram showing a state in which positioning is completed. The perspective view which shows another example of the manufacturing apparatus of a bag-shaped separator.

Hereinafter, an embodiment in which the method for manufacturing the power storage device and the bag-shaped separator is embodied in the secondary battery and the bag-shaped separator included in the secondary battery will be described with reference to FIGS. 1 to 6.
As shown in FIG. 1, the secondary battery 10 includes a metal case 11 that constitutes an outer shell. The case 11 includes a bottomed rectangular parallelepiped case body 12 having an opening 12a on one surface, and a lid 13 that closes the opening 12a of the case body 12. The case 11 contains the electrode assembly 14 and an electrolytic solution (not shown) as an electrolyte. The secondary battery 10 is a lithium ion battery. A positive electrode terminal 43 electrically connected to the positive electrode of the electrode assembly 14 and a negative electrode terminal 46 electrically connected to the negative electrode are attached to the lid 13.

As shown in FIG. 2, the electrode assembly 14 has a laminated structure in which a plurality of positive electrode electrodes 21 and a plurality of negative electrode electrodes 31 are alternately stacked with a resin bag-shaped separator 27 interposed between them. Has. The positive electrode electrode 21 has a positive electrode metal foil (aluminum foil in this embodiment) 22 as a positive electrode current collector, and a rectangular positive electrode active material layer 23 provided on both sides of the positive electrode metal foil 22. The positive electrode metal foil 22 comprises a rectangular sheet-shaped positive electrode metal foil main body 22a and, as will be described later, a positive electrode tab 22b formed so as to partially extend and project from the positive electrode metal foil main body 22a. The positive electrode active material layer 23 exists on both sides of the positive electrode metal foil main body 22a with the same planar shape and the same thickness, and faces each other with the positive electrode metal foil main body 22a interposed therebetween.

The positive electrode electrode 21 includes a first edge 21a at one edge extending in the longitudinal direction, and a second edge 21b at the other edge opposite to the first edge 21a. The first edge 21a exists on one long edge of the positive electrode metal foil body 22a and the positive electrode active material layer 23, and the second edge 21b is the other long edge of the positive electrode metal foil body 22a and the positive electrode active material layer 23. Exists in the department. The positive electrode electrode 21 includes a positive electrode tab 22b protruding from a part of the first edge 21a. Further, the positive electrode electrode 21 has a third edge 21c formed by the edge of the positive electrode metal foil main body 22a and the positive electrode active material layer 23 on a pair of edge connecting the first edge 21a and the second edge 21b. Have.

The negative electrode electrode 31 has a negative electrode metal foil (copper foil in this embodiment) 32 as a negative electrode current collector, and a rectangular negative electrode active material layer 33 provided on both sides of the negative electrode metal foil 32. The negative electrode metal foil 32 includes a rectangular sheet-shaped negative electrode metal foil main body 32a and, as will be described later, a negative electrode tab 32b formed so as to partially extend and project from the negative electrode metal foil main body 32a. The negative electrode active material layer 33 exists on both sides of the negative electrode metal foil main body 32a with the same planar shape and the same thickness, and faces each other with the negative electrode metal foil main body 32a interposed therebetween.

The negative electrode electrode 31 includes a first end edge 31a at one end edge extending in the longitudinal direction, and a second end edge 31b at the other end edge opposite to the first end edge 31a. The first edge 31a exists on one long edge portion of the negative electrode metal foil body 32a and the negative electrode active material layer 33, and the second edge 31b is the other long edge of the negative electrode metal foil body 32a and the negative electrode active material layer 33. Exists in the department. The negative electrode electrode 31 includes a negative electrode tab 32b protruding from a part of the first edge 31a. Further, the negative electrode electrode 31 has a pair of edge edges connecting the first edge 31a and the second edge 31b, and a third edge 31c formed by the edge of the negative electrode metal foil body 32a and the negative electrode active material layer 33. Be prepared.

In the positive electrode 21 and the negative electrode 31, the lengths of the two adjacent sides of the negative electrode active material layer 33 (the length in the longitudinal direction and the length in the lateral direction) are 2 adjacent to the positive electrode active material layer 23. It is set longer than the length of each side (length in the longitudinal direction and length in the lateral direction). That is, the negative electrode active material layer 33 is set to a size capable of covering the entire surface of the positive electrode active material layer 23.

The positive electrode 21 is housed in the bag-shaped separator 27. The bag-shaped separator 27 is formed by welding the four end edges of a pair of separator members 28 facing each other. The pair of separator members 28 have the same size and are in the shape of a rectangular sheet larger than the outer shape of the positive electrode 21. The pair of separator members 28 include protruding portions 28a that protrude from the first edge 21a, the second edge 21b, and the third edge 21c of the positive electrode 21 in a state of sandwiching the positive electrode 21. The bag-shaped separator 27 is formed by heat welding the protruding portions 28a along the four end edges of the pair of separator members 28, and is provided with a storage portion 28b in a portion surrounded by the protruding portions 28a. The separator member 28 in this embodiment is a porous resin sheet made of polypropylene (PP). The material of the separator member 28 may be polyethylene (PE) or the like.

