JP2017139097A - Method of manufacturing power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a power storage device that can suppress occurrence of burr.SOLUTION: When a secondary battery is manufactured, a lid body 14 is mounted on the distal end faces 24 of side walls 22, 23 of a case body 13 in which an electrode assembly is housed. A contact surface 34 of a pressing jig 31 is brought into contact with a pressing portion 36 of the lid body 14 to press the lid body 14 against the case body 13. The pressing portion 36 is a site of the lid body 14 which faces an area extending from the inner surface to the outer surface of the peripheral wall 21 of the case body 13 and has a dimension which is equal to or more than the half the thickness T of the peripheral wall 21 and less than a value obtained by subtracting a penetration length M from the thickness T of the peripheral wall 21.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for manufacturing a power storage device.

  A vehicle such as an EV (Electric Vehicle) or a PHV (Plug in Hybrid Vehicle) is equipped with a secondary battery such as a lithium ion battery as a power storage device that stores power supplied to an electric motor serving as a prime mover. In this type of secondary battery, the electrode assembly is housed in the case body, and the airtightness of the case body is maintained by closing the opening of the case body with a lid.

  The secondary battery described in Patent Document 1 includes a bottomed square cylindrical case body and a square plate-like lid. Both the case main body and the lid are made of metal. The case main body includes a rectangular flat plate-like bottom wall and a rectangular tubular peripheral wall that is erected from the periphery of the bottom wall. The lid is superimposed on a tip surface (hereinafter simply referred to as a tip surface) in the standing direction of the peripheral wall of the case main body, and is welded to the case main body.

  The case body and the lid are welded by placing the lid on the front end surface of the case body and irradiating a laser at the joint between the case body and the lid. At this time, for the purpose of bringing the lid into close contact with the front end surface of the case body or suppressing the displacement of the lid body, the lid body is generally pressed from above with a holding jig, and the lid body is moved to the case body. Press on.

Japanese Patent Laying-Open No. 2015-222663

  By the way, if the metal melted by laser irradiation solidifies following the outer shape of the holding jig, or if the metal adhering to the holding jig is pulled by the holding jig when the holding jig is separated from the lid, May occur.

  An object of the present invention is to provide a method of manufacturing a power storage device that can suppress the occurrence of burrs.

  A manufacturing method of a power storage device that solves the above problems is a battery case in which a lid that closes an opening of the case body is welded to a bottomed cylindrical case body in which a peripheral wall is erected from the periphery of the bottom wall; A method of manufacturing a power storage device including an electrode assembly housed in the battery case, wherein the lid is placed on a front end surface of the case body in a standing direction of the peripheral wall, and the inner surface of the peripheral wall is To the outer surface, when the portion of the lid body facing the region having a dimension less than half the thickness of the peripheral wall and less than the value obtained by subtracting the melting length from the thickness of the peripheral wall is a pressing portion, A laser is applied to the joint between the case body and the lid while pressing the holding portion toward the case body.

  Since the laser is emitted from the outside of the case body to the joint between the case body and the lid, the case body and the lid are melted in a direction from the outer surface of the peripheral wall toward the inner surface. The penetration length is a dimension along the thickness direction of the peripheral wall in the portion that melts during welding, and is a dimension that is less than half the thickness of the peripheral wall. By subtracting the penetration length from the thickness of the peripheral wall, it is possible to grasp the portion of the lid that does not melt during welding. In addition, in order to bring the lid into close contact with the front end surface of the case main body and to prevent the positional displacement of the lid body, the range of more than half of the thickness of the peripheral wall is selected from the portion of the lid body facing the front end surface of the peripheral wall. It needs to be pressed. And it can suppress that the molten metal adheres to a pressing jig by pressing the pressing site | part which satisfy | fills these conditions with a pressing jig. Therefore, generation | occurrence | production of the burr | flash by the molten metal adhering to a holding jig can be suppressed.

  According to the present invention, the generation of burrs can be suppressed.

The perspective view of the holding jig used when manufacturing a secondary battery and a secondary battery. The enlarged view which shows the pressing jig which is pressing the cover body toward the case main body. The top view of a case main body. Sectional drawing which shows the holding jig of a modification.

Hereinafter, an embodiment of a method for manufacturing a power storage device will be described.
As shown in FIG. 1, a secondary battery 10 as a power storage device includes a battery case 11 and an electrode assembly 12 accommodated in the battery case 11. The electrode assembly 12 is configured by laminating a positive electrode and a negative electrode in a state in which they are insulated from each other. The secondary battery 10 is a prismatic battery and is a lithium ion battery.

  The battery case 11 includes a case body 13 having a bottomed rectangular tube shape and a lid body 14 that closes an opening of the case body 13. The case main body 13 includes a rectangular flat plate-like bottom wall 20 and a peripheral wall 21 erected from the periphery of the bottom wall 20. The peripheral wall 21 includes a pair of long side walls 22 erected from the long side of the bottom wall 20 and a pair of short side walls 23 erected from the short side of the bottom wall 20. In the present embodiment, the long side wall 22 and the short side wall 23 have the same thickness.

