JP6900671B2 - Manufacturing method of power storage device - Google Patents

Description

The present invention relates to a method for manufacturing a power storage device including an insulating sheet that insulates a case and an electrode assembly.

Power storage devices such as secondary batteries and capacitors are widely used as power sources because they can be recharged and can be used repeatedly. As a secondary battery, there is a battery provided with a laminated electrode assembly in which a plurality of rectangular sheet-shaped positive electrodes and negative electrodes are laminated with a separator interposed therebetween. In addition, there is also one provided with a wound electrode assembly in which a band-shaped positive electrode and a band-shaped negative electrode are wound with a band-shaped separator in between. That is, the electrode assembly has a layered structure in which a separator is interposed between the positive electrode and the negative electrode. Generally, the electrode assembly is covered with an insulating sheet and insulated from the case containing the electrode assembly.

Further, in order to prevent the positive electrode, the negative electrode, and the separator from being displaced from each other and the layered structure of the electrode assembly from collapsing, for example, in the power storage device described in Patent Document 1, holding tapes are attached to a plurality of places of the electrode assembly. There is.

Japanese Unexamined Patent Publication No. 2015-53220

However, when the power storage device described in Patent Document 1 is manufactured, a step of attaching and restraining a holding tape to the electrode assembly and a step of covering the electrode assembly with an insulating sheet are required, and the productivity of the power storage device is lowered. There was a problem.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for manufacturing a power storage device capable of improving the productivity of a power storage device including an electrode assembly having a layered structure. It is in.

A method for manufacturing a power storage device for solving the above problems is to include an electrode assembly having a layered structure in which electrodes having different polarities are insulated from each other, a metal case accommodating the electrode assembly, and the electrode assembly. An insulating sheet that covers and insulates the case and the electrode assembly is provided, and the insulating sheet has a pair of protruding portions that protrude from both sides of the electrode assembly in the stacking direction and face each other in the stacking direction. A method for manufacturing a power storage device in which the pair of protruding portions are joined, the joining step is performed on at least one of the pair of protruding portions in a state of being pulled in the protruding direction, and the pair of protruding portions are joined. The gist is to join.

According to this, the pair of protruding portions are joined so that tension in the stacking direction is applied to at least one protruding portion. The tension of the protruding portion becomes a binding force that restrains the electrode assembly of the insulating sheet in the stacking direction, and this binding force suppresses the collapse of the layered structure of the electrode assembly. In this case, since the step of restraining the electrode assembly and the step of covering the electrode assembly with the insulating sheet are performed at the same time, the productivity of the power storage device including the electrode assembly having a layered structure can be improved.

Further, regarding the method of manufacturing the power storage device, it is preferable to pull the pair of protruding portions together.
According to this, the number of devices for pulling the protruding portions can be reduced as compared with the case where the protruding portions are pulled respectively.

Further, regarding the method of manufacturing the power storage device, the electrode assembly is a laminated electrode assembly, and it is preferable that the pair of protruding portions are joined at the center in the stacking direction.
According to this, since the tension of the protruding portion can be directed to the center in the stacking direction, the balance of the binding force of the insulating sheet with respect to the electrode assembly in the stacking direction can be improved.

Further, as for the manufacturing method of the power storage device, it is preferable that at least one of the pair of protruding portions is pulled in the protruding direction while a load is applied to the electrode assembly from at least one direction in the stacking direction. ..

According to this, a restoring force (reaction force) in the stacking direction is generated in the electrode assembly, but the electrode assembly is restrained by the insulating sheet as a drag against the restoring force. Therefore, the binding force of the insulating sheet on the electrode assembly can be made stronger.

Further, regarding the method of manufacturing the power storage device, the insulating sheet is provided with the pair of protruding portions on both sides of the electrode assembly, and the pair of protruding portions on both sides of the electrode assembly are pulled in the protruding directions. It is preferable to join in a state.

According to this, in addition to the pair of protruding portions protruding to one side, the pair of protruding portions protruding to the other side are also joined in a pulled state, so that the balance of the binding force in the protruding direction of the insulating sheet with respect to the electrode assembly is good. Can be done.