The bag-shaped separator 27 is provided with a first edge 27a at one end extending along the first edge 21a of the positive electrode 21, is opposite to the first edge 27a, and is along the second edge 21b of the positive electrode 21. A second end edge 27b is provided on the other end edge extending from the end. Further, the bag-shaped separator 27 includes a third edge 27c at an edge that connects the first edge 27a and the second edge 27b and extends along the third edge 21c of the positive electrode electrode 21. The positive electrode tab 22b of the positive electrode electrode 21 projects from a part of the first edge 27a of the bag-shaped separator 27.

Further, each separator member 28 is provided with a tab facing portion 30 in a portion of the protruding portion 28a facing the positive electrode tab 22b. Each tab facing portion 30 projects along the positive electrode tab 22b from other portions on the first edge 27a of the bag-shaped separator 27. The tab facing portion 30 covers a part of the positive electrode tab 22b.

The bag-shaped separator 27 is provided with a welded portion along the first to third edge 27a to 27c, which are the four edge edges. As the welded portion, the first welded portion 29a is provided in the portion along the first edge 27a except for the tab facing portion 30, and the first welded portion 29a is a protruding portion 28a along the first edge 27a. Is formed by heat welding. Further, the welded portion includes a second welded portion 29b formed by welding the protruding portion 28a along the second edge 27b, and is formed by heat welding the protruding portion 28a along each third edge 27c. The third welded portion 29c is provided.

The dimensions H3 in the lateral direction of the first to third welded portions 29a to 29c along the surface of the bag-shaped separator 27 are all the same. The first to third welded portions 29a to 29c are formed by heat welding the strip-shaped separator material 51 (see FIG. 3), which is the material of the separator member 28. At the time of manufacture, the first welded portion 29a is subjected to a larger amount of heat per unit area than the second welded portion 29b and the third welded portion 29c. Therefore, the first welded portion 29a has a larger amount of heat shrinkage, fewer holes, and a higher resin density than the second welded portion 29b and the third welded portion 29c. As a result, the first welded portion 29a is in a highly contracted state, which is harder and more rigid than the second welded portion 29b and the third welded portion 29c. In the present embodiment, the first welded portion 29a constitutes a highly shrinkable welded portion.

When the bag-shaped separator 27 and the negative electrode electrode 31 are alternately laminated to manufacture the electrode assembly 14, the first welding portion 29a is a positioning member 64 (see FIG. 6B) for adjusting the height of the electrode assembly 14. ) Is pressed.

As shown in FIG. 1, a straight line that passes through the middle of the length of the first end edge 27a of the bag-shaped separator 27 and extends in the height direction is defined as the center line M. The first welded portion 29a is located on both sides of the tab facing portion 30, but the first welded portion 29a is located at a position where the shorter portion of the first welded portion 29a is line-symmetrical with respect to the center line M. There is a longer part of.

Further, as shown in FIG. 2, a straight line L extending at the shortest distance connects the portion of the first end edge 27a of the bag-shaped separator 27 excluding the tab facing portion 30 and the second end edge 27b of the bag-shaped separator 27. The direction is the height direction, and the extending direction of the straight line L connecting the first end edge 31a and the second end edge 31b of the negative electrode electrode 31 at the shortest distance is the height direction. The dimension H1 in the height direction of the bag-shaped separator 27 and the dimension H2 in the height direction of the negative electrode electrode 31 are the same.

Here, the position where the first welded portion 29a is formed will be described. As the first welded portion 29a is brought closer to the second welded portion 29b along the height direction of the bag-shaped separator 27, the dimension of the storage portion 28b in the height direction becomes shorter, and as a result, the positive electrode 21 that can be stored becomes smaller. It ends up. When the positive electrode 21 becomes smaller, the area of the positive electrode active material layer 23 also becomes smaller, and the capacity of the secondary battery 10 decreases, which is not preferable. Therefore, the position for forming the first welded portion 29a is set so that the position of the first welded portion 29a is not too close to the second welded portion 29b.

As shown in FIG. 5, the dimension of the strip-shaped separator material 51 in the lateral direction is defined as the width W. Assuming that the edge of the first welded portion 29a near the second welded portion 29b is the welded edge U, the first welded portion 29a is formed so that the welded edge U of the first welded portion 29a is located at the position described below. Will be done.

Welding of the first welded portion 29a from the value (W- (H2 + H3)) obtained by subtracting the sum of the design dimension H3 of the first welded portion 29a and the dimension H2 of the negative electrode electrode 31 from the width W of the strip-shaped separator material 51. The first welded portion 29a is formed so that the edge U does not approach the second welded portion 29b.