  The lid body 14 has a rectangular plate shape, and the dimension L1 in the longitudinal direction of the lid body 14 is the same as the length of a straight line connecting the outer surfaces of the pair of short side walls 23 with the shortest distance. The dimension W1 is the same as the length of a straight line connecting the outer surfaces of the pair of long side walls 22 with the shortest distance. The lid 14 is overlaid on the front end surface 24 in the standing direction of the peripheral wall 21 so as to close the opening of the case body 13. The case body 13 and the lid body 14 are welded. The case body 13 and the lid body 14 are made of metal, for example, aluminum.

  The lid body 14 is provided with two holes 16. A cylindrical insulating ring 17 is fitted in the hole 16, and the terminal 15 penetrates the insulating ring 17 and protrudes from the battery case 11 to the outside of the battery case 11.

Next, the manufacturing method and operation of the secondary battery 10 of the present embodiment will be described.
When manufacturing the secondary battery 10 as shown in FIGS. 1 and 2, the lid body 14 is placed on the front end surface 24 of each side wall 22, 23 of the case body 13 in which the electrode assembly 12 is accommodated. To do. Then, a pressing jig 31 that can be brought into and out of contact with the lid body 14 is pressed against the outer surface 14 a from above the lid body 14 by an actuator (not shown) to press the lid body 14 toward the case body 13. In this state, laser is irradiated from the laser irradiation head 32 toward the joint between the case main body 13 and the lid body 14. When the laser is irradiated, portions around the laser irradiation position in the case main body 13 and the lid 14 are melted. Since the laser is irradiated from the outside of the case main body 13, the case main body 13 and the lid body 14 are melted in the direction from the outer surface along the laser irradiation direction toward the inner surface. In the case main body 13 and the lid body 14, a portion that melts during welding is referred to as a melting portion 33. In the following description, the dimension of the melted portion 33 along the thickness direction of the side walls 22 and 23 is referred to as a penetration length (penetration depth) M. The penetration length M is less than half (T / 2) of the thickness T of each side wall 22, 23.

  The holding jig 31 has a rectangular parallelepiped shape and includes a contact surface 34 that contacts the outer surface 14 a of the lid body 14. The holding jig 31 includes through holes 35 extending from the contact surface 34 toward the opposite surface of the contact surface 34 at two locations. The center-to-center distance between the through holes 35 is the same as the center-to-center distance between the holes 16 of the lid body 14. The diameter of the through hole 35 is slightly larger than the outer diameter of the insulating ring 17. The holding jig 31 is preferably made of a metal that efficiently conducts the heat of the lid body 14, and is made of, for example, copper.

  Here, the lid body 14 is provided with a pressing portion 36 where the contact surface 34 of the pressing jig 31 comes into contact with a portion facing the front end surface 24 of the case main body 13. The holding part 36 is a part facing the region A <b> 1 set on each side wall 22, 23 of the case body 13.

  As shown in FIG. 3, in the area A1, the dimension from the inner surface along the thickness direction of each side wall 22, 23 is not less than half the thickness T of each side wall 22, 23, and the thickness T of each side wall 22, 23. Is less than the value obtained by subtracting the penetration length M from In the area A1, the minimum value of the dimension along the thickness direction of the side walls 22 and 23 is half the thickness of the side walls 22 and 23, and is the dimension in the area indicated by dots in FIG. In the area A1, the maximum dimension along the thickness direction of each of the side walls 22 and 23 is the dimension in the hatched area in addition to the area shown in FIG. Since the holding part 36 is a part facing the area A1 of the lid body 14, the holding part 36 is an area in the same range as the area A1.

  In order to bring the lid 14 into close contact with the distal end surface 24 of the case main body 13 with the holding jig 31 and to prevent the positional displacement of the lid 14, at least a half of the thickness T of each side wall 22, 23 is opposed. It is necessary to press the contact surface 34 in contact with the part. Note that “half or more of the thickness T” is a value derived based on an experiment or a simulation result.

  On the other hand, when the contact surface 34 is brought into contact with the entire portion of the lid body 14 facing the front end surface 24, when the melting portion 33 is melted to reach the outer surface 14 a of the lid body 14, the molten metal is pressed by the holding jig 31. There is a risk of sticking to. For this reason, it is necessary to retract the contact surface 34 from the outer surface of each side wall 22, 23 based on the penetration length M so that the molten metal does not adhere to the pressing jig 31. The upper limit is set.

  The portion of the lid body 14 facing the region having a dimension less than the value obtained by subtracting the penetration length M from the thickness T of each side wall 22, 23 from the inner surface to the outer surface of each side wall 22, 23 is a portion that does not melt during welding. The lid body 14 is not melted until reaching the outer surface 14a of the lid body 14. The penetration length M can be obtained from the output of the laser, the material of the case body 13 and the lid body 14, the laser irradiation angle, and the like.