Further, regarding the method of manufacturing the power storage device, it is preferable to cover at least one surface of the electrode assembly with the insulating sheet so as to open.
According to this, it is possible to correspond to an electrode assembly having a tab, for example.

According to the present invention, it is possible to improve the productivity of a power storage device including an electrode assembly having a layered structure.

An exploded perspective view of the secondary battery of the embodiment. The perspective view which shows the appearance of a secondary battery. An exploded perspective view showing the components of the electrode assembly. (A) to (d) are schematic plan views for explaining a manufacturing process of a secondary battery. An exploded perspective view of another example secondary battery.

Hereinafter, embodiments in which the power storage device is embodied in a secondary battery will be described with reference to FIGS. 1 to 4.
As shown in FIGS. 1 and 2, the secondary battery 10 as a power storage device includes a case 11. The secondary battery 10 includes an electrode assembly 12 housed in a case 11. The case 11 has a rectangular parallelepiped main body member 13 and a rectangular flat plate-shaped lid member 14 that closes the opening 13a of the main body member 13. The main body member 13 and the lid member 14 constituting the case 11 are both made of metal (for example, stainless steel or aluminum). Further, the secondary battery 10 of the present embodiment is a square battery having a square appearance. Further, the secondary battery 10 of the present embodiment is a lithium ion battery.

The secondary battery 10 includes a positive electrode terminal 15 and a negative electrode terminal 16 for extracting electricity from the electrode assembly 12. The positive electrode terminal 15 and the negative electrode terminal 16 are exposed to the outside of the case 11 through a pair of holes 14a arranged side by side at a predetermined interval in the lid member 14. Further, a ring-shaped insulating ring 17a for insulating from the case 11 is attached to the positive electrode terminal 15 and the negative electrode terminal 16, respectively.

As shown in FIG. 3, the electrode assembly 12 includes a sheet-shaped positive electrode 20 and a sheet-shaped negative electrode 21 as electrodes having different polarities. The positive electrode electrode 20 has a positive electrode metal foil (aluminum foil in this embodiment) 22 and a positive electrode active material layer 23 formed by applying a positive electrode active material on both surfaces thereof. The negative electrode electrode 21 has a negative electrode metal foil (copper foil in this embodiment) 24 and a negative electrode active material layer 25 formed by applying a negative electrode active material on both surfaces thereof. The electrode assembly 12 is a laminated body having a layered structure in which a microporous film separator 26 is interposed between the positive electrode 20 and the negative electrode 21. The electrode assembly 12 is configured by, for example, alternately laminating a plurality of positive electrode electrodes 20 and a plurality of negative electrode electrodes 21. That is, the electrode assembly 12 has a plurality of sets composed of the positive electrode 20, the negative electrode 21, and the separator 26.

As shown in FIG. 3, the positive electrode electrode 20 includes a positive electrode current collecting tab 28 made of a positive electrode metal foil 22 at an edge (one end). The positive electrode current collecting tab 28 is formed at the same position and in the same shape on each positive electrode 20 constituting the electrode assembly 12. Further, the negative electrode electrode 21 is provided with a negative electrode current collecting tab 30 made of a negative electrode metal foil 24 at an edge (one end). The negative electrode current collecting tab 30 is formed at the same position and in the same shape on each negative electrode 21 constituting the electrode assembly 12.

The positive electrode electrodes 20 are laminated so that the positive electrode current collecting tabs 28 are arranged in a row along the stacking direction X of the electrode assembly 12. Similarly, the negative electrode electrodes 21 are laminated so that the negative electrode current collecting tabs 30 are arranged in a row along the stacking direction X of the electrode assembly 12 so that the negative electrode current collecting tabs 30 do not overlap with the positive electrode current collecting tabs 28. .. Then, as shown in FIG. 1, each positive electrode current collecting tab 28 is collected in a range from one end to the other end of the stacking direction X in the electrode assembly 12 to form a positive electrode current collecting group 31. The positive electrode terminal 15 is electrically joined to the positive electrode current collecting group 31. Similarly, each negative electrode current collecting tab 30 is also collected in the range from one end to the other end of the stacking direction X in the electrode assembly 12 to form a negative electrode current collecting group 32. The negative electrode terminal 16 is electrically connected to the negative electrode current collecting group 32.