On the other hand, the more the first edge 27a is separated from the second welded portion 29b along the height direction of the bag-shaped separator 27, the more the negative electrode 31 is attached to the first edge 27a of the bag-shaped separator 27 during the manufacture of the electrode assembly 14. When the first edge 31a is matched, the second edge 31b of the negative electrode 31 is located closer to the first edge 21a than the second edge 21b of the positive electrode 21. Then, a portion where the negative electrode active material layer 33 does not face the positive electrode active material layer 23 is likely to occur, which is not preferable. Therefore, the position for forming the first welded portion 29a is set so that the position of the first welded portion 29a including the first edge 27a is not too far from the second welded portion 29b. The first welded portion 29a is formed from the long edge of the strip-shaped separator material 51 to a position separated by the dimension H3 of the second welded portion 29b.

Further, assuming that the direction along the first edge 27a of the bag-shaped separator 27 is the longitudinal direction and the direction along the second edge 31b of the negative electrode electrode 31 is the longitudinal direction, the dimensions of the bag-shaped separator 27 in the longitudinal direction and The dimensions of the negative electrode 31 in the longitudinal direction are the same.

The bag-shaped separator 27 containing the positive electrode 21 and the negative electrode 31 are arranged in a row along the stacking direction, and the negative electrode tab 32b is arranged in the stacking direction at a position where the positive electrode tab 22b does not overlap with the positive electrode tab 22b. They are laminated so as to be arranged in a row along the line. The secondary battery 10 has a portion in the electrode assembly 14 in which the first edge 31a of the negative electrode 31 and the first edge 27a of the bag-shaped separator 27 are aligned in the height direction, and the negative electrode 31 is the first. The two edge 31b and the second edge 27b of the bag-shaped separator 27 have a portion aligned in the height direction. However, the tab facing portion 30 protrudes from the first edge 31a of the negative electrode electrode 31.

As shown in FIG. 1 or 2, in the electrode assembly 14, the third edge 31c of the negative electrode 31 and the third edge 27c of the bag-shaped separator 27 are aligned in the longitudinal direction. Then, in a state where the edges are aligned, the negative electrode active material layer 33 faces the entire surface of the positive electrode active material layer 23 via the separator member 28 of the bag-shaped separator 27.

In the electrode assembly 14, the positive electrode tab 22b and the negative electrode tab 32b are bent in a state of being collected (bunched) within a range from one end to the other end in the stacking direction in the electrode assembly 14. The positive electrode terminal 43 is electrically connected to the positive electrode tab 22b, and the negative electrode terminal 46 is electrically connected to the negative electrode tab 32b.

Next, a method for manufacturing the bag-shaped separator 27 will be described.
As shown in FIG. 3, in the method for manufacturing the bag-shaped separator 27, first, two strip-shaped separator materials 51, which are the materials of the separator member 28, are stacked, and the first positive electrode 21 is sandwiched between the strip-shaped separator materials 51. It has an arrangement step of arranging the positive electrode 21 so that the edge 21a and the second edge 21b extend in the longitudinal direction of the strip separator material 51.

The method for producing the bag-shaped separator 27 includes a welding step performed after the placement step, and the welding step includes a first welding step and a second welding step. The first welding step is a step of heat welding the positions surrounding the first to third end edges 21a to 21c of the positive electrode 21 in the strip-shaped separator material 51 while avoiding the positive electrode tab 22b.

In the second welding step performed after the first welding step, only the portion of the strip-shaped separator material 51 that has been heat-welded to form the first edge 27a of the bag-shaped separator 27 is set to the heating temperature in the first welding step. This is a process of heat welding at the same temperature or a higher temperature. Further, in the method for manufacturing the bag-shaped separator 27, the strip-shaped separator material 51 that has undergone the first welding step and the second welding step is cut in the longitudinal direction according to the dimensions of the positive electrode 21 to manufacture the individual bag-shaped separator 27. Has a cutting process to be performed.

Next, the manufacturing apparatus 50 that performs the arrangement step, the welding step (the first welding step and the second welding step), and the cutting step will be described.
The manufacturing apparatus 50 includes a supply apparatus 52 that supplies the strip-shaped separator material 51. The supply device 52 includes a first supply reel 52a and a second supply reel 52b wound with a strip-shaped separator material 51. The first supply reel 52a is located below the second supply reel 52b. The first supply reel 52a and the second supply reel 52b are wound so that the longitudinal direction of the strip-shaped separator material 51 extends in the circumferential direction of the respective supply reels 52a and 52b. The first supply reel 52a and the second supply reel 52b are supported by a drive device (not shown) so that they can rotate around their respective axes.

The first supply reel 52a and the second supply reel 52b supply the strip-shaped separator material 51 so that the surfaces in the thickness direction orthogonal to the longitudinal direction and the lateral direction of the strip-shaped separator material 51 face each other. The positive electrode 21 is transported between the strip-shaped separator material 51 supplied from the first supply reel 52a and the strip-shaped separator material 51 supplied from the second supply reel 52b by an electrode transfer device (not shown), and an arrangement step is performed. ..