In order to press the pressing portion 36 described above, the dimension L2 in the longitudinal direction of the contact surface 34 is determined so as to satisfy the following expression (1).
L1-T ≦ L2 <L1-2M (1)
Specifically, the dimension L2 in the longitudinal direction of the contact surface 34 is equal to or larger than the dimension (L1−T) obtained by subtracting the thickness T of the long side wall 22 from the dimension L1 in the longitudinal direction of the lid body 14, and It is less than the dimension (L1-2M) obtained by subtracting the dimension twice the penetration length M from the dimension L1 in the longitudinal direction.

In order to press the pressing portion 36 described above, the dimension W2 in the short direction of the contact surface 34 is determined so as to satisfy the following expression (2).
W1-T ≦ W2 <W1-2M (2)
Specifically, the dimension W2 in the short direction of the contact surface 34 is equal to or greater than the dimension (W1-T) obtained by subtracting the thickness T of the short side wall 23 from the dimension W1 in the short direction of the lid 14 and the lid. It is less than the dimension (W1-2M) obtained by subtracting the dimension twice the penetration length M from the dimension W1 in the short direction of 14.

  When the lid 14 is pressed toward the case body 13 by the holding jig 31, the longitudinal direction of the contact surface 34 and the longitudinal direction of the lid 14 are matched, and the short side direction of the contact surface 34 and the lid 14 are aligned. Match the short direction of. In addition, the center positions of the contact surface 34 in the longitudinal direction and the short direction are matched with the center positions of the lid body 14 in the longitudinal direction and the short direction. Then, the contact surface 34 is brought into contact with the outer surface 14 a of the lid body 14, and the lid body 14 is pressed toward the case main body 13. The contact surface 34 is in contact with the pressing portion 36 and does not contact a region on the peripheral side of the lid body 14 with respect to the pressing portion 36.

Therefore, according to the above embodiment, the following effects can be obtained.
(1) The holding jig 31 presses the lid body 14 toward the case body 13 in a state where the contact surface 34 is in contact with the pressing portion 36 of the lid body 14. The pressing portion 36 has a lower limit that allows the lid 14 to be in close contact with the distal end surface 24 of the case body 13 and prevents the positional displacement of the lid 14, and the metal melted during welding is pressed by the pressing jig 31. The range that does not adhere to the surface is a region defined as the upper limit. For this reason, the contact surface 34 of the pressing jig 31 is brought into contact with the pressing portion 36 to press the lid body 14, thereby suppressing the occurrence of burrs caused by the molten metal adhering to the pressing jig 31. it can.

(2) Since the holding jig 31 is made of metal, the heat of the lid body 14 is easily conducted to the holding jig 31. For this reason, the temperature of the lid body 14 raised during welding is easily radiated.
In addition, you may change embodiment as follows.

  The shape of the holding jig other than the contact surface 34 may be different from that of the embodiment. For example, as shown in FIG. 4, the pressing jig 51 is enlarged so that the upper surface has the same size as the surface in the thickness direction of the lid body 14, while the contact surface 34 has the same size as the embodiment, The shape around 34 may be tapered (solid line in the figure) or stepped (two-dot chain line in the figure). In this case, the volume and surface area of the holding jig 51 can be made larger than those of the holding jig 31 of the embodiment, and the temperature of the lid 14 that has risen during welding is easily radiated.

The holding jig 31 is not limited to metal, and may be made of ceramic or wood.
The shape of the case body 13 is not limited to a bottomed rectangular tube shape, and may be any shape as long as the side wall is erected from the bottom wall. Note that the shape of the lid is changed in accordance with the shape of the case body 13.

The power storage device may be a power storage device other than the secondary battery 10 such as a capacitor.
The thickness of the long side wall 22 and the short side wall 23 may be different.

  M: Melting length, A1 region, 10 ... Secondary battery, 11 ... Battery case, 12 ... Electrode assembly, 13 ... Case body, 14 ... Lid body, 20 ... Bottom wall, 21 ... Peripheral wall, 22 ... Long side wall, 23 ... Short side wall, 24 ... tip surface, 31 ... pressing jig.

Claims (1)

A battery case in which a cover body that closes an opening of the case body is welded to a bottomed cylindrical case body having a peripheral wall standing from the periphery of the bottom wall, and an electrode assembly housed in the battery case. A method of manufacturing a power storage device comprising:
Placing the lid on the distal end surface of the peripheral wall of the case body in the standing direction;
From the inner surface of the peripheral wall toward the outer surface, when the portion of the lid facing the region having a dimension less than half the thickness of the peripheral wall and less than the value obtained by subtracting the melting length from the thickness of the peripheral wall, A method for manufacturing a power storage device, wherein a laser is irradiated to a joint between the case main body and the lid body while pressing the pressing portion toward the case main body with a pressing jig.

Images