The electrode assembly 12 of the present embodiment is a rectangular parallelepiped having six faces. The six surfaces of the electrode assembly 12 are the surfaces 12a and 12b that are both sides of the electrode assembly 12 in the stacking direction X, and four side surfaces that are connected to the two surfaces and are orthogonal to the stacking direction X of the electrode assembly 12. It consists of 12c, 12d, 12e, and 12f. The side surface 12e is a current collecting side side surface on which the positive electrode current collecting tab 28 and the negative electrode current collecting tab 30 project. The positive electrode current collecting tab 28 and the negative electrode current collecting tab 30 project in the same direction from one side surface 12e. Further, the side surface 12f is a bottom side surface as an opposite surface facing the side surface 12e. Further, the side surfaces 12c and 12d are side surfaces orthogonal to the side surfaces 12e and 12f, respectively, and are surfaces facing the width direction Y orthogonal to the stacking direction X of the electrode assembly 12.

The electrode assembly 12 is covered with an insulating film 33 as an insulating sheet. The insulating film 33 is an insulating sheet for insulating the electrode assembly 12 from the metal case 11, and is made of polypropylene (PP), for example. The insulating film 33 is formed in a bag shape by folding and welding one insulating film 33.

Here, the insulating film 33 before welding will be described.
As shown in FIG. 4A, the insulating film 33 includes a rectangular first region 33a larger than the surface 12a of the electrode assembly 12 and a rectangular second region 33b larger than the surface 12b of the electrode assembly 12. It has a rectangular third region 33c that is larger than the side surface 12f of the electrode assembly 12. The first region 33a is a portion that covers the entire surface 12a of the electrode assembly 12, the second region 33b is a portion that covers the entire surface 12b of the electrode assembly 12, and the third region 33c is the electrode assembly. It is a portion that covers the entire surface of the side surface 12f of the solid body 12.

The first region 33a includes a protruding portion 34 protruding from the surface 12a of the electrode assembly 12 on one side in the width direction Y, and a protruding portion 35 protruding from the surface 12a in the width direction Y on the other side. The second region 33b includes a protruding portion 36 protruding from the surface 12b of the electrode assembly 12 on one side in the width direction Y, and a protruding portion 37 protruding from the surface 12b in the width direction Y on the other side. The third region 33c includes a protruding portion 38 protruding from the side surface 12f of the electrode assembly 12 on one side in the width direction Y, and a protruding portion 39 protruding from the other side in the width direction Y. The protruding dimensions of the protruding portions 34 and 36 and the protruding dimensions of the protruding portions 35 and 37 from the surfaces 12a and 12b of the electrode assembly 12 are shorter than the dimensions of the electrode assembly 12 in the stacking direction X.

Next, the insulating film 33 that covers the electrode assembly 12 will be described.
As shown in FIG. 1, the insulating film 33 has a covering portion 41 that covers the side surface 12c of the electrode assembly 12. The covering portion 41 is composed of a root portion 34a of the protruding portion 34 and a root portion 36a of the protruding portion 36. Further, the insulating film 33 has a polymerized portion 42 that protrudes from the covering portion 41. The polymerization portion 42 is composed of a surplus portion 34b which is a tip portion of the protruding portion 34 and a surplus portion 36b which is a tip portion of the protruding portion 36 facing the surplus portion 34b. The insulating film 33 has a welded portion 43 in which the surplus portion 34b of the protruding portion 34 and the surplus portion 36b of the protruding portion 36 are hot-welded. The welded portion 43 of the present embodiment is located at the center of the stacking direction X of the electrode assembly 12 and near the side surface 12c.