The manufacturing apparatus 50 includes a pair of nip rollers 53 downstream of the first supply reel 52a and the second supply reel 52b. The pair of nip rollers 53 are arranged so as to face each other with the pair of strip-shaped separator materials 51 interposed therebetween. The pair of nip rollers 53 are supported by a drive device (not shown) so that they can rotate about the axis. A pair of strip-shaped separator materials 51 sandwiching the positive electrode electrode 21 are passed between the pair of nip rollers 53.

By driving the supply device 52 and the nip roller 53, the pair of strip-shaped separator materials 51 sandwiching the positive electrode electrode 21 are conveyed along the transfer direction X1. Further, among the directions along the surface of the strip-shaped separator material 51, the direction orthogonal to the transport direction X1 is defined as the lateral direction X2 of the strip-shaped separator material 51.

The manufacturing apparatus 50 includes a first heater roller 70 and a second heater roller 71 that perform a first welding step, and a third heater roller 74 that performs a second welding step.
The first heater roller 70 includes a pair of rollers 70a and 70b that face each other with the strip-shaped separator material 51 interposed therebetween. The rollers 70a and 70b are supported by a drive device (not shown) so that they can rotate around the axis. The first heater roller 70 welds the pair of strip-shaped separator materials 51 that are being conveyed over the entire area of the lateral direction X2.

As shown in FIG. 4A, one roller 70a of the first heater roller 70 is provided with a heater portion 70c whose length extends in the extending direction of the axial center on the outer peripheral surface. The heater portion 70c projects by a certain amount with respect to the outer peripheral surface of the columnar roller 70a (not shown). The entire roller 70a is heated. The first heater roller 70 heat-welds the positions of the strip-shaped separator material 51 that surround the first to third edge 21a to 21c of the positive electrode 21 along the third edge 21c.

Then, in the first welding step, the first heater roller 70 rotates while sandwiching a pair of strip-shaped separator materials 51 between the heater portion 70c of the entire heated roller 70a and the outer peripheral surface of the other roller 70b. As a result, the pair of strip-shaped separator materials 51 are welded at intervals according to the length of the outer circumference of the roller 70a. The other roller 70b also includes a heater portion 70c, and both rollers 70a and 70b may heat the pair of strip-shaped separator materials 51.

As shown in FIG. 5, the band-shaped separator materials 51 are heat-welded to each other by the heater portion 70c of the first heater roller 70, and the band-shaped separator materials 51 are alternately arranged apart from each other in the longitudinal direction, and the positive electrode 21 A first welding region R1 is formed along the third edge 21c of the above. The first welding region R1 slightly shrinks in the longitudinal direction of the strip-shaped separator material 51, but is not shown. Further, the dimension of the first welding region R1 along the longitudinal direction of the strip-shaped separator material 51 is twice that of the third welding portion 29c in the bag-shaped separator 27.

As shown in FIG. 3 or FIG. 4B, the second heater roller 71 includes a pair of rollers 71a and 71b that face each other with the strip-shaped separator material 51 interposed therebetween. The rollers 71a and 71b are supported by a drive device (not shown) so that they can rotate around the axis.

The second heater roller 71 welds the pair of strip-shaped separator materials 51 being conveyed along the longitudinal direction. One roller 71a includes a first heater portion 71c extending in the circumferential direction of the roller 71a on one end side in the extending direction of the axial center, and a first heater portion 71c extending in the circumferential direction of the roller 71a on the other end side in the extending direction of the axial center. 2 Heater unit 71d is provided.

The first heater portion 71c exists over the entire circumferential direction of the roller 71a and is annular. On the other hand, the second heater portion 71d includes a tab recess 71e in which a part in the circumferential direction is missing. In the first heater portion 71c and the second heater portion 71d, the dimension of the roller 71a in the extending direction of the axial center is longer in the second heater portion 71d.

The first heater portion 71c and the second heater portion 71d project by a certain amount with respect to the outer peripheral surface of the columnar roller 71a (not shown). The entire roller 71a is heated. The second heater roller 71 heat-welds the positions of the strip-shaped separator material 51 that surround the first to third edge 21a to 21c of the positive electrode 21 along the first edge 21a and the second edge 21b.

Then, in the first welding step, the second heater roller 71 rotates while sandwiching a pair of strip-shaped separator materials 51 between the heated first heater portion 71c and second heater portion 71d and the outer peripheral surface of the other roller 71b. do. As a result, both long edges of the pair of strip-shaped separator materials 51 are welded according to the length of the outer circumference of the roller 71a. The other roller 71b also includes a first heater portion 71c and a second heater portion 71d, and both rollers 71a and 71b may heat the pair of strip-shaped separator materials 51.

The first heater portion 71c forms a second welding region R2 along one long edge portion of the strip-shaped separator material 51 and connecting a pair of first welding regions R1. Further, the second heater portion 71d welds a portion along the other long edge portion of the strip-shaped separator material 51 and connecting the pair of first welding regions R1 to form a primary welding portion K. Further, in the primary welding portion K, the portion corresponding to the tab recess 71e is not welded, and the positive electrode tab 22b is located at the portion that is not welded.

The first heater portion 71c and the second heater portion 71d are heated to the same temperature as the heater portion 70c of the first heater roller 70. Therefore, the first welding region R1, the second welding region R2, and the primary welding portion K are heat-welded under the same conditions. The primary welding portion K is longer than the second welding region R2 in the dimensions of the strip-shaped separator material 51 along the lateral direction X2.

As shown in FIG. 3 or FIG. 4 (c), the third heater roller 74 includes a pair of rollers 74a and 74b that face each other with the strip-shaped separator material 51 interposed therebetween. The rollers 74a and 74b are supported by a drive device (not shown) so that they can rotate around the axis.

The third heater roller 74 welds the pair of strip-shaped separator materials 51 that are being conveyed along the longitudinal direction. One roller 74a includes a heater portion 74c extending in the circumferential direction of the roller 74a on one end side in the direction in which the axis extends. The heater portion 74c projects by a certain amount with respect to the outer peripheral surface of the columnar roller 74a (not shown). The entire roller 74a is heated. The heater portion 74c includes a tab recess 74e in which a part in the circumferential direction is missing.

The heater portion 74c and the tab recess 74e of the third heater roller 74 have the same shape as the second heater portion 71d and the tab recess 71e of the second heater roller 71, and have the same length in the circumferential direction. Therefore, the heater portion 74c heats the primary welding portion K formed by the second heater roller 71 and heat-welds it. Further, the temperature of the heater portion 74c of the third heater roller 74 is set to be the same as or higher than the temperature of the first heater portion 71c of the second heater roller 71.

Then, in the second welding step, the third heater roller 74 rotates while sandwiching the pair of strip-shaped separator materials 51 between the heated heater portion 74c and the outer peripheral surface of the other roller 74b. As a result, the primary welded portion K in the pair of strip-shaped separator materials 51 is heated again according to the length of the outer circumference of the roller 74a. As a result, a larger amount of heat is applied to the primary welding portion K per unit area as compared with the other welding portions, the first welding region R1 and the second welding region R2. The other roller 74b also includes a heater portion 74c, and both rollers 74a and 74b may heat the pair of strip-shaped separator materials 51.

As shown in FIG. 5, the primary welding portion K is further heat-shrinked by the heater portion 74c of the third heater roller 74. Then, the third welding region R3 is formed by reheating by the heater portion 74c. Due to the heat shrinkage of the primary welding portion K, the dimension of the third welding region R3 along the lateral direction of the strip-shaped separator material 51 becomes the same as the dimension of the second welding region R2.

As shown in FIG. 3, the manufacturing apparatus 50 places the strip-shaped separator material 51 in which the portion surrounding the positive electrode electrode 21 is welded by the first heater roller 70, the second heater roller 71, and the third heater roller 74 at equal intervals along the longitudinal direction. The cutting device 90 is provided. The cutting device 90 performs a cutting step.

The cutting device 90 includes a cutting blade 91 extending along the lateral direction X2. The cutting blade 91 cuts the strip-shaped separator material 51 at predetermined intervals by reciprocating at a predetermined cycle. The cutting blade 91 cuts an intermediate position along the longitudinal direction of the strip-shaped separator material 51 in the first welding region R1. The bag-shaped separator 27 is obtained by cutting the strip-shaped separator material 51 at the first welding region R1. That is, the third welded portion 29c is formed from the first welded region R1 and the second welded portion 29b is formed from the second welded region R2. Further, the first welded portion 29a is formed from the third welded region R3. The manufacturing apparatus 50 includes a transport device 92 for transporting the bag-shaped separator 27, and the bag-shaped separator 27 manufactured by cutting with the cutting blade 91 is conveyed by the transport device 92.

Next, the manufacturing method of the electrode assembly 14 will be described together with the action.
As shown in FIG. 6A, the bag-shaped separator 27 containing the positive electrode 21 and the negative electrode 31 are stacked. At this time, the bag-shaped separator 27 and the negative electrode electrode 31 are manufactured by using the positioning jig 60. The positioning jig 60 includes a base 61 having a rectangular shape in a plan view. The positioning jig 60 includes a plan-view U-shaped guide 62 erected from the upper surface 61a of the base 61. The guide 62 includes a first guide surface 62a along the second end edge 27b of the bag-shaped separator 27 and the second end edge 31b of the negative electrode electrode 31 at the time of alignment. Further, the guide 62 includes a pair of third end edges 27c of the bag-shaped separator 27 and a second guide surface 62b along the third end edge 31c of the negative electrode electrode 31 at the time of alignment.

The first guide surface 62a of the guide 62 restricts the movement of the bag-shaped separator 27 and the negative electrode electrode 31 in the height direction, and the second guide surface 62b restricts the movement of the bag-shaped separator 27 and the negative electrode electrode 31 in the longitudinal direction. Is regulated.