As shown in FIG. 4C, the insulating film 33 has a covering portion 44 that covers the side surface 12d of the electrode assembly 12. The covering portion 44 is composed of a root portion 35a of the protruding portion 35 and a root portion 37a of the protruding portion 37. Further, the insulating film 33 has a polymerized portion 45 that protrudes from the covering portion 44. The polymerization portion 45 is composed of a surplus portion 35b which is a tip portion of the protruding portion 35 and a surplus portion 37b which is a tip portion of the protruding portion 37 facing the surplus portion 35b. The insulating film 33 has a welded portion 46 in which the surplus portion 35b of the protruding portion 35 and the surplus portion 37b of the protruding portion 37 are hot-welded. The welded portion 46 of the present embodiment is located at the center of the stacking direction X of the electrode assembly 12 and near the side surface 12d.

In the insulating film 33, tension is generated in the covering portions 41 and 44 toward the center of the stacking direction X. Due to this tension, the first region 33a and the second region 33b are pulled toward the center of the stacking direction X. The first region 33a and the second region 33b are in close contact with the surfaces 12a and 12b of the electrode assembly 12.

In this way, the insulating film 33 covers five surfaces of the electrode assembly 12, excluding the side surface 12e. Then, the electrode assembly 12 covered with the insulating film 33 is inserted through the opening 13a of the main body member 13 and housed in the case 11.

Next, the manufacturing process of the secondary battery 10, particularly the procedure of covering the electrode assembly 12 with the insulating film 33 will be described in detail.
First, as shown in FIG. 4A, the electrode assembly 12 is arranged between the insulating films 33 bent in a U shape. At this time, the first region 33a of the insulating film 33 faces the surface 12a of the electrode assembly 12, the second region 33b of the insulating film 33 faces the surface 12b of the electrode assembly 12, and the third region of the insulating film 33 faces. 33c is opposed to the side surface 12f of the electrode assembly 12. As a result, the entire surfaces of the surfaces 12a and 12b and the side surfaces 12f of the electrode assembly 12 are covered with the insulating film 33. Further, by arranging the electrode assembly 12 at the center of the insulating film 33 in the width direction Y, the protruding portions 34 to 39 of the first to third regions 33a to 33c are in a state of protruding from the electrode assembly 12.

Further, a load K is applied to the electrode assembly 12 from both directions of the stacking direction X, the first region 33a of the insulating film 33 is brought into close contact with the surface 12a of the electrode assembly 12, and the second region 33b of the insulating film 33 is set as an electrode. It is brought into close contact with the surface 12b of the solid body 12.

Next, as shown in FIG. 4B, the protruding portions 38 and 39 are bent along the side surfaces 12c and 12d of the electrode assembly 12. After that, using the clamp 51, the tip of the protruding portion 34 and the tip of the protruding portion 36 are collectively held as a pair of protruding portions 34, 36, and are pulled outward in the width direction Y as the protruding direction. As a result, the protruding portions 34 and 36 are in a state of being tensioned. Similarly, using the clamp 52, the tip of the protruding portion 35 and the tip of the protruding portion 37 are collectively held as a pair of protruding portions 35, 37, and are pulled outward in the width direction Y as the protruding direction. As a result, the protruding portions 35 and 37 are in a state of being tensioned. Even when the protruding portions 34 to 37 are pulled, the load K is continuously applied to the electrode assembly 12.

As shown in FIG. 4B, heaters 61 and 62 paired in the stacking direction X are arranged on both sides of the pair of protruding portions 34 and 36. Each of the heaters 61 and 62 can be moved in the stacking direction X at a position near the side surface 12c of the electrode assembly 12. Further, heaters 63 and 64 paired in the stacking direction X are arranged on both sides of the pair of protruding portions 35 and 37. Each of the heaters 63 and 64 can be moved in the stacking direction X at a position near the side surface 12d of the electrode assembly 12. The power of each heater 61 to 64 is off.

Next, as shown in FIG. 4C, one of the heaters 61 is moved to the center of the stacking direction X while the pair of protruding portions 34, 36 are pulled outward in the width direction Y as the protruding direction. The heater 61 comes into contact with the protruding portion 34, and the root portion 34a is bent along the side surface 12c of the electrode assembly 12. Further, at the same time as the movement of one heater 61, the other heater 62 is moved to the center of the stacking direction X. The heater 62 comes into contact with the protruding portion 36, and the root portion 36a is bent along the side surface 12c of the electrode assembly 12.