Then, when stacking the bag-shaped separators 27 while aligning them with the positioning jig 60, the pair of third end edges 27c of the bag-shaped separators 27 are aligned with the second guide surface 62b in the longitudinal direction of the bag-shaped separators 27. Regulate movement to. Further, the pair of third end edges 31c of the negative electrode electrode 31 is aligned with the second guide surface 62b to restrict the movement of the negative electrode electrode 31 in the longitudinal direction.

Next, as shown in FIG. 6B, among the first welding portions 29a (high shrinkage welding portions) located at the first end edge 27a of the bag-shaped separator 27, the first welding on both sides of the positive electrode tab 22b is sandwiched. The positioning member 64 is brought into contact with the portion 29a, and the bag-shaped separator 27 is pressed toward the first guide surface 62a by the positioning member 64. Further, the positioning member 64 is brought into contact with the first end edge 31a of the negative electrode electrode 31, and the negative electrode electrode 31 is pressed toward the first guide surface 62a by the positioning member 64. Then, the bag-shaped separator 27 and the negative electrode electrode 31 move toward the first guide surface 62a, and the second edge edges 27b and 31b come into contact with the first guide surface 62a.

As a result, as shown in FIG. 6C, the movement of the bag-shaped separator 27 and the negative electrode electrode 31 in the height direction is restricted, and the second edge 27b of the bag-shaped separator 27 and the second negative electrode 31 are second. The edges 31b are aligned in the height direction. Further, the first end edge 27a of the bag-shaped separator 27 and the first end edge 31a of the negative electrode electrode 31 are aligned in the height direction. As a result, the four end edges of the bag-shaped separator 27 and the negative electrode electrode 31 are in the same state. Then, when a predetermined number of bag-shaped separators 27 and negative electrode electrodes 31 are stacked, the electrode assembly 14 is manufactured.

According to the above embodiment, the following effects can be obtained.
(1) The bag-shaped separator 27 includes a first welded portion 29a as a highly shrinkable welded portion on the first edge 27a. The first welded portion 29a is harder than the second welded portion 29b and the third welded portion 29c of the bag-shaped separator 27. Since the first edge 27a of the bag-shaped separator 27 can be reinforced by the first welded portion 29a, the vicinity of the first edge 27a of the bag-shaped separator 27 when the positioning member 64 comes into contact with the first edge 27a. Deformation can be suppressed. As a result, when the positioning member 64 is brought into contact with the bag-shaped separator 27 to move the positive electrode 21, it is possible to suppress an insufficient movement amount due to deformation of the bag-shaped separator 27. Therefore, the first edge 27a of the bag-shaped separator 27 and the first edge 31a of the negative electrode electrode 31 can be easily matched, and the electrode assembly is performed with the entire surface of the positive electrode active material layer 23 facing the negative electrode active material layer 33. The solid 14 can be manufactured.

(2) The first welded portion 29a as the highly shrinkable welded portion is located on both sides of the positive electrode tab 22b and is located at a position line-symmetrical with respect to the center line M of the bag-shaped separator 27. Therefore, even if the positioning member 64 is brought into contact with and pressed against the first welding portions 29a on both sides of the bag-shaped separator 27, the rotation of the bag-shaped separator 27 can be suppressed.

(3) The position of the welding edge U of the first welding portion 29a is obtained by subtracting the sum of the dimension H3 of the first welding portion 29a and the dimension H2 of the negative electrode electrode 31 from the width W of the strip-shaped separator material 51. 2 It was set so as not to approach the welded portion 29b. By doing so, the first welded portion 29a is prevented from coming too close to the second welded portion 29b, the positive electrode 21 that can be stored in the bag-shaped separator 27 is suppressed from becoming small, and the capacity of the secondary battery 10 is increased. Suppress the decrease.

(4) The first welded portion 29a is formed from the long edge of the strip-shaped separator material 51 to a position separated by the dimension H3 of the second welded portion 29b. Therefore, when the first edge 27a of the bag-shaped separator 27 and the first edge 31a of the negative electrode 31 are aligned in the height direction, the negative electrode active material layer 33 faces the positive electrode active material layer 23. Can be maintained.

(5) The bag-shaped separator 27 is provided with a tab facing portion 30 at a position facing the positive electrode tab 22b. Even when the first edge 31a of the negative electrode 31 and the first edge 27a of the bag-shaped separator 27 are aligned, the tab facing portion 30 causes the positive electrode tab 22b and the negative electrode 31 to be short-circuited. Can be suppressed.

(6) The dimension H1 of the bag-shaped separator 27 in the height direction and the dimension H2 of the negative electrode electrode 31 in the height direction are the same. Therefore, with the second edge 31b of the negative electrode electrode 31 and the second edge 27b of the bag-shaped separator 27 aligned in the height direction, the first edge 31a of the negative electrode 31 and the bag-shaped separator 27 By confirming whether or not the first edge 27a is aligned, it is possible to detect whether or not the negative electrode electrode 31 and the bag-shaped separator 27 are displaced in the height direction.