When the heaters 61 and 62 reach the center of the stacking direction X, the heaters 61 and 62 face each other via the pair of protruding portions 34 and 36. Then, the covering portion 41 is formed by the root portions 34a and 36a of the protruding portions 34 and 36 that cover the side surface 12c of the electrode assembly 12, and the tip portions that become surplus without covering the side surface 12c become the surplus portions 34b and 36b. .. The pair of surplus portions 34b and 36b are bent so as to be separated from the side surface 12c and overlap to form the overlapping portion 42.

After that, the power of the heaters 61 and 62 is turned on. Then, the heaters 61 and 62 in a high temperature state are pressed against the root portions of the surplus portions 34b and 36b of the protruding portions 34 and 36 to heat, and heat welding is performed to join the pair of surplus portions 34b and 36b. As a result, the welded portion 43 is formed in the pair of surplus portions 34b and 36b. The load K is continuously applied to the electrode assembly 12 even when the heaters 61 and 62 are moved and the protruding portions 34 and 36 are welded. Therefore, the covering portion 41 and the covering portion 41 and the second region 33b of the insulating film 33 remain in close contact with the surface 12b of the electrode assembly 12 while the first region 33a of the insulating film 33 is in close contact with the surface 12a of the electrode assembly 12. The welded portion 43 is formed.

Similarly, one heater 63 is moved to the center of the stacking direction X while the pair of protruding portions 35, 37 are pulled outward in the width direction Y as the protruding direction. The heater 63 comes into contact with the protruding portion 35, and the root portion 35a is bent along the side surface 12d of the electrode assembly 12. Further, at the same time as the movement of one heater 63, the other heater 64 is moved to the center of the stacking direction X. The heater 64 comes into contact with the protruding portion 37, and the root portion 37a is bent along the side surface 12d of the electrode assembly 12.

When each of the heaters 63 and 64 reaches the center of the stacking direction X, the heater 63 and the heater 64 face each other via the pair of protruding portions 35 and 37. Then, the covering portion 44 is formed by the root portions 35a and 37a of the protruding portions 35 and 37 covering the side surface 12d of the electrode assembly 12, and the surplus tip portions that do not cover the side surface 12d become the surplus portions 35b and 37b. .. The surplus portions 35b and 36b are bent so as to be separated from the side surface 12d and overlapped to form the overlapping portion 45.

After that, the power of the heaters 63 and 64 is turned on. Then, the heaters 63, 64 in a high temperature state are pressed against the root portions of the surplus portions 35b, 37b of the protruding portions 35, 37 to heat, and heat welding is performed to join the pair of surplus portions 35b, 37b. As a result, a welded portion 46 is formed on the pair of surplus portions 35b and 37b.

The load K is continuously applied to the electrode assembly 12 even when the heaters 63 and 64 are moved and when the protruding portions 35 and 37 are welded. Therefore, the covering portion 44 and the covering portion 44 and the second region 33b of the insulating film 33 remain in close contact with the surface 12b of the electrode assembly 12 while the first region 33a of the insulating film 33 is in close contact with the surface 12a of the electrode assembly 12. The welded portion 46 is formed.

When the welded portions 43 and 46 are formed in this way, the insulating film 33 has a bottomed bag shape. After that, the load K is applied to the electrode assembly 12, and the protrusions 34 to 37 are pulled by the clamps 51 and 52.

Finally, as shown in FIG. 4D, the polymerization portion 42 (a pair of surplus portions 34b and 36b having a welding portion 43) is bent along the side surface 12c of the electrode assembly 12. In the present embodiment, the surplus portion 36b is bent so as to face the side surface 12c of the electrode assembly 12. Similarly, the polymerization portion 45 (a pair of surplus portions 35b, 37b having the welding portion 46) is bent along the side surface 12d of the electrode assembly 12. In the present embodiment, the surplus portion 37b is bent so as to face the side surface 12d of the electrode assembly 12.

Next, the operation of this embodiment will be described.
Since the pair of protruding portions 34, 36 are heated and joined in a state of being pulled outward in the width direction Y, tension is generated in the covering portion 41 covering the side surface 12c of the electrode assembly 12 toward the center of the stacking direction X. Similarly, since the pair of protruding portions 35 and 37 are heated and joined in a state of being pulled outward in the width direction Y, tension is generated in the covering portion 44 covering the side surface 12d of the electrode assembly 12 toward the center of the stacking direction X. To do. Therefore, the first and second regions 33a and 33b of the insulating film 33 are maintained in close contact with the surfaces 12a and 12b of the electrode assembly 12.

Next, the characteristic effects of this embodiment will be described.
(1) Since the pair of protruding portions 34, 36 are heated and joined in a state of being pulled outward in the width direction Y, tension is generated in the covering portion 41 covering the side surface 12c of the electrode assembly 12 toward the center of the stacking direction X. To do. Since this tension acts as a binding force that constrains the electrode assembly 12 in the first region 33a and the second region 33b in the stacking direction X, the collapse (stacking deviation) of the layered structure of the electrode assembly 12 is suppressed.

Similarly, since the pair of protruding portions 35 and 37 are heated and joined in a state of being pulled outward in the width direction Y, tension is generated in the covering portion 44 covering the side surface 12d of the electrode assembly 12 toward the center of the stacking direction X. To do. Since this tension acts as a binding force that constrains the electrode assembly 12 in the first region 33a and the second region 33b in the stacking direction X, the collapse (stacking deviation) of the layered structure of the electrode assembly 12 is suppressed.

In this case, since the step of restraining the electrode assembly 12 and the step of covering the electrode assembly 12 with the insulating film 33 are performed at the same time, the productivity of the secondary battery 10 can be improved.
(2) Since the protruding portion 34 and the protruding portion 36 are pulled together to the outside in the width direction Y, the number of clamps 51 can be reduced as compared with the case where the protruding portions 34 and 36 are pulled separately. Similarly, since the protruding portion 35 and the protruding portion 37 are pulled together to the outside in the width direction Y, the number of clamps 52 can be reduced as compared with the case where the protruding portions 35 and 37 are pulled separately.

(3) Since the welded portions 43 and 46 are formed in the center of the stacking direction X, the tension of the protruding portions 34 to 36 can be directed to the center of the stacking direction X. Therefore, the balance of the binding force of the insulating film 33 with respect to the electrode assembly 12 in the stacking direction X can be improved.

(4) The electrode assembly 12 is covered with the insulating film 33 while applying a load K in the stacking direction X. Therefore, a restoring force in the stacking direction X is generated in the electrode assembly 12, but the electrode assembly 12 is restrained by the insulating film 33 as a drag against the restoring force. Therefore, the binding force of the insulating film 33 on the electrode assembly 12 can be made stronger.

(5) The electrode set of the insulating film 33 is formed by heating and joining the pair of protruding portions 34 and 36 protruding from one side in the width direction Y and the pair of protruding portions 35 and 37 protruding from the other side in the width direction Y, respectively. The balance of the binding force in the width direction Y with respect to the solid 12 can be improved.

(6) In order to cover the electrode assembly 12 with the insulating film 33 so as to open the side surface 12e of the electrode assembly 12, the positive electrode current collecting tab 28 and the negative electrode current collecting tab 30 provided on the side surface 12e are connected to the positive electrode terminal 15 and the negative electrode current collecting tab 30. It can be connected to the negative electrode terminal 16.

(7) With the covering portions 41 and 44 along the side surfaces 12c and 12d of the electrode assembly 12, the protruding portions 34 to 37 are heated and joined. Therefore, the insulating film 33 can restrain the electrode assembly 12 not only in the stacking direction X but also in the width direction Y.

The above embodiment may be changed as follows.
◯ The electrode assembly 12 may be a winding type electrode assembly.
The positive electrode active material layer 23 of the positive electrode electrode 20 is formed on both sides of the positive electrode metal foil 22, but may be formed on only one side. The negative electrode active material layer 25 of the negative electrode electrode 21 is formed on both sides of the negative electrode metal foil 24, but may be formed on only one side.