The above embodiment may be changed as follows.
○ As shown in FIG. 7, in the manufacturing apparatus 50, only one heater roller may be used to weld both long edges of the strip-shaped separator material 51. The heater roller 80 in this case includes a pair of rollers 80a and 80b that face each other with the strip-shaped separator material 51 interposed therebetween. The rollers 80a and 80b are supported by a drive device (not shown) so that they can rotate around the axis.

The heater roller 80 welds a pair of strip-shaped separator materials 51 that are being conveyed along the longitudinal direction. One roller 80a is provided with a low temperature heater portion 80c extending in the circumferential direction of the roller 80a on one end side in the extending direction of the axis, and a high temperature heater extending in the circumferential direction of the roller 80a on the other end side in the extending direction of the axis. A unit 80d is provided. Further, one roller 80a is provided with a heat insulating portion 80f between the low temperature heater portion 80c and the low temperature heater portion 80c in the direction in which the axis extends.

The low-temperature heater portion 80c and the high-temperature heater portion 80d project by a certain amount with respect to the outer peripheral surface of the columnar heat insulating portion 80f (not shown). The low temperature heater unit 80c and the high temperature heater unit 80d are provided with a heating unit (not shown) inside, and the temperature can be adjusted individually. The heat insulating portion 80f insulates the low temperature heater portion 80c and the low temperature heater portion 80c. The high temperature heater portion 80d includes a tab recess 80e in which a part in the circumferential direction is missing. In the low temperature heater section 80c and the high temperature heater section 80d, the dimension of the roller 80a in the extending direction of the axis is longer in the high temperature heater section 80d.

In the method of manufacturing the bag-shaped separator 27 using the manufacturing apparatus 50 provided with the heater roller 80, first, in the first heater roller 70, a pair of strip-shaped separator materials 51 are sandwiched between the heater portions 70c of both rollers 70a and 70b. The first heater roller 70 rotates. As a result, the pair of strip-shaped separator materials 51 are welded at intervals according to the length of the outer circumference of the roller 70a, and the first welding region R1 is formed.

Next, in the heater roller 80, the heater roller 80 rotates while sandwiching a pair of strip-shaped separator materials 51 between the low-temperature heater portions 80c and the high-temperature heater portions 80d of both 80a and 80b. As a result, both long edges of the pair of strip-shaped separator materials 51 are welded according to the length of the outer circumference of the roller 80a.

At this time, the low temperature heater portion 80c forms a second welding region R2 along one long edge portion of the strip-shaped separator material 51 and connecting the pair of first welding regions R1. Further, the high temperature heater portion 80d welds a portion along the other long edge portion of the strip-shaped separator material 51 and connecting the pair of first welding regions R1. The other long edge portion of the strip-shaped separator material 51 is subjected to a large amount of heat per unit area as compared with the second welding region R2 and the first welding region R1. As a result, a highly shrinkable welded portion is formed.

○ The first welded portion 29a of the bag-shaped separator 27 may be one location as long as it is located at a position other than the tab facing portion 30 in the first end edge 27a of the bag-shaped separator 27.
○ The dimensions of the bag-shaped separator 27 in the longitudinal direction and the dimensions of the negative electrode electrode 31 in the longitudinal direction may be different.

○ The first welded portion 29a does not have to be at a position that is line-symmetric with respect to the center line M of the bag-shaped separator 27.
○ In the manufacturing apparatus 50, in consideration of the amount of heat shrinkage, the dimension of the second heater portion 71d in the roller 71a of the second heater roller 71 is made longer than the dimension of the first heater portion 71c, but the second heater portion 71d and the second heater portion 71d 1 The dimensions of the heater portion 71c may be the same. In this case, the dimension of the third welding region R3 obtained by heating the primary welding portion K with the heater portion 74c of the third heater roller 74 is shorter than the second welding region R2.

○ In the embodiment, only the first welded portion 29a of the bag-shaped separator 27 is a high-shrink welded portion, but the second welded portion 29b, which is the opposite side of the first welded portion 29a, is also added per unit area at the time of welding. The amount of heat may be increased to be larger than the portion to be the third welded portion 29c to form a highly shrinkable welded portion.

In this configuration, when the bag-shaped separator 27 is pressed toward the first guide surface 62a by the positioning member 64 and the second end edge 27b of the bag-shaped separator 27 comes into contact with the first guide surface 62a, Deformation of the second edge 27b can be suppressed.

Further, in the secondary battery 10 provided with the bag-shaped separator 27 having the first welded portion 29a and the second welded portion 29b as the highly shrinkable welded portions, the first edge 27a of the bag-shaped separator 27 and the negative electrode 31 are the first. When aligning the one end edges 31a so as to be aligned in the height direction, the positioning member 64 may be brought into contact with both the first welded portion 29a and the second welded portion 29b.

○ In the embodiment, the first welded portion 29a of the bag-shaped separator 27 is a high shrinkage welded portion, but the first welded portion 29a is not a high shrinkage welded portion, and only the second welded portion 29b is a high shrinkage welded portion. good.

In the secondary battery 10 provided with the bag-shaped separator 27 having the second welded portion 29b as the highly shrinkable welded portion, the first edge 27a of the bag-shaped separator 27 and the first edge 31a of the negative electrode 31 are in the height direction. The positioning member 64 may be brought into contact with the second welded portion 29b when aligning with the second welded portion 29b. As a result, when the positioning member 64 is brought into contact with the bag-shaped separator 27 to move the positive electrode 21, it is possible to suppress an insufficient movement amount due to deformation of the bag-shaped separator 27.

○ The secondary battery 10 may be a nickel-metal hydride battery or another secondary battery. In short, it suffices as long as the ions move between the active material for the positive electrode and the active material for the negative electrode and transfer charges.

○ The positive electrode 21 and the negative electrode 31 had a rectangular shape in which the extending directions of the first edge 21a and 31a were long, but the positive electrode 21 and the negative electrode 31 had a rectangular shape in which the extending direction of the third edge 21c and 31c was long. May be good. In this case, the shape of the case 11 is also changed according to the shapes of the positive electrode 21 and the negative electrode 31.

○ In the positive electrode 21 and the negative electrode 31, the current collector is not limited to the metal foil as long as it can support the active material layer. For example, a woven or net-like sheet may be used.

○ The power storage device may be a laminated cell in which the electrode assembly is wrapped with a laminated film.
○ The power storage device can also be applied to a power storage device other than a secondary battery, such as a capacitor.

Next, the technical idea that can be grasped from the above embodiment and another example will be added below.
(1) The power storage device is a secondary battery.
(2) The high shrinkage welded portion has a larger amount of heat shrinkage than other welded portions.

L ... straight line, M ... center line, 10 ... secondary battery as a power storage device, 11 ... case, 14 ... electrode assembly, 21 ... positive electrode electrode, 21a ... first end edge as one end edge, 21b ... other end edge 2nd edge as Second edge, 28 ... Separator member, 29a ... First welded portion as high shrinkage welded portion, 29b ... Second welded portion, 29c ... Third welded portion, 31 ... Negative electrode, 31a ... First as one end edge Edge edge, 31b ... Second edge edge as the other end edge, 32 ... Negative electrode metal foil as the negative electrode current collector, 33 ... Negative electrode active material layer, 51 ... Band-shaped separator material.

Claims (3)

A negative electrode having a rectangular negative electrode active material layer on the surface of a rectangular sheet-shaped negative electrode current collector, and a negative electrode.
A positive electrode having a positive electrode active material layer on the surface of a rectangular sheet-shaped positive electrode current collector, which is housed in a bag-shaped separator having a welded portion in which the edge of a rectangular sheet-shaped separator member facing each other is heat-welded, is formed.
Manufacture of the bag-shaped separator in a power storage device including an electrode assembly having a laminated structure in which the negative electrode active material layer is alternately stacked with the positive electrode active material layer facing each other via the bag-shaped separator. It ’s a method,
Two strip-shaped separator materials, which are materials for the separator member, are stacked, and between the pair of strip-shaped separator materials, one end edge of the positive electrode and the other end edge, which is the opposite side of the one end edge, are the strip-shaped separator materials. An arrangement step of arranging the positive electrode so as to extend in the longitudinal direction, and
The first heater roller and the second heater roller are located at positions surrounding the one end edge, the other end edge, and the pair of end edges connecting the one end edge and the other end edge of the positive electrode electrode in the pair of arranged strip-shaped separator materials. Has a welding process of heat welding using
The first heater roller has a heater portion that heat-welds the pair of edge edges of the pair of strip-shaped separator materials along the pair of edge edges of the positive electrode.
The second heater roller includes a first heater portion that heat-welds one end edge of the pair of strip-shaped separator materials along the one-end edge of the positive electrode, and the pair of strip-shaped separator materials along the other end edge of the positive electrode. It has a second heater part that heat-welds the other end edge of the
The dimension of the second heater portion in the extending direction of the axis of the second heater roller is formed longer than that of the first heater portion.
In the welding step,
A method for producing a bag-shaped separator, which comprises applying a large amount of heat per unit area to the other end edge of the pair of strip-shaped separator materials that are heat-welded by the second heater portion as compared with other edge edges. .. The welding process includes a first welding step of heat welding positions surrounding the four edges of the positive electrode, and a second welding step of applying heat only to the other end edge of said pair of strip-shaped separator material, the more The method for producing a bag-shaped separator according to claim 1. The bag shape according to claim 1 or 2 , wherein the welding step is performed by making the temperature at the time of heat welding of the other end edge of the pair of strip-shaped separator materials higher than the temperature at the time of heat welding of the other edge. How to manufacture a separator.

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