O The electrode assembly 12 may be covered with a plurality of insulating films 33.
○ Depending on the shape of the insulating film 33 and the like, the surface on which the welded portions 43 and 46 are provided may be only one of the side surface 12c and the side surface 12d.

○ The dimensions of the protruding portions 34 to 37 may be changed within a range in which the welded portions 43 and 46 can be formed. However, from the viewpoint of suppressing the increase in size of the secondary battery 10, it is preferable that the dimensions do not protrude outward from the end face of the electrode assembly 12 in the stacking direction X when the surplus portions 34b to 37b are bent. ..

The positive electrode current collecting tab 28 and the negative electrode current collecting tab 30 are provided on the side surface 12e of the electrode assembly 12, but may be provided on the side surfaces 12c, 12d, 12f. In this case, the electrode assembly 12 is covered with the insulating film 33 so as to open the side surfaces where the positive electrode current collecting tab 28 and the negative electrode current collecting tab 30 are provided. Welding portions 43 and 46 may be appropriately provided on the side surfaces where the positive electrode current collecting tab 28 and the negative electrode current collecting tab 30 are not provided. For example, when the positive electrode current collecting tab 28 and the negative electrode current collecting tab 30 are provided on the side surface 12c and the welding portions 43 and 46 are provided on the side surfaces 12e and 12f, the protruding portions 34 to 37 are orthogonal to the stacking direction X and the width direction Y. It sticks out in the direction. In this way, the protruding portions 34 to 37 may protrude so that the electrode assembly 12 is constrained by the insulating film 33.

○ The device for pulling the protruding portions 34 to 37 is not limited to the clamps 51 and 52.
○ The protruding portions 34 to 37 may be pulled at a position deviated from the center of the stacking direction X.

○ In the above embodiment, the protruding portions 34 and 36 are pulled in the width direction Y as the protruding direction, but for example, the protruding portions 34 and 36 may be pulled outside the width direction Y and toward the side surface 12f. That is, the direction in which the protruding portions 34 and 36 are pulled may be appropriately changed as long as the direction includes the protruding direction.

○ In the above embodiment, the protruding portion 34 and the protruding portion 36 are pulled together, and the protruding portion 35 and the protruding portion 37 are pulled together, but they may be pulled separately.

○ In the above embodiment, both the protruding portion 34 and the protruding portion 36 are pulled, but only one of them may be pulled. For example, when pulling only the protruding portion 34, the pair of protruding portions 34, 36 are heat-welded by moving the heater 61 to the other end side (the protruding portion 36 side) in the stacking direction while contacting the protruding portion 34. .. In this case, the covering portion 41 is composed of only the root portion 34a of the protruding portion 34. Further, the entire protruding portion 36 becomes a surplus portion 36b.

Similarly, in the above embodiment, both the protruding portion 35 and the protruding portion 37 are pulled, but only one of them may be pulled. For example, when pulling only the protruding portion 37, the pair of protruding portions 35, 37 are heat-welded by moving the heater 64 to one end side (the protruding portion 35 side) in the stacking direction while contacting the protruding portion 37. In this case, the covering portion 44 is composed of only the root portion 37a of the protruding portion 37. Further, the entire protruding portion 35 becomes a surplus portion 35b.

○ In the above embodiment, the welded portions 43 and 46 are formed at the root portions of the surplus portions 34b to 37b, but the range in which the welded portions 43 and 46 are formed may be appropriately changed in the surplus portions 34b to 37b. ..

-The welding portions 43 and 46 may be formed at positions deviated from the center of the stacking direction X.
○ The material of the insulating film 33 is not limited to polypropylene (PP), and other materials such as polyphenylene sulfide (PPS) may be used.

○ The method for forming the welded portions 43, 46 may be another welding method such as ultrasonic welding instead of heat welding by heaters 61 to 64.
○ The method for joining the protruding portions 34 to 37 is not limited to welding, and may be joining with an adhesive or caulking joining using a rivet or stapler made of an insulating material.

○ In the above embodiment, when the electrode assembly 12 is covered with the insulating film 33, the load K is applied to the electrode assembly 12 from both directions of the stacking direction X, but the load K is applied only from one direction of the stacking direction X. May be added. Further, it is not necessary to apply the load K. In this case, when the protruding portions 34 to 37 are pulled, the first and second regions 33a and 33b are brought into close contact with the surfaces 12a and 12b of the electrode assembly 12.

○ In the above embodiment, the polymerization portion 42 is bent so that the surplus portion 36b faces the side surface 12c of the electrode assembly 12, and the polymerization portion 45 is bent so that the surplus portion 37b faces the side surface 12d of the electrode assembly 12. However, the treatment method of the polymerization portions 42 and 45 is not limited to this.

For example, the overlapping portion 42 may be bent so that the surplus portion 34b faces the side surface 12c of the electrode assembly 12, or the surplus portion 35b may be bent in the direction facing the side surface 12d of the electrode assembly 12. Further, the polymerization portions 42 and 45 may be cut and removed at a position Y outside the welding portions 43 and 46 in the width direction.

○ In the above embodiment, after the protruding portions 38 and 39 are bent along the side surfaces 12c and 12d of the electrode assembly 12, the protruding portions 34 to 37 are welded, but after the protruding portions 34 to 37 are welded. , The protruding portions 38, 39 may be bent. In this case, as shown in FIG. 5, when the overlapping portions 42 and 45 are bent, the welded protruding portions 38 and 39 are bent in the same direction as the bending direction of the overlapping portions 42 and 45. After that, in the protruding portions 38 and 39, the portions protruding from the side surfaces 12c and 12d of the electrode assembly 12 are bent along the side surfaces 12c and 12d.

○ The power storage device can also be applied to a power storage device other than a secondary battery, such as a capacitor.
○ The secondary battery 10 may be a lithium ion secondary 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.

10 ... Secondary battery as a power storage device, 11 ... Case, 12 ... Electrode assembly, 12a, 12b ... Surface as a surface, 20 ... Positive electrode as an electrode, 21 ... Negative electrode as an electrode, 33 ... As an insulating sheet Insulating film, 34 to 37 ... Overhanging portion, X ... Laminating direction.

Claims (5)

An electrode assembly having a layered structure in which electrodes of different polarities are insulated from each other,
A metal case containing the electrode assembly and
An insulating sheet that covers the electrode assembly and insulates the case and the electrode assembly is provided.
The insulating sheet is a method for manufacturing a power storage device, which has a pair of protruding portions that protrude from both sides in the stacking direction and face each other in the stacking direction in the electrode assembly, and the pair of protruding portions are joined to each other.
The electrode assembly is a laminated electrode assembly, and has four side surfaces that are connected to both surfaces in the stacking direction and are orthogonal to the stacking direction, and one of the side surfaces. Is a tab protruding surface on which the positive electrode current collecting tab and the negative electrode current collecting tab in the electrode assembly project.
The root portion of the protruding portion is along the side surface of the electrode assembly in a state where the insulating sheet is brought into close contact with the surface of the electrode assembly and pulled in the protruding direction with respect to at least one of the pair of protruding portions. The electrode assembly is housed in the case in which five surfaces of the electrode assembly excluding the tab protruding surface are covered with the insulating sheet by performing a joining step of joining the pair of protruding portions by bending as described above. A method for manufacturing a power storage device. The method for manufacturing a power storage device according to claim 1, wherein the pair of protruding portions are pulled together. Method for manufacturing a power storage device according to claim 1 or claim 2 for joining before Symbol pair of protruding portions in the stacking direction center. While applying a load from at least one direction of the stacking direction with respect to the electrode assembly, any one of claims 1 to 3, state pulled in the direction protruding at least one of the pair of protruding portions The method for manufacturing a power storage device according to the item. The insulating sheet is provided with the pair of protrusions on both sides of the electrode assembly.
The method for manufacturing a power storage device according to any one of claims 1 to 4, wherein the pair of protruding portions on both sides of the electrode assembly are joined in a state of being pulled in the protruding direction.

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